Engine/Transmission (1994 - 1998) low speed miss

[SEmerson]

I have a low rpm high load miss. Any ideas how to trouble shoot this? It idles fine and seem to run smooth over 2.



This on my 97 btw

 

[bmoeller]

Low fuel pressure? Bad lift pump or overflow valve?

 

[krs]

Or check the timing, 'specially if it stumbles or burbles at one place in the range between idle and 2K rpm when cold.

 

[SEmerson]

fuel pressure ok 30-40 psi good overflow value. time at 16.

 

[bmoeller]

How many miles on the injectors? Maybe the pop off/opening pressure is off from weak springs. May need to get them tested to see how close they are to each other, and the spray pattern. Have you used any fuel additives to help clean them?

 

[SEmerson]

370's are only about 6 months old. Haven't ran any addatives.

 

[krs]

I think that 30-40 psi is too much pressure. Seems like 23-28 is normal but all I remember about too much is Illflem saying that it could "cause problems". Maybe a search would tell more... ... ... ?

 

[JoeBioDiesel]

If it's a single cylinder miss, and not an ustable idle than the most likely causes are a loss of compression or a bad injector. Either way the injectors have to come out. Yank them and have them checked, and check the compression while you're at it. There is a chance the pump is bad, or a delivery valve isn't torqued correctly letting it leak internally... . but that would normally make it miss at every load/RPM.

My 2 cents.



Joe

 

[SEmerson]

I do have a rough idle when first started. It will idle in neutral smooth. But when you put it in gear it will room room room. That is not a single cylinder miss. It sound more like a governor bouncing. If you let it idle for 30 seconds it will run fine is gear. Also if you put it in gear right away and push the pedal a little it smooth right out.



My other miss is for sure a single cylinder miss though. But It still idles smooth.



Any more thoughts????

 

[K5IP]

Has it always done this, or is this something new?

Rog

 

[SEmerson]

Not for ever but for a longtime. It seems to be related to cold weather. So it is had to say if it is getting worse or it is just the cold.

 

[CATCRACKER]

i understand the 370 dont like the cold weather sometimes until the engine warms a lil bit

 

[MToney]

My 95 with only 66k on the ticker likes to load up the cylinders when she's cold, I just get into the throttle and blow it out. It is getting better the more I run her, I am the second owner and the previous owner babied her to much. She was stiff and low on power when I first bought her last month, getting better all the time. I use Diesel Power Services fuel treatment and injector cleaner, it treats the fuel for the cold, bumps up the cetane rating and cleans the injectors. My 95 Powerstroke I once owned, before waking up and buying a CTD, did the same thing in the cold. I even had all glow plugs and injectors replaced under warrenty and it didnt help. If I plug her in at home its not as bad, but at work she sits in the cold for 9+ hours before I go home, never fails to start and with fuel costs I am not going to let her idle forever. Just ease into the throttle and try to stay below 2k on the tach. See what happens when the weather warms up. Cheers Mike