I have a 1986 mustang I recently built a motor for. I pulled a 5.0 out of a 1997 explorer and used the block. I left the bottom end stock just put main and rod bearings. I had a set of svo aluminum heads I think there x302. E303 cam brand new. New timing chain. I used factory rocker arms and lifters and pushrods. Holley SysteMAX intake and spacer. Motor craft distributor and ford racing plug wires. Got evrything put together and got it in the car I maf swapped the car from speed density and got it running, it ran very rough I timed it and it ran just a little bit better. When it gets up to temp it will backfire through the exhaust at idle and steady constant throttle and acts like it has a miss but shouldn’t be any reason it I’ve checked everything and I’m lost. I retimed it any help would be awsome. Thanks!
MEED HELP!! 86 mustang
- Thread starter Jacob0121
- Start date
It sounds like you need a tune.
Have you pulled codes?
What EEC are you using?
What injectors are you using?
What MAF are you using?
Have you pulled codes?
What EEC are you using?
What injectors are you using?
What MAF are you using?
No I don’t have a way to pull codes where it’s obd1, im using the a3m computer, the injectors are 24lb in pretty sure they’re ford injectors and im running the pro m 24lb
If this is accurate then I would say that it is also your issue.
The A3M is the Auto version of the Cobra ECU. The ECU itself is what compensates for the size of the injector. It appears you have also installed a MAF "calibrated for 24 lb injectors" but for what ECU? A standard Mustang GT ECU or an A3M/X3Z specifically?
Also: You need to pull codes either my code reader or by paperclip and volt meter/counting flashes.
If the connector exists, you can use one of these:
If not, you're going to need to trace those wires back to the ECU so you have access to them.
Refer to this thread to see what it is I'm talking about:
I’ve seen that the a3m is a manual ecu. And I’ll try that also I have a maf for a stock gt with 19 lb injectors could I try swapping it over to that to see if that’ll work? Or help anything?If this is accurate then I would say that it is also your issue.
The A3M is the Auto version of the Cobra ECU. The ECU itself is what compensates for the size of the injector. It appears you have also installed a MAF "calibrated for 24 lb injectors" but for what ECU? A standard Mustang GT ECU or an A3M/X3Z specifically?
Also: You need to pull codes either my code reader or by paperclip and volt meter/counting flashes.
If the connector exists, you can use one of these:
If not, you're going to need to trace those wires back to the ECU so you have access to them.
Refer to this thread to see what it is I'm talking about:
CAMTWO1070
Active Member
Pull up the camshaft specs for both engines [specs posted below] and compare them and youll find that the Explorer camshaft will need to start spraying fuel atleast 16 crank degrees later than the Mustang Camshaft and also has alot less overlap than the Mustang Camshaft ,,,those are a first.
Second is your spark delivery.. The BASE Spark, Altitude Spark and the Sealevel Spark timing table for the Mustang is way too aggressive. to run on the Explorer and the Explorer camshaft doesnt rev as high as the Mustang GT profile and the intake valve opens later too//..
Best thing to do is get a chip like a Quarterhorse so you can make it all jive..You'll also need a wideband controller tapped into pin #27 too..I have an AEM 30-0310..
Im running a 351w with an Explorer camshaft in it stock on an A9L...Im using a Moates Quarterhorse chip to make the changes to make it jive alot better..
Im also running a 90mm Lightning MAF ,BBK twin 61mm TB, 36lb injectors, adjustable fuel regulator,ME WAGNER adjustable PCV valve,,AEM Wdeband, shorty headders and DIY TFI module relocation kit that eliminates the ground loop Ford put in haphazardly into the system plus have all relays and solenoids protected with Shottky diodes to stave off Flyback.
Another thing to note is the wiring differences between the two harnesses...The A9L harness sends pin #30 through the clutch switch to pin #46...On the 87 harness the clutch switch runs from pin 30 to direct ground...These are very noteable differences as you can do damage to the ECU running the stock config with an A9L..
The fastest way to hook up pin #46 is through the Self Test plug and the easiest way to tap pin #27 for the wideband is through the EGR plug..
The other thing is te VSS wires...For te A9L youll need the VSS hooked up too..
On the screenshots of the spark/fuel injection tables the top are the values im using and on the bottom are the stock A9L values for comparison..
Theres lots of other values too and if you do get a Moates chip with a license I will help you out with a tune that will work no problem and it wont cost ya a dime either as I dont use my knowledge to poach pigeons..
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