TexasHonda,

I was wondering if you have had any success? I have had the same exact issue with one difference. Under heavy throttle the car hesitates.

I too have replaced much of the same parts including the intake gasket seal but I have not replaced the valve cover gasket.

Were you able to determine the root cause? My next step is the fuel pump.

Here is the link to my troubleshooting post on Toyota Nation.

Thank you

 

I wish I could report I had solved the problem, but sadly that is not the case. It's still showing CEL and running rough occasionally. My daughter is driving the car regularly, and fault is tolerable.

I'm very skeptical a fuel pump will resolve your problem.

The only real clue I have gathered is that fixing minor leaks on PCV hoses reduced the LTFT from 35% to about 20-25%. This seems to suggest that intake air leaks are real and from some source.

I have also thought about ECM as a culprit, but this is only a hunch w/ no facts to back up.

good luck

 

Thanks for the reply. I noticed that you have not replaced the intake manifold gasket yet. There is a TSB for the 2001 Celica in regards to the intake gasket. The part is only $5 and takes about an hour to replace.
I replaced mine and there was noticeable wear on the gasket but it did not fix my problem. Being that you have a 2001 that falls within the TSB and it is only $5; I would recommend giving it a try.
Just be sure to hook up all the vacuum lines back to the manifold. There is one on the back side near the throttle body that is difficult to see and it is short, making it difficult to reconnect. Failure to connect this line back will prevent the car from running at all..... speaking from experience.

Please keep me updated if you find a solution.

Pictures below show the old and new gasket... Old gasket is on the left and is compressed and melted.

 

Here is a good write up... and the TSB

Toyota TSB EG046-07M.I.L. "ON" DTC P0171, P030#, And / Or P0133 Engine Running Lean In Subfreezing Ambient Temperatures.

 

The reason I didn't replace the intake manifold gasket is I couldn't detect any indications of leaks and I tried hard spraying copious amounts of throttle body cleaner around the intake manifold. Also the vacuum level looked good to me (21" at idle).

I don't have access to the car now but may have an opportunity at some point in future to replace the gasket.

Thanks for the tip and links.

good luck

 

Just a follow-up in case others read this post.

I replaced the fuel pump yesterday and the difference is amazing. The car is more responsive and the LTFT fell into place.

I need to get a few more miles to make sure the CEL does not return but it is looking good.

 

Thanks for posting.

I found no difference w/ fuel pump replacement for my problem.

good luck

 

I took Celica to a local shop w/ good rep for diagnostics. They flow tested the fuel injectors and determined two had significant blockages. This resulted in lean fuel mixture and excess LTFT attempting to compensate.

I accepted diagnostic results, paid them $95, and returned home. I had two paths; either attempt to clean injectors myself or replace them. Since I'm planning to sell the car and no rush, I decided to attempt to clean them.

I used aligator clips and 3-AA bats to get enough voltage to open the injectors reliably. I used throttle body cleaner to clean by injecting cleaner in both directions and using air jet to force the cleaner through the injector.

After cleaning, I reinstalled injectors and fired system up w/ my OBD2 scanner to monitor LTFT. It was significantly less, < 20% and low enough that P0171 was not set after clearing all system tests. First time this car has a clean Obd2 scan in 2 years!

I got my emissions inspection and safety certificate to allow me to register car again in TX. I plan to sell shortly. Car is mechanically sound, but my daughter left body in pretty bad shape; lots of dings, dents, damage. I spent this evening getting sunroof (what a useless feature) to work.

This is first time I've run into a fuel injector problem. I had discounted possible injector problem for two reasons. I couldn't easily test them and car idled fine which suggested injectors were working. However, partial blockage apparently can result in uneven fuel distribution and resultant lean condition.

As part of my repair I reviewed videos on youtube for "fuel injector cleaning". There are plenty of good tips, but most are overly complicated. My mistake was too little cleaning. I should have done more forward/reverse cycles. I added a can of Seafoam to my gas to hopefully clean them better as I drive.

Regards

 

Good to hear you got it pass.

So what is she driving now?