rough idle, lagging acceleration - Toyota Nation Forum : Toyota Car and Truck Forums

pageone · 05-03-2004, 05:04 PM

I have a '91 Celica GT convertible with the 2200 4 cyl., automatic transmission. It currently has 112,000 miles. I have recently done a fuel injection cleaning, throttle body cleaning, air and fuel filter replacement, timing belt, oil pump, water pump replacement. New plugs, wires, distributor, (cap, rotor and a rebuilt distributor) The TPS sensor seems to be operating properly. The car is running good but not perfect. When it is in drive and just idling it's rough, the steering wheel is shaking noticeably. While driving on the freeway at 50 mph or so it seems to lack power. I have to push down to passing gear to get acceleration power. I replaced the oxygen map sensor with a map sensor from a salvage yard out of a supra about a year ago, same part number. Any suggestions about what I might check or what this may be? Thanks.

mykngdom4avvti · 05-09-2004, 11:42 PM

Usually with the circumstances you have outlined I would say check the timing and vacuum advance module on the distributor. Make absolutly sure that your timing is right on, and then work from there, checking everything (even things you have already repaired or replaced.)
Toyotas are pretty notorious for mass air flow meters and throttle position sensors dieing.
There is a fairly simple process for checking the TPS which just involves an ohm-meter. The manual will ask you to patch into two different prongs of the TPS with your meter and read the ohms value. With the srews holding the TPS to the throttle body lose, you just turn the TPS until your meter reaches the values in the manual.
If you said you have already checked the TPS and it was OK you probably already know this, but I thought I would include it in this post incase you were using a different method to check the TPS.

pageone · 05-12-2004, 02:27 PM

Thanks for your response. will try those steps...

lloydjv · 05-13-2004, 11:23 AM

Be sure to check the idle speed control sensor as well. They are also known for malfunctioning. Try this: remove the harness from the ISC, it is the white sensor attached to the throttle body directly under the t/b mouth. Then remove the mounting screws and remove the entire sensor from the t/b. Start your car and see how it runs. My idle is set to 1000 RPM, and my 91 GT runs very smooth.