• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

How Many Engines Wrecked from Overboost?

D

dtreid

New Member
Messages
46
Reaction score
0
Location
Alberta, Canada
97 Chev K3500. Put a boost gauge on and had a reoccurring problem with overboost. It would hit 20psi if I didn't watch it.
How many engines are wrecked from this problem on engines without boost gauges? If I did not have one, there is no way I would have noticed a problem.
 
97 K3500. Stock? Vac system intact? Hoses routed correctly?

No way should it hit that much boost if things are hooked up properly.
 
JiFaire said:
97 K3500. Stock? Vac system intact? Hoses routed correctly?

No way should it hit that much boost if things are hooked up properly.
Click to expand...

x2.

Could the WG solenoid vac lines be reversed? I've sen that cause an overboost.
 
Is the engine and ECM stock? Is the vac system intact?

You need to get a vacuum gauge and measure the vac before the solenoid, after the solenoid, and at the WG cannister.

Something has to be whacked... most people can't get 10 psi with the stock system...
 
jr08757 said:
My truck hits 19psi too... Hopefully the TM will help :toetap05:
Click to expand...

That's even weirder than the first one... 19 psi from a stock 'S'?

a) the stock programming calls for a de-fuel (overboost condition) at about 9-10 psi
b) the EGR should start to open before then, too...

Those 2 go against what I know about stock programming... maybe I'm about to learn something new!

Keep us posted, jr! I hope the Heath stuff helps your condition!
 
Are the high boost levels sustained, or is it just a spike, like when first accelerating?

I've seen my own boost spike 16-18 psi on take off....hold about 15-30 sec. and then return to normal.

Maybe this is what your seeing?
 
It will stay pinned above 15psi until the computer goes into limp and I get no boost. A minute later, it will kick the fuel back in and I'm back to an overboost situation.
 
Either somebody has put a boost fooler on there or your MAP sensor is broke, dtreid...

A stock truck just won't do that. Have you got a scanner? Can you watch what the PCM is seeing for boost pressure when this happens?

PCM response to overboost condition will first be to drop boost, then to defuel, if that doesn't work.

Wish I could be of more help than that.. saying 'IT WON'T DO THAT' can't be very useful, but really, something is very wonky here if the PCM is stock..

Here's another thought... have you pulled the glove box and LOOKED at the PCM to be sure it's stock?
 
JiFaire said:
Either somebody has put a boost fooler on there or your MAP sensor is broke, dtreid...

A stock truck just won't do that. Have you got a scanner? Can you watch what the PCM is seeing for boost pressure when this happens?

PCM response to overboost condition will first be to drop boost, then to defuel, if that doesn't work.

Wish I could be of more help than that.. saying 'IT WON'T DO THAT' can't be very useful, but really, something is very wonky here if the PCM is stock..

Here's another thought... have you pulled the glove box and LOOKED at the PCM to be sure it's stock?
Click to expand...
Click to expand...
Now that is quite possible, After i put in my TM on my then new to me 98,i was fully expecting to have defuelling issues,but i could run all the boost the turbo puts out without issues,I found out there was a performance chip in it already.
 
I've got arp head studs wit my holset and i've spiked to 18 or 19 a couple of times and havent seemed to have a problem yet, but if i hold her stead at 15 or so after a bit it defuels and I got no power lol. I jus need more fuel then before spring I gotta add in an intercooler but I think i'll be alright during the winter.
 
The only time I see 19psi is when i'm on the highway. I cruise at 70mph and it hangs out around 5-6psi, but when I speed up to pass someone or have a need for speed it holds at 19 psi until I let off and its not even wide open. Also when i get over or at 80 it throws a boost code dtc78 but it doesnt defuel or lose boost. :mad2:
 
You must log in or register to reply here.
Back
Top