GM Maf Translator Install Lean Idle

Silver 95 GST · Nov 28, 2009

I just installed a 3" gm maf with translator and started the car up with the suggestred settings for my stock 450cc injectors, but it idled so lean that it kept almost dying. The o2 sensor was reading a constant 0.04 volts (super lean) and would occasionally make it inot closed loop for a second or so.

I richened up the idle, but I maxed out the richness and it still idled lean.

I've got the 1st generation maf translator and yes the dip switch is set for the 3" maf.

Now I've set the base for 390cc injectors even though mine are 450's. It idles a lot beter and gets into closed loop most of the time on idle if it's warmed up.

But now I maxed out the rich adjustement. That can't be right!

Anyone know what's wrong or what to check?

All help is appreciated. Thanks in advance.

TxR6guy · Nov 28, 2009

Sounds stupid, but did you check to make sure on the translator you have it set to 3' gm, i made the mistake and had mine set on 3.5 and it did the same thing, smoking out the back and wouldn't idle.

LTUDSM · Nov 28, 2009

what kind of translator are you using?

Silver 95 GST · Nov 28, 2009

Thanks for the responses everyone.

I've got the 1st generation maf translator. I know it's not great for fine tuning, but I will try to make due.

Yes the dip switch is set for the 3" maf.

I set the base for 390cc injectors even though mine are 450's. Now it idles a lot beter and gets into closed loop most of the time on idle if it's warmed up.

But now I maxed out the rich adjustement. That can't be right!

Dsmj89 · Nov 28, 2009

Have you scanned your car with a code reader to see if your o2 sensor is gone ?
I would suggest setting your aux and base knobs back to the 450cc specs and everything else set it back to 0.
Let me know how it reacts. If it is still bad i would assume either the actual maf sensor is bad or the translator box is faulty.

Silver 95 GST · Nov 29, 2009

Thanks for the reply Dsmj89. By the way I was just in your city because I left on a cruise from there and Miami is nice!

I have scanned my car and I have no codes, but my CEL is off so I didn't really expect any.

The o2 sensor worked fine before I installed the maft. I just replaced the o2 sensor in the last year, so I doubt it's that but I'll check it again.

The car runs fine with the new maft except for idle. When I get out of the "low" fuel table and in to mid and high it runs fine. It's just that the idle is lean.

I will take your advice and set everything back to the suggested conditions for 450cc injectors and zero things out and start it up.

Do the gm maf or translator really go bad? Mine are brand new, not from a junkyard.

Thanks again all the input is appreciated.

Well I set everything to proper settings disconnected and reconncted the battery and started it up cold.

-started up and the a/f ratio went all the way rich (in open loop) until it warmed up. Then once it warmed up it went in to closed loop and the a/f ratio went all the way lean (o2 sensor reading 0.02 volts constant).

-short term and long term fuel trims started at zero on start up because the computer was reset. Then in closed loop it maxed out the short term fuel trim to get richer at +17 %. But it still was to lean and the car died.

My next step is to switch the setup back to the stock maf and see how everything is. I'll update the thread.

a91talonAWD · Jan 21, 2010

Silver 95 GST said:
Thanks for the reply Dsmj89. By the way I was just in your city because I left on a cruise from there and Miami is nice!

I have scanned my car and I have no codes, but my CEL is off so I didn't really expect any.

The o2 sensor worked fine before I installed the maft. I just replaced the o2 sensor in the last year, so I doubt it's that but I'll check it again.

The car runs fine with the new maft except for idle. When I get out of the "low" fuel table and in to mid and high it runs fine. It's just that the idle is lean.

I will take your advice and set everything back to the suggested conditions for 450cc injectors and zero things out and start it up.

Do the gm maf or translator really go bad? Mine are brand new, not from a junkyard.

Thanks again all the input is appreciated.

Well I set everything to proper settings disconnected and reconncted the battery and started it up cold.

-started up and the a/f ratio went all the way rich (in open loop) until it warmed up. Then once it warmed up it went in to closed loop and the a/f ratio went all the way lean (o2 sensor reading 0.02 volts constant).

-short term and long term fuel trims started at zero on start up because the computer was reset. Then in closed loop it maxed out the short term fuel trim to get richer at +17 %. But it still was to lean and the car died.

My next step is to switch the setup back to the stock maf and see how everything is. I'll update the thread.

I am having the similar problem with my car except I have larger injectors 750cc and need help with this issue as well... I am wondering if you found the route of this problem. I have no clue where to start or what to check first.

dsm darthvader · Jan 21, 2010

well im not sure of the maft but on the maft gen II you have the input setting (GM MAS 3in) and the output setting (in my case 2g DSM) maybe your output setting is not dialed in correctly. Also you probably did this already but check the wiring, and lastly the o2 volt output is not realiable at all when measuring A/F ratios try to get/borrow a wideband.
Something i forgot do you have it in blowthrough or stock position, sometimes when in blowthrough it reads the MAS differently, and some people set it to 3.5 and fix their problem, there is a support forum for these translator (fullthrottletech.com) and turbobob along with other people on that forum are very helpful, they have a lot of knowledge on their product.

a91talonAWD · Jan 21, 2010

dsm darthvader said:
well im not sure of the maft but on the maft gen II you have the input setting (GM MAS 3in) and the output setting (in my case 2g DSM) maybe your output setting is not dialed in correctly. Also you probably did this already but check the wiring, and lastly the o2 volt output is not realiable at all when measuring A/F ratios try to get/borrow a wideband.
Something i forgot do you have it in blowthrough or stock position, sometimes when in blowthrough it reads the MAS differently, and some people set it to 3.5 and fix their problem, there is a support forum for these translator (fullthrottletech.com) and turbobob along with other people on that forum are very helpful, they have a lot of knowledge on their product.

Yes it is set up blow through. I will try setting it to 3.5 inch. The MAFT does not have output settings or 1st or 2nd gen, you just use a different chart when selecting the injector size. I was talkine with some on full throttle but didn't get any where. thanks for your help I appreciate it.

dsmfa9nutter · Jan 21, 2010

What do you mean by 1st gen maft? Do you mean you have a v1.3 (older version of maft for 1g dsms) or do you mean you're using a maft designed for a 1st gen dsm on your 2nd gen dsm?

If you have an older version of maft, your switches and dials are different than the newer versions and require different things to be set.

dsm darthvader · Jan 21, 2010

there is the maft with its various versions and then maft gen2 and the top of the line the maft pro. All three are different tuning devices

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