Afr's change 5 months after tune? - SRT Forums

04boosted · 10-13-2009, 10:31 AM

I had the car tuned in May of this year, and I had the AFR dialed in at 11.5-11.7 at WOT. I was spiking 20 lbs, not sure what i was holding to redline then. I did a couple pulls recently, and the AFR's are 10.9-11.1 and the boost looks like it is still spiking at 20psi but falling to 15 at redline (stock boost gauge). I have a FM wg, and am on PCM control boost. I did a boost leak check and everything was good. So I'm not sure why things are looking richer, its getting cold out here too, thought that was gonna lean it out a bit.

My mods are: Stage 1 PCM, Hard pipes, HKS BOV, PTP Charge pipe, FM WG, KN CAI, MPX 62mm TB, Agp RL, Mpx 3" TBE, Walboro 255, DTEC FC.

Here is my dyno sheet from last tune:

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04boosted · 10-13-2009, 08:32 PM

Bump!

COY · 10-13-2009, 08:36 PM

colder air is denser. (is denser a fucking word?) That may explain it. I would reset your ECU and go see checksum if its something that is really bothering you/the car.

04boosted · 10-13-2009, 08:38 PM

Quote: Originally Posted by COY

colder air is denser. (is denser a fucking word?) That may explain it. I would reset your ECU and go see checksum if its something that is really bothering you/the car.

I understand that, but wouldn't the colder, denser air make the car lean out? I am experiencing a richer wot than before.

conroy9940 · 10-13-2009, 08:44 PM

colder will make it lean out more.. do a boost leak test?

Kason23 · 10-13-2009, 08:50 PM

boost leak... or gauge might be wrong.

04boosted · 10-13-2009, 09:00 PM

Quote: Originally Posted by Kason23

boost leak... or gauge might be wrong.

Well i did a boost leak test, and nothing. So i guess my next question is: even if the gauge is wrong, wouldn't the AFR's still be roughly the same, regardless of what the gauge was reading? Also my next concern is the DTEC, I am thinking about switching to the DS, because of all the rave about it. I was just wondering if its possible that the DTEC setting could have changed or if the wastegate loosened?

I guess anything is possible, just trying to see if anyone has had the similar problems. Thanks again for the help.

COY · 10-13-2009, 09:01 PM

Quote: Originally Posted by 04boosted

I understand that, but wouldn't the colder, denser air make the car lean out? I am experiencing a richer wot than before.

yeah, I am dumb. Read it fast and then realized I am dumb.

Check the dtec? If boost leak is good try to pull a bit more fuel? Check wastegate. Blown diaphragm?

I would still reset the ecu.

04boosted · 10-13-2009, 09:05 PM

Quote: Originally Posted by COY

yeah, I am dumb. Read it fast and then realized I am dumb.

Check the dtec? If boost leak is good try to pull a bit more fuel? Check wastegate. Blown diaphragm?

I would still reset the ecu.

I'm not really sure what to look for on the DTEC if you are talking about the settings, the wiring looks good, I'll reset the PCM, and check out the WG tomorrow.

Thanks again.

overboost8 · 10-17-2009, 07:04 PM

i have the same f'in problem to the t and ive checked everything and cant find nething wrong

04boosted · 10-17-2009, 07:31 PM

Quote: Originally Posted by overboost8

i have the same f'in problem to the t and ive checked everything and cant find nething wrong

Ive reset the PCM, and nothing changes, if i disconnect the RL I run too lean. like 12.5, so I wonder if the DTEC is not doing its job correctly.

04boosted · 11-14-2009, 11:50 AM

Just an update.. I found my problem, my Fuel pressure regulator was leaking boost at the adjustment screw. So i took apart and fixed that leak. Now everything is running great!

I'm stoked that i finally found it! Was driving me crazy.