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View Full Version : rough idle, noticable power loss



bear8236
09-05-2005, 07:48
I know the rough idle issue has been a topic before, but wasn't able to find the answers in past post.

I'm running an '02 Dmax with 150k miles. 6 speed manual, 4x4 with 295/75/16's. Only mods are the oversized tires, and a K&N air filter.

The problem is that the truck idles rough, rough meaning that it shakes violently. This is with and without clutch engaged. Rough idle seems to vary as day goes on. Morning isn't as bad, but evenings after drive home from work, is worse.
Have also noticed a drop in power. Have also noticed what sounds almost like an exhaust/air leak under hard acceleration.

No codes no service engine light, no excessive smoke white or black from exhaust. No fuel in crank case. Can't find any exhaust leak. Have cleaned mass air flow sensor since I've read about problems with over oiling K&N filters. I mentioned the oversized tires since I don't have any kind of speed correction on it, could that cause problems with the ECM since I'm sure it relies on speed as one of it's inputs. Could this affect idle? I don't really think this would be an issue, but I'm not ruling out anything at this point.

All 8 injectors have been changed over a year and a half ago. Never run below 1/4 tank of fuel. Have checked calibration history and it seems to be up to date.

Problems I'm thinking about are Possible bad injectors again, Fuel or fuel injector pumps, bad cylinder low compression, just sounds more and more expensive.

Had it at the dealer last Friday all day and they couldn't find anything as of yet. Got it back for the long weekend. So I'm guessing that means the computer couldn't find anything apparent.

So I guess my question is this... what could be causing this problem. Are there any other sensors I can check without a computer. Any other things I need to look for. Things I need to ask the dealer to check? Any good diesel mechanics in central Texas that anyone can recommend. Just looking for any help or advice here.

Thanks

madmatt
09-05-2005, 15:51
It could be the dual mass flywheel getting loose, rattling and causing false injector balance rates.

bear8236
09-07-2005, 17:18
madmatt
right on man, got the word back today and that's exactly what it was, good call!

madmatt
09-09-2005, 05:05
what flywheel did you put back in it? I'm anxious to hear how these new solid flywheels work.

bear8236
09-10-2005, 19:16
was kind of in a bind and needed the truck fast. didn't do all the research. went back with the stock dual mass flywheel... hope it will last. guess i'll see. if it goes again, then will probably go to a solid flywheel replacement.