O2 sensors maybe?
Thread Starter
Staging Lane
Joined: Apr 2012
Posts: 53
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O2 sensors maybe? Hey everyone, so I've had this problem for a while with my 94 Z28.
The car runs great when its cold, the throttle response is quick and fast. But after it warms up it starts to run a little rougher. If I punch it in park it doesn't rev up fast and smooth, it shakes the car and then will rev up. And I will also get some pretty nice intake backfires when warm.
There seems to be a slight miss around 2.5k rpm if I hold it when warm. Holding when cold it's smooth.
Also forgot to mention. Car runs great with the o2s unplugged
I've swapped on 3 different MAFs, no change. Tried different intake elbow with IAT sensor and no change. Tried different ICM (spaced off head and has the great) with no change. Different MAP with no change. (I have access to another z28 to try parts so I didn't buy all these lol)
The only thing I can think of is the o2 sensors since it only happens when warm and my WOT is fine. I replaced them a while ago with AC delco but maybe they went bad. My car ran super lean at one point, 14:1 thanks to my mail order tune
Wondering if that could hve hurt them? I noticed when I took my exhaust off to drop my trans, one o2 tip was white and the other looked like a normal brown.
Anyway to test them?
The car runs great when its cold, the throttle response is quick and fast. But after it warms up it starts to run a little rougher. If I punch it in park it doesn't rev up fast and smooth, it shakes the car and then will rev up. And I will also get some pretty nice intake backfires when warm.
There seems to be a slight miss around 2.5k rpm if I hold it when warm. Holding when cold it's smooth.
Also forgot to mention. Car runs great with the o2s unplugged
I've swapped on 3 different MAFs, no change. Tried different intake elbow with IAT sensor and no change. Tried different ICM (spaced off head and has the great) with no change. Different MAP with no change. (I have access to another z28 to try parts so I didn't buy all these lol)
The only thing I can think of is the o2 sensors since it only happens when warm and my WOT is fine. I replaced them a while ago with AC delco but maybe they went bad. My car ran super lean at one point, 14:1 thanks to my mail order tune
Wondering if that could hve hurt them? I noticed when I took my exhaust off to drop my trans, one o2 tip was white and the other looked like a normal brown.
Anyway to test them?
This sounds almost exactly like the issue that I am having. Does it run alright when you unplug the maf? I have tried multiple mafs and what not, and nothing works after it warms up, other than unplugging it.
My O2's were out of the car for a while when I was doing stuff to it, so maybe mine are bad too.
My O2's were out of the car for a while when I was doing stuff to it, so maybe mine are bad too.
