strange idle

[jrjackso]

I have a 92 Talon TSI AWD TURBO automatic and for some reason the idle has been erratic. I had to replace the ECU because the original took a dump. The wrong ECU was then sent to me. Out it in and the motor ran perfect except it was idleing around 1200 RPM in nuetral (seemed a little high) and then when you put it in gear, the idle would drop to around 700 RPM. Well I was able to find the right ECU for the car and installed that. Car starts right up no problems but after running for a few minutes, the idle started to drop. The idle would slowly drop to around 400-500 RPM. Almost to the point where the car was going to stall. Then the idle would slowly increase back to around 800 RPM. Once I gave some throttle, the idle picked back up with no hesitation of any sort. I also noticed what seemed to be a poof sound every couple of seconds which I never heard before. I am very new to these motors so I dont know where to start looking for the problem. I did notice that the timing belt was pretty loose and after the car ran for a while, the timing belt would tighten somewhat. I know that this is a very important part of the car running correctly, but not sure where to start. Any advice would be helpful. Thanks in advance.

 

[streetlegends]

First off you need to tighten the time belt up if you can because if the belt is loose this might be the problem. Did you buy the ECU new or used. If you got it new you might need to check and see if it needs to be reprogramed. If you have a vaccum leak this might be the problem. Check all the hoses going to the intake,turbo,and the intercooler and or check for holes in any of the piping. This will get you started.

 

[1gdsmraider]

1. I'd change the timing belt and all the components. If the timing belt tensioner is worn down.. that could cause potential problems with the engine skipping timing.

2. Check all vacuum lines for leaks *soap and water in a spray bottle* and check for anything that may be disconnected. also check the egr/gasket and see if you still have it or not, its possible that this has gone bad.

3. another idle surge problem is the throttle body seals being worn out/gaskets bad.

4. yet another idle surge problem is the ISC motor gone bad. Do a search on this and you'll pull up a library worth of issues concerning this.