Intermittent lean when in boost.

Basic tech questions such as future setups, different turbo kits, car diagnosis, etc
Post Reply
gearhead290
Dreams of owning a 240!
Posts: 66
Joined: Thu Aug 11, 2005 7:41 pm
Location: Sioux Falls, SD

Intermittent lean when in boost.

Post by gearhead290 »

I've started having a problem with my KA-t intermittently leaning out at WOT. Sometimes my AFRs are perfect in the mid 11s, but then the next time I do a pull it'll be low-mid 12s, or even get into the 13s. The car runs E85, 1000cc injectors, Walbro 450 lph pump (hardwired, and brand new), a Sard FPR, and an Enthalpy tune. The car has been on its current setup for 3 years now, and this is the first issue I've had (aside from blown up transmissions :dance: ). I've already checked fuel pressure (behaves how it should), had my injectors cleaned and flow benched (they really needed it), changed spark plugs, I can't find a vacuum leak anywhere, TPS behaves properly, and the MAFS behaves properly. Anybody have any idea or suggestions?
User avatar
supakat
SuperMod
Posts: 8018
Joined: Sun Oct 08, 2006 12:13 pm
Location: FL

Re: Intermittent lean when in boost.

Post by supakat »

I wonder if the fuel is heating up after the run. I have an oil cooler on my return line before getting to the tank. I do not have any issues leaning up after multiple runs. That is the only suggestion I have. Everything you stated seems spot on. After the lean WOT, if you chill for a bit then do a pull, is it good again?
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
KA24DE-T
Image
Build thread/Blog
YouTube Channel
gearhead290
Dreams of owning a 240!
Posts: 66
Joined: Thu Aug 11, 2005 7:41 pm
Location: Sioux Falls, SD

Re: Intermittent lean when in boost.

Post by gearhead290 »

It isn't always after multiple runs, sometimes it'll do it right after I start the car and let it warm up.
User avatar
supakat
SuperMod
Posts: 8018
Joined: Sun Oct 08, 2006 12:13 pm
Location: FL

Re: Intermittent lean when in boost.

Post by supakat »

May want to check out your ecu coolant sensor. It could be on its way out.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
KA24DE-T
Image
Build thread/Blog
YouTube Channel
gearhead290
Dreams of owning a 240!
Posts: 66
Joined: Thu Aug 11, 2005 7:41 pm
Location: Sioux Falls, SD

Re: Intermittent lean when in boost.

Post by gearhead290 »

I assumed the ECU temp sensor was good because I replaced it and soldiered in a new pigtail a couple years ago. That's a good idea though, I'll have to check it one of these days and verify it hasn't failed again.
User avatar
supakat
SuperMod
Posts: 8018
Joined: Sun Oct 08, 2006 12:13 pm
Location: FL

Re: Intermittent lean when in boost.

Post by supakat »

Maybe clean MAF as well.
12.96 @ 116.36 - 2.1 60ft - 11/2011
13.1 @ 114 - 2.3 60ft - 8/2012
KA24DE-T
Image
Build thread/Blog
YouTube Channel
Post Reply