"Joe Dirt" 98 GMC 2wd RCSB #autocross

[TacosnBeer]

i take it you're getting a stumble under load and wot? what size are your tires? i have been trying to figure out if i am going to stick with 15's or go to 17's

Yessir, stumbling under load (I think its the overdrive) and not downshifting at the right time - all symptoms lead to the TPS/computer relationship. As for tires... I have the stock 15x7s with 235/75r15s right now and for how low I have it set, the fronts are too tall... not to mention the steering knuckles on the drop spindles sits right on the rim... need at least 17s. These 15s were just till I could find another set of wheels and tires. ...eventually.

 

[Jerryred94silvy]

Yessir, stumbling under load (I think its the overdrive) and not downshifting at the right time - all symptoms lead to the TPS/computer relationship.

Wait a second, mine does this too. Like it’s lugging real bad in overdrive but will NOT downshift unless you blip the throttle? It holds OD all the way down to like 45-50mph where it’s lugging super bad.

 

[TacosnBeer]

Wait a second, mine does this too. Like it’s lugging real bad in overdrive but will NOT downshift unless you blip the throttle? It holds OD all the way down to like 45-50mph where it’s lugging super bad.

For the record, my truck is a 98 that had a MPFI 305 that was swapped out for a carbed 350... no more electronics but, the TPS is set up to tell the computer throttle position to control the 4L60e. Not all the bugs have been worked out from the swap but, it runs and drives. Your issue may be something else... dont know.

 

[Donald Mitchell]

can google overdrive lookup switch and find an answer to part of your problem. A lot of diy info.

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[Jerryred94silvy]

For the record, my truck is a 98 that had a MPFI 305 that was swapped out for a carbed 350... no more electronics but, the TPS is set up to tell the computer throttle position to control the 4L60e. Not all the bugs have been worked out from the swap but, it runs and drives. Your issue may be something else... dont know.

Mine is a carbureted 350 as well. After market TPS sends the signal to the computer to make the magic happen. Might just need some adjusting, who knows.

 

[MrPink]

For the record, my truck is a 98 that had a MPFI 305 that was swapped out for a carbed 350... no more electronics but, the TPS is set up to tell the computer throttle position to control the 4L60e. Not all the bugs have been worked out from the swap but, it runs and drives. Your issue may be something else... dont know.

If my fueling issue isn't fixed with the new injector/regulator setup i am highly debating saying eff it and going with a Holley Sniper and an Atomic trans controller as i have the oddball one off year of 1995 lmao. i have been looking into LS swapping it too lol, but again i would have to run a trans controller unless i went with a matching 4l60e. mine was recently rebuilt(before i bought it).

Have you tested your TPS sensor? If you need to replace it go with a AC Delco or a GM genuine part. Our trucks are very finicky when it comes to what parts they like. hell if your truck still has the vortec fuel pump in it, you could always do a EFI setup(L31 marine Manifold) and a 0411 ECM and control both the trans and EFI from it. With yours being a 98 it would be easy.

 

[jgreen16]

i have been looking into LS swapping it too lol,

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[MrPink]

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never said he should, it is something i have considered since i have the oddball year transmission.

 

[TacosnBeer]

Ya so, I have a new crate motor ... LS isnt even on the radar. Just need to work out the bugs and I will be stoked. I know my issue, just need to fix it. I have the B&M TPS and have messed with the adjustment with no luck. If I run my truck in 3 vs overdrive D, it is fine. Gonna switch to the TCI TPS soon and if hopefully the relationship between the TPS and Tranny can be better! LOL

 

[TacosnBeer]

Not perfect but, clean... nice Hot Air Intake too! LOL

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