Rough Idle on Warmup
 

Lately when I start my truck when the engine is completely cool it has this weird surge. It's not enough that there is a noticeable change in RPM and you can't even tell from the engine compartment but it causes the whole truck to shake a little bit like a cylinder might not be firing. As soon as its warmed up it goes away and doesn't happen again until the engine is completely cool. Has anyone experienced anything like this? I took a video so yall can see what I'm talking about.


My truck is a 2003, no serious upgrades besides a 4" straight pipe from the turbo back, CAI, GDP big line kit with Fleetguard 2 mic and a Baldwin PF7977 in the fuel bowl. I might be overreacting but I'd rather be on the safe side. I appreciate any insight...Thanks!!

Sounds like a bad injector. Be careful the Cummins has a way to compensate for the bad injector and still run good I've seen pistons melt due to this!

If this is a bad injector are there any other warning signs I should be looking for? There doesn't seem to be any noticeable loss in power. EGT is nice and low. I'm starting to think it is an injector because I'm starting to notice that not so smooth idle even after I've been driving for a while. I was planning to go to 60hp injectors however, I can't afford that at the moment. If I felt so inclined, how would I go about finding the bad injector so I can replace it for the time being?

The dealer can scan it but if one is bad they are all likely going out also! Don't forget the 2 micron filter before the CP3 when you put the new injectors in!

That was the first thing I did to the truck when I bought it. However the previous owner was running a pressure box without any extra filtration so I guess I can't undo the damage that was likely already done when I bought it. :argh:

Well start saving or use the credit card because a bad injector can eat a piston! Make sure to boroscope the cylinders when you have the injectors out!

No kidding about that I have a #6 injector crap out and left me with this.

After hearing about issues with loose injector lines I decided to get under the hood and do a really good visual inspection first. I found a small amount of fuel leaking from underneath the cap to the fuel bowl. I grabbed a new cap and replaced my Fleetguard 2 micron filter and now she is running as smooth as can be. :jump:

I didn't know fleet guard made a 2 Mic. Fuel filter. Whats the part number?


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FF5320 I replaced it with a CAT 1R-0750 which is a better filter from what I understand. Both are rated at 2 micron.