Engine/Transmission (1994 - 1998) Upper RPM Fueling ???'s

[Lonestar]

I have been playing around with my new 98' 12valve 5spd, and have come up with some questions.



When I am really getting on it, it makes tons of power in the 1800-2500rpm range. After 2500, it seems to flatten out and make lots of smoke. Is this due to a plate profile, or low boost, or something else.



I am still learning how these motors work, so sorry for the silly questions.



The truck seems to have some form of a higher performance plate, but I don't know what or how to tell what. Any ideas on how to tell the plate number?



KEEP ON TRUCKIN'

Lonestar

 

[Joe G.]

Take the AFC cover off. That will expose the top of the plate. If the plate is an after market it will have a number on it and no rivets. If there are rivets it may be a home ground plate so you don't have any idea how it affects performance. If is has a one or two digit number on it then you should be able to find out about it.

 

[GAmes]

When I am really getting on it, it makes tons of power in the 1800-2500rpm range. After 2500, it seems to flatten out and make lots of smoke. Is this due to a plate profile, or low boost, or something else.

That is normal defueling. Do a search on the 3 GSK (governor spring kit) and 4 GSK. I put a 3 GSK in mine and it now defuels at about 3600 rpm.

 

[Buck88]

All I have to say is that the 3k GSK turned my truck into a whole new animal. If I had to do it over again, the GSK would be my first mod. - Buck

 

[Timebomb]

After 2500, it seems to flatten out and make lots of smoke.

My 98 did the same thing in stock form. Now has 3500gsk and runs great no defueling.

 

[McDowra]

This is what you are wanting, plus I couldnt miss a chance for a shamless plug



3K GOV KIT



hope this helps



Tim



196487965 is a coupon code for TDR members to get free ground shipping on this item. When you get to the screen for payment information there is a box for redeeming a coupon enter the number there and click the redeem button, then enter your other payment information.



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[TAbbott]

I have been playing around with my new 98' 12valve 5spd, and have come up with some questions.



When I am really getting on it, it makes tons of power in the 1800-2500rpm range. After 2500, it seems to flatten out and make lots of smoke. Is this due to a plate profile, or low boost, or something else.



I am still learning how these motors work, so sorry for the silly questions.



The truck seems to have some form of a higher performance plate, but I don't know what or how to tell what. Any ideas on how to tell the plate number?



KEEP ON TRUCKIN'

Lonestar

I don't know anything about your plate profiles, but if your power is decreasing while your smoke is increasing it sounds like you might be running short of air, not fuel.

 

[Lonestar]

I don't know anything about your plate profiles, but if your power is decreasing while your smoke is increasing it sounds like you might be running short of air, not fuel.

that was a concern I have. I think I am going to install a BHAF. That should help some, although the indicator isnt pulled down any. I also wonder if I can get the the wastegate to open later??? I'm not sure how this works on the 12valve though. I know my last truck had a boost elbow that I changed out, is this the same?



Thanks again

Lonestar

 

[Vaughn MacKenzie]

It's not too uncommon for a 12v to make a lot of smoke & not a lot of power when you really have the throttle mashed to the floor. My '96 does it pretty bad sometimes. . . it's fairly clean midrange RPM but above 2700 it starts rolling it out. Then another time it doesn't do it under the same scenario.



Vaughn