Engine/Transmission (1998.5 - 2002) I need the PROFESSIONALS!!

[Beast2B]

Occasionally my truck will stutter and buck (Most often with a load-10k trailer). I can see the boost gauge pass 20 lbs of boost, but it will stutter between 25 and 20 lbs like the truck is defueling in an overboost condition. I got a similar reaction running the truck without the Comp box while it was getting the drag upgrade (unplugged and fuse removed, MAP harness connected stock) but with the boost fitting still in.

I have two issues-

1) My LP is about 10psi idle, I can bring it down under 5psi revving it in the driveway. Correction this weekend.

2) If the MAP sensor is giving an erroneous signal (or no signal), what does the Comp box do? Pass on some sort of error to the PCM? Continue to pass on the false info it would send if the MAP were working properly? All electrical connecions have been exercised and re-lubed with dielectric grease. I will also try grounding the box directly to the battery.

EDM3's and B1-B are waiting in the garage, but I don't want to add any more variables to the equation until it's fixed...

They're calling me, I... can't... hold... out... much... longer...

 

[Hohn]

Where's your Comp grounded?



jlh

 

[Beast2B]

Ya know, I'll have to look again. I was trying to recall yesterday, but I don't recall (I slept since the install, memory cleared... )

 

[TnLRacing]

Check it for codes... I hade the same problem, and I had a code 216... turned out to be the Injection Pump

 

[Beast2B]

I've got a buddy at a Chrysler dealership and we've checked codes a couple times.

I've had an overboost code set (snapshot on OBD showed 99 lbs of boost, engine NOT running!)

I've had MAP sensor voltage too high (snapshot normal conditions 54mph, no other odd values)

I haven't seen any pump related (at least not directly related) codes, but I am preparing myself for the pump failure possibility...

 

[2-ND TIME]

over boost

I think that the ECM is seeing over boost and cutting back your fuel or shutting it off altogether there is a plug for the three pin conn at Cummins that you could plug in and see the voltage that is there and convert it to boost pressure here in Canada it is $ 130. 00 haven't got the part number but have it at home. if you need will be on the net at hame early next week. hope that this helps.

 

[GMills]

I have similar prob with PM3. Have changed MAP sensor, soldered all connections, had wire harness and box checked. It still seems to be electrical, but cannot figure it out.

 

[Beast2B]

I have the Blue Chip pump cover for attaching my Comp. There are two wires on the cover, I exercised both connections. I can't recall and don't have the paperwork with me, is there a ground connection in the cab as well as the 12v power for the box? I'm out of town this weekend, gathering some info to proceed from here.

GMills-I have noticed my lift pump a little low at idle and revving in the driveway, ~10psi at idle. I agree, it feels electrical or fuel delivery. Haven't seen any inj pump related codes yet!

Thanks for the replies, I'll be updating and checking as I can

 

[2-ND TIME]

engine problerms

GHills YOUR truck sounds alot like mine can I ask when yours was made on the bottom left of the door sticker is the MDH Month , Day, Hour mine is 10,10,19 ,98 or Im curious if there was abad batch of the APPS's that were made??

 

[Beast2B]

Back in town. The ground I have is on the Blue Chip pump cover. I may try moving it to the battery or the body connection where the battery grounds. After exercising the connection, it SEEMS to be a bit better, but under heavy load/high boost it still feels like it is stuttering. (no LP change yet).

2-nd time, one of my original questions was if the Comp box manipulates the boost signal, how does the ECM/PCM see an overboost?

 

[2-ND TIME]

over boost

The ECM & PCM see over boost by the voltage increasing form 0. 44 to 0. 56 to 4. 44 to 4. 56 for full boost. I didn't convert it to pressure in psi but is in zero for no boost of course ( mm Hg ) 2585. 76 [ inHg] 101. 80 .

 

[KLockliear]

I have seen this problem stem from a not-so-great connection on the BC cover. I'd go right to the wire.

 

[Beast2B]

2-nd time, I agree that the voltage determines what the PCM sees, but the Comp box is also a "boost fooler". The voltage coming from te MAP sensor is then altered so that you do not send an overboost condition to the computer. With the Comp box installed, where does the voltage come from? My understanding (quite limited) is that the computer should NEVER see an overboost voltage with a "boost fooler". If that is not correct, how do people run 40, 50 or even more boost pressure?



Keith,

Thanks for perusing. I will move the ground today. Is there a preferred connection for the pump wire? I really don't want to tap" it, is there enough wire available to cut, solder and shrink-wrap the connection? Anybody else?

Thanks for all the info, I LOVE THIS SITE!!

 

[Beast2B]

Well, I moved the ground to the front left fender at the same screw that holds the ground directly to the battery neg lead. I may be going nit-pick crazy, but it didn't go completely back to smooth. So far, the biggest difference has come from disconnecting the red lead to my injection pump and running it like an EZ with the better ground. I'm gonna leave it like this for a while, get the codes checked and cleared, and install the injectors and turbo in a week or two... Probably end up piercing (or soldering) the pump wire and removing the replacement pump cover.

 

[GMills]

2-ND TIME

My HDM is 040913. Sorry on the delayed post, I was out of town.

 

[rparlaman]

engine bucking

I have a 01 and had the same problem 2 years ago. This might sound funny but its true. Only with a load,or getting on it slightly,it would buck or fill like a miss. Cummins had it for 3 i say 3 weeks. Over 60 hours,on the dyno,it was the thermostate. There is a TSB on this problem called thermostate hammering. They put the new 03 thermo. in and never did it again.





Ron















1992 CTD 167,000 )01 CTD Banks Power pack,jacobs e brake,50 gal trans flow. 30 ft forest river 5th.