Engine Tuning...?

justadude07 · May 30, 2026

So I have an 86 GT 5.0 5 speed fuel injected yadayada. Anyways it has a full trick flow intake a cam headers and different injectors then stock. It also has a MSD distributor. I believe the stock ecu has failed because the car no longer runs. I have no spark replaced the TFI and coil but still have nothing. When it did run it ran ridiculously rich. My question is if I swap a stock ecu is it even gonna be able to adjust? Or would I have to go with something like a Holley terminator x?

AeroCoupe · May 31, 2026

ECU is expecting 19 lb/hr injectors so if they are not 19’s that’s your first issue. I seriously doubt a speed density car can compensate for much of a cam change either so you are throwing more at it than it can compensate for. Even the MAF cars have their limit.

Really need to know everything that has been done in detail and if you do not know what rate the injectors are take a picture of the top of one of them and post it.

You also need to check for codes.

Electrical Thread 'How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs'

Jan 27, 2016

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it...

Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for...

Noobz347 · May 31, 2026

justadude07 said:
Anyways it has a full trick flow intake a cam headers and different injectors then stock.

I will reiterate what AeroCoupe just said. None of this is compatible with an SD computer without a chip tune.

86HO5.0 · Jun 1, 2026

SD will not like a cam and will run pig rich at an idle. Part throttle performance will also suffer greatly as the car will run incredibly lean (17+AFR).

There are a couple options for PNP Ecu's. Stinger-performance PimpXS (MS3) is a nice product, very reliable and great support on their forums for customers only. DIYAutotune also offers a PNP Ecu.

Regardless of what route you go, upgrade injectors and fuel pump if you're still running the stock pieces. Buy a wideband.

General karthief · Jun 1, 2026

Did you swap the h/c/i/d or buy it that way?

justadude07 · Jun 2, 2026

General karthief said:
Did you swap the h/c/i/d or buy it that way?

Everything done to the car was done by someone else. I got the car for free but im paying for it in headaches lol. I believe its running 30lb/hr injectors on a stock pump.

Noobz347 · Jun 2, 2026

Take pics of the EEC, inlucing any numbers on the EEC. Take a pic of the chip-port on the opposite end of the EEC from the connector.

Take an image of the tops of the fuel injectors and an overall engine bay pic.

Post those here.

There's a chance you're not getting spark [because] of the MSD.

Blown88GT · Saturday at 10:12 AM

justadude07 said:
So I have an 86 GT 5.0 5 speed fuel injected yadayada. Anyways it has a full trick flow intake a cam headers and different injectors then stock. It also has a MSD distributor. I believe the stock ecu has failed because the car no longer runs. I have no spark replaced the TFI and coil but still have nothing. When it did run it ran ridiculously rich. My question is if I swap a stock ecu is it even gonna be able to adjust? Or would I have to go with something like a Holley terminator x?

You can't go wrong with the Holley but you will have to know what injectors are in there now. Same for any other after market ECU.

Engine Tuning...?

justadude07

New Member

AeroCoupe

lube between the nut and the face. I know my lubes

Electrical Thread 'How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs'

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

86HO5.0

Active Member

General karthief

wonder how much it would cost to ship you a pair

justadude07

New Member

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Blown88GT

Similar threads

Engine Tuning...?

New Member

lube between the nut and the face. I know my lubes

Electrical Thread 'How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs'

Stangnet Facilities Maint Tech... Er... Janitor

Active Member

wonder how much it would cost to ship you a pair

New Member

Stangnet Facilities Maint Tech... Er... Janitor

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