running lean but fluctuates after shifts

Mr. Joe

Mr. Joe

New Member
May 9, 2012
17
0
1
Seattle, Wa
At idle my car runs lean at around 17 afr and while just driving around it runs between 14.7 and 16.0 afr. Under boost it runs in the mid 13's. It also has an inconsistant idle that falls somewhere between 600 and 1000 rpm.

I don't know if this is related to the problem above but after i clutch in to shift the afrs bounce rich (10-11), to off the charts lean, to the aforementioned idle at 17ish.

At first i thought it would be a vacuum leak but i checked the accordian hose, all intercooler couplers, and vacuum lines. They were all in perfect condition except I did have to reconnect one vacuum line but it was a loose fit to its nipple so i zip tied it down along with a few other slightly loose fiting hoses. However, the problem remained unchanged.

my current mods include:
large intercooler w/ 2.5" piping
wastegate shimmed to 9 Ibs.
Apexi SAFC
AEM UEGO wideband
ARP head studs
Autometer boost gauge

Thanks in advance for your help.
 
J

jake8790

Life's too short for N/A
Dec 18, 2011
395
0
0
Oregon
Is the bov vented to atmosphere? That will cause it to bounce rich and then lean while shifting. Mid 13s under boost is dangerously lean. Are the injectors stock? Make sure it has the stock AFM housing and not swapped for a lexus AFM.
 
Mr. Joe

Mr. Joe

New Member
May 9, 2012
17
0
1
Seattle, Wa
The bov is the factory recirculating one and the afm is stock as well. To my knowledge, the injectors are also stock. I was thinking that the injectors could just be getting worn out but the motor is one of those low mile JDM motors and so would they really be bad at this point?

Also, I checked for codes and got 41, 43, 51. I think the 43 is unrelated because it has to do with the starter signal (it just takes a while to start when its cold), but the 41 and 51 have to do with the tps. Although the reading on the SAFC appears to show the correct throttle %, i tested it with an ohmmeter and it did not fall within TSRM specs. I'll be replacing the TPS once i get the chance and see if that fixes the problem.
 
IndigoMKII

IndigoMKII

New Member
May 9, 2011
2,181
0
0
Madison, Virginia
Pull your EFI fuse and go drive the car again. Come back and recheck your codes.

51 is un-calibrated tps or your a/c was on or your foot was on the throttle. Make sure your throttle linkage isn't holding the throttle slightly open.

I see you have a SAFC, zero everything out before you try and find the problem.

And no, code 43 isn't important nor does it have anything to do with your hard cold starts.
 
IndigoMKII

IndigoMKII

New Member
May 9, 2011
2,181
0
0
Madison, Virginia
Mr. Joe

Mr. Joe

New Member
May 9, 2012
17
0
1
Seattle, Wa
Anyways...

After replacing the TPs, zeroing the SAFC, pulling the EFI fuse, and then going for a drive, the problem remains unchanged. When I rechecked codes I got 41 and 43 again... however, no 51. I'm not sure why the 41 keeps popping up, maybe the SAFC has something to do with it?
Another piece of information that might be relevent is that the vacuum gauge shows it pulling 16-17 in hg at idle and 20-21 in solid deceleration. And to clarify, the inconsistent idle described in the original post only happens rarely. it usually idles a little high at around 750-800 rpm but if I let it idle for a minute or so it will drop to 650 where it should be.
 
You must log in or register to reply here.
Top Bottom