low power

[d.h.]

My truck isn,t up to snuff lately. My boost only gets to 7lbs max under load,towing one horse in trailer (3500lbs) and I can,t here turbo spooling up anymore.Wife usually drives as I,m working.Would this be a wastegate problem?Or worse a turbo. My boost under load usually gets to 12-15.I checked I/c connections and all are tight.Pulled line of wastegate at idle and could feel suction(don,t have guage to measure).Any thoughts or ideas appreciated.

[markrinker]

I'll bet you have a slight vaccuum leak somewhere and are not getting full boost.

Are you seeing black exhaust smoke under load and full acceleration? If so, I would continue troubleshooting the turbo and wastegate.

If not, you might be 'under-fueled'. Check lift pump, fuel filter, injectors - especially if the truck is missing or running rough.

[Hye]

Look at the air filter, the turbo input blades, check turbo shaft play. Small axial play in and out is OK, radial play side to side should be almost imperceptable. At least one mechanic has told me the turbos are almost never the problem. Mine is still OK after 285K. The turbo will be oily inside, that is normal.
Begin a process of elimination. Bypass the vaccuum control solinoid with a short piece of hose to give max vac to wastegate controller. Or wire the wastegate to give max boost and take it for a short run.

[d.h.]

I haven't noticed any black smoke as of yet as I haven't driven in daylight. I will check this morning. I will try wiring the wastegate closed. This happened on my holidays, boost would drop off while driving at 65 mph to 0 then all of a sudden return. Truck runs smooth, no missing, hopefully process of elimination will find something. Thanks for replies.

[JohnC]

Originally posted by d.h.:
... boost would drop off while driving at 65 mph to 0 then all of a sudden return. Truck runs smooth, no missing, ...This is the behavior typical of a failing wastegate control solenoid. The PCM can't get the boost it wants so it shuts the solenoid down, dumping the wastegate vacuum. When conditions change (usually reduced ruel rate) the system starts up again. Next time you notice it drop to zero, let off the throttle and then come back on it. If boost returnss then this is most likely what's happening.

[d.h.]

John. I recall thats what happened on holidays.As soon as I released throttle and applied again boost would return.This time I have 6-7lbs under load but thats it! I wired up wastegate lever and no differance.Checked and cleaned air filter as those free flows seem to pick up more stuff.I ,m wondering if it is the boost fooler causing as 6-7 lbs boost is what I had before mods.The pyro seems a little high but I never had guages when stock to Know temps.I,m stumped :confused:

[JohnC]

If you wired the wastegate shut and only got 7-8 lbs and the aircleaner is good and there are no leaks in the induction system, then it sounds like the turbo has gone TU on you. (This would also make it hard for the PCM to get the boost it wants.) Pull off the rubber inlet boot and check for a seized impellor or impellor rubbing hard on the housing. (You'd likely hear the latter, as a police siren following you around)

[ 11-12-2004, 06:50 AM: Message edited by: JohnC ]

[d.h.]

I pulled intake off turbo yesterday,noticed slight movement but no signs off rubbing.I don,t hear any irregular noises from turbo just no " turbowhine".Drove 30 miles tonight runs great exept lack of power.I ordered wastgate solenoid today.If thats not it its got to be the boost fooler or turbo.I have a diesel engine specialty shop in the area I may pay a visit to if I can,t get it myself