Resolved 91 Talon Tsi weird issue. Need help diagnosing.

[nlg4021]

I picked up my dsm about two weeks ago and everything has been great. Ive been doing a lot of reading and catching up on maintenance items for peace of mind.

Now to yesterdays issue that has me stumped. I got in the car about 4:30pm yesterday and it was in the upper 80's here in Mobile, AL. I start the car to let it warm up for a couple of minutes as I usually do and everything was normal. As soon a I start to drive off and I cut the ac on the car power surges and the radio looses power. The car doesnt die but the CEL cuts on then off. I cut the air off and turned on the switch again and the same thing occurs but this time the car starts running rough like it has lost power. So I pull into a parking lot and cut the car off and pop the hood to make sure the battery cables are tight and check some other things.

When I turn the key on the CEL light is off. Now when I start the car it doesnt surge this time and has NO idle surge, but runs rough and the CEL does not come on until about 10 seconds after starting. I was about 25 miles away from home so I limped the car all the way back. It made it the entire way but felt like it was in limp mode.

Please note I didnt have anything to test the CEL code. I dont think it would have worked anyway because it seems the code reset itself every time you turn the ignition off.

Anyway, when I get home the first thing I do is check to see if each cylinder has spark and each cylinder did. I then swap the ECU because I was given a spare that came with the car. Start the car up and the same thing. Initially the light doesnt come on until the car runs for a few seconds. The car is idling ok but I can tell the exhaust tone is not right and it still feels like its in limp mode. So I basically give up and go inside for the night. I figured I would go to radio shack this morning and pick up a buzzer to be able to read the CEL code.

Now for the screwy part, Im swapping out everything this morning into my other vehicle before I head into work, and decide to start the car up just to hope for a miracle. Well I start it, no CEL, it revs up around 1800 rpm as usual to warm up. Once warm, the car sounds like it usually does and is running fine. I didnt want to take the chance of driving to work and it happen again so I cut it off and said Ill look into again after work today.

So has anyone had a similar experience to this?

To recap on what happened and what I checked:

1. Start car yesterday afternoon, turn on ac, car surges, radio turns off, car does no die.
2. Turn on ac again, same thing.
3. Turn off car, check battery cables, etc.
4. Turn on car, no surge when turning ac on, no idle surge, running like in limp mode, CEL comes on about 10sec into idling.
5. Limp 25 miles home, CEL ON, car feels like its in limp mode.
6. Get home, check for spark on each cylinder, each produces spark.
7. Put in spare ecu, start car, no idle surge, still running like in limp mode, CEL light on after about 10sec. Quit fo the night since its getting late.
8. Start this morning just because, no CEL, car warms up, sounds fine, pull around the yard and everything feels normal, still no CEL.... STUMPED!

Any thoughts or guess on what it could be would be greatly appreciated.

 

[92AWDHX40]

Got a video? Get a way to read the code how are you going to know some shops here in town will do it for free my shop does, get a logger or find one it will realy help when you need to read a code or link, i had a logger helped , now link life is much easier.

 

[kchaazz]

Its looking like a severe voltage drop to me, which isnt manifesting itself until the alternator gets sufficiently "warm" enough, which is very common and will wreak havoc on the entire electrical system, and give you a check engine light along with all sorts of error codes. The power steering line, where the banjo fitting hooks to the top of the pump usually leaks on these cars, as the fitting uses two rubber orings to seal, which go bad, and when it leaks, the fluid likes to go directly onto and into the alternator. It will eventually kill the alternator, but sometimes they last for awhile and just begin to exibit poor charging ability when they get hot. If there's no oil leaking onto the alternator, examine the belt tension and condition of the belt. The belt will usually squeal if its loose and slipping, but not always. If I were you, Id just drive the car until it begins acting up again and when it does,measure the voltage at the positive terminal with a multimeter with the engine running. If all this checks out, move on to checking the ignitor, cas, and injector plugs to be sure they are securely plugged in with the retainer clips in place, and that the wires are in good shape.

 

[nlg4021]

Thanks guys, the voltage problem went away and is charging fine. I am going to get something to read the code if I get it again. I just though it was weird that when I started the car this morning it was like nothing had ever went wrong. I would lean toward the power transistor but I still had spark when it was acting up. Can the CAS go in and out like the power transistor does soemtimes before it dies? Im leaving work around lunch and I am going to try to drive the car to see if it happens again so I can pull a code on it.

 

[Th3Revreant]

Check all the injector plugs as well, mine was doing that due to one of the plugs coming loose. The plug was making just enough contact to fire it sometimes and not others, IE while driving. Long shot, never hurts to look

 

[nlg4021]

Thanks, I will check that too. Could very well be a possiblity. Hopefully it will be something that doesnt hurt the old wallet to bad.

Thanks for the responses, found out it was an injector. Good thing I already had a set on the way!