Hesitation and surging


Old 07-22-02, 06:37 AM
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Hesitation and surging

I own a 1990 Toyota Celica GTS with the 2.2L engine. The problem I am experiencing is hesitation and surging.

The hesitation only seems apparent when the air-conditioning is running and occurs just after the gas pedal is depressed when taking off from a stopped position (at roughly 1200 RPM). Once the vehicle is already in motion the hesitation does not seem apparent. Depressing the pedal further for an instant will allow the car to continue to accelerate or holding the pedal steady during the hesitation and waiting for it to subside.

The surging takes place whether the air-conditioning is on or not and seems most predominant between 1800 RPM to about 2400 RPM while the gas pedal is kept steady and before the car has completely warmed up. It also seems like it is an intermittent problem, however, with the air-conditioning on it is usually much more apparent.

I have already taken the liberty in replacing and checking some items for either previous problems and/or diagnosis.

The EGR Valve was recently replaced due to a stalling problem and the spark plugs and wires and distributor cap and rotor and fuel filter were replaced in order to rule them out as a contributing factor. All parts were purchased from Toyota and are genuine Toyota parts. Also, I recently adjusted the TPS (throttle position sensor) as to make sure it is within specification and replaced the air filter (genuine Toyota).

Inspection of the air intake plenum has revealed a buildup of a black oil residue, however, it does NOT appear to be blocking any vacuum passageways etc.. Also, it may be interesting to note that once the vacuum from the EGR valve is disconnected the problems dissappear.

Any help on this matter would be appreciated.
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Old 07-22-02, 07:14 AM
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Sounds like a clogged EGR port to me or a stuck EGR valve.

Take it out and have a look. Does the vehicle burn any oil? How's the PCV system?
Old 07-22-02, 07:25 AM
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Thank you for the quick response Joe.

I had a look at the EGR port in throttle body when I had replaced the EGR valve, which was only a couple of weeks ago and there doesn't seem to be any blockage. I doubt the EGR valve is sticking as it had been recently replaced with a new one. Unless of course it is has a manufacturing defect.

On the 1990 Toyota Celicas there is not a PCV valve and only a PCV hose and it had also been recently replaced with a new one due to the old one being cracked. At this time I cleaned out the throttle body and checked for blockage of the hose and cleaned as neccessary.

Assuming it is not the EGR valve, is there anything else that may be causing the problem?

Old 07-22-02, 09:15 AM
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Some Toyotas have vacuum solenoids that regulate when the valve comes into play. You might look at testing those.

I suggest you pick up a Toyota OEM manual or it's going to get expensive throwing parts at the problem....

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