Red Tag IP on a 94?

[bison]

a buddy of mine dropped in today,he got a 94 dooly 5 sp standard.,he's complaining he has not nearly the power he used to have before a IP change up in the yukon last yr.

i looked in to it,and found the replacement IP has a red tag on it with model # 8483. Does that ring a bell to some one?
I cannot find a IP with that # in the sticky.
My buddy dont know what IP was on there to start with,but it has been replaced once before in 98 under ext warranty

Question,what IP was original on these 94 trucks,door sticker says dec 93.
would above IP be a good match,or is it an oddball?

I'll put it on the scanner to check the timing tonight.

 

[buddy]

If you get the PCM part number and the EPROM code off of the PCM, and then the EPROM code off of the chip itself that would help. Is that part of the IP part number or the model? Where is the tag located? Have to read it on the side facing the intake, with an inspection mirror.

With GMTDScan you can just get the PCM cal ID listed on the dashboard screen, instead of actually opening up the PCM to see the chip.

It could have had a 5068 IP being a 1994 3500, otherwise 5067 which is compatable with the newer IP models

 

[bison]

Pump ID tag is on back of pump,I read it with a small mirror.
There only 3 # on there, 8483 being the shortest one.

I hooked it up to the GMTD scanner,timing was off a wee bit,relearn did peg TDoffset at .44
actual timing 4.7,desired timing 4.7. No codes found.
Fuel press 4.5 psi at idle

before scanner hookup,i noticed a slight misfire or fishbyting on fast acceleration only, after relearn, the misfire became more pronounced,but does it only when i stomp on it.
when slowly accelerating RPM rice is smooth without misses or stumble.
OS filter funky?

 

[buddy]

Take OS filter off if it has one. Was the TDCO +.44 or -.44, if it is +.44 then loosen IP and adavance it to the driver side, so you get somewhere like -0.5 to -2.0

The tag may be a rebuilders specific tag, but should have the real part number on it.

I ran a 95 PCM EPROM in my 94 for a long time, worked well. After you get TDCO set good you can try putting your spare EPROM into his truck and see if it runs better. Since you both have manual tranny trucks. But if you could send me the PCM cal ID off of GMTDScan I can verify his EPROM is not for a special 5068 HO IP.

 

[kojo]

Sounds like your frend would have wrong ip, i have tested different chips and ip's and those are exact symptons when truck has chip for 5068 oddball ip and normal ip installed to engine. there are 2 ways to fix it:
-Change ip
-Change chip
Both will work...

 

[bison]

OK folks,things changed drasticly, I took the intake cover off to have an better look at the tag. IP is red tag DS4 8453-5521.
ECM call id 5175.

Inj des timing 4.8
inj measured timing 4.8
actual timing 27.1
TDCOffset 0.44 (no + or - observed)
fuel rate 11.56

Mismatched IP/Eprom?

 

[buddy]

That PCM cal ID is off of a 1993 5.7L gasser with auto trans. Well thats according to Caldata software anyway.

Are you sure it wasnt 0175? If you really get 5175 open up PCM and get the chip code off the chip.

 

[bison]

That PCM cal ID is off of a 1993 5.7L gasser with auto trans. Well thats according to Caldata software anyway.

Are you sure it wasnt 0175? If you really get 5175 open up PCM and get the chip code off the chip.

94 ECM # On the barcode BKWH, 86BKWHM233442263.
Eprom # BNTF
1621
5261

I put the ECM and Eprom from the 95 in,(cal id 5205) did relearn TDC offset.My buddy is happy, engine starts and runs exellent now,stumbling and hestitation disapeared.He says power is back where it was.

I think the timing is not where it should be.He says,leave it alone.
desired and measured timing is 9.1 degree,
actual timing is 30.98.
TDC offset 0.26
Fuel rate is only 4.38 mm
inj pulse witdh 1.74

What do ye think?

 

[matuva]

+0.26 I bet ? Even if -.26, TDCOfset and timing are out of specs.
like buddy says, TDCOfset must stand between -.50 and -1.94
Mine is set at -1.50 and is a good compromise.

 

[buddy]

ill have more info when I get home from work but glad to hear your EPROM worked better for him.

The TDCO should still be changed by turning the IP a little toward drivers side. You want TDCO between -.25 and -1.94. Factory setting is -.25 to -.5, but will be much happier around -1.5. Right now it is retarded a little bit so might not get full burn of all the fuel. Any black smoke?

9 degrees is good timing for off the line power.
Fuel rate is much too low though, should be about 7-8mm3. Pulse width is good.

Ill check the Cal IDs and broadcast codes in a few hours at home.

 

[NVW]

Fuel rate is much too low though, should be about 7-8mm3. Pulse width is good.

If it idles fine I wouldn't worry about it. You just have the max. optic bump.

Leo

 

[buddy]

The 95 came up correct as BNTK for PCM Cal ID: 5205

But the info for the 94 is confusing my computer, because it can't find any of that info on that EPROM, neither the BNTF or BKWH. There are some similar codes, but not them, its possible the database is missing both, but thats a strange coincidence.

The PCM service # is what is used as its part #, please tell me what that is because now I am really curious.

But at the minimum it shows that the PCM has been messed with, since the EPROM does not match the EPROM code on the outside of the PCM. BNTF vs BKWH.

 

[bison]

Buddy, to satisfy your curiousety, i know the puter has been tampered with ,based on visable evidence.

94 PCM, 2 barcodes.

Service # 16183977 BKWH.
///////////////////////////////
#86BKWHM233442263

1620335 BKWH
///////////////////////////////
86BKWHM233442263

 

[kojo]

If it idles fine I wouldn't worry about it. You just have the max. optic bump.

Leo

My truck idles @1-2mm fuel rate
What you say about that?
Ok, it's HUGE optic bump ):h and i had to tweak fuel rates from chip to get some sense to throttle pedal :rolleyes5:

 

[buddy]

Well at least the PCM service number is correct.

So was an optic bump done to this truck?

The scanner shows actual commanded fuel rate I thought, are you saying it is actually sending more fuel than that because of the optic bump? Or is it actually able to run on the lower rates?

 

[NVW]

The optic bump just fools the computer, The scanner sees xmm3 at idle but the IP is actually delivering more. Then when the computer commands xmm3 at WOT the IP is delivering more fuel if it is capable of doing so.

Leo

 

[buddy]

Thats where I'll have to invetigate some more, because the fuel rate is dependent on the PMD output, which is dependent on the PCM telling it what to do based on many factors such as timing and temperature. So I havent connected the dots on how moving the OS ups the fuel rate. If the PCM is commanding less fuel rate then the PMD, which is the only input the IP receives on shooting fuel, should be giving less fuel. Unless moving the OS somehow clears some restriction in the fuel flow so the volume of fuel per fuel solenoid closure is greater.

 

[NVW]

Basically it is a mechanical change in the IP

Leo

 

[bison]

I doubt if an optic bump was done on the truck,I think it ws just a fluke the timing ended up this way as the engine had lost all power after new IP install.
I left the settings as they where after the last relearn,cause the truck runs like a bat out off hell right now.
I wanted to tweek the pump today, but my friend said leave it be,I want to try it out for a while.
How the original PCM/EPROM combination ended up in this truck is a mistery as my friend said,I never had a breakdown with the engine of any kind before the recent IP swap,in the 14 yrs he's owned it. not even a fried PMD in the 280 k he put on. Just reg maintenance.