Engine New electrical issues

Canadianfox · Aug 16, 2020

So I fixed 98% of my issues with a used ford MAF sensor .All my idle issues and intake knocking are gone as well as stinky exhaust .The only thing now I have is I can’t pull codes ,paper clip or OBD1 scanner .I followed the directions on here to a tee and nothing .So my main question now is ,is there a place in the harness where wiring rubs or is defective that causes this ? The écu has been swapped so it isn’t a cpu problem the original one is back in and all issues are gone .I did get a chk engine light with the old ford MAF but the car ran mint (never ran this good ever ).Id like to fix the chk engine and have finally a running fix body with no issues .

I would pull the ecm and check it for burnt traces and/or bloated/corroded diodes.
All computer grounds good?

Even the écu thats good I swapped same issues ,seems like a harness issue

General karthief said:
I would pull the ecm and check it for burnt traces and/or bloated/corroded diodes.
All computer grounds good?

So I could t run the codes the paper clip way but I did manager thanks to a post on here try another way and it worked .I grounded the Sti wire to the battery and dumped the codes that way .Got 11,33,41 .With that said is there an issue with the wire that comes from the cpu you think? Other than that with my new ford MAF sensor car runs great

I have a 1993 foxbody that keeps dumping codes 41/91 and runs in open loop fuel dumping in excess about 15min after starting her cold .This is everything I’ve done to her and honestly I’d pay good money to anyone who can fix her :

Idle control new
Injectors new
Fuel pump and filter new
Fuel regulator new
Plug wires ,dist new
TPS new
MAF and filter new
Pcv new
Upper intake gasket new
Ignition module new(the one glued behind dis)
Exhaust leaks checked exhaust new
O2 sensors and harness new
Wires to o2 good
Egr and smog pump delete head holes blocked off
Coolant sensor new
MAF swapped for OEM cleaned
Three vacuum leak tests done no visable leaks
Cats new

I’m lost and tired now cars mint but for the love of god she won’t run proper

Pulled codes?
93 has a check engine light but the computer may have issues that don't trip the light.

General karthief said:
Pulled codes?
93 has a check engine light but the computer may have issues that don't trip the light.

Light comes in , codes are 33 but I deleted egr , 41/91

How did you do the vacuum leak test? Is the FPR like a stock replacement or adjustable one?

Smoke test and the FPR is an adjustable one vs stock

Are the injectors, TB, MAF, cam, intake - stock units or aftermarket. If aftermarket which ones?

If you have not already go to Post #4 in this thread:

L

Thread 'KOER Code = 41?'

Aug 19, 2005

Can anyone tell me what a KOER Code of 41 means?
I've got some kind of engine problem and ran the KOEO and KOER codes and one of the codes I got on the KOER (running) test is a 41.
The code tables on fordfuelinjection.com show a KOEO and CM code of 41 related to the right O2 sensor but don't show anything for a 41 on the KOER.

I'm a little confused on the code sequences.
I thought the codes you got with the key on but engine not running were the KOEO codes followed by the CM (continuous) codes. I got a KOEO of 67 (because I don't have the transmission harness) and a CM of 11 which...

KRUISR said:
Are the injectors, TB, MAF, cam, intake - stock units or aftermarket. If aftermarket which ones?

All stock even the MAF had to buy one on eBay to replace the CAI BBK one that was on the car when I bought it .all other parts are 100% stock . Only think I did remove off the car was the smog /pump and EGR with the appropriate block off plate and head plugs off LMR

I have a dumb question but those thermactor plugs do they have to be flush to the head ? They don’t leak but does the depth on the inside have anything to do with it ?

I do not believe so. As long as they don’t leak you are good to go. I will say that the few sets I have installed (long ago) did go flush.

Thread 'Help me create the "Surging Idle Checklist"'

Apr 10, 2005

Updated 05 July 2022 to add rough idle when cold and smooth idle when up to normal operating temperature. See the EGR tech information, section #15 for more help.

Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of a systematic process that checks and eliminates possible causes. This idle problem checklist will use the same troubleshooting strategy and methodology.

By the term surging idle, I mean an idle that...

Canadianfox · Jul 5, 2025

So as I’ve posted a few times I’ve been fighting a 41/91 code / chk engine , and when it happened she falls into open loop and the runs fuel rich enough the cars smell of rotten eggs .

With that said I’ve weeded out per the instructions of many members the following:

All ÉCU pins for o2’s good to go

Fuel system pressure is now perfect literally perfect

Zero vacuum leaks at all full perfect vacuum

The car only does this when it gets hot like a switch .Drives perfect , then once it seems to hit 180c like a switch chk engine and popping in intake then maybe 2/3 min later she falls into open loop and runs fine except the excesssive fuel

With that said I have two questions :

1: is there wiring to check and how for the ACT?

2: will an ACT relocation near the cold air intake fix this ?

Canadianfox · Jul 5, 2025

Canadianfox said:
So as I’ve posted a few times I’ve been fighting a 41/91 code / chk engine , and when it happened she falls into open loop and the runs fuel rich enough the cars smell of rotten eggs .

With that said I’ve weeded out per the instructions of many members the following:

All ÉCU pins for o2’s good to go

Fuel system pressure is now perfect literally perfect

Zero vacuum leaks at all full perfect vacuum

The car only does this when it gets hot like a switch .Drives perfect , then once it seems to hit 180c like a switch chk engine and popping in intake then maybe 2/3 min later she falls into open loop and runs fine except the excesssive fuel

With that said I have two questions :

1: is there wiring to check and how for the ACT?

2: will an ACT relocation near the cold air intake fix this ?

And on a side note would a megsquirt écu fix all this mess for me?

Canadianfox · Jul 5, 2025

Also one last question but can two large electric fans offset the heating /calculations ?

General karthief · Jul 5, 2025

You gotta thread with vehicle issue here somewhere?
I don't wanna ask all the important questions that have been asked already.

AeroCoupe · Jul 5, 2025

Literally this is the fourth thread. Can one of the mods push them all together as this is confusing.

General karthief · Jul 6, 2025

I jam'd a couple threads together that had some info on the car and what's been done but honestly don't know what to do, too many posts with symptoms and repairs that are all over the place, sick to one thread for your issue(s) and maybe we can help you.

Mustang5L5 · Jul 7, 2025

Canadianfox said:
1: is there wiring to check and how for the ACT?

The ECT and ACT work off resistance and the values are the same between the two

You can verify resistance at temp to see if the sensor is giving the proper reading. No reason to relocate the sensor. It works fine where it is located.

170-180 is where the can transitions from open to closed loop and depends on sensor input.

I'd focus on the code 41/91. Those are lean codes. Given that you replaced both O2's, have you looked for vac leaks? smoke test? Is the orange O2 sensor ground in the injector harness securely connected to ground?

It also wouldn't hurt to check the pin 46 trace on the ECU. Using a digital multimeter set to continitty. Test between pin 46 and pin 40 and pin 60. SHould ring out in all conditions. If it doesn't, pin 46 is burned. When that happens, the car runs like junk and can pig rich and such. It's sensor ground.

Noobz347 · Jul 11, 2025

Closing this thread.

If you are still having this issue, include that information to the thread that you created here:

C

Electrical Thread 'New fox body owner little worried'

Aug 19, 2019

I hate being a first time poster with a tech issue but I’ve totally run out of ideas and need some help.Ive done a ton of reading and mechanical work based off the forums on this site trying to solve my issues .

I own a 1993 lx 5.0 convertible and am having idling issues ( sounds like its camed but isn’t) and predetonation ,and à first this last weekend the power lose in 5th,4th where my car just lost speed when I was floored on the highway and all I can watch was my speedo drop .No backfiring ,stalling just power loss until I got to a certain rpm .

Here is what I’ve done based off many...

Engine New electrical issues

Canadianfox

Member

Thread 'KOER Code = 41?'

Thread 'Help me create the "Surging Idle Checklist"'

Canadianfox

Member

Canadianfox

Member

Canadianfox

Member

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

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

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

Noobz347

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

Electrical Thread 'New fox body owner little worried'

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Engine New electrical issues

Member

Member

Member

Member

wonder how much it would cost to ship you a pair

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

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

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

Electrical Thread 'New fox body owner little worried'

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