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IP or PCM issue?

D

dka99burb

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Messages
650
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Location
Reidsville, NC
Ok. I am still struggling with the touchy throttle, cruise control, TCC lockup issue. It is all acting very strange. Here is the scenario:
Good:
1. Starts and idles excellent. Cold start is good with one heat cycle. Hot start is good too.
2. Drops back to idle when you release pedal.
3. Drops to lower idle when you tap the brake pedal.
4. Checked all grounds. 0-3 ohms between everything.
5. APP and PMD are both known to be good.

Bad:
1. Pedal is super sensitive. Barely use the top of the pedal. 1/4 pedal is fast and 1/2 pedal is like WOT. Heck, 1/4 is black smoke! Cannot do a controlled rev.
2. Cruise control seems to have same problem with response; accel, idle, accel, idle, etc.
3. TCC doesn't want to lock at the right times. (possibly due to 'NASCAR mode')
TCC stays locked on highway as long as I am pulling a hill or accelerating. It unlocks when holding a constant speed. 8% APP is the magic number for the lock/unlock.
4. No codes.

I bought the truck this summer and it cruised fine. I later figured out that the turbo was not working. Replaced the wastegate vac solonoid and that fixed it.

I have tried a new PMD even though the Heath kit on the truck is only 6mo and about 5k miles old. I have also tried a APP unit. Both made no difference.

There have been suggestions that it can be the IP but it is not doing what I have read as the tell-tell signs of failure. No stalling and no running out of control.

I want to make sure I have covered all bases before throwing an expensive IP at it, not to mention my time to do it. I would be really upset if I put one on and it's not fixed! :eek:

Is it possible that the PCM needs to be reprogrammed? If so, how do I do this? Do I have to see the dealership? Cost??
 
If you have access to a scanner find the idle fuel rate, it should be 6-10 mm3. Below 6mm3 could give you a touchy throttle. Check that before condemning the IP.
 
I hope this is it! Reading 15psi at idle...

I borrowed a friend's Genisys. There were a few readings that I was not sure about but boost shouldn't be 15psi at idle, or at all.
This was taken at idle.
Turbo Boost: 15psi
Wastegate Solonoid: 71%
Fuel Rate: 3.75 mm3

I will try to get a boost sensor tomorrow. Would the boost reading effect the Fuel Rate or that something that can be adjusted?
 
dka99burb said:
I borrowed a friend's Genisys. There were a few readings that I was not sure about but boost shouldn't be 15psi at idle, or at all.
This was taken at idle.
Turbo Boost: 15psi
Wastegate Solonoid: 71%
Fuel Rate: 3.75 mm3

I will try to get a boost sensor tomorrow. Would the boost reading effect the Fuel Rate or that something that can be adjusted?
Click to expand...

The boost would be correct, it reads atmospheric pressure which is about 14.5 or so.

Here is a thread that will tell you how to adjust the OS, off hand I forget which way to adjust it
http://www.dieselplace.com/forum/showthread.php?t=28752&highlight=optic+bump+repost
 
Crap. I thought it would read gauge pressure, not absolute. Oh well.
Based on what I have read in you link I am going to make observations while driving tomorrow and see what kind of fuel rate I have high APP input.
Probably going to need an injector pump though huh? Can 3.75-4.0 mm3 at idle cause these big of issues? How would it get 'bumped' without my doing it?
 
Check to see if your scanner had a corrected boost display.

That fuel rat can cause a touchy throttle.

Refresh my memory, how long have you owned this truck? Was the throttle fine when you first got it? IDK but maybe an OS can change as it wears?
 
The idle fuel rate can be changed with an adjustment to the OS. IIRC it was outlined in that thread. It's actually quite easy to do, it may take a couple tries to get it where you want. It takes very little movement to get 1-2mm3.
 
I just bought it this summer and have only put about 1500 miles on it. It didn't seem to have these issues when I bought it. I am going to drive it some today and record readings. I will probably try it with the wastegate solonoid disconnected for a run to see if maybe I just didn't notice it when the turbo wasn't working.
 
I used Genisys , also. I do not remember the boost pressure being in absolute scale. I think waste gate percentage may be wrong at idle also. I agree fuel rate is low, though. If I can get ahold of my friendly neighborhood mechanic, I can hook on Mon., and let you know.
 
That would be awesome! I am hoping to have some time during the holiday weekend to try to adjust the OS. I ran out of time today and didn't get to try monitoring with wastegate soloniod disconnected. I am leaving it at work and working with it there. I don't feel comfortable driving it on the highway much as annoying as it is.
 
My Burb is at work but I was just sitting here thinking about staying late tomorrow to take a look at it. Can I get to the optic sensor without pulling the lower intake? I hope so, otherwise it will talk a lot longer......

indybeck, I appreciate your willing to get me those values. I may just run mine and take pictures of the output for reference later now that I think about it.
 
No trouble here. I'll get that done tomorrow if I have a chance. To get to optic sensor, take upper plenum off, do your adjustment, and then just set plenum on, and plug in sensors for testing. Oil will seep between plenum and intake while running, but makes it easier to adjust again.
 
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