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boosting but not moving

so my car does build boost but doesnt move like it use to but also my car was boosting 12psi and now its at 9pis i dint do anything just from one day to another does anyone know or have a clue wut it could be??? maybe spark plugs i just rebuilt the motor not to long ago it only has 1500 miles on the motor.. /ubbthreads/images/graemlins/dunno.gif
 

mitsuturbo

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your CEL coming on? blowing black smoke under boost?

could be a knock sensor, excessive knock, bad timing, or bad caps... for starters
 

Correct me if I am wrong, please. But doesnt the ECU retard the boot to 9psi in lean conditions? Could of sworn I read that somewhere.

Healthy: 12psi, learn 9psi and retard the timing.

Anyway, I'm bettin on a boost leak. But its food for thought if someone can confirm the 12 to 9psi detail / data he added to this thread.

If you have the stock pipes, pay extra attention to the rubber hose with the fabric weave over it. I have read those can hide a leak under them.
 

Quoting KiNgMaRty:
Sounds like a boost leak



It does not sound like a boost leak, I think Anthony is on the right track with it being, timing, knock sensor etc...

I think you may have jumped timing, that fits the bill. What most people don't understand is that when you have a boost leak your car runs like sh*t, not just "not as good" but sh*t. Even the smallest crack can cause severe issues with your pressure.

Now seeing how you said your car "doesn't move like it used to" makes me think more along the lines of a timing issue. Did you rev your motor real high? How good is your timing belt tensioner?
 
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1990ggsxnj

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If all else checks out ok there you can also run a compression test to make sure no valves kissed pistons if RPM's were super high at one point ( beyond 7.5k)
 

turbowop

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If the knock sensor tells the ECU that the engine is knocking, the ECU will pull boost from the stock 11.1psi down to about 9psi via the BCS solenoid. It will also retard timing.

Your issue could be due to many things, but that is most likely the reason you're seeing lower boost/timing.

If you're using California piss gas (91 octane) that doesn't help.

And to those that think revs over 7500 are high...no. People run North of 8k all the time with upgraded cams even without issue.
 
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my timing is fine no knock code i dont rev it past six but i do have the stock rubber pipes
 

turbowop

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No knock code? /ubbthreads/images/graemlins/confused.gif I'm not really sure what you mean by that...

The car is stock, no? Get a datalogger and see how many knock counts you build when you go WOT. If you get anything over like 7 counts, the ECU will start to pull timing and boost. Timing will come back anytime you get on it and there isn't any knock, but boost will stay low until the ECU doesn't see knock for awhile. This is why people get Eprom chips that have the "octane value reset" added to them. It resets everytime the car is shut off so that the ECU doesn't pull boost. None of this matters if you bypass the stock BCS and use a separate boost controller though.
 
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1990ggsxnj

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Quoting turbowop:


And to those that think revs over 7500 are high...no. People run North of 8k all the time with upgraded cams even without issue.


Thanks for the catch - I meant 8.5k...certainly not the stock rev limit. Combined with a significant dip in performance afterward and it could potentially mean something. Jus' sayin'
 

the car is bone stock no codes are coming up the only code that comes on low key is the tps but that was on before this happened the car is running rich and my bov doesnt sound like it use to so i think its a boost leak i checked my compression today 150 all across so thats fine..... any other ideas that dont involve putting more money in the car i already dumped 2grand into it and i havent even done one single upgrade besides the full 3inch turbo back
 

Check your timing. Disable the ECU automatic timing and put a timing light on #1 cylinder (driver side) and check for 5º.
Follow this thread if you have never checked / adjusted timing on a 4g63:
http://www.dsmtalk.com/forums/showthread.php?p=1984412
and:
http://www.plymouthlaser.com/timin.htm
Hmm, thought it was 10º in the haynes manual... Now I gotta go check my timing...


Check your Knock sensor, its on the block near the firewall in the middle just below your intake. You are looking for the black all melted / messed up, missing, not plugged in etc. I thought I had phantom knock but it was a reallllly bad sensor. Don't remove it (unless you want to) just jam your hand back there and feel for damage.
IMG_3863.jpg


Really bad knock sensor:
1111091655.jpg



Inspect your intake and all the pipes, again. If you can see the pipes, feel for the leaks or build yourself a boost leak tester.

Tester: http://vfaq.com/mods/ICtester.html

Hope this helps,
Chad
 

if the knock sensor was messed up or not plugged in wouldnt the check engine light come on??
 

CutlassJim

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When my knock sensor isn't plugged in it sets of a code. /ubbthreads/images/graemlins/dunno.gif
 

turbowop

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Oh, I didn't see the "not plugged in" part. Yeah, the ECU will throw a code for that. It won't throw a code for the goo melting out though.
 

mitsuturbo

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are the revs going up, yet the car is not moving well? If this is the case, it could be stripped Tcase splines, or a busted rear axle
 
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