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Hesitation Issues (In Case You're Bored At Work)


Apr 11, 2017
Troy, MI
1992 Black Z07
This is my second post. I have had 0 starting issues since I ripped out the aftermarket alarm, replaced the battery, and refreshed some grounds. But I'm still having a small hesitation issue on my 92 LT1 6 speed.

Sometimes when driving, mostly under load but not always, I get some hesitation or stumbling. The only codes i've been getting are for a rich condition. I am getting some popping and a backfire here and there when decelerating.
It fires right up and idles smooth. After 1/2 hour the idle increases to about 1100 rpm. Not sure if that's related.

New Parts Recently: o2 sensors, fuel filter, plugs, wires, battery.
Fuel pressure was about 38psi, 44 with vac hose removed from reg, stayed steady at throttle, leaked down to about 25psi after 1 hour. Regulator hose was dry.

Any ideas? I'm thinking of trying to secure the fuel pressure gauge and see what the readings are when it's warmed up and driving under load. I haven't checked any of the injectors yet, but the old plugs that came out all looked ok. I was leaning toward fuel pump, but the pressure looks good unless it's intermittent. Intermittent issues are the wost. It does have 130,000 miles and seems to have mostly original parts. I
- Fuel Pump?
- Ignition?
- Vacuum Leak?

Also, if anyone knows how to get the terribly cheap door panels to stay attached after replacing the door seals and window seals please let me know. It's bugging the crap out of me.
;squint: UPDATE:
On the drive home stumbling was much more apparent. It cut out a couple times enough that the engine stalled on the freeway. Luckily it started back up and continued on though. The CEL was on and off every 5 minutes. Idle also bumped up again to between 1500 and 2000 rpm. Lastly there's a squealing - pulley, belt, alternator? Codes from when I got home:
H45 - Right O2 rich
H65 - Left O2 rich
H53 - System voltage fault

So, yeah. I guess I should start with the alternator. Maybe a couple issues going on, unless alternator on the fritz can cause weird issues.
Oh, and in dash gauge voltage was going back and forth between 4.1 and 4.7 volts.
Still Stumbling Under Load

The alternator went in along with new plug wires. No problems there. However I'm still getting hesitation under heavy throttle. Idle and cruising are perfect.
No CEL lights came on this time. I'm not sure what to start looking at. Maybe it's time to get data logging.
Maybe it's time for you to get a Factory Service Manual and read the diagnostic info for those codes.

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