Bought a 2000, automatic Hyundai Elantra. Fluids look good, engine seemed to run alright, except that from 0 to 25 mph it sputtered. From 25 up to 70 it runs just fine. Codes indicated misfire on 3, random misfire, MAF sensor issue.

Changed the wires and plugs (gapped to .044) and the MAF sensor. Started it up and now it's missing on 3 and 4. While the car was running we pulled the plugs out of each cylinder. 1 killed the car, 2 caused it to run rough, 3 and 4 didn't change anything so we figure those are the culprits. We pulled the plugs on all cylinders 1 & 2 were white and hot, 3 and 4 were sooty...

We changed the coil out and ended up with the same results. We changed out another sensor attached to the intake manifold with no change. While running, removal of the MAF sensor does nothing.

Based on this information on my 4 cylinder motor, can anyone think of anything to try next? Thanks much in advance!

 

Hey man I had the same problem. Except it was just number 3. I found out I had a bad injector, computer, idle air control. Or i thought. It would idle rough as a old rv cam'd 350. If i unplugged the tps with IAC plgged in it would run and if i switched it plugged in the TPS and unplugged the IAC. So i switched the ECM out and idles great but miss fires over 1900 rpms. So try unplugging a few things and see if the engine changes any. Also double check your coil pack you may have a dead coil. Other than that good luck.

 

We changed out the coil pack with no results. I will try unplugging some of those other things.

Originally it was only number 3 I was having problems with.

 

the catalytic converter is red hot after 10 minutes of driving, and this morning the battery died after a few attempts of trying to start it. I've taken the leads off of the batter and have it trickle charging.

 

Are you saying it's glowing? if so that's bad. Check your timing belt, I just checked mine this morning and I have a half inch of play in it which is why i'm getting miss fire at higher rpm's. I actually shocked mine it running. And do you have to cat's or 1 i have 1 at the manifold and 1 under the car. When you were trying to start it did it sound like it wanted too start or crank over easy. These cars timing belt is suppose to be changed every 60,000 miles. I'm thinking thats the best place to start.

 

another symptom? When I press on the gas, even slightly, the car motor dies, but if I manipulate the throttle from under the hood it revs right up.

 

Ok mine was doing that and the bad news is I went to the junk yard and grabbed a ECM and ran. Installed it and poof that problem was gone now i have a stretched timing belt. Gotta love hyundai.

 

I took my injectors out and sent them in for professional cleaning. I'm going to a junk yard later to pick some sensors off an elantra there and see if any of those help. Next week I'll buy and install a timing belt.

When I'm done doing some of the less expensive stuff... I hope it runs!

 

Hey you maybe on the right track with the injectors. I pulled my inline fuel filter and the fuel was orange. My car was sitting a year before I got it. I'm getting less and less mis-fires every day. I may change the injector's and the in-tank filter.

 

Hey man, I just found my problem. I had a gas tank fuel of rust. It wasnt hard at all to clean out it should take 5 mintues to see if thats your problem. There's 2 12mm bolts in the seat, then pop the cover plate off unconnect the 2 plugs. Use 10 mm to unconnect the main fuel line, pull clamp off return line and use screww drive to take screws off. Look and filter at end of pump and see how dirty it is. If it's clean slap back together and move on I guess.