Late '99 down on power...

[18inchapes]

OK I have a post on the dieselstop page also, but no one knows how to reply there i guess... anyways.

I have a power loss with my '99 (late) SD. This has been going on for 3 years now. It get more noticable in the winter months then summer and also with rain, so I'm thinking its electrical.
Now, i get the P01249 code when it happens. I have performed ALL the checks for leaks and hoses and all looks good there.
Heres what happens.
When you start from a full stop, the truck shifts firm from 1-2, then 2-3 from 3 to convertor lock up it gets soft and by the time it gets to 4 it slides in. If you going up a hill (or overpass) in 3rd before lock up,it will not shift unless you either push the throttle harder or crest the hill. by that time, you throw the P01249. Now while all of this is going on, the truck never boosts over 12 psi (15 on the Autometer gauge). How do you get an overboost code at 12 PSI?
Some other numbers
my EBP PSI is 15 while idling, never goes above 27 when driving.
also, will not cycle until the truck is moving.
EX.I did a cold start, Oil temp was 88 and IAT was 32, no EBPV cycle. Started driving and the IAT went down to 23, then EBPV started to cycle while driving. about 5 mins.
Maybe and issue?
ICP numbers
ICP PSI at idle 567 WOT 2600
ICP % at idle 12 WOT 39
is this low?
Fuel pressure at idle 45
I have ordered a fuel pump and will install when recieved.
Also EPC numbers
EPC PSI 5 at idle and NOT running? Why?
number will bounce from 50 when taking off then go to 23, normal?
WOT will go to 101 then go to 70 kepping the pedal in the same position
EPC voltage bounces around between 6.93 -7.29 at KOEO stays consistant with KOER 8.1 and will increase to 12.9 at WOT
Maybe related?
I have changed the CPS last week from the grey one to the dk blue, slight change with idle (not as rough) but perdels were the same (#8 a& 4.5,#3 &1.8)
I have/can check other sensors if needed. I just need to know what to look for.
FWIW.. Back in late Sept, truck was running like a top, I can't remember the last time it ran so good. weather was low humidity and in the 60's I don't drive this all the time.
Thanks guys, Jeff

[justinlogue5_0]

For ya. Curious to see what people say.

[duck fan]

What are you using to scan your sensors? With your key on but the engine off, check MAP pressure and Exhaust back pressure. They should be the same. If not, the EBPS is bad or the tube and sensor are clogged.

[18inchapes]

Duck, thanks for the response.
I have the snap on solus pro scan tool.
My EBP reading with KOEO is 15. The MAP reading is 16.They will keep in tune with each other when driving, but 1-2 numbers off. ( one at 16 the other 17 etc)
The tube is clean. I don't remember if I checked the bracket/fitting. I'll take it apart again and check. I do remember checking the sensor and it looked clean. How else can you check/clean the sensor?
Question, Is 27 a good number for the EBV sensor on the high end? I read somewhere 50 is the high side number. can you confirm? I'm thinking that the sensor is not working right, just don't want to buy one if its not the problem. Exhaust system is 3 months old and tight.(4" turbo back) Up pipes are not leaking (no soot).
Thanks again, Jeff

[duck fan]

A 1psi variation isn't too much to worry about. Looks like your back pressure is within acceptable numbers. Are you running some sort of tuner/programmer? That would explain the P1249 code.

[18inchapes]

Hi Duck, No, no programming. stock tune.
Heres the million dollar question that if someone could answer I'd find my problem.
A program tune will throw a P01249 code, that I understand, my question would be what does the program do the the parameters in the PCM to make the truck "think" theres a wastegate problem? overfuel?
My problem lies in the mid range RPM band (1200-1800 RPM) you can feel it.
Like I posted before, truck ran great ( best I can remember) back in Sept and I remember thinking it felt real "smooth"? if that makes sense. I don't think the trucks missing. Throttle pedal was more responsive
I'm thinking that I throw the code because the PCM sees 12 PSI of boost at 41 MPH
in 3rd gear and the throttle pedal pushed down more to make power and/or shift. I shouldn't need 12 PSI of boost to make the truck move 5-7 ..OK 12 no.
Jeff

[18inchapes]

Hey Duck,
I found this thread... any idea what part hes talking about?
Maybe related to my problem?
2001 4x4 crew cab 7.3 DTC P1249

Thanks again for your help, Jeff

[18inchapes]

I'm wondering if I have a PCM problem. Its weird that I can drive all summer long and not get a code,but if it gets damp out (humid change) it will throw a code.Or if I'm driving then stop for fuel, then start driving again it will throw the code.
In the colder months (under 50) i can throw the code everyday.
My EBP doesn't work right either. Last time I was checking numbers, the IAT was 32 and oil temp was 88, thing should of been working from what i've been reading. It started working after I started driving, IAT went down to 23 oil went up to 118 ..weird
I know the BARO reading are internal to the PCM, maybe thats why I have problems when seasonal?
Anyone else had goofy stuff go on like this? Jeff

[duck fan]

Reading that thread it sounds like the thing he replaced was a Glow Plug Control Module. It is only present on CA trucks and Excursions. It is in no way related to the wastegate.

I found a file I had saved years ago on how the wastegate system operates and how to test that it is working correctly. Hopefully this gets you pointed in the right direction.

[18inchapes]

Hi Duck, thanks for the info. I'll check it over the weekend.
thanks again, Jeff