Question for you PCM gurus.

0

04rcmoneypit

Full Access Member
Joined
Feb 22, 2008
Messages
630
Reaction score
0
Location
Carrollton, Ga.
Here's my situation. My afr gauge pegs at 18 when it goes into decel. I assume this is okay. The other day after going into decel and stopping at a light, the gauge is staying at 18, and the idle is kinda muffled. I think it is staying in decel at idle and I can blip the throttle and it goes back to idling normally. So what combination of things have to happen for the PCM to go into decel?
 
i haven't set up my failsafe yet, but i can tell you that i'm not terribly happy with my last aem purchase... had two sensors go out within a week of each other...

i'm wondering if the failsafe part of the gauge is conflicting with something in the PCM....
 
viperhauler said:
i haven't set up my failsafe yet, but i can tell you that i'm not terribly happy with my last aem purchase... had two sensors go out within a week of each other...

i'm wondering if the failsafe part of the gauge is conflicting with something in the PCM....
Click to expand...

I have not connected the failsafe wires yet either. I am just using the gauge for afr readings. I feel like it is trying to stay in decel because the idle sounds funny when it happens. A quick touch of the throttle and it goes back to idling normal. So I know when you foot comes off the pedal, plus something else, maybe a speed reading into the PCM tells it to go into decel? Idk. I do know this just started out of the blue. It's a Mopar PCM also.
 
maybe the TB is sticking and causing the pcm to freak out?

though, if that were the case, i guess it would want to run rich, not lean?

i'm thinking something in the tune, or at the very least, something a tune can fix?
 
Goes along with your screen name, moneypit......lol. Hope you get it figured out bud, keep us posted. That caliper issue seems to be getting common on the 05-06's.
 
TPS takin a dump???
 
04rcmoneypit said:
Well...... Possible I guess, but runs too good. I would just like to know what two or more things need to happen for the PCM to go into decel.
Click to expand...

Hey bud, your PCM goes Into decel when you are cruising and let off gas pedal. It resumes normal fueling as RPMs close to idle or you clutch in.
Your problem is likely simple and your IAC or idle air controller is sticking and allowing more air in than the PCM expects under the load/TPS.
Your IAC will allow too much air in at idle and will change exhaust note as well.
Your A/F gauge is working correctly. It's further downstream and takes a decent exhaust flow to read accurately. Especially at idle.
A couple other possibilities are a bad 02 sensor or a header leak. Have you installed headers? What gaskets if so? Any codes stored in PCM?
 
VENOMOUS1 RACING said:
Hey bud, your PCM goes Into decel when you are cruising and let off gas pedal. It resumes normal fueling as RPMs close to idle or you clutch in.
Your problem is likely simple and your IAC or idle air controller is sticking and allowing more air in than the PCM expects under the load/TPS.
Your IAC will allow too much air in at idle and will change exhaust note as well.
Your A/F gauge is working correctly. It's further downstream and takes a decent exhaust flow to read accurately. Especially at idle.
A couple other possibilities are a bad 02 sensor or a header leak. Have you installed headers? What gaskets if so? Any codes stored in PCM?
Click to expand...

IAC is new (for what its worth.) Clutch in..... I shoulda thought of that, I moved the pedals the other day. What voltage should the tps put out at idle? Seems like I remember 6.8 or something like that. Does speed factor in to going into decal? Seems like it would or it would go into decal at idle with clutch out:dontknow: And yes, custom turbo headers, only codes are leak detection pump, which I don't worry about cause the mopar pcm doesn't give a cel.
 
04rcmoneypit said:
IAC is new (for what its worth.) Clutch in..... I shoulda thought of that, I moved the pedals the other day. What voltage should the tps put out at idle? Seems like I remember 6.8 or something like that. Does speed factor in to going into decal? Seems like it would or it would go into decal at idle with clutch out:dontknow: And yes, custom turbo headers, only codes are leak detection pump, which I don't worry about cause the mopar pcm doesn't give a cel.
Click to expand...

.68 on TPS at idle. Try unplugging IAC with key in on position. Plug back up and start and drive. Should reset iac parameters. Otherwise is still look for a vacuum/exhaust leak. It can play games on the pcm correction.
Yes speed sensor is factored in when decel is happening.
 
I forgot to update this thread, after ohming the injector harness and investigating a burnt spot from the header, I think an injector plug was my problem. Runs good now. Thanks for the input, guys.
 
04rcmoneypit said:
I forgot to update this thread, after ohming the injector harness and investigating a burnt spot from the header, I think an injector plug was my problem. Runs good now. Thanks for the input, guys.
Click to expand...

Good work on the fix!
I have a aem failsafe to it also runs full lean (18)on deceleration so that's good to hear that's normal.

Have you connected the rpm wire? If so what to? I've run mine into a coil signal but the aem doesn't want to play? How about the failsafe is there a good place to run that to? Didn't fancy cutting the power to the PCM.
 
Oggers said:
Good work on the fix!
I have a aem failsafe to it also runs full lean (18)on deceleration so that's good to hear that's normal.

Have you connected the rpm wire? If so what to? I've run mine into a coil signal but the aem doesn't want to play? How about the failsafe is there a good place to run that to? Didn't fancy cutting the power to the PCM.
Click to expand...

The instructions from AEM don't help very much. You may be better off contacting AEM to find out what type of signal the gauge needs for rpm. If its just a 12 volt signal, an injector control wire may work. As far as the failsafe, I don't know. If you are not supercharged or turbo'ed, I wouldn't bother hooking it up. Your stock electronics will take care of you. With forced induction, things happen fast, so if you are FI, it may be worth hooking up. Good luck.
 
You must log in or register to reply here.

Latest posts

Support Us

Become A Supporting Member Today!

Click Here For Details

Random Media

image
100 9819
thumbnail 20160510 114251
Photoshoot with Big Ryan from Severed Ties TX
Back
Top