Hello. I'm looking for advice on my car problem. Since I bought my 92 Corolla All-Trac wagon, it's had a horrendous hesitation problem. It basically cuts out intermittently, as if someone is flicking a light switch that's connected to the spark plugs as I'm driving. It happens alot under acceleration, more so when cold, but also occurs at seemingly random intervals while cruising at any given speed. I can be driving comfortably down the road at 100 km/h and suddenly experience a nasty jerking. Sometimes it just jerks once, and sometimes it can keep happening, until I step on the gas hard and let go, or put the clutch in and rev the engine, or something to interrupt it.
I checked the ECU for codes and only got the steady 'it's all good' flash. I also checked for vacuum leaks with unmixed propane through a
1/4" rubber hose, in all the places I could think to look. I also checked the oxygen sensor for proper voltage swing and the correction factor - that's right in the middle.I suspect the EGR valve. A few times I have tried disconnecting and plugging the vacuum hoses to the EGR, after which the hesitation will go away for a period of time, but then it always returns. Then I reconnect the hoses, the same thing happens - it gets better, but only for a while.
Accompanying this hesitation is intermittent rough idle / surging, sometimes when I let off the gas after taking it out of gear it will hold at 1500 rpm or so before returning to 800. Also there is an intermittent gurgling noise coming from the air intake, which comes and goes, and sounds alot like exhaust going through the EGR valve. This happens at idle. I can't do anything to make it start or stop, including messing with the EGR vacuum hoses.
Though I suspect the EGR valve, it checks out fine when tested according to the book. I get vacuum when I should, and no vacuum when I shouldn't. Could it be leaking?
This car was owned by one meticulous owner before myself, and they did everything to it when it had to be done - I have the service records. Fuel filter, spark plugs, wires, injection cleaning, etc. were all done regularly.
I'm looking for suggestions - am I right to suspect the EGR? If so, can anyone tell me where the pipe is that brings the exhaust to the EGR valve? I can't seem to find that, it's so buried under there. Do I have to take the intake manifold off to replace the EGR? The manual was uncharacteristically silent on both of those matters.