Ky944TurboNewbie

I am going to apologize up front as I am going to be really busy the next month or two and probably won't have much time to address this issue. But my curiosity got the better of me and I want to ask this question to get some opinions.

My car has only been driven about 1,000 miles in the last 3 years. Maybe only 200 miles in the last 2 years. I was having some issues that needed to be addressed before it could be driven. I decided to attack these issues this spring and since then, I have done the water pump, timing/balance belts, front seals, rollers, rebuilt the p/s pump and replaced the p/s rack, and fuel pressure regulator, and ignition rotor. Before I did this work, the car was cutting out intermittently. I am still having problems with an intermittent cut off.

The car dies and will always immediately restart. This happens when the car is accelerating. It is much more frequent just after it is started cold, but will do it sometimes after it gets to operating temperature. It usually happens when accelerating in first gear at about 2000 rpm's. However, it has done it (infrequently) at higher rpm's and second or third gear. The cut off is drastic, like it is going into limp mode, but will always die and need to be restarted.

The engine is completely stock. I have checked the TPS, ISV, MAF, and reset the Idle per Clarks Garage procedure. The fuel / ignition system has been through troubleshooting by an independent Porsche mechanic. Other than the fuel pressure regulator, all was good. Neither I or the Mechanic can find any vacuum leaks. The mechanic noticed a lot of carbon deposit and recommended running some cleaner in the fuel in addition to a couple of tanks of premium gasoline. I put a can of Seafoam and filled the tank and I have run through about a 1/4 tank of that so far.

I have already seriously blown my budget getting the car running again and it is driving really nice except this one issue. I don't want to start replacing things randomly as I am over budget already. Who has an easy quick and cheap fix for me? I know about the only fix that I have ever done on this Porsche that was easy cheap and quick was to replace the heater clip, but I am hopeful.

Thanks,

Michael

Tom M'Guinn

Sorry to hear, those types of problems can be a real pain -- been there done that. If might be as easy as a DME relay going bad. When the car dies, check to see if the boost gauge still works -- right after the car dies leave it in gear so the motor keeps turning and watch the boost gauge as you press the throttle. If the DME is still getting power, the gauge will move up to ambient pressure as you push down the throttle and return closer to zero when you close the throttle. If it does not move at all, then worth checking to see if the DME relay cut all power to the DME. If that's not it, then you might hook up LED's to the coil and injectors to see if one or both of those are cutting out. The speed and reference sensors are a likely suspect and/or the injector harness. The KLR can also go bad, causing symptoms like you are getting, but hopefully it is something more simple. Good luck!

P. Ortiz

I had a similar problem once. It usually happened on full boost. I investigated and found it to be a cracked hose from the banjo bolt at the pressure tube from the turbo going to the cycle valve. Since the valve wasn't getting a pressure read, the motor was cutting-out to prevent over-boosting. Several inches of new hose fixed it. Good luck.

Crackership

is this not common practice for you? If you have the same sticker inside your gas flap as I do, it clearly says 91 octane minimum... I don't mean to come off harshly or anything, but too low of octane can seriously, and perhaps permanently, damage your engine. I'm not sure exactly how harshly the KLR combats knocking (I've never experienced it), but some cars will kill the ignition if a certain knock threshold is reached... and if you're running 87 octane, you could easily be knocking badly.

chrly924s

87 octane will not cause shut down at 2000 rpm. Knock sensor will adjust timing to supress knock with a resulting loss of performance. This just takes away some of what the car is all about. Its beyond me why someone will drive a high performance car and try to save $2-3 on a tank of gas. This sounds like an overboost shutdown like I had ( LR boost enhancer was loose), but again, not at 2000 rpm. I think I would go with Tom on where to look. Good tip on the boost gauge/dme check. Thats why I'm a RL member.

Tom M'Guinn

If the motor is dying entirely, requiring you to restart it, then it is likely something other than overboost protection.

Ky944TurboNewbie

When it dies, the boost guage isn't moving at all. I noticed that last night and took a picture before I restarted as I was on a side street. The boost guage was pegged at 1.0 and didn't change until I turned the key to the off position and then back to the start it. If I am reading Tom correctly, this means I need a new DME relay? That would be awesome it that was all it is.

Tom M'Guinn

Was it pegged at 0 even though the motor was still turning (without firing) and in gear, with the key still in the ON position? That would indeed suggest the DME/KLR is losing power, which very well could be the relay (or factory alarm, or wiring harness, or ignition switch, etc.). Might try jumping the relay contacts (for test purposes only) to see if that eliminates the problem...

Ky944TurboNewbie

Tom,

It was pegged at 1 even though the motor was stil turning and in gear with the key still in the ON position. Are you talking about jumping like you do to test the fuel pump and taking it for a drive?

Tom M'Guinn

Sorry, just reread this and think I lead you astray. It needs power from the DME to be at the 1 position (i.e., in the middle of the gauge) so if it was there even after the motor died, then that would suggest the DME does have power. When you said the boost gauge didn't move at all, I was thinking it was dead to the left, like it would without DME power (even though you clearly said it was at 1).

So you are saying it was at the middle 1 position while the motor was still turning in gear and your foot off the gas? That would be odd -- with the DME getting power but the KLR not registering vacuum for some reason?

Ky944TurboNewbie

Here is what the guage looked like after it died. Then I rolled over to the curb and took this picture. Nothing moved or changed until the key was turned off and back on. Pressing on the gas pedal didn't change the boost guage. It is like the guage was frozen. Next time it happens. I will see if it changes position when I turn the key off, or when I turn it back on. Not sure about that at this point.

chrly924s

This may be unrelated to your problem, but mine was doing a no start on me unless I jumpered the the DME relay. A new relay didnt fix the problem. Search on here got me to a thread that fixed my problem. K had gotten water in the alarm box next to the DME/KLR. I unplugged thd alarm and jumped the +/- in the plug and that was the end of that problem. It never gave a hint that the alarm was at fault until the day before I fixed it. It started tooting tbe alarm horn.

Ky944TurboNewbie

Now I have a bad video of the car stalling. It was kind of difficult to drive safely and hold my phone on the guage cluster. Let me know what your thoughts are. It is like the fuel is being cut off and I need to turn off the ignition completely to get it to start again. Anything else I should be doing to help troubleshoot this problem?

http://s1227.photobucket.com/albums/...t=9a58d3bb.mp4

Thanks,

Michael

Tedro951

The gauge is frozen at atmospheric pressure. I didn't see any boost coming on in the vid, but it may not have been a situation where u were asking for boost. There were some wild fluctuations on the boost gauge, though.

Check the coil wire to dist cap (less than 1 minute).
If someone has a good DME nearby it might be worth a quick swap to see what happens.

Ky944TurboNewbie

This is not in a boost situation. The RPM's are low and very slight acceleration. The wild fluctuations in the boost are because I was pumping the throttle after it died. Because there are fluctuations, I assume that means the DME is still getting power so I assume it isn't a DME relay that is going bad. I don't believe this is an overboost situation. It may be similar in that the fuel is cut by the DME. It will not start again until the key is moved to the off position and then it always starts. Doesn't this reset the DME compluter when the key is cycled?

I am wondering if there is a situation where the AFM and the TPS are not in sync and therefore the fuel is cut off. Another possibility is that the knock sensor is causing the KLR to cut fuel. I have been running the octane too low for a couple of years and won't do it anymore. Not sure what that might have damaged. I am not an expert and guessing from what I have read in other threads.

What am I checking on the coil wire to the distributor cap? Just that it is tight? Am I looking for arcs? I am a pretty green mechanic, and specifics would be appreciated.

Thanks for your replies!

Michael