Well first off I just came back from Colorado to Tennessee and saw not only a pretty substantial change in altitude but also went up to 93 octane fuel. First thing I noticed was that off throttle vacuum went from 18-19 in/hg to 20-22 in/hg which is all fine and good but when under full throttle the car will spool up like normal and make around 13psi, then it will climb (over a few seconds) to 15 psi, but the power doesn't feel linear. Its like boost pressure hits a wall at 13psi then takes a strange amount of time to hit 15. Maybe trying to learn the 93 octane? Its got me confused. This was today on a 50* day just doing a second gear pull onto the highway.

I would have suspected a boost leak and I will check that here in a minute but I had read some people were having issues with wastegate solenoids leaking off pressure. I cant really think of any reason why altitude or fuel would have anything but a positive effect but the car feels slower. I was thinking maybe I should disconnect the battery overnight so it can "re-learn" the altitude/fuel etc.

Second issue is that my stock BPV stopped making noise. I'm running the ebay lower charge pipe and the stock upper with the ebay FMIC so unless there is a boost/vacuum leak (doubtful) I cant think of why it wouldn't be venting. When I let off the throttle the boost drops off immediately but there is either no or very little sound associated with the rapid closure of the throttle body.

If anyone has any insight I would appreciate it - when my car isn't running right (or I perceive it to be not running right) it drives me INSANE. Someone save me from myself.

 

Was it cold? Cause my turbo on stock tune when it's about -10 will goto 10 psi and slowly climb to 15

 

I'm gonna assume learn down, but I honestly have no idea

 

Maybe learn down. I guess i'll run another tank through it and see what happens. Temperature was about 50* this morning. Just a spring day in Nashville, TN. I'll report back if I see any changes. Like I mentioned above, I'm hyper sensitive when my car seems to be acting up - maybe nothing.

 

mine does that, well it seems to hit 10ish on mild throttle, then WOT its going to about 14-17 it varies... havent had it in warm months yet, so i cant add much other than just go with it if you dont have any codes/issue and see what happens

 

Are you on a stock tune? If so the boost you make is to a degree, irrelevant. The car will make what it needs to make to give you 260/260. As you pointed out, you have an altitude change and an octane change in the equation.

However, the fact that your BPV no longer makes any sound could mean the vacuum line is pinched or the diaphragm is punctured or torn, and if so then all bets are off. It's only 3 10mm bolts to inspect that. Might be worth your while.

 

https://www.cobaltss.net/forums/2-0l...61/index2.html

looking into ^ now... Its raining out and I don't feel like messing with the car untilit clears up - probably tomorrow.

Also - forgive my ignorance, are any defects with the bpv pretty obvious? Like i stated above the car is making 20-22mm/hg at idle so i doubt its any issue which would cause a leak.

Thanks!

 

If the BPV diaphragm is leaking it's probably not going to leak to the atmosphere, so it might not show up as a vacuum leak.

It's not 100% clear to me though that the car isn't running right. Ignoring the boost gauge, does the seat of your pants tell you that there is an issue?

 

Just by feel it seems like the car isn't pulling in a linear fashion, as if it is cutting timing or cam phase or something 2 or 3 times a second, which makes me think it might be learn down. Its not terribly noticeable but it feels like the car pulls hard and smooth until it hits a certain point in the RPM range (i'll have to look next time to give you a accurate number) then it feels like it is pulling something back. Again I am hypersensitive to these sort of things (radio off windows down listening to the car whenever I get on it) makes me wish I had the RPD to look at A/F, timing etc. so I could know what's actually going on.

Just filled the car up with 93 and have a 130 mile drive ahead of me this afternoon and if the roads dry up a little i'll try again and see if maybe it works itself out. Thanks for the help so far, I would like to find someone around me with another LNF so I can have something to compare my car to, I just got it for a bargain and that thought hasn't left my head since the day I bought it!

 

well - checked out the BPV diaphragm and spring and everything looked brand new, no tears or anything. Bypassed the vacuum storage tank with some free vacuum line I was given from AutoZone (had it laying around or something) & tightened up all the charge piping clamps (as I was suspecting a leak). While doing all this I was very careful around the intake and the glasslike intake breather tube. no issues getting it off - but of course I broke it getting it back on. The break was pretty clean and straight across so I threw some superglue on it and was careful to check that it was sealed well.

I put everything back together and double checked* that everything was tight and started driving out of the neighborhood and everything went to hell - no power, flashing CEL the works. Pulled over and shut it down - in my haste I forgot to tighten down the intake tube to the air box and also In the meantime blew apart the shitty vacuum line they gave me at auto zone (like split it. I was pissed and tossed it out so no picture but it was a catastrophic failure).

luckily I had enough tools to fix the airbox and hook the vacuum tank back up. Stopped by AutoZone and had them pull the codes. Had 3 MAF codes, a BPV stuck closed, and a lean condition at idle. They wouldn't clear the codes (claimed it was a federal law) so I had to go back home and unplug the battery to reset the computer.

Now the car idles much better, butafter letting it idle for a few minutes and shutting it down/ starting it back up I had a CEL again. Went back to check my codes and I had all 3 MAF codes (high, low, and a generic one?) Car pulls fine and feels more responsive somehow - the clamp on the throttle body was suspiciously loose so it was probably leaking.

Do you think I need to replace my intake or do the money/women fix? I cant see how my repair could be leaking and it feels pretty damn strong after letting the glue cure for an hour (I applied quite a bit of force to ensure it wouldn't just fall off again).

Again thanks in advance for any insight.

 

bump... Anyone have this issue before, does it need more cycles before the light goes off or something?

 

Try unplugging your ECU for a little while then plugging it back in. The turn the car "on" without starting it for a few seconds then start the car. Maybe you need to reset the ECU for the change.

Just a guess though

 

did some more troubleshooting. When I reset the ecu the car is 100% fine at idle. let it run for 5-10 minutes and shut it off and turned it back on. no cel, no problems. When I go to drive it it drives fine until boost gets above 10psi or so and it pulls fine but as soon as I slow down and downshift into 2nd (after doing a pull) I get a big backfire, then it limits boost to 1-2lbs and the next time I turn it on it has a CEL. I did this twice today and it did the exact same thing both times. As long as I don't get the boost up I don't have a cel or any issues but as soon as It goes over 10psi it has issues. seems like it would drive around at <10psi all day long without incident as long as I didn't get on it.

I don't want to take it to the dealer - no one has had any issues like this?

 

Never heard of it. Do you still have mixed fuels in there? Not that that's the problem, but just curious.

Maybe you have bad gas?

I don't know man. If the dealership is out here's what I'd try and keep in mind everything I know about cars has been learned from this site, so I'm novice at best.

In no particular order

• Boost leak check
• Exhaust leak check
• Check CEL Code and research code
• Empty out gas then reset ECU

 

just did a boost leak check on the turbo inlet (I know some have said bad idea, but I was only testing to 10psi to see if my bpv was installed incorrectly somehow.

when I did this with the oil cap open it would not hold ANY pressure at all. Covering the oil filler hole with my hand stopped the leaking sound and allowed it to begin to build pressure. Is this how it should be? When the oil cap was on it pressurized right up to 10psi and seemed like it would hold there forever with absolutely 0 drop in pressure.

I also cleaned the MAF sensor and did the brass fitting fix for my breather tube. I'm currently waiting on the glue/ epoxy to dry before I plug the ECU and negative terminal and then I'll give it another shot.

This is driving me nuts. I think I've followed the logical troubleshooting path with not much to show for results.

 

Just saw the first question - I already ran a full tank of 93 through it (filled up when very very empty on 91) to near empty and just put 20$ worth of 93 in this morning, so I would think the fuel is pretty much all 93 at this point.