96 GT Starting/Running issues

[LaserRed01GT]

Back to reevesracing, did you get a chance to check the fuel pressure and look at the fuel system wiring?

Another thing I was thinking about was, sometimes the fuel pump driver module can have a short or open circuit and not throw a code. This can drain the battery and keep the pump from correctly operating. I would start back probing from the pump harness by the tank and go forward. Also check all connectors along the way for a loose connection or moisture in the connector.

The Fuel Pump Monitor (FPM) circuit is spliced into the Fuel Pump Power (FP PWR) circuit and is used by the PCM for diagnostic purposes. The PCM continously draws a low current voltage down the FPM circuit. With the fuel pump off, this voltage is pulled low by the path to ground through the fuel pump. With the fuel pump off and the FPM circuit low, the PCM can verify that the FPM circuit and the FP PWR circuit are complete from the FPM splice through the fuel pump to ground. This also confirms that the FP PWR or FPM circuits are not shorted to power.

 

[Mike97gt]

EWMA is used for far more than just monitoring catalyst efficiency or any monitoring for fast/slow constant filters for that matter. It is used in conjunction with the MAF and IAT to accurately estimate air mass and air density for load and fueling spark calculations. Another example of EWMA implementation, the engine is monitored for excessive torque generation at idle. If excessive torque is being produced at idle, the injectors can be turned off in order to reduce torque. If the frequency of injector cut-off is higher than the EWMA threshold, a P2279 code will be set and the adaptive fuel strategy (AFS) table can also be altered.

The rear O2 sensors are controlled with a MUCH slower switching amplitude and don’t have their output voltages used by the PCM software in a dynamic fashion like the front O2 sensors are. There is no way for the PCM to use the rear O2 sensor data to somehow try to “draw up” a front O2 sensor pattern to be used in case of a failure or hard fault. When you saw the abnormal readings on the scope during your training session, that had nothing to do with the PCM trying to look at the rear O2 sensors to try and re-establish a “normal” front O2 sensor pattern, it was simply the botched multiplexed signal that was returned to the PCM. When you have a total failure of one or both front O2 sensors or a loss of STFT/LTFT control, the PCM will simply resort back to its stored and learned front O2 data within the KAM. When O2 sensor input is perceived to be out-of-limits by the PCM, the memorized data from the KAM will be instantly be initiated. The PCM constantly checks the sensors against records of normal readings during normal operating conditions similar to its current state, specifically during specific speed-load points. Information gathered at different speed-load points are stored in fuel trim cells in the fuel trim tables, which can be used in the actual final fuel calculation. The PCM looks at the previously stored front O2 data to see if the engine is operating within normal “historical” conditions and if it is, the PCM replaces the sensor reading with a “educated guess” from the KAM. Mike I think you are a good and knowledgeable tech, but just keep up with your studies and you will learn more about the PCM as your experience grows, and you understand more about how the PCM works. The PCM operation and theory used to be an industry secret, but it hasn’t been for some time. When I was going through my L1 cert, a few NATEF instructors on the advisory committee recommended a series of books to me that opened the door to PCMs for me. They are even endorsed by NATEF. The author of the books is named Barry Hollembeak. He covers just about everything including even some of the extrapolated algorithms. Some of his books are actually used in classroom instruction. I'd highly recommend them to anyone wanting to get a more in depth understanding of OBD/PCM fundamentals.

Additionally the air mass cells are used for much more than just monitoring or diagnostic tests. Depending on RPM, load, min-bed cat temp, and number of front crosscounts, the PCM makes the determination which air mass cell to use. Depending on which air mass cell the PCM is currently operating in will dictate which algorithms the PCM will use to calculate the fueling/spark strategies.

I never said that all ewma is used for is the catalyst monitor... I just gave a short simple answer so you know that I know what it is.

AND I never said that air mass cells are only used for monitors and diagnostic tests.. Please point out where I said this.. YOU KNOW that is not what I was saying.

Now I see why some people on this site get pissed at you... You are trying to make it look like I don't know what I am talking about by adding in stuff i never said and then "correcting" this stuff I never said, plus you like to take a quote that is written in layman terms and then answer to it in highly technical terms to try and make the other guy look dumb to the average onlooker that is not paying attention

for example here is my quote

You are only looking at how the PCM handles it's OBD-2 monitoring, when your talking about air mass cells you are talking about the parameters that the PCM looks for to run a OBD-2 test such as catalyst efficiency.. Plus the rear 02 readings are used as one of the parameters for type a misfire detection, it's also used by the pcm as a input for inferred catalyst temp

How did you come to the conclusion from that quote that I said that air mass cells are only used for catalyst monitors???

You said in a earlier post that the rear 02's are only used by the PCM in certain air mass cells, and I took that as you saying that the PCM only uses the rear 02 data in the three typical air mass cells used in the catalyst monitor that's why I posted that quote above.. I DID NOT say that those are the only air mass cells that exists or that's the only way air mass cells are used.

I think you are only looking at how the PCM uses data in normal closed loop operation, I am talking about Failure Mode Effects Management and how the pcm uses alternate system strategy.

Now about this demonstration on the crown vic..

No it was not a botched multiplexed signal from the 02 sensors, the ENTIRE point of this demonstration was to show how the pcm has the ability to use other inputs and take a guess to try and reestablish front 02 sensor switching, as we both know if the mixture is is far enough off of stoch then the factory narrow band 02's will be out of range and will not be a accurate input to the pcm.

It is clear to me at this point that this discussion is getting nowhere, but I am going to check out those books as soon as i get a chance I am always looking for new stuff to read on this subject.

now about revees problem, has he checked fuel presure under load when this power loss happens?

 

[Mike97gt]

My passenger side front O2 sensor was bad, and that eliminated the code being thrown.

As for the bogginess and the power drain, I am now on the fuel pump relay and fuel pump as being the issue. Still tracing back.

a couple of quick questions..

1. have you cleared the KAM after your 02 repair, that bad sensor threw you into closed loop fault mode, the top of your readout tells you that.. anytime the fuel trims were thrown way off it's a good idea to clear the KAM and let the PCM relearn it's fuel trims.

2. have you checked the oil, since this car is falling flat on it's face it's possible that the oil could be contaminated with fuel, if there is a large amount of fuel vapors in the oil this can also mess with the pcm's ability to control the fuel mixture it would make it run rich and fall flat on it's face at higher rpm's/load.. misfires or running pig rich can lead to this contamination.

both of these are a long shot but sometimes the simple stuff can bite you in the ass if you don't check..

If those are ok then you need to check fuel presure while this concern is happening to see if you have propper fuel presure at high loads.

 

[LaserRed01GT]

I never said that all ewma is used for is the catalyst monitor... I just gave a short simple answer so you know that I know what it is.

AND I never said that air mass cells are only used for monitors and diagnostic tests.. Please point out where I said this.. YOU KNOW that is not what I was saying.

Now I see why some people on this site get pissed at you... You are trying to make it look like I don't know what I am talking about by adding in stuff i never said and then "correcting" this stuff I never said, plus you like to take a quote that is written in layman terms and then answer to it in highly technical terms to try and make the other guy look dumb to the average onlooker that is not paying attention

for example here is my quote


How did you come to the conclusion from that quote that I said that air mass cells are only used for catalyst monitors???

You said in a earlier post that the rear 02's are only used by the PCM in certain air mass cells, and I took that as you saying that the PCM only uses the rear 02 data in the three typical air mass cells used in the catalyst monitor that's why I posted that quote above.. I DID NOT say that those are the only air mass cells that exists or that's the only way air mass cells are used.

I think you are only looking at how the PCM uses data in normal closed loop operation, I am talking about Failure Mode Effects Management and how the pcm uses alternate system strategy.

Now about this demonstration on the crown vic..

No it was not a botched multiplexed signal from the 02 sensors, the ENTIRE point of this demonstration was to show how the pcm has the ability to use other inputs and take a guess to try and reestablish front 02 sensor switching, as we both know if the mixture is is far enough off of stoch then the factory narrow band 02's will be out of range and will not be a accurate input to the pcm.

It is clear to me at this point that this discussion is getting nowhere, but I am going to check out those books as soon as i get a chance I am always looking for new stuff to read on this subject.

now about revees problem, has he checked fuel presure under load when this power loss happens?

You will enjoy reading those books. I learned a BUNCH from that guy. He or one of his partners (I can't remember which) were directly involved with developing the hardware/software for Ford OBD-1/OBD-II PCM's. He talks a lot about FMEM. Everything I have ever read about FMEM in my Oasis, Ford, Alldata and other service manuals is consistent with what Barry writes. As the describe FMEM, it is described how I described it above about the PCM ignoring the real time input from ALL O2 sensors and making an educated guess. So what about cars that don’t have rear O2’s or have MIL’s or have them programmed out? What you are saying about the PCM trying to use the rear O2’s once FMEM is initiated just goes against everything I was taught getting my L1 and all the manuals and books I have read, and from my own experience. That’s all I’m saying. I’m not sure what they were trying to show you on the Crown Vic, but I have messed around with the O2 sensors before and you can look at all the data within certain tables relative to fueling. Then if you plug in 1 or 2 bad front O2 sensors, you can obviously watch the data in the tables immediately lock, and you can see the PCM go directly to the KAM reading stored front O2 sensor data which is exactly what it is supposed to do. BTW the rear O2 sensor crosscounts are only stored in one air mass cell, not 3. It says so right in the Motorcraft service manual.

when your talking about air mass cells you are talking about the parameters that the PCM looks for to run a OBD-2 test such as catalyst efficency

To me that sounds like you were trying to say the air mass cells were used for testing parameters only, and that was the only reason I responded with that in mind. I wasn’t trying to make it look like you didn’t know what you were talking about or make you look bad to people who weren’t paying attention. What in the world made you think that? I thought we were having a good technical discussion, not sure how it turned personal.

Anyway, you and I both know it's really difficult to diagnose problems like reevesracing's problem over the internet. I thought it might be related to the FPM since he had enough draw on the system to completely kill a new battery in just 48 hrs. I have seen that happen before. He was going to check fuel pressure and post back.

 

[reevesracing]

Sorry for not getting back on here sooner (And it looks like I missed a LOT of discussion). The first few days of the week are hectic with work, and my son's baseball/boy scout activities.

Anyway, I have checked the oil to see if there is any fuel smell, and there is not.

Also, I attempted to recheck the fuel pressure and I am not getting any pressure back at the schraeder valve at KOEO for a while (MANY starting attempts), so I ordered a new fuel pump over the weekend and it just arrived today.

I have had several people on other forums tell me that they have had similiar problems with their fuel pumps, so I hope that this will be it. After almost $500 in parts I hope so. (And all of those parts were in need of replacement).

Is there an easy way to drain the tanks on this model Mustang? I have not seen any note of a drain plug in the service manuals, nor have I been able to spot one on the tank. The reason that I am asking is because the tank is 90% full..

 

[LaserRed01GT]

Well there is a way to jumper 2 pins on the PCM/EEC junction bulkhead to make the pump run continuously, but if your pump has quit that probably wouldn't do you much good. I guess you will just have to siphon it out if you don't want to drop the tank with it being full.

A little trick I have used before is to get some 3/8" vacuum or gas hose and run it all the way into the tank first, then outside the tank poke a small hole into the hose. Then I get an air blow nozzle and insert it at an angle pointing away from the gas tank. When you blow the air through the hose it will immediately start sucking gas. Just have a few gas cans handy.

 

[Mike97gt]

You will enjoy reading those books. I learned a BUNCH from that guy. He or one of his partners (I can't remember which) were directly involved with developing the hardware/software for Ford OBD-1/OBD-II PCM's. He talks a lot about FMEM. Everything I have ever read about FMEM in my Oasis, Ford, Alldata and other service manuals is consistent with what Barry writes. As the describe FMEM, it is described how I described it above about the PCM ignoring the real time input from ALL O2 sensors and making an educated guess. So what about cars that don’t have rear O2’s or have MIL’s or have them programmed out? What you are saying about the PCM trying to use the rear O2’s once FMEM is initiated just goes against everything I was taught getting my L1 and all the manuals and books I have read, and from my own experience. That’s all I’m saying. I’m not sure what they were trying to show you on the Crown Vic, but I have messed around with the O2 sensors before and you can look at all the data within certain tables relative to fueling. Then if you plug in 1 or 2 bad front O2 sensors, you can obviously watch the data in the tables immediately lock, and you can see the PCM go directly to the KAM reading stored front O2 sensor data which is exactly what it is supposed to do. BTW the rear O2 sensor crosscounts are only stored in one air mass cell, not 3. It says so right in the Motorcraft service manual.




To me that sounds like you were trying to say the air mass cells were used for testing parameters only, and that was the only reason I responded with that in mind. I wasn’t trying to make it look like you didn’t know what you were talking about or make you look bad to people who weren’t paying attention. What in the world made you think that? I thought we were having a good technical discussion, not sure how it turned personal.

Anyway, you and I both know it's really difficult to diagnose problems like reevesracing's problem over the internet. I thought it might be related to the FPM since he had enough draw on the system to completely kill a new battery in just 48 hrs. I have seen that happen before. He was going to check fuel pressure and post back.

Cool.. Yeah I think we were non understanding each other right there.. ohh well, still was a good discussion..

His problem might just be with the FPM.. lets see what he comes up with for fuel presure readings under load.

 

[Mike97gt]

Sorry for not getting back on here sooner (And it looks like I missed a LOT of discussion). The first few days of the week are hectic with work, and my son's baseball/boy scout activities.

Anyway, I have checked the oil to see if there is any fuel smell, and there is not.

Also, I attempted to recheck the fuel pressure and I am not getting any pressure back at the schraeder valve at KOEO for a while (MANY starting attempts), so I ordered a new fuel pump over the weekend and it just arrived today.

I have had several people on other forums tell me that they have had similiar problems with their fuel pumps, so I hope that this will be it. After almost $500 in parts I hope so. (And all of those parts were in need of replacement).

Is there an easy way to drain the tanks on this model Mustang? I have not seen any note of a drain plug in the service manuals, nor have I been able to spot one on the tank. The reason that I am asking is because the tank is 90% full..

I think it is very likely the fuel pump will fix this.. a fuel presure test under load would have helped pinpoint it.

 

[LaserRed01GT]

Cool.. Yeah I think we were non understanding each other right there.. ohh well, still was a good discussion..

His problem might just be with the FPM.. lets see what he comes up with for fuel presure readings under load.

All good brother.

 

[reevesracing]

I was unable to even get the car to run with the dead pump, otherwise I would have gotten it.

I was able to get the tank dropped, and drained, and removed the fuel pump. The strainer was plugged, and there is a residue at the bottom of the tank so evidently there must have been some water in the tank.

The plugged strainer could have led to additional stress on the fuel pump, causing it to short out.

Anyway, I am letting the assembly dry out overnight because I am going to have to slightly modify the bracket for the pump in order to install the new 155LPH pump. Plus it is dark, the mosquitos are out and I have to get up at 3:30am for work.

It will be Friday morning before I will be able to reinstall everything and test it out.

I am going to put the gas that I recovered from the tank aside and use it in the lawn mower, and I am going to run some Sea Foam and gas dryer in the tank for a little while as well.

I will post again once I get it all back together!

PS- Thanks again to BOTH of you for all the help so far. Hopefully this is the final problem, because this '07 Mustang that I am renting from Avis is burning a hole in my pocket bigger than this GT

 

[Mike97gt]

I was unable to even get the car to run with the dead pump, otherwise I would have gotten it.

I was able to get the tank dropped, and drained, and removed the fuel pump. The strainer was plugged, and there is a residue at the bottom of the tank so evidently there must have been some water in the tank.

The plugged strainer could have led to additional stress on the fuel pump, causing it to short out.

Anyway, I am letting the assembly dry out overnight because I am going to have to slightly modify the bracket for the pump in order to install the new 155LPH pump. Plus it is dark, the mosquitos are out and I have to get up at 3:30am for work.

It will be Friday morning before I will be able to reinstall everything and test it out.

I am going to put the gas that I recovered from the tank aside and use it in the lawn mower, and I am going to run some Sea Foam and gas dryer in the tank for a little while as well.

I will post again once I get it all back together!

PS- Thanks again to BOTH of you for all the help so far. Hopefully this is the final problem, because this '07 Mustang that I am renting from Avis is burning a hole in my pocket bigger than this GT

I would install a entire new sending unit since you see all that junk at the screen, but I think you have found your problem

 

[reevesracing]

Well, the replacement fuel pump (Got a Holley 155LPH) kit, the car cycled up to 48 psig after 2 on/off sequences.

I air-freed the fuel line as best I could, and the car started immediately!

It is holding 44 psig at idle, which is MUCH better than what it was previously. I can also hear the pump prime at start-up, which I could not hear before (Which should have sent up a red flag).

But, I guess if you think about it, I would not have found all the other issues and resolved them if I immediately went to the fuel pump.

Nobody had a sending unit on hand, so I did not replace it. I had to return the rental yesterday, and needed this car running today. I still have to do a driving test yet this morning (To ensure that my performance issue is resolved), and get the caster/camber plates installed so I can get the front end aligned, so I am not completely out of the woods yet. Also, I don't know if my battery draining issue is resolved just yet. I hope it was an internal short on the fuel pump, but I am not convinced just yet.

Anyway, I will post more this evening after I fill up the tank with some good gas and drive it around.

 

[reevesracing]

Took it up on the highway, and did some 25MPH and dead drop pulls, and it does not have the bog like it had before. It is definitely much more improved than it was before. It still does not pull like I think it should (My 88 GT would run circles around this GT) but at least I can make it a daily driver. Now I just have to fix the alignment issues.

Thanks again for all your help!

 

[reevesracing]

Just to follow up on this to help other out, I had to do some more work on the car to fix the performance issue.

After posting this, I was still getting misfire codes, purge gas solenoid codes, and the car would bog down some while driving. (Mostly under medium to full load).

Well, I checked my plugs and they were fine, but I changed out the Autolite platinum plugs with the Motorcraft replacement plugs, and then changed out the EGR valve on the car. I cleared out the keep alive memory after making this change, I had a whole new car.

All of the previous problems were gone. No more stumbling, a smooth idle, and no more codes.

Also, the car now has the power that it had been missing.

Hope this helps others in this situation. Remember, it is not always the IAC, or in my case just the IAC. The EGR valve can go out just as easily, and have a detrimental effect on your performance.

 

[reevesracing]

My final follow-up to my post.

I finally my problem with my battery draining after a few days.

Initially, I did not have a radio installed in my car, and it has the MACH 460 system. Well, after I installed the stock head units, I noticed that there was no bass coming from the stereo, and I had to turn the volume up all the way to hear it.

So, I tested out the amps in the rear and found that both of them were fried.

Needless to say, after disconnecting them my car now retains its battery life after sitting idle for a few days.

 

[Mike97gt]

thank you for following up