Cylinder 2 Misfire - Can't track down the cause


Nov 17, 2021
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Las Vegas
I am hoping you guys can help me find the gremlin that is haunting my #2 cylinder.

The vehicle: 98 Tahoe, 2 Door, 4WD, 5.7, 223K miles - no knowledge of maintenance prior to 176k miles prior to purchasing the truck myself.

I will try to quickly run down everything I have done already trying to fix the issue as well as recent history of work.

Little backstory and recent work:
Originally, I was having some random misfires, especially under load, rough idle, a random O2 code here and there. I wasn't quite sure if I was looking at a fuel or ignition issue, but it was also time to do some tune-up type things regardless and I hoped the random misfires and such would be resolved when done.
About 3 weeks ago (222,500 miles) I went ahead and replaced the spark plugs (AC Delco 41-993), plug wires (AC Delco 9718Q), distributor rotor (AC Delco D465), distributor cap (AC Delco D329A) and did the CFI to MPFI (Standard Motor Products FJ504 injectors w/ gaskets and bracket) swap including a new fuel filter, air filter and oil change. When all work was done, smooth as butter. Really, the truck ran phenomenally for about 400-450 miles, by far the best since I had bought it.
Then out of nowhere, start getting a bad misfire. I pull the codes and P0302, cylinder 2 comes up. None of the cylinders throw misfire codes, no generic code for misfires. Just cylinder 2. So I started trying to determine the cause.
First, ran compression test - checked each cylinder twice. This seems to look fine.

Cylinder 1 - 165 | 165
Cylinder 2 - 169 | 170
Cylinder 3 - 167 | 170
Cylinder 4 - 170 | 168
Cylinder 5 - 170 | 167
Cylinder 6 - 160 | 165
Cylinder 7 - 164 | 172
Cylinder 8 - 173 | 170

Next, fuel pressure test. Numbers appear to be a little low, but wouldn't that affect other cylinders as well? Not just cylinder 2?

Key On - 60
Idle - 52
10 Min - 52
Driving/Missing - 55

I also swapped the plug and plug wire from cylinder 2 with a different one to see if the issue would follow the plug or the wire. Neither swap made a difference.

At this point, I noticed the plastic screw tab on the distributor was broken and the cap wasn't seating 100%. Great, I go ahead and replace the distributor as the original one was still in use. Based on recommendations, I put in the UNITED MOTOR PRODUCTS 9362 distributor and UNITED MOTOR PRODUCTS DCR820X cap. I verified the CMP retard is within spec at -1.4 degrees.

Still running rough and getting P0302 almost immediately if I clear the code.

Any thoughts or ideas? Things to look at next?

Thanks for any help.


I'm Awesome
Aug 7, 2019
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Dallas, TX
60 psi with key on, engine off is within spec. I think you can rule out fuel delivery issues (fuel pump.)

A fuel delivery problem would cause multiple misfires on both banks AND a lean code.

Since your idle pressure seems a a bit low (I don't remember the actual spec) it could be fuel pressure regulator.

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