Intermittent Stalling on a Hot Engine Issue
10-30-2014, 09:55 PM
#76
Did the car ever run correctly after having the ECU Doctors flash the module?
Ernie,
If it were me, I would do nothing further until I begged, borrowed, or stole
, a 97 or 98 ECM for a week usage and ultimately a sanity check.
(I say this because I always heard the 97 and 98 ECM's were esentially the same) Loren would certainly know more about such things!
To many unknowns on the Doctor handled ECM, other than it never worked properly from day one.
BTW, who did the engine rebuild and to what extent was it rebuilt? Top end only or did they split the cases?
To answer your most pertinent question about whether the reflashed ECU ever worked correctly the answer is NO. From the first start until today, the stalling issue appeared immediately after completing the engine rebuild, which included the reflash of the ECU. So, the ECU has got to be suspect.
If it were me, I would do nothing further until I begged, borrowed, or stole
, a 97 or 98 ECM for a week usage and ultimately a sanity check.(I say this because I always heard the 97 and 98 ECM's were esentially the same) Loren would certainly know more about such things!
To many unknowns on the Doctor handled ECM, other than it never worked properly from day one.
BTW, who did the engine rebuild and to what extent was it rebuilt? Top end only or did they split the cases?
10-31-2014, 01:08 AM
#77
"So, to have Loren materialize on this thread is welcomed, although his opening remark about my "Big Mistake" is confusing and unfortunate. Was the mistake that I sent the ECU to ECU Doctors? Was it that I had the ECU house defeat the immobilizer? Or, was it that I did anything with the ECU? I guess that I will have to wait for Loren to clarify his comments. I truly welcome the assistance of anyone that has knowledge of ECU's and how to get mine correctly evaluated."
The implication of my post was that too many variables were changed at once,
i.e. an engine rebuild and an the DME ECM mod. Now it's really unknown which of the
two is the source of the problem. Obviously it was more convenient to mod both
when the car was 'down'. So as the thread has converged on a relative simple
solution, i.e. find another ECM, notwithstanding that difficulty, but other aspects of
the present state of the vehicle can be analyzed.
Back to the initial post:
"In other words, you can be driving along at 30 mph, in an appropriate gear,
and in preparing to stop, you depress the clutch. On about the fifth or sixth
stop once the engine reaches temperature, when the clutch is depressed the
engine speed will drop to a low enough point where it will stall. Conversely,
on 5 out of 6 stops from speed, the engine speed will drop to the proper idle
speed without incident."
What you describe is the typical idle RPM undershoot which results from a change to a light flywheel,
which you indicate was done way before the re-flash. So that should not be an issue now
unless some other mod besides the immobilizer patch was part of the re-flash. With regard
to the adaption problem, the long trim values provided by the ECM actual values should
provide an insight to that.
You really need to have someone with a PST2 or Piwis tester (Porsche factory diagnostic tools)
analyze all the actual data values in the ECM at this point before trying the difficult task of finding
another ECM. As minimum, utilize an OBDII scanner to evaluate the ECM actual values.
Furthermore, the more times the ECM leaves your possession, the greater is the likelihood
of a real problem developing. Besides, a bench test versus an in the car test rarely ever provides
a truly robust test, as it very difficult to simulate all the conditions of an actual test drive.
"As noted before, the ECU got a clean bill of health from ECU Doctors in Florida. But, the ECU is one of the items that underwent modifications during my rebuild. The ECU was sent off to have it modified to adjust for the slightly more aggressive cams installed."
So more was done to the ECM than just an immobilizer 'patch'. The late 993s have an inherent problem of a very low
idle which exacerbates idle roughness and a slight idle undershoot. This ECM mod you mention could be additionally
affecting the idle causing the stalling. Also, no one really knows what effect the "aggressive cams" have on the idle
and potential random stalling. The modded cams combined with the LWF mod and the ECM tweak, could now have
resulted in your present situation. Also, cam timing being slightly off has known to be a cause of idle problems.
The implication of my post was that too many variables were changed at once,
i.e. an engine rebuild and an the DME ECM mod. Now it's really unknown which of the
two is the source of the problem. Obviously it was more convenient to mod both
when the car was 'down'. So as the thread has converged on a relative simple
solution, i.e. find another ECM, notwithstanding that difficulty, but other aspects of
the present state of the vehicle can be analyzed.
Back to the initial post:
"In other words, you can be driving along at 30 mph, in an appropriate gear,
and in preparing to stop, you depress the clutch. On about the fifth or sixth
stop once the engine reaches temperature, when the clutch is depressed the
engine speed will drop to a low enough point where it will stall. Conversely,
on 5 out of 6 stops from speed, the engine speed will drop to the proper idle
speed without incident."
What you describe is the typical idle RPM undershoot which results from a change to a light flywheel,
which you indicate was done way before the re-flash. So that should not be an issue now
unless some other mod besides the immobilizer patch was part of the re-flash. With regard
to the adaption problem, the long trim values provided by the ECM actual values should
provide an insight to that.
You really need to have someone with a PST2 or Piwis tester (Porsche factory diagnostic tools)
analyze all the actual data values in the ECM at this point before trying the difficult task of finding
another ECM. As minimum, utilize an OBDII scanner to evaluate the ECM actual values.
Furthermore, the more times the ECM leaves your possession, the greater is the likelihood
of a real problem developing. Besides, a bench test versus an in the car test rarely ever provides
a truly robust test, as it very difficult to simulate all the conditions of an actual test drive.
"As noted before, the ECU got a clean bill of health from ECU Doctors in Florida. But, the ECU is one of the items that underwent modifications during my rebuild. The ECU was sent off to have it modified to adjust for the slightly more aggressive cams installed."
So more was done to the ECM than just an immobilizer 'patch'. The late 993s have an inherent problem of a very low
idle which exacerbates idle roughness and a slight idle undershoot. This ECM mod you mention could be additionally
affecting the idle causing the stalling. Also, no one really knows what effect the "aggressive cams" have on the idle
and potential random stalling. The modded cams combined with the LWF mod and the ECM tweak, could now have
resulted in your present situation. Also, cam timing being slightly off has known to be a cause of idle problems.
Last edited by Lorenfb; 10-31-2014 at 12:22 PM.
10-31-2014, 12:16 PM
#78
If the problem is idle undershoot due to lwt flywheel and/or cam, then one quick fix is to modify the ISV to open up a little bit more. See if that fixes or help your problem.
It's not that hard to do. There are DIYs on this out there.
It's not that hard to do. There are DIYs on this out there.
10-31-2014, 12:46 PM
#79
I can truely appreciate how Loren put this all together and provided a well thought out analytical response.
Trying to methodically sift through all the variables further agravates the ability to arrive at a solution.
Here is a link to adjusting the ISV; if and when it may be viewed as a potential solution...
https://rennlist.com/forums/993-foru...djustable.html
Trying to methodically sift through all the variables further agravates the ability to arrive at a solution.
Here is a link to adjusting the ISV; if and when it may be viewed as a potential solution...
https://rennlist.com/forums/993-foru...djustable.html
11-01-2014, 12:56 AM
#80
Burning Brakes
Thread Starter
Did the car ever run correctly after having the ECU Doctors flash the module?
Ernie,
If it were me, I would do nothing further until I begged, borrowed, or stole, a 97 or 98 ECM for a week usage and ultimately a sanity check.
(I say this because I always heard the 97 and 98 ECM's were esentially the same) Loren would certainly know more about such things!
To many unknowns on the Doctor handled ECM, other than it never worked properly from day one.
BTW, who did the engine rebuild and to what extent was it rebuilt? Top end only or did they split the cases?
Ernie,
If it were me, I would do nothing further until I begged, borrowed, or stole
, a 97 or 98 ECM for a week usage and ultimately a sanity check.(I say this because I always heard the 97 and 98 ECM's were esentially the same) Loren would certainly know more about such things!
To many unknowns on the Doctor handled ECM, other than it never worked properly from day one.
BTW, who did the engine rebuild and to what extent was it rebuilt? Top end only or did they split the cases?
Actually, I did the engine rebuild with a lot of coaching from Steve Wiener. I originally took the motor down because of the plugged SAI ports. I could not get the car to smog out in Illinois. So, I used that as a reason to pull the motor. I have been involved with these cars for about 30 years and had done two other rebuilds on much "simpler" motors for cars that were 1970 and 71 vintage 911's. So, I was intrigued to find out what was different about my 3.6 versus the 2.2 motors I had played with years ago.
So, I "assumed" that I was going to get into an upper end refresh. Essentially a valve job in conjunction with fixing the myriad of oil leaks that my engine evidenced. The engine had 110k miles on it, which is way past the life of Porsche valve guides! So, it was time.
When I got down to the cams, I found that I had galling on one lobe, probably due to the inferiority of today's oils now that the zinc has been reduced in the ZDDP additives. So, I was in store for restoring the cams.....or upgrading the cams (which was the route I took). I discussed options with Steve W. who advised that there was very little extra power to be had at low cost on this motor. In the end, he suggested going to RS cams and bumping the intakes up to the RS diameter valves. And, ref lashing the ECU to take advantage of the upgrades. The PO had installed a LWF which was nice. And, that is what I did. I went back with Web Cam RS grind cams (stayed with hydraulic lifters since I am lazy) and had Steve recondition the heads and install the 52mm intakes.
Since I was concerned about the cam damage, I elected to pull the cylinders for a better visual inspection of the motor, and rapidly discovered a piston with a broken compression ring. Amazing....and the car seemed to be running fine when I took it down!
So, as you can see, I was on the "slippery slope" and decided to split the case so that I knew exactly the condition of all the parts. The engine has right at 110k miles on it, so the valve job was not a surprise. The cam and piston ring failures were a shock. Incidentally, the bottom end of the motor was perfect. I could have just reinstalled the old bearings and driven another 100k miles!
So, I went back together with a pretty much stock engine except for cams and RS intake valves. Steve did some nice machine work on my heads and he opened up the SAI passages in both the heads and the cam towers. He also rebuild my distributor and a hand full of other things to do "while in there".
The one major change I made on assembly was to back date the cam timing arrangement so that cam timing could be dialed in rather than the fixed timing allowed for by the 993 design. I also did not have the tooling to index the cams as they are in the 993 design. So, I backdated the system to that used on the 964, which is essentially the same arrangement used on all previous 911 engines since 1965!
11-01-2014, 01:28 AM
#81
Burning Brakes
Thread Starter
"So, to have Loren materialize on this thread is welcomed, although his opening remark about my "Big Mistake" is confusing and unfortunate. Was the mistake that I sent the ECU to ECU Doctors? Was it that I had the ECU house defeat the immobilizer? Or, was it that I did anything with the ECU? I guess that I will have to wait for Loren to clarify his comments. I truly welcome the assistance of anyone that has knowledge of ECU's and how to get mine correctly evaluated."
The implication of my post was that too many variables were changed at once,
i.e. an engine rebuild and an the DME ECM mod. Now it's really unknown which of the
two is the source of the problem. Obviously it was more convenient to mod both
when the car was 'down'. So as the thread has converged on a relative simple
solution, i.e. find another ECM, notwithstanding that difficulty, but other aspects of
the present state of the vehicle can be analyzed.
Back to the initial post:
"In other words, you can be driving along at 30 mph, in an appropriate gear,
and in preparing to stop, you depress the clutch. On about the fifth or sixth
stop once the engine reaches temperature, when the clutch is depressed the
engine speed will drop to a low enough point where it will stall. Conversely,
on 5 out of 6 stops from speed, the engine speed will drop to the proper idle
speed without incident."
What you describe is the typical idle RPM undershoot which results from a change to a light flywheel,
which you indicate was done way before the re-flash. So that should not be an issue now
unless some other mod besides the immobilizer patch was part of the re-flash. With regard
to the adaption problem, the long trim values provided by the ECM actual values should
provide an insight to that.
You really need to have someone with a PST2 or Piwis tester (Porsche factory diagnostic tools)
analyze all the actual data values in the ECM at this point before trying the difficult task of finding
another ECM. As minimum, utilize an OBDII scanner to evaluate the ECM actual values.
Furthermore, the more times the ECM leaves your possession, the greater is the likelihood
of a real problem developing. Besides, a bench test versus an in the car test rarely ever provides
a truly robust test, as it very difficult to simulate all the conditions of an actual test drive.
"As noted before, the ECU got a clean bill of health from ECU Doctors in Florida. But, the ECU is one of the items that underwent modifications during my rebuild. The ECU was sent off to have it modified to adjust for the slightly more aggressive cams installed."
So more was done to the ECM than just an immobilizer 'patch'. The late 993s have an inherent problem of a very low
idle which exacerbates idle roughness and a slight idle undershoot. This ECM mod you mention could be additionally
affecting the idle causing the stalling. Also, no one really knows what effect the "aggressive cams" have on the idle
and potential random stalling. The modded cams combined with the LWF mod and the ECM tweak, could now have
resulted in your present situation. Also, cam timing being slightly off has known to be a cause of idle problems.
The implication of my post was that too many variables were changed at once,
i.e. an engine rebuild and an the DME ECM mod. Now it's really unknown which of the
two is the source of the problem. Obviously it was more convenient to mod both
when the car was 'down'. So as the thread has converged on a relative simple
solution, i.e. find another ECM, notwithstanding that difficulty, but other aspects of
the present state of the vehicle can be analyzed.
Back to the initial post:
"In other words, you can be driving along at 30 mph, in an appropriate gear,
and in preparing to stop, you depress the clutch. On about the fifth or sixth
stop once the engine reaches temperature, when the clutch is depressed the
engine speed will drop to a low enough point where it will stall. Conversely,
on 5 out of 6 stops from speed, the engine speed will drop to the proper idle
speed without incident."
What you describe is the typical idle RPM undershoot which results from a change to a light flywheel,
which you indicate was done way before the re-flash. So that should not be an issue now
unless some other mod besides the immobilizer patch was part of the re-flash. With regard
to the adaption problem, the long trim values provided by the ECM actual values should
provide an insight to that.
You really need to have someone with a PST2 or Piwis tester (Porsche factory diagnostic tools)
analyze all the actual data values in the ECM at this point before trying the difficult task of finding
another ECM. As minimum, utilize an OBDII scanner to evaluate the ECM actual values.
Furthermore, the more times the ECM leaves your possession, the greater is the likelihood
of a real problem developing. Besides, a bench test versus an in the car test rarely ever provides
a truly robust test, as it very difficult to simulate all the conditions of an actual test drive.
"As noted before, the ECU got a clean bill of health from ECU Doctors in Florida. But, the ECU is one of the items that underwent modifications during my rebuild. The ECU was sent off to have it modified to adjust for the slightly more aggressive cams installed."
So more was done to the ECM than just an immobilizer 'patch'. The late 993s have an inherent problem of a very low
idle which exacerbates idle roughness and a slight idle undershoot. This ECM mod you mention could be additionally
affecting the idle causing the stalling. Also, no one really knows what effect the "aggressive cams" have on the idle
and potential random stalling. The modded cams combined with the LWF mod and the ECM tweak, could now have
resulted in your present situation. Also, cam timing being slightly off has known to be a cause of idle problems.
Loren,
I sincerely want to thank you for taking the time to clarify your first note. I agree with you whole heartedly. As an engineer I was always schooled to only change one variable at a time. And, obviously, on an engine rebuild involving modifications, many variables were changed all at the same time. And, you are absolutely correct in that I am paying the price for that complication in resolving this stalling issue. But, my logic was that the changes I was making were not unique and had been done successfully by others.
The positive for me out of all this effort is that I now understand the control systems for the 993 when I had essentially limited knowledge before I encountered my stalling issue.
Though we were not able to dyno the car, the shop that did my work did use a number of analyzers to evaluate the engine under running conditions. I'm not certain if they had the Bosch Hammer or a PWISS, but they did tell me that they were able to monitor real time engine functions.
So, I am now of the opinion that we have proved out all of the engine controls leaving the ECU as the potential culprit. As stated before, the ECU was sent off to be reflashed for the LWF and cams. And, at the same time, I had them disable the immobilizer functionality.
I had a long discussion with ECU Doctors yesterday who clarified what was checked on my ECU when it was first sent in to them for evaluation. They stated that they simply are able to evaluate the ECU hardware only. They do not look at the software.
In discussing my particular issue (stalling), it would seem that all the things that had been done to my engine can imperil the idle. It was noted that many 993's seem to idle a little on the low side and slightly rough. The addition of the LWF probably impacted the idle stability, though the car never did stall with just the LWF. But, now add in the slightly more aggressive cams which give the motor a little bit of a lope, and the possibility that there is some "issue" with the performance software, and that could be the cause of my stalling. Sounds logical to me.
So, what we are going to do is have ECU Doctors supply me with a "loaner" ECU configured to run in my car......but, using their performance software. If that arrangement eliminates the stalling, then they will remove the software on my ECU and replace it with their package and Ill try that out. If that fixes my situation, I'll just purchase the upgrade from them. If their software does not fix my issue, they can restore my ECU to its original configuration (since they will save any software they remove). Or, if their "loaner" ECU with performance software fixes my issues, they will do an exchange with me.....but, at a much higher cost.
They will also investigate the possibility of programming a slight increase in idle speed into either ECU.
So, that is what we have discussed. Your comments would be appreciated.
11-01-2014, 10:20 AM
#82
Burning Brakes
Thread Starter
The issue occurs at idle as well so it should not be related to the clutch. It could be the DMF if so equipped. Have you checked fuel pressure when the engine is hot? The trick will be to do this when the engine is running rough. I'm guessing that the fuel pump and pressure regulator are not the issue, but it would be good to rule them out. 
11-01-2014, 03:58 PM
#83
Rennlist Member
The issue occurs at idle as well so it should not be related to the clutch. It could be the DMF if so equipped. Have you checked fuel pressure when the engine is hot? The trick will be to do this when the engine is running rough. I'm guessing that the fuel pump and pressure regulator are not the issue, but it would be good to rule them out.
11-01-2014, 03:59 PM
#84
Rennlist Member
Good luck with the ECU swap-hope it's the low hanging fruit in all of this.
Loren,
I sincerely want to thank you for taking the time to clarify your first note. I agree with you whole heartedly. As an engineer I was always schooled to only change one variable at a time. And, obviously, on an engine rebuild involving modifications, many variables were changed all at the same time. And, you are absolutely correct in that I am paying the price for that complication in resolving this stalling issue. But, my logic was that the changes I was making were not unique and had been done successfully by others.
The positive for me out of all this effort is that I now understand the control systems for the 993 when I had essentially limited knowledge before I encountered my stalling issue.
Though we were not able to dyno the car, the shop that did my work did use a number of analyzers to evaluate the engine under running conditions. I'm not certain if they had the Bosch Hammer or a PWISS, but they did tell me that they were able to monitor real time engine functions.
So, I am now of the opinion that we have proved out all of the engine controls leaving the ECU as the potential culprit. As stated before, the ECU was sent off to be reflashed for the LWF and cams. And, at the same time, I had them disable the immobilizer functionality.
I had a long discussion with ECU Doctors yesterday who clarified what was checked on my ECU when it was first sent in to them for evaluation. They stated that they simply are able to evaluate the ECU hardware only. They do not look at the software.
In discussing my particular issue (stalling), it would seem that all the things that had been done to my engine can imperil the idle. It was noted that many 993's seem to idle a little on the low side and slightly rough. The addition of the LWF probably impacted the idle stability, though the car never did stall with just the LWF. But, now add in the slightly more aggressive cams which give the motor a little bit of a lope, and the possibility that there is some "issue" with the performance software, and that could be the cause of my stalling. Sounds logical to me.
So, what we are going to do is have ECU Doctors supply me with a "loaner" ECU configured to run in my car......but, using their performance software. If that arrangement eliminates the stalling, then they will remove the software on my ECU and replace it with their package and Ill try that out. If that fixes my situation, I'll just purchase the upgrade from them. If their software does not fix my issue, they can restore my ECU to its original configuration (since they will save any software they remove). Or, if their "loaner" ECU with performance software fixes my issues, they will do an exchange with me.....but, at a much higher cost.
They will also investigate the possibility of programming a slight increase in idle speed into either ECU.
So, that is what we have discussed. Your comments would be appreciated.
I sincerely want to thank you for taking the time to clarify your first note. I agree with you whole heartedly. As an engineer I was always schooled to only change one variable at a time. And, obviously, on an engine rebuild involving modifications, many variables were changed all at the same time. And, you are absolutely correct in that I am paying the price for that complication in resolving this stalling issue. But, my logic was that the changes I was making were not unique and had been done successfully by others.
The positive for me out of all this effort is that I now understand the control systems for the 993 when I had essentially limited knowledge before I encountered my stalling issue.
Though we were not able to dyno the car, the shop that did my work did use a number of analyzers to evaluate the engine under running conditions. I'm not certain if they had the Bosch Hammer or a PWISS, but they did tell me that they were able to monitor real time engine functions.
So, I am now of the opinion that we have proved out all of the engine controls leaving the ECU as the potential culprit. As stated before, the ECU was sent off to be reflashed for the LWF and cams. And, at the same time, I had them disable the immobilizer functionality.
I had a long discussion with ECU Doctors yesterday who clarified what was checked on my ECU when it was first sent in to them for evaluation. They stated that they simply are able to evaluate the ECU hardware only. They do not look at the software.
In discussing my particular issue (stalling), it would seem that all the things that had been done to my engine can imperil the idle. It was noted that many 993's seem to idle a little on the low side and slightly rough. The addition of the LWF probably impacted the idle stability, though the car never did stall with just the LWF. But, now add in the slightly more aggressive cams which give the motor a little bit of a lope, and the possibility that there is some "issue" with the performance software, and that could be the cause of my stalling. Sounds logical to me.
So, what we are going to do is have ECU Doctors supply me with a "loaner" ECU configured to run in my car......but, using their performance software. If that arrangement eliminates the stalling, then they will remove the software on my ECU and replace it with their package and Ill try that out. If that fixes my situation, I'll just purchase the upgrade from them. If their software does not fix my issue, they can restore my ECU to its original configuration (since they will save any software they remove). Or, if their "loaner" ECU with performance software fixes my issues, they will do an exchange with me.....but, at a much higher cost.
They will also investigate the possibility of programming a slight increase in idle speed into either ECU.
So, that is what we have discussed. Your comments would be appreciated.
11-01-2014, 07:55 PM
#85
Burning Brakes
Thread Starter
I can truely appreciate how Loren put this all together and provided a well thought out analytical response.
Trying to methodically sift through all the variables further agravates the ability to arrive at a solution.
Here is a link to adjusting the ISV; if and when it may be viewed as a potential solution...
https://rennlist.com/forums/993-foru...djustable.html
Trying to methodically sift through all the variables further agravates the ability to arrive at a solution.
Here is a link to adjusting the ISV; if and when it may be viewed as a potential solution...
https://rennlist.com/forums/993-foru...djustable.html
What a gem to find that the idle speed is adjustable! I wonder why my shop didn't attempt that to cure my stalling issue. I personally feel that if I can raise my idle speed by about 50-75 rpm, that it might be enough to compensate for the loping cams and the LWF in the car. So, if this works, it will be amazing.
When I first encountered the stalling issue, I thought ISV, since the unit on the car was of unknown age to me. So, I replaced it with a new ISV, which as we now know did not cure my stalling issue. So, what I think I will do is to modify the old ISV and give it a try. Once in the past I had encountered some stalling, but found the ISV to be gunked up. I cleaned it up as others do, and that cured my stalling issue. So, I'll clean up the old unit, remove the epoxy to allow adjustment and see if it works.
Is there a consensus of just where the idle should be set in order to stop the stalling? Or, do I just need to experiment with it?
I'm going to do this before I pull the ECU to send off to ECU Doctors.
I'll report back on the results of adjusting the ISV.
11-01-2014, 08:04 PM
#86
Burning Brakes
Thread Starter
Hi Ed,
Thanks for sharing your thoughts. I did not mean to infer that I was going to disregard the comments about fuel pump and fuel pressure. My apologies to anyone that might have been offended.
Early on, my tech put a pressure gauge on the fuel rails to determine if fuel delivery was an issue. That test was uneventful. And, they did a functional test of each injector which was also uneventful. I had the injectors cleaned, flow tested, and fitted with new seals prior to installation.
And, early on someone had suggested a malfunctioning clutch; but, the symptoms did not fit those of a clutch issue.
I am a true believer that there are no dumb comments or questions. Every comment prompts you to think through the scenario described..
Thanks for sharing your thoughts. I did not mean to infer that I was going to disregard the comments about fuel pump and fuel pressure. My apologies to anyone that might have been offended.
Early on, my tech put a pressure gauge on the fuel rails to determine if fuel delivery was an issue. That test was uneventful. And, they did a functional test of each injector which was also uneventful. I had the injectors cleaned, flow tested, and fitted with new seals prior to installation.
And, early on someone had suggested a malfunctioning clutch; but, the symptoms did not fit those of a clutch issue.
I am a true believer that there are no dumb comments or questions. Every comment prompts you to think through the scenario described..
11-02-2014, 02:46 PM
#87
Per the thread, I believe you make small adjustments, and see where the idle settles and how it reacts when at operating temp.
As I understand it, there is not a whole lot of adjustment available, but if you bump your idle speed up 100-200 rpm and it solved the stalling issue, would you be satisfied with your car idling at say 900-1000 rpm at operating temp? I know I would.
I'm sure Loren, with his significant knowledge of the system can chime in if there is any detrimental effects to this potential solution.
11-02-2014, 03:31 PM
#88
The mod to the idle valve only changes the idle speed temporarily, idle is controlled by the DME through an adaptive feedback loop. When actual idle is below the programmed value the DME sigansl the idle valve to open more, when idle is higher than programmed the DME signals the idle valve to close some, there is a constant torsion battle between the 2, tips have an additional input to prevent creep at a stop light.
There is also a throttle pot which is also adaptive, and requires the driver to not use the gas pedal on a start after the battery or DME have been disconnected.
the 2 key figures for this pot are 1° and 65°, these values can be read by a 'Hammer' below 1° the idle map is in control, above 65° the full throttle map is in control
There is also a throttle pot which is also adaptive, and requires the driver to not use the gas pedal on a start after the battery or DME have been disconnected.
the 2 key figures for this pot are 1° and 65°, these values can be read by a 'Hammer' below 1° the idle map is in control, above 65° the full throttle map is in control
11-02-2014, 06:04 PM
#89
Rennlist Member
I really made that comment based on the posters comment on DMF. It sure looked like that person hadn't taken the time to ingest the situation.
Hi Ed,
Thanks for sharing your thoughts. I did not mean to infer that I was going to disregard the comments about fuel pump and fuel pressure. My apologies to anyone that might have been offended.
Early on, my tech put a pressure gauge on the fuel rails to determine if fuel delivery was an issue. That test was uneventful. And, they did a functional test of each injector which was also uneventful. I had the injectors cleaned, flow tested, and fitted with new seals prior to installation.
And, early on someone had suggested a malfunctioning clutch; but, the symptoms did not fit those of a clutch issue.
I am a true believer that there are no dumb comments or questions. Every comment prompts you to think through the scenario described..
Thanks for sharing your thoughts. I did not mean to infer that I was going to disregard the comments about fuel pump and fuel pressure. My apologies to anyone that might have been offended.
Early on, my tech put a pressure gauge on the fuel rails to determine if fuel delivery was an issue. That test was uneventful. And, they did a functional test of each injector which was also uneventful. I had the injectors cleaned, flow tested, and fitted with new seals prior to installation.
And, early on someone had suggested a malfunctioning clutch; but, the symptoms did not fit those of a clutch issue.
I am a true believer that there are no dumb comments or questions. Every comment prompts you to think through the scenario described..
11-02-2014, 09:45 PM
#90
Burning Brakes
Thread Starter