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baz2328 12-18-2011 11:15 AM

2006 GC 5.7 hemi
Hi, new to this but could you tell me how you can tell MDS is working and does the fact that it has been converted to run on lpg affect this? Since the lpg conversion in Nov, the engine management light is on at all times yet there does not appear to be any loss in performance. Any info thanks.

Escape 12-18-2011 12:35 PM

Re: 2006 GC 5.7 hemi
Pushing the tow/haul button disables MDS.

There is a write up somewhere in these forums on how to add a light so you know when it's on/off.

A Diablo predator can turn MDS off.

I would talk to whomever converted it to see if it is indeed compatible with MDS.

Since the engine light is on what are the codes?

jeepgcoman 12-18-2011 12:48 PM

Re: 2006 GC 5.7 hemi
I am the one that came up with the MDS "ON" Light about 5-6 years ago, over on the LXForums. It's under my screen name, magnuman, over there.

That being said, what Escape is saying and asking is all true. First check for codes. Generally, if you have a MIL illuminated, your MDS will probably NOT be working as, I believe, most Engine Management MIL's and DTC's deactivate it and take it back to the normal, non MDS mode until the problem is resolved. If the LPG is causing this, you'll probably have to live with it. Like Escape said, ask the folks that installed the system, although I'd be surprised if they're familiar with the MDS Hemi, and the "how's and why's that it works.

baz2328 12-18-2011 02:22 PM

Re: 2006 GC 5.7 hemi
Thanks, I will check to see what codes are showing.

baz2328 01-08-2012 10:03 AM

Re: 2006 GC 5.7 hemi
Just got a scanner and the codes (4 off) are P0171 and P0174, live and pending, cheers, Baz

jeepgcoman 01-08-2012 03:40 PM

Re: 2006 GC 5.7 hemi
That's showing both cylinder banks front (the ones that read the air/fuel mixture) O2 sensors sending lean signals to the PCM. You, for sure, will not have MDS with those codes showing. How do they control the LPG mixture with that system?

baz2328 01-11-2012 11:58 AM

Re: 2006 GC 5.7 hemi
Cheers for that, jeep is going back to installer tomorrow for remedial tuning.



Escape 01-11-2012 02:26 PM

Re: 2006 GC 5.7 hemi
I would have to see how it was installed and how it is delivered to the engine but LPG does have a different stoichiometric AFR value

Gas = 14.7
LPG = 15.8

Higher is leaner (less fuel)

This in turn would throw the codes your looking at.

You are going to have to reset the AFR values your PCM is looking for by 1.1 point since you changed fuel types.

baz2328 01-12-2012 05:54 AM

Re: 2006 GC 5.7 hemi
Thanks Escape, had it back today, took jeep out and mapped on petrol then turned on gas and re-mapped, it did show lean, tuned gas map on way back to garage and all seems ok - no MIL on the way home. Installer did say to return if light comes on again.



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