my '91 SE 5spd has been missing, or hesitating at low rpms in lower gears. it almost always happens while the engine is under load somewhere north of 1100 and maybe 2000 rpm. over 2 grand it still runs like a raped ape. any ideas?

at first i chalked it up to winter weather and water in the gas. then i noticed my coil wire was basicly off. but, fully plugged in it only ran marginally better and still missed. so far i've replaced the plugs, wires, cap and rotor and still runs the same. also tried a different coil, to no avail.

it does run better on very low humidity days. grounding seems to be a possibility...as does a bad injector, however a bad injector would make the engine run badly at any rpm.

appreciate any input!

 

Mine does the same thing, especially when the engine is cold.

 

It could be a few things, but Im thinking it's the TPS(Throttle Position Sensor). Read somewhere that it causes hesitation up until about 2,000 RPM. Normally I think they get dirty or something like that and don't function properlly. Maybe needs adjustment(if possible) or replacement.

I actually have the same exact problem you are talking about. On less hot days, the car performs beautifully.. Still didn't get a chance to check it out. Also, if it was a bad injector you would feel some shaking coming from the engine bay aside from major performance loss.

 

If it does it only when the engine is warm, you might have a bad o2, so check that one out, I had heistation around there, but only when the engine was warm, turns out it was the o2 sensor for me.

I probably have some tps issues too with regards to my bad idle since I just cleaned my intake manifold and EGR valve so....

 

ENGINE uses TPS only when cold. Clean, adjust:

How? http://www.cardomain.com/memberpage/748507/6

 

I see, so after engine is at operating temperature, hesitation should go away if TPS was the problem?

 

1. Cold engine: MAF & TPS. (...of course always THE temp sensor)

2. Hot engine: When engine becomes to operating temp, O2 sensor will be used by ECU. Only MAF & O2.

2+ TPS is still used by autotranny to calculate gas pedal movement speeds =drivers desires: if tranny gearchange has also problems --->TPS.
check out http://www.cardomain.com/memberpage/748507/15



Whattodo? with TPS http://www.cardomain.com/memberpage/748507/6

Whattodo ?with heS hitation http://www.cardomain.com/memberpage/748507/9




Get rid of this noise! Do your groundwork.
see http://www.cardomain.com/memberpage/748507/10





After groundings are in place, see how nice this same squarevawe becomes! No ECU distracting signal spikes...

 

thanks for the info guy's! i've noticed in my particular case it only happens when the engine warmed up. runs beautiful at cold idle. some times there is major bucking, but mostly just gross hesitation and burbling. i'll check into the O2 sensor. with 180k on the clock i'm sure there is other issues as well

 

I had the same, almost exact, problem with my 91SE. It was the O2 sensor. You can test it out by disconnecting the O2 sensor (unplug the connector between the engine and firewall, near the bottom), and then seeing if your hesitation goes away. It helped me that I had a long uphill road that _always_ caused the hesitation.

The Haynes manual describes how to disconnect and test.

M

 

I sell o2 sensors