91 Celica St Hesitation

Some things to check:

Check the air filter to make sure it is not clogged.

Check the plastic intake snorkel between the air filter housing and throttle body for cracks or holes.

I can't remember if that car uses an air flow meter with a hinged flap or if it uses a mass air flow type meter. If it is the type with the flap, make sure it moves smoothly and freely. If it is the MAF type sensor, make sure there is no gunk built up in the sensor opening that sticks into the air flow.

Check ignition base timing.

Try a bottle of Chevron Techron fuel injector cleaner.

If you used aftermarket ignition parts, that may be the cause of the hesitation.

Thanks for the info. Cleaned all electrical connections, Intake Throttle, mass flow sensor, and replaced cracked intake hose where throttle meet. and still same problem. Could it be the EGR Valve? :roll:

"Coyoteboy" wrote: > > I can't remember if that car uses an air flow meter with a > hinged flap or > > if it uses a mass air flow type meter. If it is the type > with the flap, > > make sure it moves smoothly and freely. If it is the MAF > type sensor, > > make sure there is no gunk built up in the sensor opening > that sticks into > > the air flow. > >

Did you clean the electrical connection for the MAF sensor or did you clean the wire inside the sensor? If you did not clean the hot wire inside the MAF sensor, give it a shot of carb cleaner and gently swab it out but do not break the wire!

You can check the EGR valve by temporarily disconnecting the vacuum and blocking the hoses to the EGR valve. If the hesitation goes away, remove the EGR valve and clean out the black gunk that has accumulated inside and put everything back together. If cleaning doesn't work, replace the EGR valve.

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I think I just got ripped off... I finally gave up and took it to my mechanic. He said it took him a week to find out what was wrong. He said it was the distributor that somehow got oil inside. He also replaced the spark plugs that he said were cheap. He told me not to use cheap parts. I just looked at my old receipt that stated that he replaced the Spark plugs 8 months ago. He said he bought a use Distributor for $100, but it looks the same to me ( color, dirt, no scratches on the bolts, etc. ) He returns only 3 spark plug, were is the fourth? ( possible the damaged on and were is the old Distributor? I think the problem was a bad spark plug and he got me for this. I will never trust him again and my friends and family will also not go to him again...

"CoolPR" wrote: > Thanks for the info. Cleaned all electrical connections, > Intake Throttle, mass flow sensor, and replaced cracked intake > hose where throttle meet. and still same problem. Could it be > the EGR Valve? :roll:

Oil can get into the distributor past the O-ring on the distributor shaft. It is not necessary to replace the entire distributor to fix the problem, just replace the O-ring.

Toyotas tend to run better on OEM ignition parts.