Engine/Transmission (1994 - 1998) Help understanding 1996 performance enhancements or lack there of!

[DFerguson]

All,



Need help understanding why my trucks performance mods are not giving it the performance enhancements that I’m after.



Setup: 1996 Auto with DTT 93% torque converter, livestock valve body and master overhaul kit, TST #8 plate (230 hp, 605 torque) in factory position, AFC slide full forward. No Cat, has flow through style muffler, and 4” pipe all the way back. I ran the truck for years with this setup and it worked great. Pulling my 5th wheel on steep interstate hills the boost would hit 32 lbs and the cruise would always hold 74 mph (2000 rpm). The truck would always have enough power to hold the speed. When pulling my 4WD on a 16’ trailer I learned how to pass going uphill!



Well like others I thought I could improve further on a good thing: I had the timing adjusted to 15. 75 deg (CPL 2174, 4. 85 mm plunger lift), and a 3000 RPM Governor Spring Kit installed. I have checked the timing myself to verify that it was in fact set correctly.



Here is what its doing ever since the timing was bumped and GSK addition: The max boost used to come in early like 32 lbs by 2000 rpm. Now the only way the truck pulls 30-32 lbs boost is with the overdrive locked out and letting the rpm’s get to about 2600. It now only pulls 20-24 lbs in drive at 2000 rpm’s. What this means is now the truck does not have enough power to pull steep interstate hills with the cruse control set. It gets behind going up the hill then over shoots when passing the top. The engine will now freely rev to redline…so the GSK seems to be working. I just don’t like the fact that the max boost has been slide so far to the right and is no longer accessible in drive while on the interstate. I have really thought about removing the GSK. Can the GSK be adjusted to allow more boost at lower RPM while still allowing the engine to rev to around 2800 rpm when overdrive is looked out? I’ve checked the fuel pressure and it is 24 psi at idle, 33 psi at 2500 rpm, and 30 psi with foot on floor during speed run. I’ve also tried moving the TST #8 plate all the way forward. This did not help with moving max boost to lower RPM only created a problem where the engine would “buck” when I put the pedal down while towing. I moved the #8 plate back to the factory position.



Would appreciate advice from any of you that have been there done that and found a good solution!



Thanks,



Don Ferguson

 

[Bob V]

The GSK changes the relationship between the fuel plate and RPM. In a way it "detunes" the plate and gives you less fuel vs RPM. Most vendors recomend the #10 plate with the GSK.

 

[Joe G.]

You might want to put the stock governor springs back in and see what happens. I didn't buy a GSK. Instead I turned the governor spring washers in a couple of clicks. Mine will turn up to 3K if I want to run it that fast. It also really pulls when I need it to.

 

[DFerguson]

Bob - I had read that the #10 works best with the GSK. One of the venders told me to slide my #8 forward... . did that and as stated above caused a new problem.



Joe - Do you know if I can turn the GSK spring washers out a few turns?



Anyone using the GSK remove a TST #8 plate and replace with the TST #10... if so tell me about it!



thanks,



Don

 

[Joe G.]

I don't have a GSK so I don't know anything about them. I found that I could get the RPM I wanted without one. In fact, I adjusted my governor springs before a GSK was available. I saw no need to get one for my truck.

 

[JFaughn]

I'm trying to get how the system works in my mind so that I can get a little more when I can afford a Georand trans .
So heres my guess , there is a relationship between all of these , your systems seems like your fuel is coming in late [ fuel runs the turbo ] so some fine tuning of the plate , AFC , smoke screw , rack travel .
The tricky part is getting all of these adjustments right in relationship to each other [ kind like getting 5-6 parts , with only 2 hands , held together with one bolt ] .
I just saw a post [ with link ] that may offer some help .


Rack Travel - Competition Diesel. Com - Bringing The BEST Together

 

[DRAG DIESEL]

Don, two things concerned me in your top post.



1. The "bucking" comment. That's only one of two things... a fueling delivery issue, or your converter clutch slipping. And before the nay sayers get on the DTT converter can't slip bandwagon... that's why I said one of TWO things it COULD (not is) be.



2. If you want more snap on the bottom end, put the timing back to the stock setting. More timing is only going to give you more "lag" until the RPM's come up. A lot of people run 15 to 16*, but if you live at altitude you might not like how that drives.



I noticed no difference when I put my 3k's in my truck, but then again that was back in 99 when all the springs came from the same place... who know's what's out there today.



Make sure you have constant pressure going to the afc, and that the line is not cracked and the diaphragm is in good shape... I blew a hole in mine once.



Make sure your wastegate is either disabled and shut or working and opening at over 32psi.



Hope this helps a little,

~jake

 

[Jim Fulmer]

Bob - I had read that the #10 works best with the GSK. One of the venders told me to slide my #8 forward... . did that and as stated above caused a new problem.



Joe - Do you know if I can turn the GSK spring washers out a few turns?



Anyone using the GSK remove a TST #8 plate and replace with the TST #10... if so tell me about it!



thanks,



Don

I would switch over to a #10 considering you towing that much. The 10 is the best plate for this situation. If you were looking for more all out performance I would go with a #6 or #5, a 6 has a softer bottom end... . I run a 6.



Take this info and run with it, a vendor should swap out the plates for you with a little money to bout. If you put any plate in be sure to check the relationship between Gov arm and plate... . were it strikes with the fuel shut off up. Look into the thread on competition diesel that was supplied, Weston put lots of pics and info in there and it's good stuff. Remember everything in a P-Pump and the way it's setup is a relationship.



Last thing is I have heard vendors say to me... ... . well that won't work or that's no what we recommend..... had to bite my tongue and smile.



Jim

 

[DFerguson]

Thanks for all the good advice guys. I wish I'd had done the timing and GSK in two steps but then you know what they say about hind sight!



Can increasing the timing to 15. 75 really shut the low end boost down this much?



I don't think the torque converter clutch is slipping since when it's locked up in third at 2600+ rpm, 30 lbs boost and pulling my 5th like a train the tach moves as expected.



One thing I did notice right after the GSK install was that it takes more force to mash the pedal down. Is this expected? I'm getting full travel of the cable and it's not sticking... . just takes more force.



Can the addition of the 3K GSK change the relationship (adjustment) between the Gov arm and plate? The #8 plate is now back in the same place as it was prior to the GSK and timing (when it was making better boost).



Last question - How does a zero plate stack up compared to the TST #8 plate? Or compared to a #10 or 100 plate?





Don

 

[JFaughn]

It would seem to me that if you do not see a surge on the tach , with no speed change , or set of your pants feel , then your trans/TQ can't be slipping .

 

[Jim Fulmer]

Thanks for all the good advice guys. I wish I'd had done the timing and GSK in two steps but then you know what they say about hind sight!

Can increasing the timing to 15. 75 really shut the low end boost down this much?

Nope, a little timing always helps responsiveness till after 16 then it drops off a tad till 20 then it falls.

I don't think the torque converter clutch is slipping since when it's locked up in third at 2600+ rpm, 30 lbs boost and pulling my 5th like a train the tach moves as expected.

Then it's not slipping, and if it were the clutches would slip first. FYI anyone with a tad of knowledge can sabatoge a transmission and make it slip with one adjustment, takes about 2 minutes to do.

One thing I did notice right after the GSK install was that it takes more force to mash the pedal down. Is this expected? I'm getting full travel of the cable and it's not sticking... . just takes my force.

Check the linkage and makes sure it's not binding.

Can the addition of the 3K GSK change the relationship (adjustment) between the Gov arm and plate? The #8 plate is now back in the same place as it was prior to the GSK and timing (when it was making better boost).

Yes the Gov arm will drop when you add spring tension, this why when you put a #5 or #6 plate in with springs you have to raise the Gov arm to make it work right.



Jim

 

[DFerguson]

Jim - Thanks for your reply.

Knowing that 15. 75 deg timing is most likely not the problem is a relief. Understanding that the GSK can cause the Gov arm to drop with the increased spring tension explains alot. That is exactly how the truck feels. Thanks for taking the time to hammer that point home. I see now that you said it in your 1st post but it did not sink in.

I will order up a # 10 plate and adjust the Gov arm for the new plate. I assume that if I move the new plate forward of OEM then it's worth checking the Gov arm adjustment again.



thanks,

Don

 

[RWorth]

Siff pedal

I had this happen to my truck as well. Set up was a #11 plate and AFC set boost was 26 to 28 psi. While pulling the camper to the lake I noticed fluctuation of the needle on the boost gauge. When I got back home I started checkng for leaks in all the intercooler hoses from the turbo to the intake and I didn't find anything. Well after about a week of this it started to take more foot pressure on the accelerator pedal and at this time I also noticed that boost would not get above 21 psi and the power had dropped off. I did a search on here checking for boost leaks and found where someone made a jig to where you can pressurize the system with shop air. Well this ended up being a great deal because I finally found the leak. The boost line from the intake to the boost gauge had been vibrating on the oil dip stick tube which developed a rub mark deep enough in the line that caused the line to split and when boost increased the crack would seperate more. This was affecting the pressure to the AFC which in turn was working like the Valet condition that some use.

Hope this helps

 

[KAlder]

Would the throttle feel stiffer if the gov arm was under the plate?

 

[McLaughlin]

One thing I did notice right after the GSK install was that it takes more force to mash the pedal down. Is this expected? I'm getting full travel of the cable and it's not sticking... . just takes more force.



Can the addition of the 3K GSK change the relationship (adjustment) between the Gov arm and plate? The #8 plate is now back in the same place as it was prior to the GSK and timing (when it was making better boost).





Don

It seems it can. I recently was "checking" my fuel plate location and caused a similar problem. When I reinstalled everything I placed the AFC housing and the #10 plate full back (towards the cab) and moved the star wheel about half way back. Prior to the adjustment, the pedal pressure was fairly light and the boost would rise really quick to about 32-36lbs. After the adjustment, the pedal pressure was a lot higher and the boost took a lot (4 or 5 seconds) longer to come on. As a result, I went back in and moved the plate just a bit less then 1/2 way. After the second adjustment, the pedal pressure was a lot less and turbo boost came on quite a bit quicker. In this case they pedal pressure was still higher then the original but less then the first change and the boost came on slower then originally but quicker then the first change.

 

[hsmith]

Jim, I may be a little late with this reply, but have always thought a #10 was too much for towing. With my set up, I can still get pretty hot if I get too heavy with the right foot. I tow a heavy 5er in 4th over just a little over the speed limit usually. May get a #10 and give it a try.

Thanks

 

[dpuckett]

You guys with later 5spds keep in mind his 180hp auto will behave more like a 175hp stick transmission.



I dont know where the stop limit is, but increasing your timing beyond a certain point will take some off the bottom end and add to the top end. I didnt know til recently that the P7100 didnt have the RPM timing advance like the VEs have. Guess that's why they can make so much more torque than the later ones- have retarded timing at lower RPM, then timing moves up as RPM increases.



I know there is a governor adjustment that is needed in some instances with a plate change. Might look into that before switching plates. The #10 wont give you much over stock, other than fuelling curve, will it?



DP

 

[JAmos]

Hmmmm... ... I can't remeber the order of mods on my old truck(95,160pump), but I never had any problems with governor springs. I put in a 4k kit and it was great. I put in a #6 plate and I had to adjust the gov. arm to keep it from hanging up under the plate. I never really felt a power gain from the plate-just lack of power and very hard pedal when the gov. arm was getting hung up. The only other noticable mod was getting the timing set. To sum up I did timing and gsk and loved them, no problems.



Jordan

 

[TPCDrafting]

I have the 11 plate, 3k gsk timing at 16. 5, gov. arm adjusted and it runs hot. Recently we put in a phat shaft 62/80, 4 inch inline brake, ats manifold thinking this would cool things down. Now it's more laggy and it runs hotter. I've backed the plate to stock position and this helped cool some, but now it's wimpier. The major differences are it's not as snappy on the pyrometer and the turbo is much quieter than the HTT stage 3/hx35/12 I had before. Any thoughts on a different plate? Pump adjustments I should make? I was under the assumption that this would cool things down a ton, more air without adding fuel.