Wont Go Away!!!!

[l3LacK Tsi]

ok i have a 1991 eagle talon tsi fwd. only free mods done. but i had this problem before them so i doubt they are having this effect. but anyways the problem is as follows i was having a idle problem so i replaced the isc plugs wires fuel filter and checked base timing all are good. today i replaced the tps and adjusted it to .49 ohms (.48-.52 ohm tolerance)when the car is at idle i get a check engine light but it idles fine. as soon as i give it some throttle the engine light goes away and if i hold the throttle at 1500rpm or higher it pops and almost sounds like a misfire also it smokes alot but not at idle only when im giving it some throttle anywhere from 1500 on up i would say greyish smoke. if anyone has any ideas please let me know im pulling my hair out over this. if anyone is in the virginia beach area and willing to stop by and give me a hand it would be great. but if not all ideas welcome...

 

[92awddsm]

when the car is at idle i get a check engine light but it idles fine. as soon as i give it some throttle the engine light goes away and if i hold the throttle at 1500rpm or higher it pops and almost sounds like a misfire also it smokes alot but not at idle only when im giving it some throttle anywhere from 1500 on up i would say greyish smoke.

Did you happen to check ecu codes to see why the cel is on? If not, go here And learn how to. Also pull the ecu and check for leaking caps. You can see how to do that here

 

[johnk]

If it goes away when you press the gas I would put 50 bucks on your TPS being bad. Your CEL code will tell if I'm right so check that before you go replacing things randomly. Mine did the same thing except that it would only show symptoms when the engine warmed up. The misfiring could be from the TPS registering anything mine would typically go WOT I could easily tell it was because I had a logger but also because my O2 would shoot up somewhere in the .8 - .9 range and stay there during cruise.

 

[l3LacK Tsi]

didnt check the code but im sure the ecu is good i just replaced it when i bought the car because the owner before me had the bright idea to replace it with a n/t ecu but ill check the code and update in about 30 min or so

 

[johnk]

I'm assuming the ECU is good. Checking the code will tell you what error it is detecting and turning on the CEL.

 

[l3LacK Tsi]

ok checked the code pulled a 14 which is for the tps but could the code have triggered while i was adjusting the tps? i tested it before i put it on the car aswell as the new isc and both tested ok. ill test the tps again on car so i can check the ohms as i move the throttle. but if it is bad why would the engine light go away when i give it throttle?

 

[johnk]

I missed the part where you said you replaced it. Yes the code is a stored one and you should reset your ECU (disconnect the battery for a min). Then drive the car around for 5-10 mins and see if the code comes back or not. As I said before it is much more likely to show when the engine has been warmed up for a bit.

 

[l3LacK Tsi]

ok im going to clear the code and see what happenes but is there any other things that could cause the pop/misfire? like i said from 1500 and up if i hold the throttle stable it makes the popping from the exhaust misfire sound almost.

 

[l3LacK Tsi]

ok took off the neg bat cable and let it sit for way more then 10 -15 sec code went away then came back....

 

[johnk]

Well if your sure it's set right then sounds like you have a bum sensor. Only other possibility is bad wiring but I really doubt it. Best thing you could do is borrow a datalogger and check it out otherwise buy a new sensor.

Edit: Plugs are most likely fowled you've been running rich if your TPS is out of whack maybe your misfire problem.

 

[l3LacK Tsi]

ill pull the plugs and check them tomorrow along with recheck the tps and make sure its set correctly. if all else fails ill just have to get another sensor. ill contact the guy i got it from in the first place and see if i cant get a replacement if its bad

 

[oldman]

ok took off the neg bat cable and let it sit for way more then 10 -15 sec code went away then came back....

You need to leave it off for at least 15-20 mins.

 

[oldman]

You need to leave it off for at least 15-20 mins.

Correction: Just spoke to steve, the ecu expert, he had inform me that 1min would be enough.

 

[l3LacK Tsi]

cool thanks. before i do that im gonna check all the specs again make sure its set up right then ill take it off and let it sit. i just put the plugs in it maybe a month ago would it be worth it to clean them or should i just get new ones? i also noticed a puff of smoke from the engine when i brought it up to about 3800 rpms then let off. any ideas on that one?

 

[oldman]

i also noticed a puff of smoke from the engine when i brought it up to about 3800 rpms then let off. any ideas on that one?

Check the turbo for shaft play and licp and ic for oil. If you still have the breather hoses routed back to the intake, disable it and plug up the nipple on the intake then clean out the licp and ic. Go back and check for any signs of oil after couple days of driving. Make sure you perform a leak test after everything is done. A puff of smoke right after letting off usually points to the turbo. If wouldn't hurt to do a compression test as well.

 

[l3LacK Tsi]

ya i figured it would be the turbo. the guy i bought it from drove it around his land like a mad man so im sure he beat the hell out of it. as for compression that was the first thing i checked when i went to go buy it. it was 172 on all 4. ill pop off the licp and check for oil while im waiting for the code to clear. thanks for all the help ill keep upates on how it comes out.

 

[steve]

today i replaced the tps and adjusted it to .49 ohms (.48-.52 ohm tolerance)

I'd guess your confused. The setting of a 1G TPS is to 0.48 to 0.52 volts as measured between pins 2 and 4 at the TPS or pins 19 and 24 at the ECU on ohms. If you have a datalogger, that should be about 10%.

Steve

 

[l3LacK Tsi]

no im not cofused but thanks for posting. i ment to put volts for setting it ohms for testing it. .48-.52 volts to set it to test the sensor it self its 3.5 6.5 kohms sorry bout the misprint from me before. but thanks again for reading my post and anyother input you have would be great. oh ya pulled the plugs they looked pretty good.

 

[steve]

If the TPS error code comes back after resetting the ECU (removing power) then it's likely the TPS or it's wiring is bad. The get old and wear out. Mine tested good cold but as soon as it warmed up it would go intermittant and the voltage would drop out causing the CEL and the engine to buck and miss.

Steve

 

[l3LacK Tsi]

thats what its doing for me. it only misses when i hold the throttle steady anywhere from 1500 on up. and it smokes bad once it warms up smells like oil/fuel no more CEL though

 

[johnk]

The light won't show if the pedal is depressed. There are 2 sensors involved in getting that code to show. One the obvious TPS sensor you've been trying to fix. Two is the idle switch on the back side of the throttle. The ECU can only "know" that the input from the TPS is wrong when the idle switch says the throttle is closed and the TPS says that it's part or wide open throttle.

Really wish you had a datalogger you could read the ECU input from the TPS. It's a worth while investment if you plan to go far with modding your car. A used palm and patch cable are cheap off ebay and the software you can get for free.

 

[l3LacK Tsi]

yeah i saw that switch in a diagram but wasnt sure if it would have any effect on it. can i get one of those anywhere of should i try the guy i got my other stuff from ?

 

[johnk]

You can check it by checking it with an ohm meter. See if the pin grounds when you press the switch.

 

[l3LacK Tsi]

what do you mean press the switch? all this has on it is a single wire connecter.

 

[steve]

When the throttle is closed that connector should be grounded (switch is closed). When you open the throttle slightly the connector should be not grounded (switch is open). If you do it while the ignition is on your see 12v at the connector when the switch is open and 0v when it's closed.

Also check to make sure the grounding strap for the throttle body hasn't been removed. It runs from one of the mounting studs to a screw on the top of the throttle body.

Steve