Pulsing at idle

[cadiwa]

Any ideas why my C-9 pulsates when idling (slow or fast idle) Engine speed pulses on its own - varies about 200 RPM.

[TonyDi]

What happens when you drive it, does it surge then? Or does it just do it when there is no load on the engine? Check your fuel filters and water separator. Next would be to have the ECM checked. Good luck.

[mel s]

Originally Posted by cadiwa

Any ideas why my C-9 pulsates when idling (slow or fast idle) Engine speed pulses on its own - varies about 200 RPM.

cadiwa

The similar "pulsing", (by my 250hp 3126 Cat, at 106k miles), was caused by a bad IAPCV, (Injection Activation Pressure Control Valve), Cat p/n 122-5803.

BTW, a friend, (with a 300 hp 3126 Cat engine), found that a loose electrical connection on one of his injectors was the cause.

(However, I don't know if a C-9 would/could be the same).

Mel
'96 Safari

[2 Stroker]

Originally Posted by cadiwa

Any ideas why my C-9 pulsates when idling (slow or fast idle) Engine speed pulses on its own - varies about 200 RPM.

Mine will do the same thing when cold if I use the Cruise Control and set the idle up after about 3 or 4min the motor starts to pulstate. Just got it back from cat, had the valves adj and they ran the ECM had 1 a low boost, with no active codes. Will see what happens on the next startup.
2 stroker

[cadiwa]

Thanks everyone-will drive it awhile and see if it quits

[akeyzoo]

Originally Posted by 2 Stroker

Mine will do the same thing when cold if I use the Cruise Control and set the idle up after about 3 or 4min the motor starts to pulstate. Just got it back from cat, had the valves adj and they ran the ECM had 1 a low boost, with no active codes. Will see what happens on the next startup.
2 stroker

2 Stroker,
Any difference after valve lash adjustment? Mine ran markedly better cold.

Chris

[2 Stroker]

Originally Posted by akeyzoo

2 Stroker,
Any difference after valve lash adjustment? Mine ran markedly better cold.

Chris

Chris
Got it home and changed the oil and filter need to grease it. I think it runs better hot, time will tell when cold. Hope to get it out around the 25th for a week or so.
2 stroker

[mel s]

Ca

Originally Posted by akeyzoo

2 Stroker,
Any difference after valve lash adjustment? Mine ran markedly better cold.
Chris

Chris
My 1st, and only, valve lash adjustment was done at a Cat shop, (at 95k miles).
I have not noticed any difference in the 37k miles since that adjustment.

BTW my 3126 Cat engine has always "run best" after I allow it to warm up.

Mel
'96 Safari, 132k miles

[akeyzoo]

Originally Posted by mel s

Ca

Chris
My 1st, and only, valve lash adjustment was done at a Cat shop, (at 95k miles).
I have not noticed any difference in the 37k miles since that adjustment.

BTW my 3126 Cat engine has always "run best" after I allow it to warm up.

Mel
'96 Safari, 132k miles

Mel,
Mine runs best warm as well, but per CAT I just get going gently after a minute or two. I noticed mine runs better and much less "noisy" when cold. I also had an ECU update that helped (but wouldn't help the noise).

[mel s]

Originally Posted by akeyzoo

Mel,
Mine runs best warm as well, but per CAT I just get going gently after a minute or two. I noticed mine runs better and much less "noisy" when cold. I also had an ECU update that helped (but wouldn't help the noise).

akeyzoo
I finally figured out that "runs better cold" means that your C9, "runs better while warming up, (after the valve adjustment), than it did while warming up before the valve adjustment".

When you wrote that your C9 "runs better cold", I though you meant that it, "runs better cold than it does after it warms up".

Now that I understand what you meant, I'm embarrassed that I questioned your post.
Sorry!

Mel