Its Fixin' Time

January 16, 2008

Alright i NEED to get this fixed.

When i start from a stop i go through 1st, 2nd and then in 3rd gear it almost starts to bog down if i give it a little throttle. but then if i give it some more it usually continues going pretty well. ALL of the sudden it gets to TQ Lockup. then my accel slows to a crawl, has no power, and when it finally gets to 4th (58-65MPH) i go NO WHERE without stepping on the pedal hard enough to get it into passing gear / Kickdown. it has always done this. ive had the tranny rebuilt about 1000 miles ago and didnt change a thing.

I dont know wahts going on here because i know nobody esle with the same problem as me. I would like to hear comments other than ("TBI Motors dont have very much power") i know this but this obviously isnt normal. My gears are 3.42 but im still not sure if that would cause this. i think its a cable adjustment but ive been to the tranny shop about 6, yes 6 times and everytime has told me he cant get it any better. This is sooo anoying. if you need ANY more details let me know ill fiind out everything i can

Motor is a 90' 350 TBI

700R4

Im really hopeing somebody could get me the golden fix that could make this go away forever.

ws6_guy · January 16, 2008

hmm, could it be injectors?

January 16, 2008

Actually no, not only have i been putting Lucas Oil Fuel Treatment in everytank but i had it checked over one day and they DID say they were very clean. But did find a intake manifold vacumm leak, (which i have had fixed for some time)

Wingnut · January 16, 2008

Does it knock or ping when you hammer it?

January 16, 2008

no, it does not. What are you thinking a Knock Sensor? If you think that is really a problem i could try replacing it. i think they are like $20?

dietz4ibanez · January 16, 2008

It should be less than that for a knock sensor. I will call my friend he has a 87 I think with the same transmission. It was the first year they had fuel injection in that truck at least. I think that he has had a similar problem as what you are describing.

I will call him tomorrow and let you know as soon as I can.

January 16, 2008

thanks i want to get this fixed really really bad. its gone on forever but does it in none of my friends trucks. Im hoping its just a few sensors or something easy. Thanks for any and ALL help.

thecraft · January 16, 2008

"TBI Motors dont have very much power"

So not true, but your 3.42 gear ratio and 35" (??) tires are not helping.

January 16, 2008

Yes i know, but the tires are only 33"

2004GMC1500CC · January 16, 2008

Alright i NEED to get this fixed.

When i start from a stop i go through 1st, 2nd and then in 3rd gear it almost starts to bog down if i give it a little throttle. but then if i give it some more it usually continues going pretty well. ALL of the sudden it gets to TQ Lockup. then my accel slows to a crawl, has no power, and when it finally gets to 4th (58-65MPH) i go NO WHERE without stepping on the pedal hard enough to get it into passing gear / Kickdown. it has always done this. ive had the tranny rebuilt about 1000 miles ago and didnt change a thing.

I dont know wahts going on here because i know nobody esle with the same problem as me. I would like to hear comments other than ("TBI Motors dont have very much power") i know this but this obviously isnt normal. My gears are 3.42 but im still not sure if that would cause this. i think its a cable adjustment but ive been to the tranny shop about 6, yes 6 times and everytime has told me he cant get it any better. This is sooo anoying. if you need ANY more details let me know ill fiind out everything i can

Motor is a 90' 350 TBI

700R4

Im really hopeing somebody could get me the golden fix that could make this go away forever.

How old are your cats? Could be a symptom of a clogged cat, but I dont' think it would go on this long.

superjim · January 16, 2008

Have you checked the timing? If it is timed too slow, I think that might cause it.

Does the trans have a vacumn modulator? It sounds like the TC lockup is kicking in too quick.

Could be bad commication from the ECM to the trans. Have you checked the throttle position sensor? Maybe the ECM is confused about the throttle position and is causing the TC to lockup too quick and the trans to shift too quick. If you are out of the torque curve, it will not have much power at all.

Jim from Texas

January 17, 2008

its new enough that the timing is automaticly done by computer, i think? the TQ converter locks up at 45 miles per hour like it is supposed to (i think)

1st - 2nd - 10-13 MPH

2nd - 3rd - 35 - 40 MPH

3rd - 4th - 55-65 MPH

the mph varies if i let off the throttle a little bit or im going full bore.

Im not sure what it could be its not the original motor in the truck, BUT i have the computer, wires, everything from a donor truck and i still have the donor truck. i scanned at school with a scan tool and found no errors but it is a GM-1 connection so i dont know how in depth it gets but it was reading the RPM and such. The Tranny is from the truck originally and rebuilt less than 1000 miles ago. the Transfer case is also NOT from the truck.

And for the Cats, i dont have any cats.

Can i ask what a TP sensor is? And What it does?

Schmids5.3l · January 17, 2008

Weren't you messing around with your transmission earlier? Say.. the ''gas engine tech'' section? Unplugging a connector to the transmission? Redvett mentioned something about that being a bad idea