pspees

He everyone, glad to be here! So my problem is: 92 pick up/22re cylinder #4 is fouling spark plugs. Truck seems to run fine with no problems other than loss of power and check engine light is on. No oil consumption or misfire, the plugs, wires, cap, and rotor are all new. Someone said it could be a weak spark, possibly from a bad coil. I was also told it could be from a bad injector. Thanks.

millball

A compression test would help in diagnosis.
Best to check and adjust valves first.
Bad coil would likely affect all cylinders, not just 1.
Could be the injector. Possible to move the injector to a different cylinder and see if the problem follows it.

RJR

How quickly is the spark plug fouling, and how severe is it? Generally the plug will foul either from excess oil (takes a lot!), or from unburned fuel due to misfiring. Sounds like it's the latter for you.

Possible causes:
- poor compression (likely bad valve)
- poor spark (bad plug, wire, etc.)
- over-rich fuel due to sticking/stuck injector.

Adjusting valves isn't a bad idea, but if the valve is leaking enough to cause misfiring, it's not just out of adjustment. It's either bent or it's burned and damaged probably due to already running for an extended time out of adjustment with inadequate lifter clearance.

snobdds

Well, I hate to break it to everyone, but the 22re never came with coils/coil packs. They have a dizzy with a rotor that flows current through the wire to the spark plug, which is all fed off of a ignitor.

I would check, in order of relevance, the following:

Cap
rotor
wires
ignitor
dizzy air gap

It's a simple system, but in order to not have a fouling plug, you need a strong spark.

millball

Not exactly accurate.

The ignitor is just part of the electronic breakerless ignition system that includes the low voltage components that are inside the distributor. All the ignitor does is make and break the primary current that flows into the ignition coil proper.
It does this using the signal it gets from the distributor, along with input from the ECM.

The ignitor is piggy-backed onto a single conventional high tension coil that provides the high voltage current back to the dizzy and then to the plugs, just like an old fashioned system that uses breaker points inside the distributor does.

pspees

Mine has a coil. I think it's oil on the plug too, not fuel. How do I know for sure if a ring is bad or maybe a leaky valve guide? Head was replaced with a new one about 2 years ago so I don't see why a valve guide would be bad. I'll try checking/adjusting the valves...

pspees

It did start hesitating and running like ˟˟˟˟ shortly after the head was installed. Took it back to the mechanic and he re-adjusted the valves. Ran perfect ever since. Maybe though, a valve got messed up from being far out enough to make the engine run poorly? I wonder...it's hard to trust anyone with my stuff.

Kiroshu

Compression Check.