Engine/Transmission (1998.5 - 2002) loping idle and bouncing tach (new twist)

[jlccc]

I've never been too concerned about the slightly bouncing tach readings. However, since the installation of 275RV injectors, the engine has somewhat of a more "loping" sound that corresponds exactly to the bouncing tach readings.



It seems like the loping sounds is more pronounced when the engine is first started, before it gets up to temperature. It seems to smooth out some when the engine is warmed up.



Anyone care to speculate as to the cause? Plugged injector? Bad CPS? Or ... ?



Thanks.

 

[andrewkoperdak]

I have some 335 hp injectors installed. My tack is a stable as it has ever been. It bounces about 30 RPM. It sounds like it is stable though. I am not worried about it. Just remember that your injector is shootig a large shot of fuel in the combustion chamber. This might account for you idle situation. I would not worry about it. When I engage my clutch with the engine cold I can definitely here the computer trying to bring the idle to 800 rpm. Sounds kind of cool, but to the uneducated I guess it would be unnerving.

I would not worry if I were you.

Andy

 

[jlccc]

Originally posted by AKoperdak

I have some 335 hp injectors installed. My tack is a stable as it has ever been. It bounces about 30 RPM. It sounds like it is stable though.

That's just it, mine doesn't sound stable. I could care less if the gauge bounces (it always has a little) it's just that you can definitely tell the idle is bouncing by the sound it makes.

Just remember that your injector is shootig a large shot of fuel in the combustion chamber. This might account for you idle situation. I would not worry about it. When I engage my clutch with the engine cold I can definitely here the computer trying to bring the idle to 800 rpm. Sounds kind of cool, but to the uneducated I guess it would be unnerving.

Yeah, I know THAT sound, but the sound I'm talking about is when I'm just sitting in neutral.

 

[Bigsaint]

Ditto on Andy's reply. Mine did it with the BD step 3's, especially when cold or when I pushed in the clutch to put it neutral, coming to a stop. You should hear the lope I get with the 5's, when I push in the clutch with the A/C on. I never really watched the tach. , but it must be swinging close to 400 rpms . Only lasts for a fleeting second, then goes back to a very smooth idle.



When I warm my truck up with the ebrake in the winter, it goes through several short cycles of 'lopiness'. Once it's up to running temperature, 99% of the time it has a very smooth idle.



Scott W.

 

[jlccc]

Thanks for the replies. I'll try to keep a closer eye/ear on it and report back. Perhaps I could record it and put it on my website for you to listen to and then give your opinion.



Thanks again.