My idle surge breakdown.

[Richimself]

I have a 1990 Eagle Talon Tsi AWD that has been idle surging since I bought it back in November '06. I suspect it's the boost leak that I already know I have but I'm interested to hear some feedback from you guys to see if it could be something else. When I did the boost leak test I connected the tester to the turbo inlet and used a bicycle pump to pressurize. The system basically held no pressure and you could hear a very loud hiss from around the intake runner area. I wasn't able to find out exactly where the boost leak was so I'll probably be taking it to a shop near me to be fixed.

Things like the outdoor temperature seem to affect the idle surge (which I thought was strange). When it was colder around the time I bought the car the idle was just garbage - sometimes it would idle at 2000 rpm and hold for a while before backing down to the normal 1200-1500 idle surge point. But now that it's warmer the idle seems better; Now it's just that I have to stop the car from stalling when I start it by holding the rpms up for a few seconds to make sure the rpms don't drop and stall the car.

I've eliminated the egr as the culprit by blocking it off and seeing that it didn't help, and the TB I'm not sure about as i only removed the intake pipe on the elbow and didn't feel comfortable opening up the TB itself.

Sorry for the long post - any feedback is appreciated, and I'll be sure to answer any other questions that may have been left unanswered.

 

[Locke]

Here's the link you didn't know you were looking for.

http://www.dsm.org/how-tos/tttt/tttt3.html

You're very welcome!

 

[Richimself]

Thanks - I've actually read through that a couple of times and found a lot of useful information but what I'm really wondering is if there's a correlation between the temperature affecting the idle and whether that could be traced back to the boost leak being the problem(or if it points to something else). But I'll give the troubleshooting page another read through and see if I can find something I missed that can help me out. Thanks again for your reply

 

[Locke]

I would lean towards the FIAV.

 

[Richimself]

Alright small update - Me and a friend went to look into the ISC which we've come to find out is different on the 1990's and ended up undoing the TPS instead, which we promptly put back on. After that we looked around on the boards a bit but didn't get a clear picture of where exactly the ISC was or what it looks like, so we reinstalled the UICP that we removed to make room for a wrench on the lower TPS screw, as well as the vacuum lines we removed for the same reason. However, when I went to check to see if the car started and ran correctly we neglected to re-attach the ISC connector and started the car with it off, which triggered a CEL. After plugging it back in (with the car still running) the CEL didn't go off so I shut the car off and turned it back on; the CEL went away (or so it seemed). Then when I went to leave the CEL came back on and the car was running very rich. After looking around to make sure everything was connected I disconnected the idle switch, which made the CEL go away. But after restarting the car it came back.

The strangest part is that when I got home I kept trying to fix it and the only thing that will make it go away is disconnecting the idle switch and/or the ISC connector (which makes the car idle perfect when both are disconnected). I haven't tried driving the car with either the ISC connector or idle switch disconnected, but as soon as I shut the car off - reconnect both things - the idle is stumbly and the CEL comes on.

So any ideas on the situation? Sorry for another long post, just wanna be thorough.

 

[Auto RS T]

Allight, you may want to start out by re-connecting everything then clearing the Check engine light.

To clear the CEL simply remove the negative battery cable for 30 seconds then re-attach.

On a 90 style TB the ISC is located in the same spot as a 91-99 car. Like you mentioned, it just does not look similar. It is held on with two small bolts and is an all aluminum piece.

Follow the harness off the ISC and do the ISC resistance test from the connecter.

Keep us updated, I hope I have steered you in the right direction.

When you are ready to set the idle be sure to go through the BISS procedure.

http://vfaq.com/mods/BISS-1G.html

 

[Richimself]

I actually removed the both battery terminals just before coming back inside to see your response. It didn't make the CEL go away and the car is riding kind of weird. The car bucks down hard when I let off and go to change gear. I'm thinking my friend and I may have thrown the TPS off the correct setting somehow when we took it off. Is there any way just removing the TPS could have done that? My friend was still thinking it was the ISC when we messed with the TPS, and tried to wiggle out the little plug that gets exposed after unbolting the TPS. But from what I could see I don't think the plug moved at all.

Any ideas on whether or not my TPS has been thrown off by our stupidity? And why removing the idle switch makes the CEL go away?

Lastly the CEL only comes on when I fully let off the gas and then goes away after depressing the throttle even the tinniest bit.

I hope I've provided enough details, any help is much appreciated.

 

[Auto RS T]

Pull the DTC's using this method, let us know what you come up with.

http://www.dsmtuners.com/forums/showthread.php?t=190021

Double check that all connections are connected.

Only the TPS should have the ability to light the CEL... at least in the area of the engine bay you are working in.

 

[Richimself]

Hey thanks for your reply. I checked for the code via the instructions from your link. And indeed I came up with error code 14 (TPS). Me and my friend have been searching around on how to set the TPS and as far as I could understand: to get the reading from the TPS itself you need to use alligator clip jumpers to bridge between the connector and the other end on the firewall. Am I mistaken in that assumption? Because the pins in the connector that lead back to the TPS seem to be impossible to get the clips on.

Also we found out that you only need to loosen and rotate the TPS to set it so we messed with it a bit. I thought maybe we'd get lucky but of course we didn't; although the car seems to be running somewhat better after messing with it.

Last thing - my boost gauge seems to be behaving differently than it did before. I just noticed it this morning that under boost after I let off, the needle hesitates and moves upward a bit and then drops. Is this just the crappy boost gauge being retarded or is it a sign of something bad?

 

[Auto RS T]

I have not set a TPS sensor by jumping the wires like you have described however, I did come across the post I think you got that from. (Last post)

http://www.dsmtuners.com/forums/showthread.php?t=242134&highlight=setting+90+tps

If you have a logger it makes setting the TPS a breeze. Just rotate the TPS until the logger reads 10%.

I found this thread to be informative, even though it is short. Post two tells you how to set the TPS via the output pin. The rest of the thread goes on to describe how the other method can be inaccurate.

http://www.dsmtuners.com/forums/showthread.php?t=191288&highlight=setting+90+tps

Lets worry about the gauge after the problems are fixed, it could be due to the TPS issue or just a crappy gauge or kinked gauge vacuum line.

 

[Richimself]

Do you know of any cheap loggers? I know I should search this but I figure while you're still around you might be able to point me in the right direction. I don't have a laptop or anything, but I know a bunch of people with one's I could probably use. So is there an inexpensive logging software you know of that will run off of a newer style laptop?

Thanks for another helpful response and I'll try to set it without the logger for now.

Edit: Nevermind, found free logger software after a search. It's the "TunerStein" laptop software. That should be sufficient right?

 

[Auto RS T]

I actually picked my logger off of ebay The package was 100 bucks.

I haven't heard of TunerStein, but I have heard of Palm n Stein. I use MMCD, its user friendly.

I would guess TunerStein should be good enough.