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1996 S10 2.2 liter; cylinder 1 miss fire

Hi all, my S10 pickup has been having some ‘issues’. Truck has been kind to me over the years, but now is runing a bit rough. It has an irreguler idle and continues to run this way through all speeds. The blinking code reads “cylinder 1 missfire”. I did all the basics. I changed the plugs and wires, ignition coils and fuel filter. Here is where is gets tricky, after changing the fuel filter, it ran great again. Then it started to run rough again later that day. I thought I somehow clogged up the new filter, so I removed the new one for inspection. Realizing there was nothing wrong with it, I reinstalled. Truck ran great again. Went out to drive it to work a couple hours later and it started fine, then after about 10 seconds of running, it went back to the rough idle. Any help would be appreciated. Thanks!

Fuel pressure? Motor runs ok till it gets hot. U fiddle with stuff so it cools down. Runs ok again. Do u have good compression? Stuck rings, burned valve?

Good fuel pressure. Motor warms up as normal. Oil pressure looks normal. Not sure how to check for stuck rings or burnt valve.

I also forgot to mention that sometimes, while it’s running rough, will run smooth again. It can go back and forth while I’m driving or idling.

Cylinder 1 miss fire is the only code? Does the engine make any different noises while missing such as a lifter not pumping up correctly or valve not closing fast enough?

A compression test is simple enough on a 4 cyl motor. If u find low compression in cylinder, than u figure out why. But if miss comes and goes, than it could be ignition. Bad plug, wire, coil, ign module. Could be faulty fuel injector. Though I think this motor has a Tbi style shared injector?

I would suggest doing a compression test. See how cylinder 1 compares to the rest.

Cylinder 1 miss fire is the only code.

Say the compression is low for cylinder 1, where do I go from there?

Stoveguyy, I replaced the plugs, wires, both coils. Could this be the result of a clogged injector?

A clogged injector could also be the culprit, but if my memory serves, that 2.2 is throttle body injection?

@Vhyle it is TBI

I don’t believe a clogged TBI injector would cause a misfire on one cylinder only.

@wheeler31 if #1 compression is low, squirt oil into the spark plug hole and check compression again. If it’s higher, the rings and/or cylinder are worn. It it’s the same, the problems’ top end (valve job, most likely)

Sounds like this may be serious. I really don’t want to get rid of it. Truck has paid for itself time and time again. Only has 84,000 miles, worn cylinders?

I’ll have to get ahold of a compression tester and post back here. Thanks all for your input.

@wheeler31 don’t freak out until you’ve performed that compression test.
Once you have, please post the numbers.

Got it, thanks! I will have time this weekend.

Just being curious, I checked the info in one of my manuals and it shows the truck uses MFI with 4 fuel injectors.

If so, then maybe you could consider a failing fuel injector or to a lesser extent, a wiring connector or harness glitch.
If you have a VOM maybe a resistance check of the No. 1 injector would reveal something although there are other ways for an injector to fail.

I will have to pull out my Haynes for that, also. I had seen somewhere in there about testing the injectors. I will check the wiring as well. Thank you

@ok4450 shows the engine as having TBI. Are you sure you’re not thinking of a later model year s10? I believe 1997 - 2003 had MFI.

I checked, it is a multi-port fuel injected(MFI) vehicle. My old 4.3 Vortec had a throttle body on it, but my 2.2 does have 4 injectors.