97 6.5L low power/ smoke / low boost

[bonez02]

Hi im new to the forum and i bought a 1997 GMC 3500 with the 6.5L turbo diesel and it rarely ever has boost and when it does its a max of 3psi? and at full throttle there is black smoke flowing out of the exhaust? it has a performace exhaust system on it and ecu.... where should i start? is this Turbo/Wastegate problems? what is max psi these engines can handle? any help will be appreciated thanks

[Shikaroka]

If you search around there are lots of threads and good info on this subject.
The most commen problems seem to be the vacuume/wastegate control system. Either the vacuum pump is dead on the control solenoid has failed.
There are several threads that tell you how to test the system.

[DennisG01]

Also, maybe a cracked vac line

[bonez02]

any chance you could link me to a few? been looking haven't come across any also what pump are people talking about turning up?

[sailun]

Here's the deal:
Engine is idling.

Lever on wastegate control should be v. difficult to move. If it moves easily, you have no vacuum, or a vacuum leak somewhere, or solenoid failure, or WG controller failure.

Get a vac guage. Pull the vac lines and rubber thing off the vac solenoid. Measure vacuum coming from the vac pump (orange line), should be 15" or so. Maybe 25" here, I forget. If no vac here, you need vacuum pump or lines.

Now go test at the connection , pump line to orange vac line. (shut off motor, and this connection can be tough to get apart.

Reinstall, pull black vac line off wastegate controller. measure vacuum, should be 15".

Plan on breaking vac lines when you handle them. They get real brittle. Just get a new set, there only $10 or so at dealer.

Sometimes vac solenoid will get fluky, might start working again after removing and replacing the elec plug. Buy a spare to throw in the glove box

Depending on what parts fail, it's far more economical to get a Turbomaster.

When my wastegate controller failed this year, dealer quoted me $380, GM Parts Direct $220. Another member here sold me a used one for far less.

If I hadn't replaced vac pump last year ($200+), and already ordered a vac solenoid ($35), I would just get the Turbomaster ($110).

[bonez02]

when moving the lever on the wastegate controll with motor off i can here air hissing out somewhere... when running lever is not very difficult to move where is the solenoid located?

[bonez02]

when talking about the wastegate controller.... at idle should the lever be in the up position or should it be in the down position? which way is open and which way is closed?

[bonez02]

i have 0" of vacuum at the wastegate, at the solenoid and at the vacuum pump.... so hopefully replacing the vacuum pump will fix the problem.

[bonez02]

well i got a new vacuum pump cost 119$ and reaplaced it and now i have hit up to 18LBS OF BOOST WOOOAAAA

[a5150nut]

well i got a new vacuum pump cost 119$ and reaplaced it and now i have hit up to 18LBS OF BOOST WOOOAAAA

I hope you have an inter cooler. At that much boost the heat gains will far out weigh the added boost.

[bonez02]

i dont have a intercooler :0 just a 4" exhaust and a aftermarket ecm and K&N air filter... what is stock boost? what is highest safe boost level?

[JohnC]

Stock boost maxes out around 8 psi and peaks around 10 psi. Max safe boost without an intercooler is probably 10-12 psi. You need EGT and boost gauges for safe operation, though.

If you're getting 18 psi with stock hardware, something is still wrong. The vacuum pump must be connected to the solenoid port with the restriction in it. The wastegate actuator connects to the open port. Vacuum pulls the actuator rod in.

[Robyn]

If you indeed have 18 PSI the computer will soon find that and toss a code.
The 6.5 should not boot over about 10 PSI.

Unless the thing has a chip in it as well as a boost fooler or the wategate is stuck shut you should not be able to get that much boost.

[bonez02]

well the first day I bought it a 1997 3500 Crew Cab Dually i knew nothing about it and it had so little power and blew smoke black smoke everywhere that i thought that the guys at the Truck performance center could do a few upgrades so that I could get it to tow my race car trailer (30ft Pace American Shadow) over 50mph down the freeway.. I had them install a 3.5" exhaust system on it with no cat and they did a ECM change out along with boost and egt temp gauges, new fuel filter, and K&N Air Filter... after all this it ran better but still blew black smoke everywhere and still worked very hard to tow my trailer and only had 3lbs of boost when wide open and 0lbs cruising at 60... the shop claimed that thats how it is supposed to be... after taking a trip to oregon and back I decided this was pathetic and had to either find something else or look for other things wrong with the truck... thats when I got on here and started looking at a few topics about the vacuum pump... Im pretty dissapointed in the Truck Shop that they didnt even test the vacuum system and completely blew it off... spent 3,000$ on these upgrades and it turns out to be a 119.99$ part im pretty dissapointed but still thrilled that it tows amazing now and have seen peak boost at 18lbs... hopefully it doesnt blow up now

[bonez02]

I forgot to say the service engine soon light was always on ever since they did the ECM change out they told me to just ignore it but now with the new vacuum pump its gone out... the truck also has 240,000 miles on it too :eek:

[DennisG01]

Read the codes, note what they say, clear the codes, see if they come back. Telling you to disregard the SES light wasn't the brightest of statements...:eek:

Peak boost and Max Sustained boost are two different things. Unless Peak boost is something astronomical, disregard it. To find your Max Sustained, you need to be in 3rd gear (automatic) with the converter locked and the pedal mashed. That's the important number to find out. Probably going to be in the 60/65 mph range.

[JohnC]

Sounds like those guys handed you a loaded gun and said to point it at your head and pull the trigger. No worries, mate!

So, if I get you correctly, it's running 18 psi boost because of the chip, and with no intercooler? Guess I should have said "large caliber loaded gun".

Where is the EGT probe located?

What did they give you for an EGT limit?

How high was the EGT when it was blowing black smoke?

[bonez02]

when the vacuum pump was bad all it did was blow out black smoke when 90%-100% throttle...now theres no black smoke and when i got on it full throttle getting onto the free way the peak boost was right around 17/18lbs (note this was without a trailer on it)

dennis next time I am out i will check and see what i have in 3rd gear with the petal smashed

[Shikaroka]

you need to be in 3rd gear (automatic) with the converter locked and the pedal mashed.

But, won't that unlock the TC?

My boost drops a little at full throttle and will regain some when I left off a bit.

[bonez02]

tried it saw around 12-14 high of 16 note i had a trailer on the back.... egt never got above 1000...

[DennisG01]

Your boost sounds about right for a performance ECM. I'll get about 15-16 Max sustained with mine, but without an intercooler (getting one soon) I back off the throttle a bit when I see that.

Shikaroka: It all depends on your speed (although I suppose it's actually RPM's) - if you're going fast enough it won't unlock. It's been a while, but I think it stays locked around 60ish MPH (in 3rd gear) - with 3.73 gears.