reduced boost and very wierd tranny shifting

[Bentt]

As my signature reads its a 97 3500 with a l480 trans

firstly my truck runs 14 to 15 psi of boost ie overdrive highway driving say 60mph and I want to pass or pulling load up hills. It just generates boost and keeps pulling

wastegate is still vacuum operated

ecm looks stock Ie no aftermarket stickers however i do believe it has been reprogramed

So driving down hwy boost caps off at 11 psi and tranny shifts into 3 rd gear and hits the rev limit . This happens at around 60 mph and 11 psi . Let off it shifts back into od and psi drop .

No engine codes are produced engine runs great no tranny issues ie lost gears , lazy shifts , burnt fuild smell

No other symptoms , it seems the the engine is calling for boost and in lack of boost the ecm program downshifts the tranny or the tranny is down shifting and less boost is generated or required ????

Your help would be greatly appreciated

Thanks Ken

[sixnickel]

First thing I would is not assume and put a new fuel filter in it. Low fuel supply = low boost = low power = down shift!!

[Bentt]

I changed the fuel filter and boost and shifting has not changed . Any other ideas ?

thanks Ken

[Bentt]

so no one has any other ideas ?

[trukdoc]

...hold the pull???does it slooow down?????downshift lockout occurs at @ 64-66mph...any speed below this and downshift will occur with throttle depression.....what exactly is your problem???

[God prefers Diesels]

It's not a boost problem. You're getting less boost because it isn't pulling as hard being in a lower gear. Just forget you even have a turbo and focus on the tranny. You got a tranny that is staying in third gear too long, and you have to let off the throttle to upshift. Sounds like maybe the tranny doesn't know how fast the engine is going...

Does it do it every time? Does it only happen when you're driving the $hi+ out of it? Are the rest of your shifts firm and on time?

Lastly, do not despair. If all else fails you can get a Prius.

[Bentt]

It down shifts into 3rd with a moderate throttle on the highway and hits the rev limiter at around 60 mph will speed up but you cannot even slightly push it or it just back shifts

Speedo now does not register pass sixty miles per hr truck is going faster

Lost all boost today no ses light on

Since I lost boost i can slowerly accelerate past 60 with out down shifting occuring speedo stays at 60

Tranny shifts fine no problems

what color is the prius?

[JD_countryboy]

u say the speedo never reads over 60, but you are still gaining speed ( and engine rpm) after the speedo reads 60? almost sounds like some sorta vehicle speed sensor malfunction. Maybe a bad connection or wire goin to vss on tranny?

[Bentt]

certainly will check underneath in the morning . Why does all my truck problems happen @ minus 15 degrees?

[JD_countryboy]

Oh i forgot that prius is back. Might have a bit o damage also. Im pretty sure i sucked it thru my turbo and blew it out my exhaust last night. F150 and my 6.5 had a little fun Light to light. Darn prius got in the way. LOL. Next time ill spool the turbo and anticipate the light a touch better. Dont like cuttin it that close. Oh well, i gave him a chance, and he was almost able to capitalize,,,,,, alomst. The ol 6.5 still got it.

When do you usually vaction? Lots of people like to head for warmer weather when it turns cold. I gues our vehicle componets like to head south in the cold too. lol

[God prefers Diesels]

Yes. VSS or ESS. I don't know how your computer handles stuff. But if you're losing boost, maybe the comp is cutting fuel. Maybe all these things happening at once is the computer going bad.

[Bentt]

sorry but what does vss and ess stand for and where are these components located

[Bentt]

After reading for several hrs on past threads and info from JD and GPD this is what I found. Its possible its my vechile speed sensor , systoms as reported very hard and uninitiated backshifts into 3rd gear from od anti lock brake problem which has started oh say 2 3 weeks ago which didnt seem connected but I guess they are , and speedo screwed up .

What do you think?

I think the lost boost is an entirely separate issue ie lost vacuum or turbo boost sensor or wastegate selinoid , hope its not the turbo itself.

Does SS sell VSS or any other after market dealers or is it a stealer item only ?

[JD_countryboy]

vss = vehicle speed sensor, located on tailshaft of transfer case(4x4) or tranny(2wd) ( same place older cable speedos were driven from, now its just an electrical sensor and wires)
ess = engine speed sensor, located on rear right of engine block valley. (similar to location of distributor on a gasser, two wire plug in)
Not sure exactly if your truck uses an ess or not, but i think it does. I'm still struggling with mine, but after adjustin tps its gotten better, still not right though. Workin a bunch, and runnin outta tools at this point. But im suspect to mine being ess related now.
Your truck doesnt have a tps on the pump, your tps in on your accel pedal. and non adjustable.

I do know that your brake light switch ( when you press your brake pedal) will unlock your tcc (torque converter clutch). Any idea what kinda abs problem your havin? Possibly your vss is bad and causin your abs codes also. Have you checked for any codes?

I think you can get a vss from NAPA or other reputable places. I woulnt go with one from zone or advanced or some other el cheapo place though.

[trukdoc]

...system...lites,etc.,.....an aberant brake signal to comp. will unlock t.c.c. AND cut power.....check adjustment on brake switch under dash....

[Bentt]

where exactly is the adjustment how do you adjust what does it look like

thks Ken

[trukdoc]

...under the dash at the brake switch... on the pass.side of switch is a lever...push the brake pedal down ,at the same time pull the lever towards the rear of the vehicle..release pedal...this will adjust switch travel...trans shift is controlled by engine speed sensor,input speed sensor,output speed sensor and t.p.s......e.s.s. on my 93 is part of oil pump drive....on yours I think it gets a signal from{help me here boys} the alt....input and output sensors are mounted externaly on drivers' side of case{black sensor w/2 wire plug...t.p.s. is part of foot feed assembly..... bad brake signal will cause a default to direct drive.....intermittant signals from 2 sensors will cause a default shift to direct drive...hope this helps..jd....

[JD_countryboy]

thanks for that truckdoc. Gotta new problem to add to the mix, headin back to the other post with it.

[Bentt]

Well still at it , adjusted brake switch and changed the vss and still the same backshifting at 60mph, speedo still only goes to 60.... abs still funky any other ideas????:

On a brighter note found the source of NO TURBO it was my vacuum pump only 2inches at pump , got the gate wired up for now . Any thougths on a vacuum controlled turbo vs using a turbo masteror similiar mechanical system??

Finally changed injectors and glow plugs what a difference in starting no more smoke or rattling. Power increase is noticable or rather it delivers smoother power over the rpm range. I dont know about 40 hp but the power is noticable however Iam sure new bosch injectors would have given a power increase also after a 150k on the original set.
Ive also changed oil to a 0-40 syn rottela what a noticable difference in cold starts. Its going to be minus 23 celius tonight a great test without it plugged in . When we head to camp the truck stays parked about 8km from camp and we sled in, leaving it unplugged for 2 or 3 days at minus 20 to 30 was always a major obstacle.

Now if I can just figure out the speedo and this crazy backshifts out of OD
Ken