High Idle And Misfire After Rebuild

sounds like a vac leak man, spray starting fluid all around the intake area behind the airflow sensor. if the idle changes then you sprayed where the leak is.

I just finished reassembling my 98 Prizm with the 1ZZFE after replacing the piston rings and a valve job. When I try to start the car, it gives me an occasional sputter, and sometimes fires. When I hold down the gas about 1/2, it fires most of the time and idles at about 2500 rpm. Even after warm, it won't drop below 2500 rpm. I didn't let it run more than 3 min or so because I was afraid of overheating.

The only CEL I get is a random cylinder misfire on #4. I tried a different plug wire for #4, different plug, and different coil with no changes. All vacuum hoses are correct and wires connected to sensors.

I pulled the plug wire and it ran about the same on 3 cylinders. Just to mix it up, I replaced #4 and pulled the #1 wire and it ran the same. I don't think the issue is related to one specific cylinder even though that is where I am getting my CEL.

I'm thinking it may be a timing issue. I'm set at TDC on the compression stroke for #1 and the crank pulley is aligned with the 0 timing mark. When I installed the chain, I aligned the colored links with the marks on the sprokets. The timing marks on the cams are close but not exactly even - about 1/2 tooth off. I can't get them any closer. Maybe the crank sprocket skipped a link when I put it back together???

Anything else besides timing I should check? I'll post a picture of the timing marks tonight if I don't get it right before then.

If it is not one specific cylinder, then it must be your idle or fuel control.

 

 

No luck finding a vacuum leak. I'm thinking it isn't a vacuum leak because the engine is misfiring while reving high. The engine light is flashing and I keep getting the P0304 misfire on #4 code. I tried to limp the car out of the garage and it didn't even have enough power to get back up on the ramps. Compression checks out at 185-190 at each cylinder. I pulled the head cover again and compared my before and after timing pictures. Crank was at 0 and TDC each time. Pictures are identical.

Before:

https://i65.photobucket.com/albums/h209/rmy...m/engine012.jpg

After:

https://i65.photobucket.com/albums/h209/rmy...m/engine020.jpg

Here's a link I found for diagnosing engine misfires. 1 of 3 things:

loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression

http://www.aa1car.com/library/misfire.htm

Since you've checked compression and thats in spec, I'd check ignition next, then injectors next.