First Post - Service Engine Light
 

Hi,

Did a lot of searching on here since I got the truck (94 Suburban). No codes but I get the engine light under light throttle. Light goes out when I let up on the gas or accellerate.

I did replace and relocate the PMD. No change there.

From reading on here, it seemed that only the PMD would set the light but no codes. Is there anything else that can set the light but not have any failure codes?

It doesn't matter if the truck is hot or cold so I don't think it has anything to do with temp. Seems like the mileage is bad (about 14 mpg).

Any ideas? I am going out now to see if the wastegate solenoid is getting vacuum....

thanks,
Mike

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Got vacuum all the way to the wastegate solenoid. Also have a fault code now. Have a #35. Book says IAC valve. I need to get a diesel book. My haynes doesn't have a 6.5 section.

Can someone explain what I should see for the wastegate operation? If I hook a vacuum pump up to the solenoid, should I see the arm move? I put 15 pounds of vacuum and nothing moved. I can move the wastegate arm manually but it doesn't spring back to any certain position.

you shoudnt be able to move the wastegate arm if its pressurized to specs. is there any reason you suspect the wastegate system isnt up to snuff. do you have any excessive black smoke or is it slow.

I re-read what I wrote. I did say that I could move the arm but I forgot to say that was with the engine off. With the engine on, I couldn't move it. I was going to ask if that is normal and you already answered that.

Looked through the previous owners stack of receipts. He was working on this gripe for years!!!! Lots of parts thrown at it but the code 35 keeps on showing up.

I put a PMD on there but I just had it resting on the intake. I didn't read how the intake acted as a heat sink. I may have damaged the new one. The new one is now sitting on a remote heat sink but it may be bad. I hate to throw more parts at it but might try to find a cheap used one to test it out.

The truck has less than 50000 miles so I would think the IP is ok but it is 15 years old so I don't know. :argh:

if pmd is damaged it probably wouldnt set a code. they rarely do

Thanks. Any idea on the 35? Says something about timing and I am assuming it is the IP timing. We have a great local diesel shop. I'll have them check it out soon but till my bike is back, the truck is my DD.

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Thinking about simplifying if possible. Mechanical IP and wastegate. I know the wastegate is easy and read that people have switched to the mechanical IP but no idea as to how difficult.

I don't want to change stuff just to change stuff but it seems like this truck has had the stumble and code 35 for about three years.

Anybody out there have the know how for switching to mech pump or other non-pmd pump?