When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
First thing to do is to get the rpm signal clean! It absolutely should not read 2000 rpm at any state while idling, I would suggest saving your config, then upload an unaltered vemscfg for starters (I can send you one).
First thing to do is to get the rpm signal clean! It absolutely should not read 2000 rpm at any state while idling, I would suggest saving your config, then upload an unaltered vemscfg for starters (I can send you one).
Hi Peep,
Any insight as to why the "worst knock value" signal would be so erratic in Wayne's car? It obviously seems to be some sort of interference, but why would it show up in this particular value? Like I mentioned above, this reading seems to spike if/when I have an ignition misfire under heavy load with the original coil. What does this particular value actually represent?
Droops83...been reading a lot about your issue. And I have a similar issues. Not as major but definitely something going on. Mine is a sputtering problem. And it is all dependent on how it starts. If I have a clean start, the rpms will be at a set amount. And the car runs great. No sputtering. I can drive for 100 miles and no issues. I shut the car off. Turn it back on and the rpms May be slightly lower. And the sputter will commence. But only at idle. I shut the car off and on til I get a “good start” and there won’t be the sputtering. I’ve looked at my lambda values and it doesn’t look any different between a sputtering state and a non sputtering state. Gonna take it to my tuner and see if he can find something different between the starts that are making a difference. It’s pretty weird. Every vacuum line, wire, reference sensor, ground were just gone over or replaced when the VEMS was installed. With oem and Bosch hardware.
Droops83...been reading a lot about your issue. And I have a similar issues. Not as major but definitely something going on. Mine is a sputtering problem. And it is all dependent on how it starts. If I have a clean start, the rpms will be at a set amount. And the car runs great. No sputtering. I can drive for 100 miles and no issues. I shut the car off. Turn it back on and the rpms May be slightly lower. And the sputter will commence. But only at idle. I shut the car off and on til I get a “good start” and there won’t be the sputtering. I’ve looked at my lambda values and it doesn’t look any different between a sputtering state and a non sputtering state. Gonna take it to my tuner and see if he can find something different between the starts that are making a difference. It’s pretty weird. Every vacuum line, wire, reference sensor, ground were just gone over or replaced when the VEMS was installed. With oem and Bosch hardware.
I haven't had any issues----my VEMS-equipped 951 runs great and always has since I installed the system (now almost 3,000 miles on it). But it seems like several of you are having the exact same issue, so if we put our heads together we can likely figure it out. Make a datalog of the engine starting/running well, and try to log the same conditions after a "bad" start and post them here. Based on Wayne's logs (see screenshots above), it seems like something is interfering with the speed sensor/RPM signal. The reason that the AFR is different in both states is that when the VEMS thinks that it is running at 2000 RPM instead of 1000 RPM, it simply changes to a different cell in the VE table where it happens to run leaner in the case of Wayne's VE table (which looks to be an un-tuned base map for the most part).
So don't read too much into the AFR----log all of the relevant inputs and see what is different when the engine starts runs well and not. It seems like many of you guys are not taking advantage of the logging features of the VEMS; use it and analyze it before making any changes or replacing parts. If you don't know what you are looking at, post the files and/or screenshots here and we can try to help!
I haven't had any issues----my VEMS-equipped 951 runs great and always has since I installed the system (now almost 3,000 miles on it). But it seems like several of you are having the exact same issue, so if we put our heads together we can likely figure it out. Make a datalog of the engine starting/running well, and try to log the same conditions after a "bad" start and post them here. Based on Wayne's logs (see screenshots above), it seems like something is interfering with the speed sensor/RPM signal. The reason that the AFR is different in both states is that when the VEMS thinks that it is running at 2000 RPM instead of 1000 RPM, it simply changes to a different cell in the VE table where it happens to run leaner in the case of Wayne's VE table (which looks to be an un-tuned base map for the most part).
So don't read too much into the AFR----log all of the relevant inputs and see what is different when the engine starts runs well and not. It seems like many of you guys are not taking advantage of the logging features of the VEMS; use it and analyze it before making any changes or replacing parts. If you don't know what you are looking at, post the files and/or screenshots here and we can try to help!
It shouldn't be idling at 2000rpm, that was either me cruising around or revving it up to 2000rpm. But clearly something is wrong when the bad start happens. Same sputtering as mentioned. Might be interference with speed sensors on start, like starter kick back. I have the high Torque starter and I'm not sure if I have updated shielded speed sensor bracket.
Droops83...been reading a lot about your issue. And I have a similar issues. Not as major but definitely something going on. Mine is a sputtering problem. And it is all dependent on how it starts. If I have a clean start, the rpms will be at a set amount. And the car runs great. No sputtering. I can drive for 100 miles and no issues. I shut the car off. Turn it back on and the rpms May be slightly lower. And the sputter will commence. But only at idle. I shut the car off and on til I get a “good start” and there won’t be the sputtering. I’ve looked at my lambda values and it doesn’t look any different between a sputtering state and a non sputtering state. Gonna take it to my tuner and see if he can find something different between the starts that are making a difference. It’s pretty weird. Every vacuum line, wire, reference sensor, ground were just gone over or replaced when the VEMS was installed. With oem and Bosch hardware.
Do you have the updated speed sensor bracket with shielding?
I haven't had any issues----my VEMS-equipped 951 runs great and always has since I installed the system (now almost 3,000 miles on it). But it seems like several of you are having the exact same issue, so if we put our heads together we can likely figure it out. Make a datalog of the engine starting/running well, and try to log the same conditions after a "bad" start and post them here. Based on Wayne's logs (see screenshots above), it seems like something is interfering with the speed sensor/RPM signal. The reason that the AFR is different in both states is that when the VEMS thinks that it is running at 2000 RPM instead of 1000 RPM, it simply changes to a different cell in the VE table where it happens to run leaner in the case of Wayne's VE table (which looks to be an un-tuned base map for the most part).
So don't read too much into the AFR----log all of the relevant inputs and see what is different when the engine starts runs well and not. It seems like many of you guys are not taking advantage of the logging features of the VEMS; use it and analyze it before making any changes or replacing parts. If you don't know what you are looking at, post the files and/or screenshots here and we can try to help!
sorry. Not meant to put you in the group of “issue group”. I will try to get my car to my tuner to get some logs and screen shots. Yeah, mine really isnt a big deal except for the sputter at idle. But kind of annoying. 👍🏼👍🏼
It shouldn't be idling at 2000rpm, that was either me cruising around or revving it up to 2000rpm. But clearly something is wrong when the bad start happens. Same sputtering as mentioned. Might be interference with speed sensors on start, like starter kick back. I have the high Torque starter and I'm not sure if I have updated shielded speed sensor bracket.
I also have a hi torque starter and remember that at one stage my former mechanic removing the starter motor shield, as a bolt had stripped or something and couldn't be refitted without rattling. I don't have an updated sensor bracket.AFIK. I haven't played with making logs yet, so not sure I can do that, plus barely driving car ATM. I still need to do a proper autotune, but haven't had the chance yet. Maybe later in the week. I may be able to d a screen shot though.
I also have a hi torque starter and remember that at one stage my former mechanic removing the starter motor shield, as a bolt had stripped or something and couldn't be refitted without rattling. I don't have an updated sensor bracket.AFIK. I haven't played with making logs yet, so not sure I can do that, plus barely driving car ATM. I still need to do a proper autotune, but haven't had the chance yet. Maybe later in the week. I may be able to d a screen shot though.
Interesting. The neat thing about looking at someone else's VEMS log file is that you can also go through all of the menus and check their config and tune. In doing so, I noticed that Wayne's VE table appears to be very "untuned," looks to be some sort of base map. Maybe he loaded another base map/config while attempting to solve his starting issue?
I was under the impression that you guys all had the VEMS for a bit and at least had the basic low-load tune dialed in. I am hesitant to suggest any kind of tuning if there is potentially a fundamental trigger/interference issue, but if the the base VE map is completely untouched and there are huge gaps between cells, I could see certain engine conditions/temperatures causing an intermittent low/lean idle, especially if the idle control valve is deleted.
Do an autotune at idle and at low/light loads just cruising around. You won't do any damage to your engine if you stay off the boost. Once that is dialed in and the throttle response and idle are crisp, then go back and see if your intermittent bad start issue persists. It may be that all of you guys having this issue are freaked out by it and unwilling to go any further with basic tuning, which is understandable.
However, I still do not like the look of the erratic "worst knock value" reading on both of Wayne's logs, that seems to indicate some sort of interference.
Also, making a log file is easy: start the engine with the VEMS software running, then click "LOG" at the upper left of the menu bar. The icon will change from red to green to indicate that it is logging, and will do so indefinitely until you click "LOG" again or the power is cut from the ECU. The file will automatically be saved with a date/time stamp in the filename. Try to log a good start and a bad start under as similar of conditions as possible (let it idle for a bit, rev the engine in a similar manner, go for a short drive around the block, etc).
Chris, although I have had VEMS for a while I also had another issue I was chasing. I ended up having to get head redone. So I am starting from scratch. I loaded the original config from Peep, and today I adjusted req_fuel and found 5.6ms got a 14.7 when warm. I then went out and did an autotune prior to seeing your post above, so still no log. This is the screenshot of autotune. I wanted to keep going but Melbourne cup was about to race, so only got about 30 mins of driving in. This is obviously a clean start.
Interesting. The neat thing about looking at someone else's VEMS log file is that you can also go through all of the menus and check their config and tune. In doing so, I noticed that Wayne's VE table appears to be very "untuned," looks to be some sort of base map. Maybe he loaded another base map/config while attempting to solve his starting issue?
I was under the impression that you guys all had the VEMS for a bit and at least had the basic low-load tune dialed in. I am hesitant to suggest any kind of tuning if there is potentially a fundamental trigger/interference issue, but if the the base VE map is completely untouched and there are huge gaps between cells, I could see certain engine conditions/temperatures causing an intermittent low/lean idle, especially if the idle control valve is deleted.
Do an autotune at idle and at low/light loads just cruising around. You won't do any damage to your engine if you stay off the boost. Once that is dialed in and the throttle response and idle are crisp, then go back and see if your intermittent bad start issue persists. It may be that all of you guys having this issue are freaked out by it and unwilling to go any further with basic tuning, which is understandable.
However, I still do not like the look of the erratic "worst knock value" reading on both of Wayne's logs, that seems to indicate some sort of interference.
Also, making a log file is easy: start the engine with the VEMS software running, then click "LOG" at the upper left of the menu bar. The icon will change from red to green to indicate that it is logging, and will do so indefinitely until you click "LOG" again or the power is cut from the ECU. The file will automatically be saved with a date/time stamp in the filename. Try to log a good start and a bad start under as similar of conditions as possible (let it idle for a bit, rev the engine in a similar manner, go for a short drive around the block, etc).
Hope this helps.
You're correct regarding my tune. Placed another set of injectors and just tuned area under boost. I also performed auto tune with good start condition.i too haven't had much time to do much troubleshooting.i had mine in since January and just got used to it and just restarted the car a few times till i got a good start. I thought I was a special case but it doesn't seem so now. Good to know that we both have high Torque starter and not the updated shield bracket. When I have the time, I'm gonna swap out the starter for the stock unit and do more testing.
Chris, worst knock value spiking is probably some noise, in any case rpm reading should be steady not jumping up and down..
When you see worst knock value smallish spikes (that reflect real world movement) it can be misfire in fact. You can use knock chip as measuring individual power of the cylinders, just choose Individual power in knock input menu. Then you can see in the logs the misfires (power going down on cylinder) and also knocking (cylinder power spiking up). It is calculated by CPU as it is known how much time it takes at each rpm for the crank to reach TDC (ref pin is the reference as the name suggesting) and it is displayed as graph in the log.
I shot out to grab something before store closed and I got a slight bad start on way back. It got worse and that's when I noticed volt gauge was jumping around wildly up around 14+ volts. It is normally rock solid around 12.5 - 13and even with system cranked it only drops slightest bit on bass hits. Alternator is brand new 200amp unit, but the regulator has the issue wear it needs to be revved on start to kick in Alt. Anyway wasn't data logging so only an observation.
Hello! I just had a LR push clutch installed by a local mechanic and now my 951 will not start. Prior to the throwout bearing failure, the car was running well on Peep PnP VEMS. I am hypothesizing that the issue lies with the reference sensors, so I attached a reference sensor recording from the car attempting to start. I also attached the VEMS log file for the trigger log file form the start attempt. The attachments are located below the pictures. I am hoping that this will provide some insight as to what went wrong. Please let me know if I can provide anything else to help diagnose my issue!
11-04-2018, 11:22 AM
