Ok car is a 90EF 5spd.
Once in a while i'll be driving and my engine light will come on, but it will not hardcode, so i'm guessing its an o2 sensor problem. After the car is warmed up, there won't be a code. I cannot find out which code it is since it will disappear everytime i shut the car off.

Well the car also will hesitate/buck sometimes under throttle as well with no codes showing.

Tonight, the car had a really crappy idle when first started up and an immediate engine light. Car rode like crap the whole way, with twitchy throttle and lots of bucking under light throttle input. Decel even had some bucking.

However, after parking the car for 10 min, and then restarting it, i had Zero problems, no bucking, no code.

So i'm stumped... I plan on checking my plugs, fuel filter, wires, and the cap and rotor. The air element is new, so i pretty much rule out the air part of the equation... has to be either spark or fuel now right?

Any input will be greatly appreciated.

 

are you engine grounds tight? Mine did that and it was the thermo ground. Try it, ya never know!

 

i have very similar problem to the bucking. seems like mine only does it right after the car starts and sometimes only if its really hot outside and car is fully warmed up.

 

what code are you getting when the CEL pops on?

Next time you get the CEL, pull over and look at the ECU and get the codes. Don't turn the car off, just get the code.

 

on EF is there a light on the ECU instead of flashing the check engine light?

i also inspected the cap and rotor, looks like it could use replacement.

 

CODE 7!

Exactly what Im going through, measure you tps voltage. Mine wasnt even throwing a code on the dash. Only when I get on it above 4000rpm will I get some hesitation, but my car has always idled shitty, so I pulled over, didnt turn the car off and the ecu was flashing 7

Gonna fix mine tomorrow. Take 1-2 min with a digital multimeter if you have one.

Just stick the red connector into the middle wire form the tps (red wire) and the black connector to the - of your battery. You have to get it to say .45v at idle and 4.5-5v at wide open throttle.

Dont do this with your car actually on though, just click over to ignition (1 before it starts)

 

thing is car runs normal, 99% of the time, just once in a while it will hesitate. this isn't a common thing...

 

well, we cant help you till u find out what the code is,

so start there first, next time the cel comes on, pull over, pull the carpet up, and count the blinks,

get the code and post it and we can continue to help you.

My guess its the o2 sensor, my o2 sensor was bad and at 4k rpms in 5th gear if i was cruising the car would buck.

 

i too think its an o2 problem, that would be one solid blink correct?

 

yeah, basically it will blink over and over again, i counted the blink up to 20 and was like **** it, code 1

 

ok cuz usually the CEL will come on when its cold outside and the car hasn't warmed up to op temp yet and i've been doing 50mph. Sounds like the o2 to me, but also need to go ahead and replace the cap and rotor too.