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View Full Version : A/F rich while decelerating?



Local Boy
11-02-2011, 07:50 PM
Aloha Everyone,

Recently, after mashing the pedal and putting it in @ 7-9 lbs of boost...the car is not running right...when I came off the throttle, the car felt like it sucked air (1/4 tank) and the idle seemed to flutter/stumble while I was decelerating and NO throttle input. But, it did not go away...

Now...I 'am finding that the A/F moves toward the extreme (12 [rich]/ 15.9 [lean]) much more often and regularly, like it's hunting...Never did this before..

Also, the A/F shows rich (12.5) when I 'am decelerating and NO throttle input. The cause of this, I believe is my over all problem...Once the trans down shifts it goes lean (16), as should..But, I think when the T/C un-locks, the A/F goes rich (11's) again (NO throttle input - still decelerating)...

Upon start up the A/F reads 10.5 and the volts read @12...Once the A/F comes back up @ 14.5, the volts come back to 13.9 volts...This is freaky....

Otherwise, car car idles fine, accelerates fine, but stumbles when at @ 10% TPS or lower, probably when it goes rich...

No codes...or engine light...Likewise, no unusual sounds or noises from the motor...

On another issue, I have a retro fitted LCM (external relay - Thanks Jim!) but still have my head lights cutting out??? I changed out the light switch - no change - still cuts out... I have no clue why???

Any thoughts would be much appreciated...

Thanks...

Aloha

JoeBoomz
11-04-2011, 09:59 PM
Is the bypass or blowoff valve still working properly? Sounds like you may have some backwash and this might be screwing up the air metering. I have some backwash issues going on in my car and upgrading the bypass valve will be the first step.

But the first and easiest thing to try is to clean the MAF sensor.

burt ragio
11-05-2011, 04:53 AM
Some where you may have a vacum or air leak. This will send a different message to pcm.

Local Boy
11-08-2011, 02:28 PM
Thanks Guys...

Can't seem to find a vac. leak...The hose for the by-pass looks a little kinked, I'll look there ( good point Joe)

I appreciate all your help, Guys...

Aloha

RacerX
11-08-2011, 03:00 PM
A vacuum leak would make it run lean instead of rich. Can you datalog? I'm curious to see rail pressure @ vacuum and boost, fp dc, etc.

Local Boy
11-15-2011, 07:48 PM
Just wanted to Say thanks to you guys...I found the problem...

You all were right!

The Pro-Flo bypass is shot...The diaphram inside does not hold vacum...I opened it up and found that it (diaphram) had deteriorated (sp?)...so, it was pulling unmetered air through the diaphram...and the by-pass remained closed all the time...

With a new one on the way...I'm all good now...

Thanks Again Gentlemen...

Happy Holidays!

Aloha

sailsmen
11-15-2011, 08:40 PM
Per VORTECH "Where is the best place to mount a race or mondo air bypass valve?

Depending on the application, the bypass valve should be mounted on the discharge tube of the supercharger. On other applications, it may be more convenient to mount the bypass valve on the intake plenum. Often times because of space limitations it is more convenient to remote mount the bypass valve at a location where space allows. On custom applications, the location being chosen should allow for the space limitations and aesthetics of the particular systems installation."

TAKEDOWN
11-15-2011, 10:42 PM
Glad you solved the problem Bradah!

Local Boy
11-16-2011, 05:59 PM
Thanks Braddah...

Always wishing you and your family all the best this Holiday Season...

Aloha