Running rich/ not burning all fuel

[jmak06]

My 90 Talon Tsi AWD is having another issue now. After it is driven for a while, or given a lot of pedal for awhile, the rpm's will stay up around 4k until I shut the car off and let it sit. I hadn't had any problems like this with it before (except after the engine is warm, the idle surges from 1.2k-1.4k several times a second) until I let a kid test drive it. He had it out for about 15 minutes and it started revving like this between shifts and when stopped. I changed the plugs and wires (ngk 7's and ngk wires) and it still does this. I cleaned the throttle body and throttle plate, and I havn't found any boost leaks. Any ideas?

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[jmak06]

I've already read over that several times. Thanks though. I know I need to do that to fix my idle surge, but this problem is different I think. I never had problems like this before even though it idle surged. And this is only an issue if it is a WOT for more than 30 seconds or so, and then once I let off the gas, if I keep my foot on the clutch, or take the car out of gear, it will slowly lower back to about 1.2k and then start the surge.

 

[jmak06]

Well...this issue has gotten worse. Now the rpm's stay at whatever they were when I let off of the throttle. The throttle cable isnt getting stuck, I've checked at the throttle body when the car is sitting, and its releasing fully and the throttle body is closing like it should. I tried adjusting the idle down to see if that would help, but it hasn't. The only way I can get the car to idle under 1000 is if I shut it off and let it sit for several hours. Once I press the gas at all, the car just stays and idle's at whatever the rpm's were at when I let off the gas. The car has cruise control, but I'm not setting it or turning it on. Is there any way that there could be a malfunction in the cruise control keeping the idle up? I have to drive this car like a grandma, or it will sit and idle at 5k+. Any input would be greatly appreciated....

I just went out and let the car warm up, and once it starts to surge between 1200-1500 (which it does repeatedly several times a second, which I have seen is a common issue) if I unplug the MAS it stops surging. Would this just be because it drops into limp mode, or should I just assume this MAS is bad?

I think I meant MAF. Its the factory one. Also, will the MAF out of a turbo starion work for me?

 

[Lone]

I have an issue with surging at fast idle and I have assumed it was the FIAV that needed adjustment. It would mean taking off the throttle body and removing the freeze plug, which is why I have not done so.

Other than that it might be the ICS. I found one out of a Hyundai which has worked just fine.

 

[Dsmkauai]

Have you checked the tps sensor to verify its within spec or adjusted properly?

 

[jmak06]

When I hook the car up to a snap-on diagnostics computer, it gets an accurate reading from the tps, but I guess that still doesn't mean it's working correctly. It's just weird, because it's like the car doesn't throttle down, just stays wherever I had the pedal at last. The pedal goes back to where its supposed to, and when I watch at the throttle body, the cable releases the throttle to back where it should be for idle, but the rpm's never go down.