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post #1 of 14 (permalink) Old 02-19-2013, 04:12 PM Thread Starter
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Boost Issue

Cobalt SS 09 LNF - 80K KM

Bought this car from a dodge dealership a few months ago and now it seems to be acting up. Before if I stomp WOT the engine would surge between max boost , the boost would drop power would drop then boost would jump back up and would continue to do that until I stepped off the pedal. Now lately if I stomp WOT the car I get a big blast of boost then seems to go into limp mode. Note I don't get any engine lights or pending codes at all. The reason I think it goes into limp mode is I hear the turbo spooling and i get about 2psi 13KPA. I pull over and shut the car off and volla I got full boost again.

Now I was told the car was stock when I purchased it, after looking under the hood, everything in fact looks stock but you can see bent rivet and clips around the air box and lights. Any ideas what can be going on? When the engine is in limp mode is there a mechanical movement of the BOV? If so could that mean maby I have a vacuum leak and not getting enough vaccum to open the BOV then its overboosting and going into limp? Other than that the engine seems to run fine, and like I said no CEL's at all.
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post #2 of 14 (permalink) Old 02-19-2013, 06:52 PM
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stock lnf's do not come with a BOV. is there a boost controller on it?

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post #3 of 14 (permalink) Old 02-20-2013, 03:36 PM Thread Starter
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Yah I know, whatever they are called they recirculate air back into the intake manifold, but if I had low vacuum could it prevent the valve from opening quick enough to prevent overboost perhaps? And no there is not boost controller like I said everything is stock, unless the previous owner tuned it but if he did it would of most likely been a mostly stock tune so I don't think it would cause this?
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post #4 of 14 (permalink) Old 02-21-2013, 09:03 PM
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What vac do you sit at idle?

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post #5 of 14 (permalink) Old 02-23-2013, 04:16 AM
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Did you check for codes or you assumed that if the CEL wasn't on you had no code. Reason I'm saying is because ECM cannot put engine into limp mode without setting a code. Does your CEL lamp work or come on when you turn your key without starting the engine? Something is odd here.....

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post #6 of 14 (permalink) Old 03-06-2013, 04:34 PM Thread Starter
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Yah thats what I mean, I get no codes. I even plugged it in to see the history, nothing, and nothing is pending. It did it again today too, stomped on it in about 4th gear full boost, then nothing until I got it home. Shut it off for a minute started back up and full boost. I am clueless. (I don't know what my vacuum is at idle, got nothing to measure it with or tools until I get home, currently doing some training in a different province) And yes the light works, and I had to clear a code recently because my gas cap wasn't sealing properly which set off a code.
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post #7 of 14 (permalink) Old 03-06-2013, 06:26 PM
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you have a vac/boost gauge... what is your vac at idle? is your turbo hooked to your wastegate with a vac line? i'd say maybe your evap. it's hard to tell without knowing all the codes or hearing the car run

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post #8 of 14 (permalink) Old 03-07-2013, 04:51 PM Thread Starter
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Originally Posted by BankerBalt View Post
you have a vac/boost gauge... what is your vac at idle? is your turbo hooked to your wastegate with a vac line? i'd say maybe your evap. it's hard to tell without knowing all the codes or hearing the car run
I have the digital display (RPD) doesn't tell me vacuum. And like I said before there are zero codes. The car starts fine, runs fine, the issues begin at WOT. And I thought the wastegate was controlled by a solenoid? I don't know, whatever the stock setup would be.

Last edited by Mastermosley; 03-07-2013 at 04:54 PM.
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post #9 of 14 (permalink) Old 03-07-2013, 05:26 PM
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it's controlled by the compressor housing. check to see if the vacuum line is still there

---------- Post added at 07:26 PM ---------- Previous post was at 07:25 PM ----------

i'm gonna go ahead and assume either your wastegate failed or it's not hooked up

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post #10 of 14 (permalink) Old 03-07-2013, 05:48 PM
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Re: Boost Issue

Maybe your intercooler has a crack somewhere

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