ECM 41 and 91 again

shotsy242 · Dec 29, 2010

Hey Guys,

I've got the dreaded ecm 41 and 91 codes on my 92 Fox with KOER and i've thrown the book at it.

Fuel pressure is 39/40 with the vacuum disconnected from the regulator.

--Changed the regulator and fuel pump anyway

--New Ignition/complete tuneup, plugs, wires, cap, rotor, coil etc.

-- New 02 sensors on both sides

-- Egr Delete with the resistor triangle installed

-- smog pump delete (Thermactor tube just bent over)

-- All vacuum lines capped off except for brake booster and fuel pressure regulator

The only thing I can think is that I'm sucking air through the thermactor tube thats bent in half on the passenger side, I've got the plugs to go into the heads but it's going to be a PITA getting them in back there.

Anyone have any other ideas, tips or advice?

Mod's I meant to post this to Fox 5.0 Tech can you move it?

alleymad95GT · Dec 30, 2010

I think it is the result of you tricking the computer by installing the resistor...

Normally, if the EGR is not present, you get the CEL and the computer disables the EGR function...

But, when you put the resistors in there, the computer doesn't think anything is wrong, so it acts exactly as it would if the EGR was there...

And what it does when the EGR is functioning is pull fuel under light load...so, your computer is pulling fuel to compensate for what it thinks is a properly working EGR, when in fact there is no reason for it to pull fuel...so you are lean at part throttle...

My two cents...

BIGDATOWN · Dec 30, 2010

I'm having the same problem you are. Are you noticing your gas mileage getting very poor and a higher idle at most times?

shotsy242 · Dec 30, 2010

If I remove the resistor triangle will the CEL light stay on?

Also yeah I'm getting horrible mileage as the computer is dumping loads of fuel because it thinks it's lean.

BIGDATOWN · Dec 30, 2010

Please post in here if you do get it figured out because I am at a loss on my car also. But I did see another thread about the salt and pepper connectors causing a similar issue also, mainly a high idle and a ghost cel.

Zero_chance · Jan 2, 2011

I would eliminate all possibilities of vacuum leaks before I went too crazy on other things. Try spraying brake clean around all vac hoses and suspect connections to see if the idle raises.

Mustang5L5 · Jan 4, 2011

shotsy242 said:
If I remove the resistor triangle will the CEL light stay on?

Also yeah I'm getting horrible mileage as the computer is dumping loads of fuel because it thinks it's lean.

The egr plays a role in fuel economy as well.

Remove the resistors and let the computer see the egr is failed and eliminate that function. Reset all the codes, drive and see if you get the 41/91 again.

If possibly, restore the egr to working condition. There is 0hp to gain by deleting it, and having it working actually improves fuel economy. It's not bad to have.

Also, if your thermactor tube is open to atmosphere...well thats not good either. It needs to be blocked off.

liljoe07 · Jan 8, 2011

EGR resistor is not causing the lean codes.

BIGDATOWN · Jan 12, 2011

Any updates?

shotsy242 · Jan 13, 2011

I did the TRANSGO AOD-HP reprogamiing kit this past weekend ahd had to remove the O2 sensors to do it because with the LT headers theyr'e blocking the trans pan from comming down.

Anyways while I had them out I cleaned op the connectors really well and tightened the female connectors on the O2 harnes with a scribe.

After my check ride for the shift kit, I pulled the codes and the 91 is gone but the 41 still persists. I had to extend the 02 sensor leads because of the headers, so I guess now I'm going to pull the passenger o2 out again and see if I can tweak the connectors a bit more. It's been so dang cold here that I'ts hard to get out and roll around under the car.

I've also been reading the internets and it seems that long tubes can cause probs sometimes because the exhaust cools down too much (perhaps BS)

HISSIN50 · Jan 13, 2011

As you read, the LT's can allow the O2's to cool down at idle. Forcing an OL idle via a tune is one solution.

Haus · Jan 13, 2011

HISSIN50 said:
As you read, the LT's can allow the O2's to cool down at idle. Forcing an OL idle via a tune is one solution.

Whats an Open Loop Idle??

HISSIN50 · Jan 13, 2011

Haus said:
Whats an Open Loop Idle??

Since the O2's cool down at idle and affect the idle quality, the car is tuned to ignore the O2's at idle.

shotsy242 · Jan 14, 2011

I got it fixed!!!! Re tweaking the O2 harness connectors did it. Thanks for everyones help.

BIGDATOWN · Jan 14, 2011

I guess that needs to be my next step then !!

BIGDATOWN · Jan 14, 2011

Was you having a higher than normal idle also?

ECM 41 and 91 again

shotsy242

New Member

alleymad95GT

Member

BIGDATOWN

Member

shotsy242

New Member

BIGDATOWN

Member

Zero_chance

Mustang5L5

That is…until I whipped out my Bissell

liljoe07

BIGDATOWN

Member

shotsy242

New Member

HISSIN50

"How long does it take to get help in here?

Haus

Member

HISSIN50

"How long does it take to get help in here?

shotsy242

New Member

BIGDATOWN

Member

BIGDATOWN

Member

Similar threads

ECM 41 and 91 again

New Member

Member

Member

New Member

Member

That is…until I whipped out my Bissell

Member

New Member

"How long does it take to get help in here?

Member

"How long does it take to get help in here?

New Member

Member

Member

Similar threads

Privacy & Transparency

Privacy & Transparency