Cold Idle pulsing

[chuntag95]

I noticed since I got my truck back from the injector cup repair that the idle has a pulse to it. It seems to go away after it warms up to 175 or higher. It is worse when in gear. It is like one cylinder is bogging down and the engine is stumbling to catch back up or maybe a miss. It's not bad, but very annoying. I don't seem to have any response on the tach and don't feel like it is trying to run away from me. I have all of the lastest updates from 2 weeks ago. Does anyone have a suggestion? Fuel pump, injector, etc?

[woundedbear]

I have never had an injector repair, but my truck has been acting similar to this ever since I bought it 11 months ago. Like Chris

[IndigoDually]

Mine has done it since new also.

John

[mackin]

The 01's are prone with the problem and a reflash of the ECM was a fix......I have yet to do mine but I will eventually cause I think it's getting worse (bad injectors, I see smoke???)......I have noticed a slight HOT fluctuation too......OH OOOOO!!!!!!!

Surprised the 02's even have the issue as the TSB was out prior to production unless their early 02's...... :confused:

MAC

[raygreg]

I was having the hot pulses,No RPM change visable at the tach, and I don't know if it is because the weather is cooler or the fact that I started putting in that Power Service stuff from wally world in the fuel, but.......so far the pulses have gone away. Do you think the cooler weather would effect the hot idle??

[SoMnDMAX]

Mine does it hot or cold.. My truck was an early production unit, and is still running the original RPCV.

I just have to make the time to see my dealer to get it fixed.... Too many things to do, and fixing the injection pump is a low priority for now.

[hoot]

Now this question is bound to be controversial....

We know that no heads have cracked.....
Apparently someone gave us that data.

Can we find out the real scope of this HPFP (High Pressure Fuel Pump) problem?

10%... 20%... 50% failure rates?????

To me, not having a reliable injection system could be just as bad as head problems.

Why do I say this. Cause at 100,000 miles and no warranty, this baby is gonna rock the wallet.

[chuntag95]

Mac,

Mine is an early 02. It just turned one year old a week ago. Well, since I have had it anyway. I got it with 26 miles on it, so... :D What is really strange is that it did not do it UNTIL I stopped sucking coolant into the cylinders. Just plain weird. :( I guess I will make time to take it back in. I called them and they said to bring it in late so they can have it cold to start first thing in the morning. I tried hooking up my code scanner and it wasn't any help. Only had 8 variables that I could monitor. I have ordered the kit to update the software and see if that gives me more choices. I really wish I could see the injectors. Then I could tell them where to look, if that's the problem. I like to give them all the help I can and they actually seem not to mind too much.

[Tim B]

Mine was built in Mar 02 and I don't have any idle problems at all. It has not had any updates - still operating on whatever was installed when it was built.


Tim B.

[FormulaPro]

I have the cold pulse also...worse in gear. Not evident on tach. Smooth when warm.

[woundedbear]

Mine contains a born-on-date of Octocber 11, 2001.

[rberner]

Mine only does it occasionaly and doesn't seem to matter whether it is cold or not. Usually it quits after a little bit anyway. got about 28,000 on it and it only has done it for the last say 10,000 miles but as I say only occasionaly.

[Russ Denman]

Mine started doing in the last 5000 miles. It only does it when stopped and when cold. I now have 19,500 miles.

I have also noticed a little smoke or dust when I get on it when the lighting is just right.

[ 10-17-2002: Message edited by: Russ Denman ]</p>

[MaxedOut]

I noticed this idle surge condition for the first time last spring. It's different from the "Lopy" idle. I had that too but one of the software updates got rid of it. This is different. It does it only when its cold and its a rythmic surge - slightly revs up about every three seconds. If I lightly apply the brakes while in gear, it will be just enough to move the truck forward & stop, move the truck forward & stop etc. Seemed to almost go away over the summer but now that its getting colder out in the mornings its back. I had it at the dealer last spring when it first started to happen & was told there were no codes & + or - 200rpm is within normal limits for my truck. Its not getting any worse & it goes away when its warm but Id like some opinions. Bad injector, bad pump, pressure regulator? I dont know. Tried a new fuel filter. No difference.