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Thread: 89 Mini SRT Hybrid Mis-Firing

  1. #1
    Authorized Vendor Turbo Mopar Vendor mario03SRT's Avatar
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    89 Mini SRT Hybrid Mis-Firing

    All,

    I'm working on a 89 Mini with a SRT-4 engine using a Dizzy and a STG 5 HYbrid SMEC from FWD Performance.

    The Van came in with a major missfire on all 4 cyls after part throttle when going into open loop. The Van will only run decent with the boost set to 10psi.

    I have replaced - New plugs gapped to 28, new Blaster 3 coil, new 3 bar Map, Cap/Rotor, coil wire and a HEP. Has newer 7mm plug wires(?) All the vacuum lines have been replaced or re-secured. NO CODES.

    Fuel Pressure gage show good pressure and maintains pressure for hours after running. Set @ 50 psi. Currently has a 10.5 AFR @ WOT/10 psi of Boost.

    I cleaned up some wiring issues. Dizzy is set correctly I believe per the marks placed on it by the engine builder.

    It starts and runs great. The problem reminds me of spark blow out or rev limiter. When it first came in I played with the tune and could get it to run at 18 psi but with a unsteady AFR. After tuning the engine with the new components now 10 psi is the max.

    Any thoughts? The SMEC appears fine, have not monkied with the Walbro but it appears to be fine also. What am I missing?

    Thanks,

    Marion

  2. #2
    Supporting Member Turbo Mopar Contributor glhs727's Avatar
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    Re: 89 Mini SRT Hybrid Mis-Firing

    how is the distributor itself? The plate in it is riveted in with plastic rivets, and sometimes that get loose causing a distributor issue. check the plate and make sure there is no play. Is the issue only related to boost or rpm? what brand plugs are you using?
    FWD Performance is a performance shop with a significant investment in this market. We pride oursleves with a hard work ethic, friendly customer service, and honest business dealings with no hidden fees. FWD Performance, Real Race Products by Real Racers.

  3. #3
    Visit www.boostbutton.com... Turbo Mopar Contributor ShelGame's Avatar
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    Re: 89 Mini SRT Hybrid Mis-Firing

    The dizzy is on the end of the cam? And is correctly modified for reverse rotation?
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    Rob Lloyd
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  4. #4
    Authorized Vendor Turbo Mopar Vendor mario03SRT's Avatar
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    Re: 89 Mini SRT Hybrid Mis-Firing

    The Mini came with NGK Iridiums. Replaced them with NGK V Grooves. I will go out and look at the Dizzy , I did hold the shutter and tug it before and it "seemed" secure but I will look closer.

  5. #5
    Authorized Vendor Turbo Mopar Vendor mario03SRT's Avatar
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    Re: 89 Mini SRT Hybrid Mis-Firing

    Rob,

    Yes it has been on the road for a few years. Also the HEP connections are reversed and it is offset a few degrees to the right of the mounting screw. The rotor is also offset on the Dizzy shaft with a different key slot. Plug wires are also counter rotated on the Dizzy Cap.

    It runs bad --- up to 10 psi.

    Oh and I forgot to add this is a Boost only related issue as far as I can tell. 10-12 psi max. Maybe the Baro Sensor?

    Thanks,

    Marion

  6. #6
    turbo addict
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    Re: 89 Mini SRT Hybrid Mis-Firing

    Check crank pulley and damper are tight and haven't chewed anything up. Ditto the cam pulleys to be thorough.
    DD1: '02 T&C Ltd, 3.8 AWD. DD2: '15 Versa Note SV, replacing.. DDx: '14 Versa Note SV << freshly killded :( ....... Projects: '88 Voyager 3.0, Auto with shift kit, timing advance, walker sound FX muffler on 15" pumpers wrapped in 215/65/R15 H rated Nexens.... and a '95 phord escort wagon PnP head << Both may need to go :( ..... I like 3.0s ... so??? ... stop looking at me like I've got two heads!

  7. #7
    Authorized Vendor Turbo Mopar Vendor mario03SRT's Avatar
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    Re: 89 Mini SRT Hybrid Mis-Firing

    All of the pulleys and belts are fine.

  8. #8
    turbo addict
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    Re: 89 Mini SRT Hybrid Mis-Firing

    Check TPS hasn't gone dirty/noisy above normal driving range.
    DD1: '02 T&C Ltd, 3.8 AWD. DD2: '15 Versa Note SV, replacing.. DDx: '14 Versa Note SV << freshly killded :( ....... Projects: '88 Voyager 3.0, Auto with shift kit, timing advance, walker sound FX muffler on 15" pumpers wrapped in 215/65/R15 H rated Nexens.... and a '95 phord escort wagon PnP head << Both may need to go :( ..... I like 3.0s ... so??? ... stop looking at me like I've got two heads!

  9. #9

    Re: 89 Mini SRT Hybrid Mis-Firing

    Do you have the resister block for the msd coil ? other than that try gapping the plugs down as well as making sure there is no oil on the spark plug boots, the old ignition system is very weak, seems to be the biggest issue i have with my hybrid.
    Also try dropping the fuel pressure just a bit to make sure your afr moves towards 11 to rule out improper afr readings and make it easier for the ignition to light the fire, if the afr doesnt change then you might suspect improper afr readings and the mixture is too rich and blowing the spark out

  10. #10
    turbo addict
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    Re: 89 Mini SRT Hybrid Mis-Firing

    Pull the battery box out and clean/relocate the ground under it. That's the main computer ground.
    Ian Adams Function>Form 1990 shadow scrapped, too rusty:( 1991 Spirit R/T Scrapped, parts sold:( 1989 Turbo Caravan Daily beater with built-[I]ish [/I]​engine slowly evolving into weekend turbo beater.

  11. #11
    Authorized Vendor Turbo Mopar Vendor mario03SRT's Avatar
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    Re: 89 Mini SRT Hybrid Mis-Firing

    I did not use a resistor block. MSD says with a reading of >1.0v one is not needed. IDK if the stock coil has one internally but either coil I use has the same end result. I had a Blaster 2 on my 89 Shelby Daytona 2.2 and it did not need one.

    - - - Updated - - -

    Thanks for the tip. I'll check it out.

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