P0304, P0300, and P0103 oh my

[stubborn1]

Here's a follow up to a post I made last week:

"Having problems with my 98. Recently, the engine has been hesitating from 2000 rpms up to 3000 rpms under moderate acceleration. Above or below that I have no issues at all. If I'm very light on the gas, I don't have the issue either - it just takes 60 seconds to get to freeway speed. Instead, I've been driving like a mad man to keep the rpms out of the "trouble range".

No check engine light. Doesn't seem to be a fuel delivery problem. The engine almost acts like its not getting spark for a second. Makes the car jerk pretty bad. Any ideas for things I can start chasing down?"

Well, I stayed on the gas a little longer today after the engine started bogging down. After about 10 seconds, the engine lite would start flashing. Got it to stay on after about the 3rd or 4th attempt. Here's what I found with my code scanner:

Stored codes:

P0304 - Cylinder 4 misfire

Pending codes:

P0300 - random/multiple cylinder misfire
P0103 - mass or volume air flow circuit high input
P1800 - (unknown code)

I'm thinking the first thing to do is clean my MAF sensor and see if the codes reappear. I checked the plugs and wires and everything looks good. Anything else I'm forgetting to check?

Can anyone tell me what P1800 is for? Couldn't find any info on that one.

Thanks

[stubborn1]

Guess I won't be cleaning the MAF since the 98 didn't have one. Now I am really stumped.

[Patman525]

when was the last time you had your timing brlt checked/changed? idk if that could be the problem but since plugs and wires seem ok thats all i can really think of. again, i don't know if the timing belt has anything to do with the cylinder firing, but have it checked out

[white3ch0c0late]

How many miles on the Corolla and are the spark plugs original factory plugs still? Cylinder misfire could be attributed to bad plugs.

[stubborn1]

103,000 miles, but only about 10k on newer plugs.

The problem only seems to happen after the car is warmed up - doesn't happen when its cold. Also only happens under load. I can clutch it and rev the engine with no hesitation, but as soon as I put it in gear I have problems again.

[white3ch0c0late]

It could be a slipping clutch.

[epyon22]

what about your distributor?? that would cause the misfires

[littlej72]

98 has coil packs