So, I put in my new (used) TPS today. I started the car to warm it up to properly adjust the TPS when warm, and it ran absolutely pig rich; any time I would let off the gas even a little bit (I still had to hold the gas to let it warm up) it would shoot massive flames and sound like I just fired a pistol across the parking lot. Now that all my sensors are in order (BAC, TPS) is it possible that I have a bad MAF too? Any input would be appreciated. Mods in sig, still no fuel control yet, no CELs either. Thanks for the input.

 

are you sure the TPS is a good one? did you mess with the adjustments prior to replacing it? if the TPS is way out of adjustment it will think you are under a load and try to compensate by richening up the fuel trim. try adjusting the TPS with the car cold just to get it close then adjust it after it warms up. also if you adjusted the variable resistor it could have something to do with it. and the thermosensor as well has alot to do with idle mixture, be sure to test those and be sure they are plugged in tightly.

 

Check your plugs and variable resistor if its still good. Other than that you may have very leaky injectors, does it flood easily if you shut off the engine?

 

Do a full tuneup to start, then look at all the sensors. Make sure your TPS is adjusted properly, and test the water temperature sensor (back of water pump housing).

Once you have eliminated the sensors, you can pull your injectors and check them for leakage.

 

I messed with the old TPS quite a bit before I replaced it. The car seemed to run the best with it set to about 2.5 Kohms (yes, i know that is a rediculous number). It had a weak and highly variable idle, but it drove fairly well. When I set it closer to 1 Kohm (I ran out of screw at about 1.1) it would idle high, but strong, and had a nasty surge, and would occasionally just completely lose idle for whatever reason. After initially thinking the surge was the BAC valve, I replaced that, but it didn't help at all. So I bought another TPS from a forum member and put that in today. I set it to 1 Kohm cold, and put it in. After the first bout of flames and what not, I adjusted it out ot about 1.25 Kohm. Where is this variable resistor I keep hearing about? I think that might be my next target along with the water thermosensor. It starts like a champ and rarely floods, and has fresh plugs,

 

your old TPS could have been sending a faulty signal, i always try to adjust it with the signal wire to the ECU, if your ECU is covered still you can backprobe the green signal wire off the TPS (while it is still connected, key on engine off) and adjust it to 1volt, warm the engine then readjust it.

the variable resistor is on the front of the RF strut tower, if it has a cap still on it leave it alone.

the thermosensor is on the back of the water pump housing near the thermostat.

 

totally forgot about that one. You'll run rich if its bad.

Leave the TPS to 1kohm, that is factory. Next, set the timing. Third, find that vacuum leak to eliminate the surging. Surging is actually not really related to the TPS, its a combination of things, like I mentioned above this sentence.

 

What did you do for a fuel pump? Have you checked fuel pressure?

 

Fuel pump is a stock S5 TII, I have a walbro ready to go in with the fuel mods. What is a good way to go about checking the fuel pressure? Thanks for all the input so far!

 

just a simple pressure guage with a "T" fitting, hook it up inline just past the fuel filter and prior to the metal lines.

 

Wow, after running outside to look for the variable resistor, I realized I don't have one. What does the plug look like for it? Cuz there is a 2 prong white plug that looks like it could possibly hook up to something.

 

it should be right in front of and below the pressure sensor on the front strut tower, be sure as i said, if the cap is still on it or if it looks undisturbed leave it alone.

 

Then it is def not there, I only have a boost sensor there...I think that may be my problem. I'll check the thermosensor tomorrow when I have light.