[Lilliedriveman]

1995 Mustang GT. 215K original mi. I've been searching high and low for a possible vac leak. Ive smoke tested it several times. The intake is tight and doesn't leak smoke anywhere. No leaks around the engine either. I know my rear main seal is totally shot. Is it possible that if the seal is in bad enough shape it could be letting extra air into the crank case and causing symptoms of a vac leak? I ask because the hose that goes from the oil fill neck (crank case vent) to the CAI to allow air flow for the PCV must be metered by the engine somehow. And if there is a huge air leak from the rear main seal, would this disrupt the figures....

 

[07redstang]

No it would not. It would just leak a lot of oil.

 

[Lilliedriveman]

No it would not. It would just leak a lot of oil.

Oh, yeah. it's been leaking oil from there for 20 years.

 

[Cobrajet67]

How exactly do you know that you have a vacuum leak?

 

[Lilliedriveman]

How exactly do you know that you have a vacuum leak?

Sorry for the delayed response. Seems like extra air is getting into the system somehow. Idle is slightly surging infrequently. Mostly when engine fan kicks in and the resulting load on the engine. The idle has a hard time settling down and will bounce around between 750 and 950rpms
Also at cold start up in the morning. The idle with bounce from 1,000-1,100rms before settling down to 800ish. Been driving this car for 20 years and it just started doing this about a year ago. I’ve been throwing parts at it like a mad man.

Could also be running rich. Bad fuel economy. Un-burnt fuel smell at start up in the morning. Not raw gas smell. Just not fully burnt. The exhaust smell is really powerful in the morning at cold start. Pulled codes. Got 212 spout grounded. (Im on my 3rd PIP sensor in about 12 years). Thermactor code. Probably plugged ports in heads or crossover tube. And some code about the engine fan, but I think that’s because I have a circuit breaker that Ford put on because of a recall on those fans for overheating and catching fire.

New:

IAC (Motorcraft)

Throttle position sensor

Engine coolant temp sensor

Air charge temp sensor

Canister purge valve

EGR valve position sensor

Put my original fuel pressure regulator back on.

New EGR valve

Smoke tested. Several times. Intake manifold is tight. No leaks from hoses.

O2 sensors are probably 3-4years old.

Cleaned throttle body

New air filter

PCV rattles and has good suction at idle.

Local exhaust shop checked for exhaust leaks. None found. At heads or manifold.



Vacc leak from brake booster?

Timing off?

PIP sensor bearly functioning?

Electrical issue? Bad ground?

Charcoal canister full?

 

[Cobrajet67]

Sorry for the delayed response. Seems like extra air is getting into the system somehow. Idle is slightly surging infrequently. Mostly when engine fan kicks in and the resulting load on the engine. The idle has a hard time settling down and will bounce around between 750 and 950rpms
Also at cold start up in the morning. The idle with bounce from 1,000-1,100rms before settling down to 800ish. Been driving this car for 20 years and it just started doing this about a year ago. I’ve been throwing parts at it like a mad man.

Could also be running rich. Bad fuel economy. Un-burnt fuel smell at start up in the morning. Not raw gas smell. Just not fully burnt. The exhaust smell is really powerful in the morning at cold start. Pulled codes. Got 212 spout grounded. (Im on my 3rd PIP sensor in about 12 years). Thermactor code. Probably plugged ports in heads or crossover tube. And some code about the engine fan, but I think that’s because I have a circuit breaker that Ford put on because of a recall on those fans for overheating and catching fire.

New:

IAC (Motorcraft)

Throttle position sensor

Engine coolant temp sensor

Air charge temp sensor

Canister purge valve

EGR valve position sensor

Put my original fuel pressure regulator back on.

New EGR valve

Smoke tested. Several times. Intake manifold is tight. No leaks from hoses.

O2 sensors are probably 3-4years old.

Cleaned throttle body

New air filter

PCV rattles and has good suction at idle.

Local exhaust shop checked for exhaust leaks. None found. At heads or manifold.



Vacc leak from brake booster?

Timing off?

PIP sensor bearly functioning?

Electrical issue? Bad ground?

Charcoal canister full?

I don't see anything on the list with the MAF done. A good spraying with CRC brand MAF cleaner might fix the problem if it's dirty. The IAC would have been my first guess but that's new.
You can temporarily plug the port on the intake for the brake booster and see if that makes a difference.
I don't know how to test the PIP. Krem12 is an expert with old 5.0 Fox body stuff. Maybe he'll see this thread and join in.
A bad ground is a possibility.
EVAP system issues can cause problems but your system is probably a little more basic than newer systems. I'm sure there's ways of testing the canister.
The 212 code seems to be a problem with:
-the ICM(ignition control module)
-short to ground possibility in the SPOUT wire(to ECM side and to ICM side)
-IDM(ignition diagnostic monitor) wire from the ICM to ECM(open, short to ground or power)
-ECM/PCM issue(might need to be sent out for repair).
(210) Code 212 (Ignition module circuit failure/SPOUT circuit grounded) problems continue! | Ford Mustang Forum (allfordmustangs.com)

 

[Krem12]

Id throw a timing light on it and see if you're getting advance at all (since there is a code). Unfortunately hard to say whats going and even more so with the 94/95 ecm. Strategy is alot different than the one used on the earlier ECU's

 

[Lilliedriveman]

I don't see anything on the list with the MAF done. A good spraying with CRC brand MAF cleaner might fix the problem if it's dirty. The IAC would have been my first guess but that's new.
You can temporarily plug the port on the intake for the brake booster and see if that makes a difference.
I don't know how to test the PIP. Krem12 is an expert with old 5.0 Fox body stuff. Maybe he'll see this thread and join in.
A bad ground is a possibility.
EVAP system issues can cause problems but your system is probably a little more basic than newer systems. I'm sure there's ways of testing the canister.
The 212 code seems to be a problem with:
-the ICM(ignition control module)
-short to ground possibility in the SPOUT wire(to ECM side and to ICM side)
-IDM(ignition diagnostic monitor) wire from the ICM to ECM(open, short to ground or power)
-ECM/PCM issue(might need to be sent out for repair).
(210) Code 212 (Ignition module circuit failure/SPOUT circuit grounded) problems continue! | Ford Mustang Forum (allfordmustangs.com)

Thanks for the reply. I’ve cleaned the MAF sensor before. I typically spray it down with the CRC once a year.
I also ran smoke through all the evap lines that go to the charcoal canister. I also ran smoke through all the Thermactor vacc lines as well, including the egr vacc line, all the way down to the 3 solenoids.

Id throw a timing light on it and see if you're getting advance at all (since there is a code). Unfortunately hard to say whats going and even more so with the 94/95 ecm. Strategy is alot different than the one used on the earlier ECU's

I’ll find someone that can throw a light on it. Could the VSS be possibly acting up? My Speedo works fine though.

 

[Krem12]

Thanks for the reply. I’ve cleaned the MAF sensor before. I typically spray it down with the CRC once a year.
I also ran smoke through all the evap lines that go to the charcoal canister. I also ran smoke through all the Thermactor vacc lines as well, including the egr vacc line, all the way down to the 3 solenoids.


I’ll find someone that can throw a light on it. Could the VSS be possibly acting up? My Speedo works fine though.

I think the 95 speedo is fully digital off the VSS sensor. I would guess you would see jumps in it if that was the case. Speedo could be electrically dampened enough that you might not see it. If its cheap maybe you could try it. Id hate for you to throw more parts at it.

 

[Lilliedriveman]

1995 Mustang GT. Stock. 215K original mi.
After searching hard for a vacuum leak for months now, I think I’m finally onto something.
I pulled code 311 Thermactor. The smog pump is new, so I eliminated that from the equation. I starting looking into the supply vac line that comes off the intake. It supplies vac to the TAD, TAB and EGR solenoids. Yes, those hard brittle ones. (They have broke in the past and I have repaired them in 2 places.)
I pulled the vac line off the intake and capped the nipple before I headed home from work. Check engine light is now on, but I expected that. It wasn’t before. Car runs much better. Idle is better too. Is it possible I finally found the leak?
Thing is, I ran smoke through all the lines before and they were tight. Smoke would only vent out through the vents ontop of each solenoid when the car was off.
I feel like:
A) one of the lines is leaking
B) one or more of the solenoids is shot.
C) maybe the EGR is getting vacuum when it shouldn’t. Resulting in rough idle.