wll my trucks 98 and i went from 3.42s to 410s and ihaventg got it tuned could that be why?

 

Well I asked the question before my brain registered that you have a 5.7 and could be pre 99.
Do you have a tach? Is it shifting early?

 

Your truck being a '98 with the Vortec 350 is most likely running out of RPM with the 4.10's. Unlike the LS type motors, the older Vortec's stock just can't pull too much gear without running out of breath. Tunning will help your overall combination, but the earlier models will not turn past 5800rpm even with the rev limiter raised. People have been fighting this as long as there has been tunning options available and as far as I know, the only solution has been to upgrade to a 411 PCM from an '01/'02 model. However being stock, you wouldn't need to worry about spinning it any faster than that as the motor will quit pulling anyway.

 

Interesting, I went from 3.42 to 4.11 on my '06 5.3 and noticed a good difference right away, so much that I consider it the best mod I've done so far (LT's, Tune, small cam, gears). My truck definitely hits a lot harder off the line after gears and it was the last mod I did.

I guess everyone has a different SOTP feel lol.

 

i went from 3:42 to 4:56's and it was a huge difference from a dig and a roll.

 

well im not stock i have pritty much all the bolt ons and a performance 4l60e! it is shiftin a lil early wen im keepin it in drive but i stilll dont get why it slowed me down! and i dident think the 01 pcm would work with the old style 350 vortec!?

 

What he's saying is the older style engines would run out of power toward the upper rpms. while the LSX engines would make more and more. So with the 4.10s in now you are out of your power range faster and now it isn't as quick. The other way the gears would pick up speed while staying in the rpm range longer that your engine produces power at.

Seems like a good guess as most of us on here run LSX engines and don't have the issue you are having. Do you have a cam?

 

If you step to a ECM from a heavier model truck of the same make/yr you should be ok. The computer thinks it's going to pull a heavier vehicle, but it's not, and this is where you can make up a little ground. Local salvage yard here had a Tahoe ECM for my 1500 for $40. I took it to Flaco for a tune and it's perfect.

 

The 411 PCM will work just fine with the older Vortec motors as the Vans were still equipped with the Vortec 350 in the newer models and they came with the 411 PCM. It is not plug and play as you will have to re-pin the connectors, but all of this has been done before. Not only will you be able to rev it higher than 5800rpm (if it will pull that high), you will have finer control over most other functunes as well.

Oh and by the way, I for one do not consider most bolt-on's modified, I.E. pullies, spacers, air intakes, ect. Modified to me is cam, heads, intake manifold and so on, things that will extend your power range.

 

na i dont have a cam so u think il see better results if i go to 3.73s?