SEFI conversion to MAS March 14, 2017, 11:42:36 PM I am looking for information on this conversion -- i have a 1987 cougar orignal 5.0 fuel injected , installed new "HO" (roller cam with bbk intake ,GT40 alum heads , 24lbs injectors 70mm throttle body 70 mm bbk air meter) with a9l procesor - i have some driveability issues that may or may not be related to the conversion , but i have been told that the injector harness MUST be changed by some car guys , others say that it wont matter -the ecu fires them the same as fireing order of ho cam ? any ideas on this ---its a T5 car also:burnout: Quote Selected
SEFI conversion to MAS Reply #1 – March 15, 2017, 07:38:55 AM Best to look at the pinout for both ECU's for injectors. If pinout is the same you should be ok since the ECU program takes care of injector fire order.Drivability issues? A9L, 70mm TB, 24lb Injectors , aftermarket MAF and what cam? I hope you are tuning. without a tune it will run ok but will likely have low speed cruise issues like bucking, surging and a high erratic idle.John Quote Selected
SEFI conversion to MAS Reply #2 – March 15, 2017, 08:22:17 AM You DO NOT change the injector harness or the pinout for the firing order. The place where the pinout is different is the Tab/tad sensors (emissions) and the fact that there's no VSS wire (pin 6 I believe) on the stock 87 main harness. There's also no secondary fuel pump wire, however that does not affect driveability. All the info is here. http://www.coolcats.net/modifying/massair.html Quote Selected
SEFI conversion to MAS Reply #3 – March 15, 2017, 08:53:03 AM Used the above link 10 years ago when I converted to MAF (with an A9P). Has always worked great. Quote Selected
SEFI conversion to MAS Reply #4 – March 15, 2017, 11:15:43 AM thanks for the info , the car runs ok , but as mentioned by the first post , i do have some surging at cruse- also very flat (no throttle responce ) cold start after driving 3-5 mins clears after about a min (seems like hours) the reason i ask about the harness is that this has been about a 15 year project -collecting parts from here and there (except for main performance parts --ie new block heads, cam (motorsport e cam) mass air flow ) the harneses throttlebody bbk ssi intake ect "lovingly used(HA HA ) if it were just a mass conversion straight up i dont think i would have the concerns - orignal engine was 5.0 just not HO - also it now has a T5 --i expected some idle issues Quote Selected
SEFI conversion to MAS Reply #5 – March 15, 2017, 11:25:44 AM this is the package i have put together stock HO short block (rebuilt)motorsport X307 gt-40 heads (alum)motorsport M-6250-F303 camBBK SSI upper/ lower intake 24lbs injectors BBK 70 mm mass air 70 mm throttle body (lightning)T5 trans 3:73 gears Quote Selected
SEFI conversion to MAS Reply #6 – March 15, 2017, 12:17:39 PM Pressure test your intake and soap it up. The SSI intake is notorious for leaking. Your setup is mild and should run pretty good. Tuning the injectors would make for stock drivability and fix the open loop cold start overly rich condition. It clears up once you get into closed loop and I imagine you are likely hitting the limits the ECU can correct for. John Quote Selected
SEFI conversion to MAS Reply #7 – March 15, 2017, 02:50:07 PM Is it throwing any codes? Check for those first. It may be a mechanical issue or electrical. Pull the codes first and see what you're dealing with. The parts you have are not that radical. The car should run ok without a tune since you're running a calibrated MAF with the injectors.My Thunderbird (modifications in signature) idling. No tune and driveability is fine. [video=youtube;Z92w1Y0-E_4]https://www.youtube.com/watch?v=Z92w1Y0-E_4[/video] Quote Selected
SEFI conversion to MAS Reply #8 – March 15, 2017, 09:02:47 PM leaking at the base or some other spot ? i use a spray gasket sealer on each side of the gaskets Quote Selected
SEFI conversion to MAS Reply #9 – March 15, 2017, 09:56:50 PM Is the mass air meter calibrated for the 24's?The symptoms you describe sound a lot like an unmatched meter............ Quote Selected
SEFI conversion to MAS Reply #10 – March 16, 2017, 07:31:27 AM Quote from: 20thanvcat;459778leaking at the base or some other spot ? i use a spray gasket sealer on each side of the gasketsUpper to lower manifold. Also look for fuel leaks at the back of the rail.John Quote Selected
SEFI conversion to MAS Reply #11 – March 16, 2017, 10:50:08 AM Quote from: ThunderbirdSport302;459780Is the mass air meter calibrated for the 24's?The symptoms you describe sound a lot like an unmatched meter............Agreed... Quote Selected
SEFI conversion to MAS Reply #12 – March 16, 2017, 01:19:51 PM Do you have a picture of the MAF and what intake setup you're using? Quote Selected
SEFI conversion to MAS Reply #13 – March 16, 2017, 03:33:34 PM Should be easy enough to figure out..... Back probe the signal and return on the MAF at idle. A stock 672 RPM should yeild about 0.8 volt if it's a 19# calibration and about 0.6 volt for 24# at same rpm. Its unlikely you can idle that low on a 24# calibrated MAF as it takes you below the programs sweet spot in the Maf transfer so let us know what voltage you see and your idle RPM.John Quote Selected
SEFI conversion to MAS Reply #14 – March 16, 2017, 06:12:12 PM mass is calibrated , not sure of the size of throttle body Quote Selected
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