My 99 GMC truck needs a miracle

[Redrocket1045]

Originally Posted by scavanger

I think unlike my L98 vette your injectors pulse indivigually . If you had and intermitten short on the ground wire it might pulse.Or if shorting on the 12 volt supply side it might screw up the ECM and not fire any of them for an instant. I know on an L98 each bank pulses.If you get a short in one of the injectors or wire it may not fire any of that bank. Don't remember if you checked your injectors. Check the ohms on your injectors , think somewhere between 12 and 16 ohms. Just a place to start.

Scav.

Since I'm reverting back to the original stock injectors - I pulled the intake off this evening and I'll be checking each injector pig tail harness tomorrow for integrity i.e. no insulation that might have caused a short. I've got to do this anyway since I'm going back with the stock EV-1 pigtails which will be rosin core soldered and wrapped with heat shrink tubing - which I failed to do 4 1/2 years ago(just used electrical tape). I'm hoping that I'll find a pigtail that was the source of my f**king headache.

[Redrocket1045]

Originally Posted by Redrocket1045

Since I'm reverting back to the original stock injectors - I pulled the intake off this evening and I'll be checking each injector pig tail harness tomorrow for integrity i.e. no insulation that might have caused a short. I've got to do this anyway since I'm going back with the stock EV-1 pigtails which will be rosin core soldered and wrapped with heat shrink tubing - which I failed to do 4 1/2 years ago(just used electrical tape). I'm hoping that I'll find a pigtail that was the source of my f**king headache.

No such luck. Every pigtail had electrical tape where it was rosin core soldered. What I did find was that the EGR tube that goes into the rt. front side of the intake - the rubber seal was cocked to one side - as if making a half seal. Maybe this is why my vacuum readings were very low and just maybe this was somehow messing up the MAF sensor, which in turn was telling the injectors to dump more fuel. I just don't know?

[stumpuller454]

how far apart is the truck? you could go for a drive and see....

[Redrocket1045]

Originally Posted by stumpuller454

how far apart is the truck? you could go for a drive and see....

Today I soldered all 8 EV1 pigtails and used shrink tubing to keep everything good. Also - I just finished installing the original injectors back into the intake this evening and I'll install the intake tomorrow. I still need to pull off the Powerdyne supercharger tomorrow and load the factory program back into the ECM - but with rain in the forecast and a weekend of partying upon us - I'll just see what happens. Anyways - wishing all a great and safe 4th of July weekend.

[Redrocket1045]

Originally Posted by Redrocket1045

Today I soldered all 8 EV1 pigtails and used shrink tubing to keep everything good. Also - I just finished installing the original injectors back into the intake this evening and I'll install the intake tomorrow. I still need to pull off the Powerdyne supercharger tomorrow and load the factory program back into the ECM - but with rain in the forecast and a weekend of partying upon us - I'll just see what happens. Anyways - wishing all a great and safe 4th of July weekend.

MIRACLE FOUND Well. it didn't rain so I thiught I'd tackle the job ahead of me. As I mentioned in a prior post, I had a sneaky suspicion that the EGR tube rubber seal at the intake manifold might be causing all the false readings because my engine vacuum reading was too low and causing havoc with the electronics. After installing the tube and making sure the seal was seating correctly - I then snugged the 1 bolt that holds the tube in place. I removed the Predator tune and downloaded the factory tune back into the ECM and now it was time for the truth. She fired right up. Idle is right at 600 rpms. No more black smoke, throttle response is back to normal and the SES light is OFF. I don't turn a wrench for a living, and 6 mechanics that do(including the stealership) - tried their best and couldn't find the problem. I feel great now that I fixed what others couldn't. As one forum member said - it's probably something small right in front of you - and he was right. I want to thank everyone for their past advice - you guys are great.

[stumpuller454]

HEHE, good find sir, I knew it was probly vacuum related, still going to keep her stock?

[Redrocket1045]

Originally Posted by stumpuller454

HEHE, good find sir, I knew it was probly vacuum related, still going to keep her stock?

Yea, since I'll be selling the old truck. All I need to do now is remove the 1.85 ratio SLP rocker arms and install the stock ones back on.
Now - I will look for a good CAI for my 6.2L '09 Sierra Denali. Any reccomendations?

[stumpuller454]

Originally Posted by Redrocket1045

Yea, since I'll be selling the old truck. All I need to do now is remove the 1.85 ratio SLP rocker arms and install the stock ones back on.
Now - I will look for a good CAI for my 6.2L '09 Sierra Denali. Any reccomendations?

Check out VOLANT, they are very well engineered CAIs.

[Redrocket1045]

Originally Posted by stumpuller454

Check out VOLANT, they are very well engineered CAIs.

Will do - and thanks again Stumpuller 454.

Redrocket1045

[Redrocket1045]

Originally Posted by Redrocket1045

Yea, since I'll be selling the old truck. All I need to do now is remove the 1.85 ratio SLP rocker arms and install the stock ones back on.
Now - I will look for a good CAI for my 6.2L '09 Sierra Denali. Any reccomendations?

Over the weekend - I installed the stock rockers back on, installed a fresh set of spark plugs and did an oil change using Royal Purple and a Mobil 1 oil filter - the last one before I sell her. Also detailed her inside and out. She now starts like new and purrs like a kitten @ 600 - 625 rpms - no bog - no black smoke - not bad for a truck with 63,000 original miles!!! Oh - did I mention now I can get her to spin the new Goodyears pretty good. LOL