Check Engine light comes on on hard accelleration

[maillemaker]

Hi all, My Mustang is a 1995 GT with automatic transmission.

When I accelerate hard, my check engine light comes on. After I resume normal driving, it goes off.

Key On Engine Off code is: 111 (no faults)

Continuous Memory codes are: 181, 334

181: Fuel control system, bank 1 -rich adaption limit reached at part throttle, mixture lean
334: Exhaust gas recirculation (EGR) valve position sensor, closed position -voltage high

Key On Engine Running coes are: 311, 314, 334
311: Secondary air injection (AIR) system, bank 1inoperative during KOER test
314: Secondary air injection (AIR) system, bank 2 inoperative during KOER test
334: Exhaust gas recirculation (EGR) valve positionsensor, closed position -voltage high

I also notice that sometimes when I get in the car and turn it on, the air conditioning is initially blowing out of the defrost vents. After a few minutes, it will switch over to the front vents it was set on to start with.

I also notice that sometimes my cruise control does not work when I press the SET button.

I know all of these things abvoe, including the codes thrown for the thermactor and egr, are vacuum driven. I don't know about the 181 code though.

Car seems to drive fine.

What do you all think?

Is there a way to test vaccum at the components? I can see the plug-in for the vacuum lines for the EGR and thermactor motors - what kind of vacuum should I be getting there and when?

 

[07GtS197]

It sounds like you have a vacuum leak, possibly in the thermactor vacuum circuit. Check all your vacuum lines to make sure none are broken or disconnected.

 

[RAU03MACH]

sounds like more than 1

 

[ttocs]

I would start with a smoke check for vac leaks.

 

[maillemaker]

All right I'm going to break out my smoke can this weekend and smoke 'er out.

 

[96blak54]

"smoke can"...(AKA)...phat Cohiba?

 

[maillemaker]

No, I made an actual smoke can.

Found a video on YouTube how to do it. Some nichrome wire, wicking, and baby oil.

 

[joemomma]

Yep. BREW2L has a good video on it.

 

[maillemaker]

Got the smoke can going today.

Looks like smoke is coming from the EGR sensor/diaphram. But also some smoke is coming from some device on the throttle body. I believe it is the throttle position sensor.

 

[ttocs]

looks like the throttle position sensor. We had another one leaking there recently as well.

 

[maillemaker]

looks like the throttle position sensor. We had another one leaking there recently as well.

What is the fix? I don't see any gasket for it.

 

[ttocs]

I thought someone said something about an oring that is supposed to be on it but otherwise try removing it and then see if you can push the end in and see if it helps it to seal.

 

[GTamas]

looks like the throttle position sensor. We had another one leaking there recently as well.

Yes, it was me. I had exact same two locations, but I had no Check Engine Light and no error codes.

I replaced the EGR and sealed the TPS. The TPS had no O-ring or gasket, it was simply bolted to the intake. I added a small amount of rtv (oxygen sensor safe!) to the TPS. To get to the TPS, you have to remove the IAC-valve, so I replaced that gasket, too.

 

[GTamas]

311: Secondary air injection (AIR) system, bank 1inoperative during KOER test
314: Secondary air injection (AIR) system, bank 2 inoperative during KOER test

Probably not related to the CEL during hard acceleration, but you could check the AIR system.

181: Fuel control system, bank 1 -rich adaption limit reached at part throttle, mixture lean

Bank 1 is passenger side I think. Maybe a leak on that side in the exhaust, before the O2 sensor? Or an injector on that side dirty?

 

[maillemaker]

Probably not related to the CEL during hard acceleration, but you could check the AIR system.
View attachment 36422


Bank 1 is passenger side I think. Maybe a leak on that side in the exhaust, before the O2 sensor? Or an injector on that side dirty?

I have the previous owner's repair records and 3 injectors were replaced a year or so ago. Don't know why they didn't just replace them all.

 

[maillemaker]

Yes, it was me. I had exact same two locations, but I had no Check Engine Light and no error codes.

I replaced the EGR and sealed the TPS. The TPS had no O-ring or gasket, it was simply bolted to the intake. I added a small amount of rtv (oxygen sensor safe!) to the TPS. To get to the TPS, you have to remove the IAC-valve, so I replaced that gasket, too.

This looks exactly like mine. I thought about doing some RTV on the TPS also.

I've ordered a new EGR valve and will do the work here when it comes in.

 

[Musturd]

"smoke can"...(AKA)...phat Cohiba?

Phat joint

 

[maillemaker]

Got around today to replacing the EGR valve. We'll see if that clears a code.

 

[maillemaker]

It did not clear the code.

I've had problems with vacuum leaks in the past, so I figured maybe I had a leak at the solenoid gang under the passenger hood. This is where a vacuum reservoir and the solenoids for the EGR and AIR items are.

So, I pulled the wheel and the wheel well liner and looked, and all looked fine. I decided to do a serious trace of the whole vacuum system, and discovered that the VAC MAN and EGR lines were reversed back by the EGR valve. Someone had evidently disconnected them at one time and put them back on backwards.

This explains why I was getting codes for EGR and AIR systems (AIR does not throw the check engine light though).

After correcting the vacuum lines, I was able to run KOEO and KOER diagnostics and got a clean 111 bill of health!

Now to get it buttoned back up and test drive!