P0172 Toyota Celica

Hi,

I have a Toyota Celica GTS with the VVTL-I engine. I recently purchased it and was disheartened to find a check engine light after a few days of driving. My friend came over with his Actron and cleared it thinking it could have just been the fuel cap.

P0172 refers to "The PCM has determined that during testing, the fuel system for bank 1 was too rich....."

After clearing it did not come back. Driving around for a bit with no check till I unfortunately had the first hand experience of burning out the clutch. The engine light was on at the point as well but I never was told what the code was. I recieved a new clutch and oil change and was told the check engine did not come back.

So far I've driven it for 600 miles and on my way back from short drive as I was pulling in the light came back on again. After checking it is P0172 again!

I'm a broke college student but I also love my car. Does anyone have any idea where I should start looking? If I should give up the money and go into a shop and have it fixed? I am also worried about any adverse effects this issue might have on the engine.

- Josh

Edit - The car has been modified by a previous owner. The modifications include a Cold Air Intake which I do not believe fits correctly, a shifter, I am not quite sure what else might have been added.

Check/clean the MAF (if equipped), make sure that the Cold Air Intake is SEALED against any vacuum leaks.

Does it have an oil type air filter (K&N)? If it does, it can bugger up the MAF.

Check for any other vacuum leaksas well as fuel pressure.

I assume you bought it privately and not from a dealer. If you bought it from a dealer, take it back to them for repair...they may repair it for free.

Good luck and keep us posted.

P0172 indicates that the PCM reached it's correction limit and can't take away any more fuel in order to make the car run properly. It's likely a fuel system problem, so starting with a fuel pressure test and a fuel injector leak down test to see if any of the injectors are leaking. That would also be a good time to check the fuel pressure regulator for any kind of internal fuel leak past the diaphragm.

Update

First I'd like to thank you both for the replies, I will try both tommorow when I get a chance to work on the vehicle.

Here is the update. Yes unfortunately, the check engine light is back on, after about 40-50 miles.

I also inquired with one of my college professors, he is a jack of all trades. He adds that it could be a faulty oxygen sensor, most likely the one before the cat converter, but either one. Worst yet it could be the cat itself. I do get awkward moments where I can smell a sort of burning sensation but I always thought that was me being rough on the clutch. I am a new driver to standard transmissions.

So to add to the list.

Oxygen Sensors, or Cat Converter. Is there any easy way to check these items?

Again thank you all for the help. I will keep you posted on my findings.

Josh

HI ...
I also agree you are having problems on your fuel system, prssure regulator, injectors etc. Also you can make a good clean to the intake system, maybe your intake and MAF are dirty...

Sorry for such the long delay, I've been really busy. Too busy for my favorite thing in the world, its sad.

So I got to working on the car today and I do several things. I got to my instrument panel and the customized lights I wanted to fix, thats for a different forum.

I cleaned my MAF sensor. I picked up one of those cans from Pep Boys for 8 dollars. When I pulled it out, the first element dangling down on the side of the center piece was crusted with dust. Not coated but crusted. A few sprays of MAF sensor cleaner and it came right off, I made sure to get the elements on the inside of the MAF pipe. I didn't touch the elements at all only sprayed them with the cleaner.

I give it about 15 minutes to dry, 10 more then the recommended drying time on the can. So I start the car up, my friend is in a rush to get his car out of the garage so I pull it out of the drive way, which is on a hill so I throw my car in neutral and let my car coast.

I've got the car in first and I'm ready to pull around the circle so I can pull back into the driveway my car does not go anywhere. I press the gas pedal down about 2-3 inches (a lot lower than my usual 1-1.5 inches), it sounds like the gas is slowly being pushed in, when I get down there all the way down my car revs really high. It normals out from there. I pull into the garage and let it sit and its rocking in idle, its about 500-600 RPM and it sounds like as soon as hits 500 and is about to stall it gives it a little gas and brings it up to 600, so it rocks for about 30 seconds and I give it some more gas rev it up a little and its fine.

I figure at this point I've done something horribly wrong and I'm going to have to pay for it. I go upstairs to talk to my bud, he tells me to drive her around a bit and give the engine some time to recalibrate.

I start the car up, I can hear a dramatic difference. The engine is a lot, I don't know how to put it, beefier I guess. I pull it around the circle, normally the moment I touch the gas pedal I'm so high in RPMs that I have to shift into 2nd. This time, I get a nice smooth acceleration, I notice my ride being alot smoother in lower gears. Usually I get a jerky slow down and jerky acceleration.

I drive down the street at a smooth pace and I shift at around 2.5-3k RPM. When I rev her down the street, it takes longer to get from 3k-6.5k rpm. Before I'd be from 2-3k to 7k in just a few seconds, in 2nd gear. I also notice in 6k and above where the VVTL-I kicks in it feels ALOT more powerful.

Okay so the question now is, if I do an erase on that check engine code (note it hasn't turned off for several weeks now, and hasn't since I cleaned the filter today) will it come back. Now I have that option or I've been told I can pull the battery and do a check engine series of tests.

Thanks for all the help everyone. I hope that this was it and that I won't have to worry anymore. What do you guys think? I'll keep you updated.

You said the car was on a hill...do you have plenty of gas in the tank?

Clear the code, drive it for a couple of days noting drivability. If the CEL comes back on or if you have any drivability issues, check for codes and report back.