Fox Issues

#21
I had just figured it was a short somewhere, due to ecu caps being bad (leg melted off and leaking) I know caps going bad can be normal. But the melted leg worried me.

I tried another ecu and had the same issue, bad cap. But it may have been bad already. Ecu sat in a box as a spare for years. No idea what it's condition was before hand.

I'm just not the kinda person to dump money into the Unknown without thorough inspection, exp on a 29yo car
 
#22
I had just figured it was a short somewhere, due to ecu caps being bad (leg melted off and leaking) I know caps going bad can be normal. But the melted leg worried me.

I tried another ecu and had the same issue, bad cap. But it may have been bad already. Ecu sat in a box as a spare for years. No idea what it's condition was before hand.

I'm just not the kinda person to dump money into the Unknown without thorough inspection, exp on a 29yo car
 
#23
What year car?
Mass Air or Speed density?

As mentioned, please post the numeric codes.
I have 5.0 Fox Mustang specific code definitions and fixes.
 
#24
It has been a bit , code 41 and another 02 code. Don't remember the other code honestly. It was an 02 code. IF I remember correctly both were Rh o2 codes

Could be just a bad o2, But honestly got worried once I noticed I had bad ecu caps. I know leaking is normal, but the leg to one was gone, which lead me to believe I had a wiring issue.
 
#25
I originally bought the car as someone's failed 302 swap, had an SD harness all hacked up with frayed and melted wires.

Car is an 87 factory 2.3. now is a v8 maf car

So I scraped it all. Got the correct Maf harness that plugs into my dash harness. Etc. Car ran great for awhile until recently
 
#26
A9L computer. What O2 sensor harness are you running? Where is the jumper on the O2 side pinned to?

If this jumper is incorrect, it tends to cause computer issues such as voltage on the SIGRTN trace (Pin 46) causing similar issues to what you describe. Best way to check is to pull the EEC out, put a DMM on pin 46 and crank the engine. If you have voltage here, you need to move the jumper on the O2 harness.

This particular aspect is critical on 2.3L conversions. The O2 harness needs to come from a specific year range, and match the transmission (Computer type)
 
#29
MYTURBO said:
It runs rich for sure. Raw fuel.
Click to expand...
Is it raw fuel though, or just a really stinking exhaust smell. Contrary to popular belief, a car that runs excessively lean actually give off a stronger exhaust sent and higher emmisions than one that's running rich. And your O2's and surging running condition are backing that theory. Let me guess....it bucks at lower RPM and randomly backfires through the intake too?

I chased my tail for the longest time with the same issue, believing the same as you. Turned out I was way off. Idle A/F was almost 20:1. I'm surprised it even ran.

If I were you, I'd invest in a decent wide band sensor before putting all your resources into leaning the car out. You can pick up a nice sensor gauge combo for under $200.

I'm running this one on my car and it works flawlessly.

http://www.plxdevices.com/Wideband-O2-Touch-Screen-Multi-Guage-p/897346002719.htm
 
#32
Not to be a broken record, but could you please erase all current codes, and then rerun and post actual numbers?

You mentioned both codes pointed to RH o2 sensor, but are you sure? If the codes point to both sensors, my recommendation would be slightly different than if it pointed to the sensor on one side.

For instance, if you got lean codes on only one side, I'd suggest swapping the o2 sensors and seeing of the code numbers change to follow the sensor. However, if both sides read lean, that won't work for obvious reasons.

Nobody likes throwing wasted money at a problem, but it's important to get a clear picture of what the problem is when trying to diagnose over the net. We can't see what the car is doing


Sent from my big ass iPhone 6 using Tapatalk
 
#33
Yes I am positive it is the Rh only, I have cleared codes many times, swapped injectors etc. It is in fact rich. But reading lean. I replaced the lh o2 awhile back due to wires being frayed. No idea how old the Rh is.

I have an o2 I will hopefully get on the car today, but I still have to install the harnesses, and a few other things.

Is the burn capacitor leg just a coincidence everyone think ? All harnesses have checked out.
 
#36
MYTURBO said:
Ecu is good, no bad caps or burnt circuits.

I don't even know
Click to expand...
You need the all wise @jrichker @Mustang5L5 or one of the many smart guys on here.

At least you're making some kind of head way....the computer is still good.

Running rich can sometimes trigger a lean code from the unburnt oxygen in the fuel.

I hope you get this figured out.
 
#38
MYTURBO said:
Now that it's all back together, their is a mess of codes!

Koer: 41,4,66,42,14,65,32,3
Koeo: 85,95
balance test: 90 (pass)

Pulling ecu to check it out again now...
Click to expand...

Fox Mustang engine codes are all 2 digit.

Can you redo the KOER codes as 2 digit codes? I can take a guess, but if you can redo them it would help.

I would guess 41, 46, 64, 21, 46, 53, 23.

If correct, it tells us your IAT, ECT are not reading correctly, and the TPS sensor voltage is set way too high at idle.

Code 41 is system Lean RH

Code 46 is air injection (smog pump) not working

Code 64 is Intake Air Temp sensor signal low

Code 21 is Engine Coolant Temp sensor out of range (if you run the codes with cold engine, you get this)

Code 53 is TPS voltage too high

Code 23 I TPS voltage too high.


Check to see that your TPS voltage is set to 0.6 - 1.1 volts at idle. You don't need to chase a 0.99999v number. It just needs to be within that 0.6-1.1 range.
 
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