Running rough

So my fiero has been running a little rough lately, though intermittently.
Yesterday it was stumbling whenever I gave it some gas on my way
home from work. Checked all the plugs and wires and it all seemed
fine. SES light was on though and I don't have a scantool. Driving out
to Langley yesterday was perfectly fine with no issues.

Today driving to the fireworks was fine with no issue but returning
home it felt like it was weaker and revs would fluctuate at steady
throttle. The SES light was on again as well and after about 20
minutes of city driving when I looked in the engine bay the manifold
was glowing a little.

For a while now it's had some stumbling on throttle but not on every
drive. The SES light would occasionally come on when I start the car
but if I shut it off and start it up again it's fine.

I've had codes involving the o2 sensor in the past so would a
dead/dying sensor cause these problems or could it be something
else? I'll still be at autoX tomorrow so if someone there could help
diagnose things it would be good. Unless it decides to run trouble free.
I will try to take it somewhere to read the codes this week, otherwise
does anyone have a code reader that will read obd 1.5?
This is in my 3800 sc1 swap in 88gt. Motor from a '95 olds 88

I've got a very similar problem, only I have the 2.8. My
exhaust doesnt glow though

Well I replaced the o2 sensor with a new one, and it is now worse
than before. It stalled on me on my way to work this morning and was
really hiccuping quite a but. At points the throttle would just make it
stutter instead of rev up.
It idles fine and in park it is usually ok but occasionally stumbles when
I open the throttle.
Could this be a vacuum leak or bad tps or air sensor? It's quite
intermittent but has been getting worse the past few days. Hasn't
thrown any codes other then once when it actually stalled.

I will try to test the TPS tomorrow. When idling, if i blip the throttle a
little bit, it will sit around 1000-1200 for a few seconds before coming
back down to normal. I think its the MAF sensor it only has one of the
MAP/MAF sensors and I always get them mixed up. it's in the throttle
body if that helps.

I go to pennocks every now and then so maybe I will ask there.

Oops, I meant that I fixed the u2/o2 typo. I can see how that would be
confused lol.

I put clamps on a couple vacuum lines that felt a little loose and it
feels like it's running slightly better, but still not fixed. I'll try to trace
any vacuum leaks and fix those if there are any.

D_sensitized wrote: Does anyone have a spare canister they would be willing to part with at the meeting?

I can give you one.

 

Well, still havent figured out the problem. I found one cracked vacuum
hose and replaced it but it's still not better. It usually has trouble when
I first start it up in the morning and after work and is really struggling
and stuttering as if it loses power for a split second, then after a
minute or 2 it drives fine. Just a couple hiccups here and there once
I've started driving but nothing big. The speedo also flies around
sometimes when the engine stumbles and sometimes just on it's own.

This morning was the worst, ran so terribly it died after a minute or 2
and on the third try, stayed running and went on as normal with a bit
of stuttering as I drove off. Only time the SES light came on was when
it couldn't stay running that one try this morning. Gonna try to take it
to the shop tomorrow and see what the scanner has to say.

It just keeps getting worse
Am currently waiting for a towtruck on the side of the highway. Was
able to drive for a little bit and then it would get quite rough and all
throttle response would go down to zero and I would have to coast to
a stop before the engine finally cuts out. Will look up the procedures
and test as many sensors as I can to see if it's one of those, otherwise
I suspect it to be wiring, in which case I will probably take out the
whole harness and inspect it all.

Unplugged and plugged back in the MAF sensor and it coded, so I
assume it's working. O2 sensor is new so that should be fine.
Backprobed the throttle position sensor and got 4.6v at closed and
.888 at wide open. Are these values ok? Smells like it's running rich
as well so there's too much fuel going in.

Shop was too busy this week so I couldn't get a scanner on it.
Another thing is at idle, when revving up to around 3k, the speedo will
go up to around 10 km/hr when I'm sitting still.

Thats all I have time to do tonight, Sunday I will get more time to dig
into it.

You know.....I just went through your whole thread and it really seems like it's timing to me.  Like you're totally loosing timing for short periods of time.  I would check your crank sensor.  I bet it's buggered.

The Dawg