Engine Cutting Out

[albi1cnobi1]

Hey everyone. I've got a bit of an issue that has cropped up recently and is driving me crazy. What's happening is that at RPM's over 3000(sometimes around 3500) the engine kind of stalls and stutters in and out. It's really strange, not like its lugging down but actually shutting down intermittantly. The best way I can describe it is if you could pulse your foot on the gas pedal really fast. It started out happening really infrequently then got fairly regular. One particular time when it was really bad I pulled over and was trying to see anything obvious and found the plug on the MAF sensor to be a little loose, I pushed it back in and the problem seemed to clear up. It did stop for a while, but it has come back. I've checked the obvious(plugs, wires, etc.). One thing I found is that it seems to be worse when I get on it hard and put it under heavy load. If I ease up the RPM range sometimes it won't do it, but if I get on it hard it will almost always do it. I wanted to throw it out there and see if all of you had any ideas or any troubleshooting tips. Maybe some tests to run or things to check. Thanks in advance.

Oh yeah, I should probably give some background. SOHC motor, 253,x.. miles, owned since new, oil changes every 3000 miles. No timing chain rattle, Both tensioners have been replaced at 100k and 200k. The motor runs like a top all day and night at RPM's below 3000 with no issues. Thanks.

 

[4D X]

It could be a dirty MAF sensor. You could try and clean it. Autopart store has a special spray cleaner. O2 sensor could be bad or catalytic converter plugged bogging you down slowly more and more everyday. You can try and disconnect one O2 sensor and see if it stops. If it does its probably the CC.
Maybe a dirty air filter.

 

[albi1cnobi1]

Sorry, I should have mentioned that I cleaned the MAF. I also tested the TPS and it tested good. I hadn't thought about the cats though. I could try pulling the O2's one at a time and see if anything changes. Thanks.

 

[albi1cnobi1]

Any ideas? I'm open to suggestions...

 

[2000StreetRod]

original fuel pump?

I would suspect the fuel pump if still the original. Have you measured the fuel pressure? Has it been more than 50K miles since the fuel filter was replaced? Are there any misfire codes? Have the spark plug wires ever been replaced? Have you checked the spark plugs' condition and gap?

 

[albi1cnobi1]

Yes, no, yes, no, yes, yes.

 

[2000StreetRod]

CKP sensor?

You might try cleaning the crankshaft position (CKP) sensor by disconnecting/connecting the connector a few times.

 

[albi1cnobi1]

Thanks, I'll try that. It's been really crappy weather wise here in the northeast so as soon as we get some decent weather I'm going to replace the fuel filter and give the CKP sensor a good cleaning. I'm going to try things one at a time so I can try to see what corrects the problem and can post the findings.

 

[Flash]

One thing I found is that it seems to be worse when I get on it hard and put it under heavy load. If I ease up the RPM range sometimes it won't do it, but if I get on it hard it will almost always do it.

Sounds like classic plugs/wires/coil to me.

The crank sensor would / should throw a code.

 

[albi1cnobi1]

The coil is a screamin' demon coil pack. It has about 60-80k on it. Not saying it can't be bad, but it's not 1st on my suspect list. The plugs and wires are on the list, as both have about 50k on them. I kind of thought the CKP sensor would throw a code, but since it's intermittent I'll check for possible pending codes and see if it's there. Thanks Flash for the insight.