I have efi and a built trans in my 04 4500. The truck runs well, except it feels like it has some sort of governer keeping if from taking off quickly. Brayden at Fleece played with it for a while without any luck. It's sooo slow until atleast the second gear shift. At the track, it ran 17.47 with a 3.48 60'. With a load on, at times it won't even take off if there's even a slight incline. You have to back down the incline, and try to get a run at it. It just won't build any rpm's at all until it's moving at a decent rate. Then it comes on strong. Any ideas?

I have efi and a built trans in my 04 4500. The truck runs well, except it feels like it has some sort of governer keeping if from taking off quickly. Brayden at Fleece played with it for a while without any luck. It's sooo slow until atleast the second gear shift. At the track, it ran 17.47 with a 3.48 60'. With a load on, at times it won't even take off if there's even a slight incline. You have to back down the incline, and try to get a run at it. It just won't build any rpm's at all until it's moving at a decent rate. Then it comes on strong. Any ideas?

Start off with spraying the MAf off with some maf cleaner .

Are you LLY . I have some good tunes . I could send you one to try and see if it is different .

Send me your email .

glamiskodiak@hotmail.com

Johnny

Mine is an LB7.. It's very aggrivating.. I wish it were an LLY.
I'm going to have to do the injectors soon as well.. It's hazing white smoke and the fuel mileage has dropped quite a bit. I had them scanned at a dealership a long time ago, but they wouldn't replace them since they didn't sell medium duty trucks. They did say it needed it though..

Find yourself a medium duty dealer . Even a non medium duty dealer can do injectors and motor work on non medium duty . Been there before , they just can do work on the chassis . They dont want to , but you can tell them they can touch the motor though . Had this issue in a small town that wasnt a medium duty dealer and they can work on the motor . Thier mecanics qualify to work on the motor .

We actually went round and round.. They told me they wouldn't touch it.. They didn't help much.. I'll try again in KY where the truck is now.. Thanks..

Had my injectors changed last year on my 2004 4500 JB7 under the 200K mile warranty. My truck ran fine, just had dark diesel smoke at idle. John

Checked for boost leaks yet?

I have efi and a built trans in my 04 4500. The truck runs well, except it feels like it has some sort of governer keeping if from taking off quickly. Brayden at Fleece played with it for a while without any luck. It's sooo slow until atleast the second gear shift. At the track, it ran 17.47 with a 3.48 60'. With a load on, at times it won't even take off if there's even a slight incline. You have to back down the incline, and try to get a run at it. It just won't build any rpm's at all until it's moving at a decent rate. Then it comes on strong. Any ideas?

We actually went round and round.. They told me they wouldn't touch it.. They didn't help much.. I'll try again in KY where the truck is now.. Thanks..

Yea they can be lame sometimes . They can work on the motor not being a medium duty dealer . Talk to GM customer service and they will direct that dealer to look at it and do the injectors . Unless something has changed I dont know about . Had this issue when I was in Oregon . Closest medium duty dealer was 300 miles away and GM customer service told them they could work on the motor and trans only and not the chassis . I was wanting them to check the injector , but didnt end up needing them changed . I had some bad fuel with gasoline in it and the truck was cackling bad . Drained fuel and it was back to normal . Injector #8 is a real pain to do . Easiest way to get to it is cut a 3 inch hole in the floor right next to pedal and make a plate to cover and pop rivet back in place . Otherwise they have to lift the cab and drop the motor down from mounts . Some dealers with 4500 experience do the hole and others do it the hard way . Your call a bit on if you want to let them cut a hole in the floor or not . Some dealers dont know or do it this way and some do . I was going to cut the hole on mine , but instead did my injectors while I had motor out . I would do hole if I ever had to do mine now . Screw lifting the cab . What a pain and risk of cracking windshield .

Checked for boost leaks yet?

Good call Brayden . I have also cracked the plastic intercooler tank twice on driverside between radiator and intercooler on mine and why I went with the upgrade to 07 aluminum intercooler now .

Part # for aluminum intercooler is in my signature below .

I have efi and a built trans in my 04 4500. The truck runs well, except it feels like it has some sort of governer keeping if from taking off quickly. Brayden at Fleece played with it for a while without any luck. It's sooo slow until atleast the second gear shift. At the track, it ran 17.47 with a 3.48 60'. With a load on, at times it won't even take off if there's even a slight incline. You have to back down the incline, and try to get a run at it. It just won't build any rpm's at all until it's moving at a decent rate. Then it comes on strong. Any ideas?


Dude that tune was scary.. closest thing to the 40/40 tune I've ever seen.

4000 uS and near 40degrees timing.. You're lucky she still runs. :)

Dude that tune was scary.. closest thing to the 40/40 tune I've ever seen.

4000 uS and near 40degrees timing.. You're lucky she still runs. :)

Holy hell ..... thats scary right there . :eek: