so check it out i prevously posted a vacuum leak problem with my vehicle. so i tried the carb cleaner leak test and got nothing then i tried retorquing the manifold. yesterday i hooked up a vacuum gauge to the manifold and it stayed at 21 in Hg but flickered rapidly at that point. my instructor david gilbert told me that it looks like a valve problem. i know the car has a knock when its running but it always had a a little knock and use to run fine. (L26)

i dont know what to do next wont see my instructor agian until monday. and was planning on going home this weekend. the car runs like shit. it sags off the line pick up is way off and the fuel trims are horrible if i go to class in cartervill and back like 7 miles i run through a quarter of gas , and if i drive arouind town it gets even lower. need help asap

your intake valves are screwed. said and done. could be the valve, could be the valve seat, could be an epic amount of carbon. bottom line is your intake valves arent sealing and your loosing alot of compression becasue of it. you could have had a vacuum leak and your PCM may have failed to adjust for it and you could have burned your intake valves. just one possibility. any more info on the problem? MIL light? codes? no knock is a little knock. any mods?

-- Fri Feb 26, 2010 2:26 pm --

could also be clogged injectors...

_________________

"Dude!, theres enough plastic bags in here to suffocate a nursery!"

wow thats crazy there is no MIL and i have access to a tech II scan tool but already tried at the dealer once and wouldn't read because i have an 05 pcm in a 06 and lost the stock pcm win i had a house fire almost two years ago. there is knock but not excessive the car always had a little knock during operation and never hendered performance.

and i run fuel injection cleaner frequently to avoid clogging.

i have just recently read off of a service bulliten that the pcm may have to be reprogrammed for hesitation, and poor gas mileage occurs suddenly. and the car has alomst 80,000 miles on the clock. these problems started happening 2 days after installing the HV3.

MODS: ( CAI, zzp 1.0, HV3, msd coils, msd wires, fairly new NGK plugs, zzp alternator booster, wire poly trans mount, poly motor mounts, shortened dog bones, pem headers, zzp ceramic crossover pipe, heat shield, 2.5 inch zzp down pipe, and slp cat back)

what year of car is yours? wanna sell it?

its an 06 would love to but still owe alot on it

o I gotta 05 gtp

-- Fri Feb 26, 2010 5:53 pm --

all paid off too! paid cash for it at the dealership

A vacuum leak that makes it run bad would 99% of the time set a lean code, your tuning and 05 pcm might be why no mil has come on. You need to run a cylinder drop test (compression test) on all your cylinders make sure your valves are/arent the problem first. Id also say a smoke test on your intake to really find the vacuum leak, the carb cleaner or sprayer test wont always pick up the leak, especially a large one. You can message me if you have more questions or just post here i try to read the forums everyday. but messages pop up on my phone.

leakdown and smoke test. if youre feelin' frisky do a power balance test with the tech 2.

_________________

"Dude!, theres enough plastic bags in here to suffocate a nursery!"

so much work lol I wish i would have never sold my blazer i miss the 4.3

Whats an HV3 btw?

HV3 is an intake insert made by easyperformance.com and sold by both zzp and easyperformance. it replaces the stock insert inside the manifold. its a polyurethane piece that is molded to fit right in to the manifold and opens the inlet ports by a quarter inch extra. this will help increase top end power by up to 43 wheel horsepower after 6000 rpm and a tune and valvetrain set up.

if u check zzp's website and look under intake and fuel deliver there is a lot more info and testimonials

-- Wed Mar 03, 2010 10:02 am --

gonna do a smoke test and compression test on thursday my professor told me that it may be the egr valve stuck

Did this problem come up all of sudden or during some beating on the car? I have not heard about too make people having problems with valve seating in the 3.8's. Really seems to me like it would be something simpler like a damaged vacuum hose or fitting to the brake booster or something like that if it was indeed a vacuum problem.

_________________
04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

well actually the car was running sluggish before i installed the HV3. after i installed it it worked great had good performance. then two days after it started acting sluggish again. and now my gas mileage is like at 14-15 mpg highway and it hesitates.

and idle is weird during a warm start its as if its trying to find where idle is at. similar to a dirty throttle or maf sensor. but my maf is new and i cleaned the throttle inside out during the install.

I saw you were looking for a replacement MAP sensor fitting because yours was broke. Could you have a vacuum leak from that fitting now?

_________________
04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

possibly sprayed lots of carb cleaner round it while running didnt do much that stuff evaporates to quick. and the one of the flanges broke off and it may possibley need a new gasket. but its been doing this for a while the pcv cover got broke because i was trying to replace the map

i think i figured it out today it seems that the egr valve is sticking open and allowing to much exhaust gas to pass through. and my map sensor voltage was real low and it needs a new pcv cover possibley causeing a leak. my vacuum gauge that i used rattled at 21 hg used my professors and was fine. after i played with the egr valve and drove it back to campus today it ran great almost perfect. so i will be replacing the egr and pcv cover soon.
And i also hooked up the tech II it displayed real time readings but wouldnt do the special functions because of having an 05 pcm probably need to use the can bus adapter. couldnt find one so i used an actron to monitor the system and everything ran fine once i played with the egr.

thanks to all that replied and for all of your help !!!!

Congrats, glad you figured it out

_________________
04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

yeah!! what a relief and thanks for all of your input