konggmc

Wow so this will be my second time typing all of this in...

I just bought my 98 Cherokee two weeks ago. Hasn't been giving me any problems. Yesterday I passed someone on the way to work and it ran fine the whole time passing as well as on down the road until I got to the next stop sign and noticed it was idleing very rough. Drove to work fine but idled rough the whole time. Get in after work and Check engine light is on. Autozone said cylinder 1 miss fire. Plug wire looked like it had a burnt spot in it so I replaced it which fixed nothing. Drove home, removed spark plug(Bosch platinum two prong which is notoriously junk) cleaned contacts and switched with cylinder number 2 plug. Didn't fix it. Removed cap and contacts were very corroded so I cleaned with sand paper and cleaned rotor also. Still didn't help. Reset check engine light and drove again. Idle was still terrible but ran down the road a lot smoother and peppyer. Think I need to replace the plugs and cap but not sure if it could be an injector or something else wrong. Suggestions?

konggmc

I replaced the Bosch plugs today with regular copper Champions and still no fix. Suggestions guys?

Used to the 'search' feature for about 2 hours last night and didn't find any good leads.

konggmc

So the problem went away by itself almost entirely and then the other day I got on it again and it started back up and the check engine light came back on again. Broke down and replaced the dist. cap and rotor button and it didn't fix anything. Put some injector cleaner in it and about $40 worth of premium in it and started helping a little by this morning. By the time I got to work it was almost completely smoothed back out and the check engine light turned itself off.

So I assuming my next course is to investigate the cylinder 1 injector. Thinking about pulling the fuel rail and cleaning all of the injectors and replaced the injector o-rings to see if that helps. But does anyone have any input at all? Feel like I'm writing a journal here.

Rmart30

Mark it and move that injector to another cylinder and see if the miss moves with it.

Grolla42

Yeah, move the injector and see what happens. Is it cold where you live?

konggmc

Nah been pretty hot and humid in TN actually. I'm about the use the 'search' and look for whether or not there is some procedure for cleaning the injectors but incase I don't find anything and the one injector does turn out to be bad, how could I go about cleaning it?

excess650

Premium grade fuel shouldn't make the misfire go away. It actually has additives to make it harder to ignite to prevent pre-ignition in higher compression engines.

The FI cleaner likely cleared your problem. I add a bottle whenever I think I need to whether it be a couple of thousand miles or more. My 1986 F150 with MPFI would run better with 10 miles of adding a bottle.

tjwalker

Additives in the tank don't do a great job of cleaning a fouled injector. They do a better job preventively, and I do use a bottle 4 times a year for that purpose.

Consider getting a new fuel injector in there. Depending on the mileage on your 98 and if these are original injectors, you may want an entire set.

Yes, there are cleaning machines for injectors, but remember that there is also the electrical side to the injector. And with the
cost of an injector not prohibitively high, if I pull one out, a new one is what usually goes back in unless the injectors are relatively new.

konggmc

It has 123,500 miles on it. Garage kept(it would seem). I think new injectors were $45??? Can't remember for sure. Thinking about switching to the 4 squirter injectors if it doesn't already have them but gonna do more research about that first also. I gotta buddy who has a "bucket full" of em off of his 5.0 mustanks. Probably gonna buy the o-ring kits, pull the rail and switch the #1 injector with #2 this weekend and see what happens.

jjstultz

I had the same issue on my 99 except cylinder 6. I tried all of the suggestions this thread covers. It ended up being a short in the injector harness. It had a short between the two wires in the loom. Before you spend the money on new injectors,unless you're going to upgrade, test them with an ohm meter. The should test out at around 12.5 ohms.

warthog

I would do a wet and dry compression test first to rule out anything mechanical. Let us know the results

warthog

Any update on this