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i dont think theres any problem the afrs bounce around at idle
 

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sometimes mine sits there too
 

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We logged his fuel trims, they are fine while cruising etc, when idling it's around -3% (i'd have to check the log) or something along those lines, I'd have to look at the logs. His AFR gauge is working perfectly, but when he's idling for some reason he pegs lean at like 16-18 afr and it NEVER goes down. There is something funky going on for sure. When cruising in open loop he's always hovering around 14.7, but for some reason while idle it's not 14.7 it's 16-18 and never less.
 

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what wideband is it? have you checked the harness on the o2 sensor for it?
 

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It's already been said, sounds like a vacuum leak. That's where I would start, Tansu.
 

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It could be a vacuum leak but I doubt it if its fine on cruise and wot, I would just say its just air being drawn in to the exhaust, do you have a big tail pipe and where is the sensor in the system ?

ETD: afr's will change as well if you have aircon and the fans cut in as well.

Lee
 

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Discussion Starter · #11 ·
I secured the FPR hose with a zip tie long time ago. I highly doubt it is that.

Well my question is, if I have a boost leak she wouldnt constantly idle at 750rpm, would I?
It would be more like rough idle where it sounds like she is going to stall?
 

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I secured the FPR hose with a zip tie long time ago. I highly doubt it is that.

Well my question is, if I have a boost leak she wouldnt constantly idle at 750rpm, would I?
It would be more like rough idle where it sounds like she is going to stall?
Not necessarily. When I installed my boost gauge, I held the vacuum line closed with my thumb, and at idle I would take my thumb off and it would lean out all the way but it wouldn't act like its gonna die.

Maybe an exhaust leak, right where test pipe connects to dp?
Don't you think that if it was an exhaust leak, it would lean out ALL the time??

I am speaking from experience, just FYI
 

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Aem UEGO

I got my dp reinstalled, so if it was something funky with the harness we would have seen it?
Possibly. I've had a wire get yanked out of the sensor connector and had a similar issue. One day It stuck at 14.7 and lo and behold there was a hole in the harness and a wire out and in the protective sleeve. Put in a new sensor and my lean idle "problem " went away
 

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Mine does this as well, same gauge, AEM Uego. You can see it in my vid here.

I do have a known exhaust leak though, I have a stock gasket instead of the MAP one for some reason between my O2 dump downpipe and the turbo, so its leaking between my exhaust and dumpipe at idle.

So maybe it is an exhaust leak.


Hmm, I forgot when the car is cold it seems to run rich at idle, then when it heats up its more like it was at the end of the vid. Sorry vid didn't help as much as I thought lol.
 

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If it was an an exhaust leak the problem would be less apparent in higher RPM ranges because there is only so much air that can flow through the exhaust opening ( where the leak is). For instance, if the air being sucked in through the leak is at 50% max flow at idle and then 100% by 2000rpm the AFR problem would be almost non existent at WOT and high rpm because the amount of fresh air to exhaust gas would be minute. At least theoretically thats the case...But it couldnt hurt to check :)

Im not saying its not going to affect it throughout the RPM range but the affect you notice will be smaller with more exhaust gas flowing through to dilute the fresh air.

If it was a really big hole or leak then it might be more apparent throughout all RPm ranges but a small leak could have the potential to cause those symptoms
 

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Tansu, why don't you ask Bill. He probably knows, or can at least steer you in the right direction.
 

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Discussion Starter · #19 ·
If it was an an exhaust leak the problem would be less apparent in higher RPM ranges because there is only so much air that can flow through the exhaust opening ( where the leak is). For instance, if the air being sucked in through the leak is at 50% max flow at idle and then 100% by 2000rpm the AFR problem would be almost non existent at WOT and high rpm because the amount of fresh air to exhaust gas would be minute. At least theoretically thats the case...But it couldnt hurt to check :)

Im not saying its not going to affect it throughout the RPM range but the affect you notice will be smaller with more exhaust gas flowing through to dilute the fresh air.

If it was a really big hole or leak then it might be more apparent throughout all RPm ranges but a small leak could have the potential to cause those symptoms
That was my exact theory! When idle leak is more obvious as there isnt much gas going through exhaust and gets sucked out by the leak. I do smell a lot of exhaust fumes inside of the car when I am idling which I didnt have before the dp install. I just hope there is not a leak between dp and turbo...
 
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