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Thread: Tune adjustment?

  1. #1
    Mitsu booster
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    Tune adjustment?

    Just got a 89 Gtc coupe and it's running too rich, idles too high and barely starts (cranks forever and stalls).


    Specs

    2.5 T1
    287 G head
    A413
    +40 injectors
    Accufab FPR
    Stage 5? Fwd smec
    3 bar map?
    Walbro 255 pump
    Side exit straight pipe exhaust
    Srt intercooler
    Garret Turbo (was told its a Super 70 but it looks like a standard T2)
    Has a AF and boost gauge idle is pegged rich...




    Car came with a vacuum block so far hooked up Fpr,Map,Bov,wastegate,boost gauge.


    What's the correct ignition timing and fuel pressure to run on this?

    I have a fuel pressure gauge and the AF gauge seems to work.
    Last edited by reliantkcar; 11-17-2022 at 11:07 PM.

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Tune adjustment?

    If it's the correct cal for the combination, 55psi static should be the fuel pressure. Lots of variables there. Do you have the stuff to go back to stock and move forward?

  3. #3
    Mitsu booster
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    Re: Tune adjustment?

    Quote Originally Posted by cordes View Post
    If it's the correct cal for the combination, 55psi static should be the fuel pressure. Lots of variables there. Do you have the stuff to go back to stock and move forward?
    No car came heavily modified.
    I just set it to 55psi with the vac hose unplugged from the fpr. When I reconnect it pressure drops to 40psi at idle.
    Still runs like crap from cold start might just be the fwd cal I heard they idle bad cold.

  4. #4
    turbo addict
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    Re: Tune adjustment?

    FWD cals typically run very rich. They don't know how good your cylinder head is, so running fat is far better than running lean! It is common to have to turn fuel pressure down from 55 PSI (static) on these cals. Yes short dead cold start program is not very good on these cals. Something obviously gets changed in the cold start program when the cal is made. They typically run like an engine that has no choke on it for a couple minutes. Better make sure that cal was made for a g-head. A 2.5 running a g-head has proven to be fussy to tune for many.
    Todd
    Last edited by 4 l-bodies; 11-12-2022 at 07:34 PM.

  5. #5
    Mitsu booster
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    Re: Tune adjustment?

    Quote Originally Posted by 4 l-bodies View Post
    FWD cals typically run very rich. They don't know how good your cylinder head is, so running fat is far better than running lean! It is common to have to turn fuel pressure down from 55 PSI (static) on these cals. Yes short dead cold start program is not very good on these cals. Something obviously gets changed in the cold start program when the cal is made. They typically run like an engine that has no choke on it for a couple minutes. Better make sure that cal was made for a g-head. A 2.5 running a g-head has proven to be fussy to tune for many.
    Todd
    It's actually worse than my 82 Reliant and 84 Corolla. Those cars had dead chokes and would start eventually idle around 250-400rpm and have no power till a few minutes later.

    This Fwd cal cranks so long it actually killed the first battery then it starts fine but seconds later stalls if u don't pump the pedal. Holding it steady does nothing. And every time u feather the gas it shoots out plooms of black smoke. And no matter what I set the fpr to I don't get full rich on the AF gauge at WOT.

    Driver side caliper started dragging then leaking (plastic piston?) So car is down for a few days...

  6. #6
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Tune adjustment?

    I would double check that your map sensor is correct for the cal. That sounds way, way off.

  7. #7
    turbo addict
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    Re: Tune adjustment?

    12 degree spark timing with engine coolant temperature sensor unplugged.
    Make sure the cam shaft is timed correctly. http://www.thedodgegarage.com/timing_belt.html

    Contact FWD performance and see what they say about your specific tune. There should be a sticker on the chip on that ECU.
    Or make your own tune.

  8. #8
    Mitsu booster
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    Re: Tune adjustment?

    Quote Originally Posted by tryingbe View Post
    12 degree spark timing with engine coolant temperature sensor unplugged.
    Make sure the cam shaft is timed correctly. http://www.thedodgegarage.com/timing_belt.html

    Contact FWD performance and see what they say about your specific tune. There should be a sticker on the chip on that ECU.
    Or make your own tune.
    12 degrees with a G head on a 2.5?

    it's running better now after downgapping the plugs and setting the idle and Fuel pressure to 55psi.

    I pushed it to 20 psi runs fine (rich on gauge) but off the line is kind of weak. Maybe needs more base timing or less fuel pressure?

    Anyone else running a 2.5 G head on a Fwd cal?

  9. #9
    turbo addict
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    Re: Tune adjustment?

    Quote Originally Posted by reliantkcar View Post
    12 degrees with a G head on a 2.5?

    it's running better now after downgapping the plugs and setting the idle and Fuel pressure to 55psi.

    I pushed it to 20 psi runs fine (rich on gauge) but off the line is kind of weak. Maybe needs more base timing or less fuel pressure?

    Anyone else running a 2.5 G head on a Fwd cal?
    As you know, no factory car ever come with 2.5L and G head. But all the other engine setup use 12 degree as baseline.

    As general, G Head require more timing than 782 head but 2.5L needs less timing than 2.2.

    If you have access to dyno and can monitor knock, now would be a good time to test out your setup.

  10. #10
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: Tune adjustment?

    i run a stock g head on a 2.5 with 75lb injectors, stock cam, ported manifolds, mostly reasonable warmup enrichment, back road fuel and timing tuned (pretty conservative) on a SMEC.

    buy a moates.net burn2 and some 27sf512 chips (from a reputable source.... many garbage clones as they are no longer in production) and I can write a file for you to burn to a chip.

    then you can dial it in to your setup.

    Brian

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

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