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1G Where should I begin when buying someone else's project?

Posted by 90EclipsePos, Jan 28, 2018

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  1. 90EclipsePos

    90EclipsePos Proven Member

    65
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    Joined Jun 22, 2014
    Grand Junction, Colorado
    Sorry for the vague title not sure best way to put it. So just bought a 91 gsx from a guy who was the 2nd person to start this project. It originally was automatic and converted to manual. Bought it not running it has rebuild engine, 340 fuel pump, new turbo and larger cams and safc2 he also had a 2g maf installed and fmic. Having a hard time getting it to idle great. So since I have bought it here is what I've done. Had the ecu repaired and converted to eprom, new plugs gapped to .28, new tps, and new isc. I also swapped in freshly cleaned stock 450cc injectors. It looks like a new o2 sensor. Boost leaks have been taken care of. So not sure where else to begin. Any suggestions? It is trying to idle around 550-600 rpms. And while trying to adjust the idle I can't get it to change at all.
     

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    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

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    50trim   manual
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  2. Dsm panda

    Dsm panda Proven Member

    103
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    Joined Dec 8, 2017
    Franklin, Wisconsin
    did you ground anything or just play with the biss screw? What have you already tried what where the results?
     
    My DSM:
    1991 Eagle Talon TSi

    327 whp   307 lb/ft
    1990 Plymouth Laser RS Turbo

    Street Build

      manual
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  3. 90EclipsePos

    90EclipsePos Proven Member

    65
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    Joined Jun 22, 2014
    Grand Junction, Colorado
    I grounded both plugs. When I adjust the biss screw out the idle stays the same. If I screw it in all the way it dies. So far just replaced parts and trying to figure the idle issue out. Tps is set to 10.1% on MMCD. Ignition timing is correct have not checked mechanical timing yet. Only have drove it 5 miles or less since I bought it. Fuel seems close on FTRL it was at 99.2%.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  4. Vegas smith

    Vegas smith Proven Member

    1,991
    877
    Joined Dec 2, 2002
    Houston, Texas
    Have you set the fuel pressure back to stock?
     
    My DSM:
    1993 Eagle Talon TSi AWD

    Street Build

    GT30   manual
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  5. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    Yes it does have aftermarket fuel pressure regulator I pulled vacuum hose off and set to 38. Ecu came from a manual car so it's set for the 450cc injectors.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  6. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    Is there any other items I should look at that would cause the idle not to change when adjusting it? I've double checked the wiring to the maf everything looked correct. Next I'll check wiring too the safc2.
     
    Last edited: Jan 31, 2018
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  7. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    So wiring checked out fine on SAFC2. Checked mechanical timing which was off a little. Fixed that car idled closer to 750 once the car was warmed up. Still runs a little rough. The car kind of stumbles when at lower speeds. Thinking fuel is a little off due to the 2g MAF and stock injectors. Will try adjusting fuel tomorrow and see how it does. Any other suggestions you guys can come up with would be appreciated.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  8. bluespunk

    bluespunk Proven Member

    52
    11
    Joined May 29, 2011
    Chicago, Illinois
    So you've covered most of it by now, but If I'm taking over someone else's project (issues to fix or not), things's I'd run through to get a baseline of the project:
    • Fuel/Air Filters, plug wires, spark plugs, brakes, tires, hoses and accessory belts should all be checked over (I usually replace most of this stuff when I start a new project , so I'm fully aware of the maintenance window). Spark plug gap seems to something that gives a lot of people issues with these cars. Only the first few things matter for your issue right now, but those are all things to check when taking something over.
    • Boost Leak Test - You did this already
    • Exhaust Leaks - harder to find. I like to run sea foam in my motors (not everyone agrees this is ok). The smoke it makes will blow out of major exhaust leaks while it runs through the system. Smaller leaks probably won't be spotted as easily.
    • Timing - You checked the mechanical timing, but how's the tension on the belt? Any wear on the belt?
    • Compression and/or Leak down test - Mostly just to get a baseline of the engine's health
    • Sensors - Scan for codes (I've had more than one DSM with broken check engine lights, so don't wait for a light), then verify they're all set correctly. You've already started this with the BISS, but isn't the CAS adjustable on a 1G to change base timing? Have you verified it's set correctly? I'd double check to make sure that any adjustable sensor is set correctly. If the MAF is bad, you could also have issues getting it to idle. BISS adjustments are worthless on my 2G if the MAF is faulty or doesn't have a good ground (found that out messing with wiring in an IAT for speed density). If you have a wideband, make sure it's reading correctly. Some of them need to be calibrated periodically too.
    • Fuel pressure - You set the base pressure. I'd also keep an eye on it to make sure the pump is maintaining pressure consistently (ie the pump isn't failing).
    • Clean/flow test injectors (if you're budget is too tight to send them out, there's some shadetree ways to check the pattern with carb cleaner and a battery, check out youtube)
    As far as the specific issue you're having, my money is on an issue with the MAF or another sensor being off adjustment.
     
    90EclipsePos likes this.
  9. lasershark

    lasershark Proven Member

    1,126
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    Joined May 17, 2013
    over yander, Idaho
    2g maf in a 1g normally balances out for 550cc injectors which is roughly 25% or so. Try scaling positive to around 25% to offset the 2g maf and keep an eye on mmcd for stft and adjust as necessary.
     
    My DSM:
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  10. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    So it does have an exhaust leak for sure I believe it is past the o2 but is also on my list to do. As far as maintenance everything is good engine was completely rebuilt with receipts he just couldn't get it to run so gave up. I did have injectors sent off and cleaned already. He had 1000cc injectors in it with only the SAFC2 to control it which I've read is maxed out at about 660cc. So it was dumping in a lot of fuel. Ecu had leaking capacitors so shipped it off and had it repaired and converted to eprom. After doing the mechanical timing I did adjust ignition timing. One big concern for me is any wiring be he migt have done when converting it from an automatic.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  11. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    I have read it's around 20% difference. I also read of people saying their cars run great with no adjustment. I was at 5% correction yesterday going to try 20% tomorrow. Really need a wideband installed would make it a lot easier. For some reason the guy installed a narrow band which is useless. I've been trying to adjust it by watching Data logger but kind of suck at knowing what exactly I should be watching.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  12. lasershark

    lasershark Proven Member

    1,126
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    Joined May 17, 2013
    over yander, Idaho
    They are most likely running 550's though, stft (short term fuel trim) is what you want to be looking at for idle fuel trim. If you get it adjusted in the "ballpark" for idle the computer should make it idle correctly as far as afr's go and then you can dial it in with the stft. The stft doesn't immediately adjust so get it close and watch it for a few minutes.

    Are you adjusting negative or positive on the correction factor?
     
    My DSM:
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  13. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    Doing a negative correction. At least that is what I've read to do. That we should never use positive on our cars. I have been watching my FTRL it was around 105 after driving it the other day.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  14. brian9397gsx

    brian9397gsx Proven Member

    988
    50
    Joined Apr 28, 2008
    sioux city, Iowa
    I don't know if you have checked the idle switch on the throttle body. That'll play hell trying tok adjust base idle if it's not adjusted properly.
     
    My DSM:
    brian9397gsx 1993 Mitsubishi Eclipse GSX

    19.80 @ 35.55 MPH
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  15. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado

    Yes I did adjust it till I got continuity between it and throttle body.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  16. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    So reset ECU adjusted SAFC to -20% the car ran very rough. So much never got to drive it. Giving it throttle really stumbled and barely wanted to rev up constantly wanting to die. Might try a boost leak again just to make sure no connections came undone last drive.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  17. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    Can someone please confirm I'm not losing my mind. So finally got back to work on the car today first thing I wanted to check was CAS. So put the car to top dead center for cylinder 1 on compression stroke. Pull off the CAS and the marks were not lined up they were opposite. This 180 degrees out correct? So fix it thinking this will solve all my problems. Car still didn't want to idle couldn't get it to adjust again and only have maybe 3 inches of vacuum. Tried driving it around the block to help warm it up and if I gave it gas it would barely move. I was told they were reground cams. Is it possible these cams are not right? Or off of the wrong car?
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  18. motomattx

    motomattx Proven Member

    886
    167
    Joined Dec 9, 2010
    wampum, Pennsylvania
    Depending on the cams and how agressive they are, you might not ever get it to idle good, are the cams degreed? you need to know what cams they are, you also need to do a compression test asap, just because something is rebuilt doesnt mean that it was done right or that it hasnt been damaged, things can happen in seconds that can ruin a good engine, so dont rule anything out. It sounds like right now you have an igntion timing problem thats causing it to run terrible, you need to set it asap.
     
    My DSM:
    1995 Mitsubishi Eclipse GST

    Drag Race Build

    GT42   manual
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  19. lasershark

    lasershark Proven Member

    1,126
    206
    Joined May 17, 2013
    over yander, Idaho
    You are adjusting the wrong way. You need to adjust positive +20% in order to offset the -20% that the 2g maf in a 1g gives you by itself.

    By going negative, you are essentially putting a -40% value which would equate to 630-650cc injectors.

    Think about it this way, people have run 550/560cc injectors with nothing more than the 2g maf/1g car combo. This works because the 2g maf essentially reads/meters 20-25% less air which balances out the 550/560 injectors. You are running the stock 450's so to balance out the maf metering, you need to adjust positive.
     
    My DSM:
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  20. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    Reset the ignition timing after switching the CAS it's set to 5 degree BTDC. My next steps are going to be pull valve cover off and compare the cams to stock, compression test, leak down test. Any other suggestions?
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  21. motomattx

    motomattx Proven Member

    886
    167
    Joined Dec 9, 2010
    wampum, Pennsylvania
    Not right now, concentrate on the things you mentioned and lets see where that goes, no point in getting overwhelmed right now, baby steps.
     
    My DSM:
    1995 Mitsubishi Eclipse GST

    Drag Race Build

    GT42   manual
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    90EclipsePos likes this.
  22. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado

    Is this correct? Everything I've read says -20 percent because the 2g MAF flows 20 percent more air not less right? That's why larger injectors balance it out. I could be miss understanding it and if I am someone let me know.

    All I have accomplished so far is getting valve cover off and comparing cams. They checked out fine.I'll try to get the rest done here soon. Is there any other simpler things I could be missing?
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  23. lasershark

    lasershark Proven Member

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    Joined May 17, 2013
    over yander, Idaho
    Let me break it down for you...
    The safc works by "tricking" airflow readings, this we all get.

    The ecu is running 450cc injectors so it opens them and closes them based on the calculated airflow and blah blah blah...

    On a stock ecu and maf, if you just threw in the larger injectors (560's for example) the ecu would open and close them the same as it would for the 450's based on the same airflow.

    The way to get to ecu to open and shut the injectors less (spray less fuel) is to trick the airflow and make the ecu think the engine is getting less air. The ecu will "see" less air and therefore shorten the injector pulses to inject less fuel.

    The 2g maf in a 1g tricks the ecu into thinking it is getting 20-25% (or whatever) less air, therefore balancing out the (560's) which are 25ish% larger. (less air metered=less fuel injected)

    Now, since you are running stock injectors you need to balance out the airflow meter imbalance, so the computer "sees" the correct amount of air, so it will open and shut the injectors properly.

    Was only trying to help. ;)
     
    My DSM:
    1992 Eagle Talon TSi AWD (sold)

    16g   manual
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  24. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    Lasershark sorry if it came off like I didn't believe you just trying to understand. I swear everything I read says negative and that's what is confusing me. You response makes a lot of sense and I'm going to try your suggestion as soon as I get a chance. Thanks for the help.
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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  25. 90EclipsePos

    90EclipsePos Proven Member

    65
    1
    Joined Jun 22, 2014
    Grand Junction, Colorado
    So after taking your advice I adjusted SAFC2 to +20 and ran a lot better. Playing with fuel trims now to get it adjusted correct. Currently FTRL is around 125% so I'm I understanding this right I should go to maybe +30 or is that the wrong direction?
     
    My DSM:
    1991 Mitsubishi Eclipse GSX

    Street Build

    50trim   manual
    1990 Mitsubishi Eclipse GST

    Street Build

    50trim   manual
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