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1g with 2g maf issues

Posted by 90_gsx_88, Jan 10, 2012

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  1. 90_gsx_88

    90_gsx_88 Proven Member

    33
    0
    Joined Nov 30, 2011
    Fallon, Nevada
    Ok I have a 90 gsx with a 2g maf the wires on it were hacked so I went threw and sodered all the wires again didn't do anything I cleaned the air filter and the maf still nothing I went and got another maf still nothing the car is idling at 11.2 on the a/f ratio I have adjusted the safc to the point the low setting was at -35% from 1k rpm to 7k rpm and then adjusted the hi to +35 all the way across the car runs lean for about 10 seconds then starts droping back down when I give the car gas it spits and spudders and jerks but if I give it full throtle it acts like nothing is wrong while its accelerating but steady idle under 4k it runs like crap the check engine light is on the code was for the maf please help
     
  2. CrawlinZX14

    CrawlinZX14 Proven Member

    455
    3
    Joined Sep 7, 2011
    Carpentersville, Illinois
    Is your ECU programmed to accept the 2g maf? You will need to have an eprom that is set to read a 2g maf. I did my 2g maf into my 1g and had my eprom tuned exactly for it. When I upgraded to my gm maf and a maft, I had the exact same problems as you at first because i forgot to set the dip switch for the 2g maf instead of 1g. You are going to need a tune on your ecu for the 2g maf. I know someone who sockets and chips for your setup tho if you have an eprom.
     
  3. NOSLO2PT0

    NOSLO2PT0 Proven Member

    2,002
    11
    Joined Aug 31, 2002
    Joliet, Illinois
    Pat, can I buy a period? Taking out 35% of fuel at low throttle will cause your timing maps to go thru the roof. The part throttle jerking is because you have so much timing advance. And WHY would you have your AFC set to +35 on the high side? That is where you should be running it at -30%.

    if the CEL shows a bad maf code, then it sounds like you messed up the wiring. Go over it again.
     
    Last edited by a moderator: Jul 10, 2014
  4. XiKeiyaZI

    XiKeiyaZI Proven Member

    2,443
    40
    Joined Dec 28, 2008
    Dyersburg, Tennessee
    This is helpful information but not -exactly- correct. The 2G MAF in a 1G thing has been around since the first 2G MAF became available. While it is very smart to compensate for the change via ECU tuning, it is not mandatory. There can be adjustments made in several other areas to counter-act the difference in airflow - or you can simply leave it be and enjoy whatever effects it brings. I own a 1G that I bought with a 2G maf installed and in all honesty? There are no noticeable differences in the way it drives. I've personally not noticed a richer/leaner condition with it wired up. Though I'm sure that different things effect different setups in different ways - the ECU Compensation for the maf is not needed for the car to run. I'd have to say in this situation he's likely looking at a dead maf all together ontop of poor compensation via his SAFC.
     

    772  0

    1998 Eagle Talon TSi AWD
    manual · 2G DSM
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  5. bryanwheat

    bryanwheat DSM Wiseman

    6,978
    169
    Joined Aug 16, 2004
    Columbia, Missouri
    You should actually have to add fuel to run the 2g maf not remove it. It will cause the car to run a leaner, that is why throwing in a set of 550's will somewhat even it out.
     
  6. NOSLO2PT0

    NOSLO2PT0 Proven Member

    2,002
    11
    Joined Aug 31, 2002
    Joliet, Illinois
    His profile states he has 650's. Not sure how current it is tho.
     
  7. XiKeiyaZI

    XiKeiyaZI Proven Member

    2,443
    40
    Joined Dec 28, 2008
    Dyersburg, Tennessee
    I would assume that increasing fuel pressure would also be an alternative?
     

    772  0

    1998 Eagle Talon TSi AWD
    manual · 2G DSM
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  8. 90_gsx_88

    90_gsx_88 Proven Member

    33
    0
    Joined Nov 30, 2011
    Fallon, Nevada
    I got the car the way it sits with everything done to it it ran just fine when I got the car I blew the head gasket and since then I have had nothing but issues after changing the head gasket with the maf I have a aero motive fuel pressure regulator its set at 40 on idler and 50 on wot the reason for trying to run the safc at -35 on the low throtle was because the car is idleing at 11.1 a/f taking fuel out that low should lean it out a bunch but its not and I'm not getting any reading from the maf to my safc the safc will show the fuel curve when I give it gas but when I swap it to the air % it don't do anything like I said car had all this already when I got it and ran great I re did the wires I did 1 at a time so I wouldn't screw up
     
    Last edited by a moderator: Jul 10, 2014
  9. XiKeiyaZI

    XiKeiyaZI Proven Member

    2,443
    40
    Joined Dec 28, 2008
    Dyersburg, Tennessee
    Headgasket replacement. This leaves a few questions.

    1 : Is timing correct?
    2 : How is the compression?
    3 : Have you performed a leakdown test?
    4 : Check for boost leaks? Lean at idle tells me you have a bad vacuum leak.
    5 : Was your CAS adjusted properly?

    Check these things first and get back with us.
     
    Last edited by a moderator: Jul 10, 2014

    772  0

    1998 Eagle Talon TSi AWD
    manual · 2G DSM
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