Intermittent Stalling on a Hot Engine Issue
10-02-2014, 01:21 AM
#46
Burning Brakes
Thread Starter
"AXL911 - I discussed your "way out there" thought that a malfunctioning Fuel Evap Valve could exacerbate a stall given that the car is fitted with a LWF. My tech was intrigued with that idea and will take a close look at the valve. Stay posted on that."
Testing the valve is simple. A 12v signal is applied and the valve opens allowing the car to suck in the air from the Fuel Evap canister. Maybe it got stuck open or stuck closed.
Pull it out, apply 12V, see if you can blow thru it.
Testing the valve is simple. A 12v signal is applied and the valve opens allowing the car to suck in the air from the Fuel Evap canister. Maybe it got stuck open or stuck closed.
Pull it out, apply 12V, see if you can blow thru it.
Axl,
Excuse my ignorance, but I am having problems locating the fuel eval valve on the 993 PET. Can you point me to it? Perhaps a part number or tell me where it is on the PET. I looked through my build notes and apparently completely overlooked this valve. So, it sounds as though it is a solenoid operated valve. As I think through my issues, if that valve were to be stuck open, we may have found my vacuum issue. And, if it is intermittently sticking open, it could be part of my stalling issue.
10-02-2014, 11:36 AM
#49
From the pcarworkshop.com DIY 993 Reference Pics.
See the connector tree? The VERY TOP black hose is connected to a cylindrical object with a 2 wire plug.
http://pcarworkshop.com/images/d/d9/051231_-_0021.JPG
See the connector tree? The VERY TOP black hose is connected to a cylindrical object with a 2 wire plug.
http://pcarworkshop.com/images/d/d9/051231_-_0021.JPG
10-02-2014, 11:41 AM
#50
Here it is from the back. Again, top black hose to cylindrical object with the electrical plug.
http://pcarworkshop.com/images/5/5e/060101_-_0031.JPG
http://pcarworkshop.com/images/5/5e/060101_-_0031.JPG
10-04-2014, 02:23 AM
#51
Burning Brakes
Thread Starter
Here it is from the back. Again, top black hose to cylindrical object with the electrical plug.
http://pcarworkshop.com/images/5/5e/060101_-_0031.JPG
http://pcarworkshop.com/images/5/5e/060101_-_0031.JPG
Thanks. Now I remember it. When I installed the new harness, it took a while before I figured out that the one loose connector on the new harness mated up to that valve, which I didn't see since it was hidden by the christmas tree.
Last edited by earossi; 10-06-2014 at 12:01 AM.
10-22-2014, 08:44 AM
#52
Burning Brakes
Thread Starter
OK, it's been a couple of weeks since I last posted any updates. We've been out of town on a vacation.
We still do not have the issue solved.
The carbon canister solenoid valve was tested for operation. They even placed a vacuum on it and checked it out. It operates correctly.
My tech did squawk another item which they are rethinking. They claim that on several occasions, they have seen the CEL illuminating "dimly", which has them puzzled. The illumination is intermittent and not tied to anything they have observed.
So, they are currently rechecking all items that have been tested. Color coding on all sensor wiring connectors will be confirmed against the wiring diagram for the car.
And, as discussed before, a new tech will be assigned to the car in hopes of observing something that has not been seen before.
Frustrating to say the least. Thanks again to all who have offered up potential things to check out. I'm certain that when we finally get it figured out, it will turn out to be something "simple".
We still do not have the issue solved.
The carbon canister solenoid valve was tested for operation. They even placed a vacuum on it and checked it out. It operates correctly.
My tech did squawk another item which they are rethinking. They claim that on several occasions, they have seen the CEL illuminating "dimly", which has them puzzled. The illumination is intermittent and not tied to anything they have observed.
So, they are currently rechecking all items that have been tested. Color coding on all sensor wiring connectors will be confirmed against the wiring diagram for the car.
And, as discussed before, a new tech will be assigned to the car in hopes of observing something that has not been seen before.
Frustrating to say the least. Thanks again to all who have offered up potential things to check out. I'm certain that when we finally get it figured out, it will turn out to be something "simple".
10-22-2014, 10:36 PM
#53
Rennlist Member
On a previous post I recommended replacing the battery ground strap. In my opinion on cars the age of ours three electrical item should be replaced as preventive measures. 1) ground strap 2) fuel pump relay 3) electrical portion of ignition switch. I also did the fuel pump on mine just because. You know these things are going to go bad so do it now and make life easy.
10-23-2014, 12:41 PM
#54
On a previous post I recommended replacing the battery ground strap. In my opinion on cars the age of ours three electrical item should be replaced as preventive measures. 1) ground strap 2) fuel pump relay 3) electrical portion of ignition switch. I also did the fuel pump on mine just because. You know these things are going to go bad so do it now and make life easy.
10-23-2014, 01:19 PM
#55
Rennlist Member
They were asked to perform ECU work to allow me the use of the better breathing expected from installing RS cams in the motor, along with a bump up to the RS intake valving. I assumed that this would result in some minor tweaks to raised the red line a bit and perhaps adjust the mapping slightly to capture any power increase potentials made possible with the slightly more aggressive cams.
The firm that performed the programming changes also disabled the immobilizer function of the ECU. I followed that up by replacing the engine starter relay with a jumper relay as recommended on this board by Bill V.
When we suspected the ECU, it was sent off to ECU Doctors, in Florida for evaluation testing. So, they were, indeed, a third party set of cold eyes to look over the ECU. They did not find anything amiss with the ECU. Their suggestion was to consider a reprogram of the ECU. I'm not really interested in that. So, the ECU was reinstalled in the car.
The firm that performed the programming changes also disabled the immobilizer function of the ECU. I followed that up by replacing the engine starter relay with a jumper relay as recommended on this board by Bill V.
When we suspected the ECU, it was sent off to ECU Doctors, in Florida for evaluation testing. So, they were, indeed, a third party set of cold eyes to look over the ECU. They did not find anything amiss with the ECU. Their suggestion was to consider a reprogram of the ECU. I'm not really interested in that. So, the ECU was reinstalled in the car.
As noted in my threads, we thought that we had eliminated everything other than the ECU; so, he finally pulled that and sent it out the Bosch ECU guy in Florida who has been recommended by others. And, as noted, they did not find anything wrong with the ECU. I still kind of suspect that unit, but finding one to swap out is easier said than done. The unit is almost $2000 from Porsche, and they are year specific. And, they are set up with immobilizers that are specific to the car. So, you just don't take one off the shelf and put it in the car. To date, I have not been able to locate one that is correct for my year car. If I could find a used one at a reasonable price, I would send it off to have it configured to work in my car. But, so far, I have struck out in that camp.
10-23-2014, 07:18 PM
#56
RL Community Team
Rennlist Member
Rennlist Member
Yes I agree with this as the cracked solder joints in the relay warm up the DME may be getting all sorts of noise or intermittent voltage.
Keep it simple the relay is $30 or less at an import auto parts store. I would replace it on your way to see the mechanic and you may just keep on driving,
Andy :-)
Keep it simple the relay is $30 or less at an import auto parts store. I would replace it on your way to see the mechanic and you may just keep on driving,
Andy :-)
10-25-2014, 11:13 AM
#57
Burning Brakes
Thread Starter
Yes I agree with this as the cracked solder joints in the relay warm up the DME may be getting all sorts of noise or intermittent voltage.
Keep it simple the relay is $30 or less at an import auto parts store. I would replace it on your way to see the mechanic and you may just keep on driving,
Andy :-)
Keep it simple the relay is $30 or less at an import auto parts store. I would replace it on your way to see the mechanic and you may just keep on driving,
Andy :-)
10-25-2014, 01:11 PM
#58
Burning Brakes
10-25-2014, 02:17 PM
#59
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DME relay
I had a very similar symptoms with my 96 c4s. Genuine new DME relay and problem solved. I also have a LWF installed. Curious if they used a new relay or a used one from the shelf. I hope it gets sorted.
10-26-2014, 12:22 AM
#60
Burning Brakes
Thread Starter
They will substitute used parts from running cars to determine if the change out of the part makes a difference. If this proves the original part was defective, then they pull the "test" part and replace it with a new OEM Porsche part. They do not use anything other than Porsche OEM parts. Using this system, I don't get charged for parts that were installed, but not needed.
I can't answer your question on the DME relay, but was told that the relay was one of the first things replaced. Since they are not a high cost item, I suspect that they just installed a new OEM part for which I will be charged.