Engine 1990 5.0 bogs and pops over half throttle

[Sander]

Hi, I have a 67 Mustang with a 5.0 HO 90 engine and T5 trans.

It have been down on power fore a while but ran smoode still.

Recently it started to bog and pop from the exhaust over half throttle.

I have checked a bunch of things and replaced parts with some extras I had laying around.

TPS is fine.
MAF is fine.
O2’s are fine.
Fuses are fine.
Timing is fine.
Fuel pressure is fine.
No vacuum leaks.
Replaced fuel pump.
Replaced fuel regulator.
Replaced plugs, rotor and cap 1/2 a year ago.
Replaced fuel filter 1 year ago.
Replaced tank 3 years ago.

After trying and fault finding a bunch of things I replaced the ECU with one I hade laying around, but that’s from a 88 crown vic.

It ran great and was strong for about 15min than it started to bog and pop in the exhaust and was down on power.

Checked the connections and ground to the ECU and cleaned them up but no luck.

Swaped the correct ECU backs in and still the same problems.

Have anyone else had similar problems?
All tips would be appreciated.

-Sander

 

[Noobz347]

KOEO KOER codes?

Is this a recent build or did the parts cannon come out for this issue specifically?


Note: I would be mindful of swapping in random ECUs unless you have 1000% ensured that they are pinned the same!

 

[AeroCoupe]

Crown Vic ECU will not work so quit that.

You need to check for codes. My guess is you do not have a check engine light (CEL) with this being a swap. Even if you do they will only illuminate if you have emissions related codes so you could have codes and the CEL would not come on. Go here to learn how to pull 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...

• jrichker
• Replies: 10
• Forum: Fox 5.0 Mustang Tech

• 

If you do this procedure and you cannot get it to dump any codes the it’s most likely the ECU needs to be sent off for repair. At a minimum you should get a Code 11 when doing the KOEO dump and if you do then at a minimum you should get a Code 11 for the KOER dump. Failure to get that typically means the ECU needs repair.

 

[Sander]

Thanks for the tips. Got it running good again. Signal from the MAF was jumpy while idel and stayed the same way when rev’ing it up. Replaced with spare MAF and car ran fine again.

 

[AeroCoupe]

Man that is awesome! Glad you got it figured out as that crap is super frustrating. Just curious but were you able to pull codes?