Engine/Transmission (1994 - 1998) Did some mods and got a flat spot.

[FDavid]

Truck is a 98 12v 5spd. Until yesterday the only mods were a banks twin ram manifold, bhaf, 5" exhaust, banks turbine housing and a banks plate. Well yesterday, it got a 4k gsk with heavy duty valve springs, afc spring kit and a tst 10 plate.



Now the truck goes flat on its face if you stomp the pedal around 2000 rpms and then very very slowly builds rpms. Once its hit about 2800 rpm, boost goes from about 5 to 35 lbs. and the truck explodes with speed and power all the way til I shut it off (~4000 rpm).



No black smoke what so ever, fuel pressure is fine. It feels like a huge single or a sport bike,only really taking off hard when the rpm is way up



-Dave



PS went to do kdp yesterday as well, found the dowel pin missing and the timing case cracked in 2 places :{ Now accepting donations :-laf

 

[SEmerson]

Your afc is ajusted way wrong. It is holding your lever back too long. Also before you start tuning it where is the lever starting on the plate? That is the first thing to start with. Then mess with the plate position and afc springs and position.

 

[Matthug]

There may be several things contributing. I'll ask this though, when you replaced the plate and AFC, do you have the plate and/or the AFC housing full forward? Also what spring did you put in the AFC, the medium or light spring? I have the light spring in my truck, had the AFC housing off last week just playing with some shop air. Well turns out the AFC arm doesn't get full travel until 30+ PSI. For some reason the springs you get in the kit are longer than the stock one, well this puts more preload on the spring defeating the purpose! Soon as I get a chance I'm putting the stocker back in and the truck should be more responsive.

Also, what method did you use of setting the governer springs? Also you did remember to leave the shims out right?

 

[Matthug]

Oops sorry SEmerson your post wasn't there when I was replying I just took a really long time to reply. I believe you are 100% correct though the governer arm is probably going below the plate. Here's how to fix it-

http://www.piersdiesel.com/TechLeverAdj.htm