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Discussion Starter #1
First let me say I am sorry for posting here even though I don't have a Mustang but I thought I might be able to find some help here since I have not found what I needed anywhere else.

I have just replaced the speed density system on my 351W with a MASS air conversion kit. The kit I got was the truck kit (for my 92 F150) from here: IST Products

The installation went fine, no major problems, but the engine runs like snot. It is really rich when I smell the exhaust, sounds like the timing is off, and it doesn't respond to the gas pedal really well. I have a vortech supercharger (which is disconnected now) on the engine. As part of the conversion I have not yet installed the second oxygen sensor (not sure if that may be the issue).

I can't for the life of me figure out what I can do to either identify the problem through some testing or fix the problem. I have gone over the installation and everything looks good.

I am not really sure what else I can do to find the problem and am hoping that more Mustang owners have gone through this than what I have found in the truck forums.

Does anyone know what tests I can do or how I can begin to understand this to fix the problem?
 

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If you don't have the oxygen sensor hooked up, it will give a false lean code. The computer will try to add fuel to compensate. Thus you have a rich condition.

Just so we are clear. You did use a Mass air computer right?

And you did remove the vacuum line from the Map/BP sensor correct?
 

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Discussion Starter #3
If you don't have the oxygen sensor hooked up, it will give a false lean code. The computer will try to add fuel to compensate. Thus you have a rich condition.

Just so we are clear. You did use a Mass air computer right?

And you did remove the vacuum line from the Map/BP sensor correct?

Answer is yes to both questions. The MASS air computer was part of the kit I bought and I followed the instructions about modifying the MAP sensor to a BAP sensor.

Is there a way to test the issue with the O2 sensor you mentioned? To do this conversion work I moved the truck to my back yard and really the only way I can get it out would be to drive it, which is the reason why I don't have the second O2 sensor installed - I can't drive it to the welding shop. My only other option is to see if I can find a mobile mechanic do this work (I can't weld) and see if that fixes the problem, which is why I asked if there was a test I could do to confirm this issue.
 

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Go ahead and run the codes from the computer first.

This all came about after the conversion right?
 

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Discussion Starter #5
Go ahead and run the codes from the computer first.

This all came about after the conversion right?
Right now the only code I am getting out of the system is Park/Neutral circuit fault - PNP. So I need to replace that and see if I get any other codes...but I am getting codes so I know the computer is working properly.
 

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Is this an Auto or 5 speed setup?

I have to assume its code 67 you have gotten. That code will not allow the Engine running code test to start.

There are two different tests for codes.

KOEO= Key On, Engine Off
KOER= Key On, Engine Running
 

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Discussion Starter #7
Is this an Auto or 5 speed setup?

I have to assume its code 67 you have gotten. That code will not allow the Engine running code test to start.

There are two different tests for codes.

KOEO= Key On, Engine Off
KOER= Key On, Engine Running
This is for an E40D transmission. My old code reader broke so I was using the jumper method. I plan to get a new code reader either today or tomorrow. Once I do that and get the codes, I will post back.

Thanks for the help, you seem to know your stuff.
 

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As long as the wiring is in tact. Id venture to guess the MLPS is the problem. Either that or it needs to be adjusted. I am far from an auto guy, let alone a E4OD. LoL But the MLPS should operate the same.
 

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Discussion Starter #11
As long as the wiring is in tact. Id venture to guess the MLPS is the problem. Either that or it needs to be adjusted. I am far from an auto guy, let alone a E4OD. LoL But the MLPS should operate the same.

They are cheap enough and I was going to get a new one but I don't see how that would cause a problem with the engine. To me, it seems more likely to be the issue with not having both oxygen sensors installed to cause the engine problems.
 

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You are correct. But the point is. You need to run the engine running codes to get a better idea of whats going on. And code 67 will not let that happen. As the ECM thinks the trans is in gear. Some codes will only show in the Key on Engine running test. So the MLPS switch issue has to be resolved. Not to mention code 67 can cause idle issues.
 

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Discussion Starter #13
You are correct. But the point is. You need to run the engine running codes to get a better idea of whats going on. And code 67 will not let that happen. As the ECM thinks the trans is in gear. Some codes will only show in the Key on Engine running test. So the MLPS switch issue has to be resolved. Not to mention code 67 can cause idle issues.
A little bit of progress...

for some reason I called the company that makes the transmission controller and talked to them about the code 67 fault. I was able to make a wired connection between two wires to fix that, when I run the KOEO test, it checks OK, now I need to run the KOER test.
 

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man..the 98/66 code seems to be running rampant with MAF conversions lately(including my own lol)

before assuming/replacing the sensor
verify your wiring is correct

the MAF meter reads ABCD

PIN A = 12v- PIN 37/57
PIN B = Ground -PIN 40/60
PIN C = goes to PIN 9 MAF return
PIN D = goes to PIN 50 MAF signal

verify the PINS are routed correctly, there are no abd solder spots/breaks,etc..make sure they are properly seated in the MAF plug,and also the 60 PIN connector at the EEC..if they arent properly seated (ie; bad connection),the EEC wont read the MAF signal

heres how to test the sensor to see if its good or not
please walk a dummy through testing a mass air meter fox 5.0
 

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Discussion Starter #16
man..the 98/66 code seems to be running rampant with MAF conversions lately(including my own lol)

before assuming/replacing the sensor
verify your wiring is correct

the MAF meter reads ABCD

PIN A = 12v- PIN 37/57
PIN B = Ground -PIN 40/60
PIN C = goes to PIN 9 MAF return
PIN D = goes to PIN 50 MAF signal

verify the PINS are routed correctly, there are no abd solder spots/breaks,etc..make sure they are properly seated in the MAF plug,and also the 60 PIN connector at the EEC..if they arent properly seated (ie; bad connection),the EEC wont read the MAF signal

heres how to test the sensor to see if its good or not
please walk a dummy through testing a mass air meter fox 5.0
Wiring is correct.

When testing the sensor I am not getting much, if anything at all, in the sensor return. I measured between 0 and 0.8mv when the engine was on. I had +12v power and the blue wire measured about 0.34 volts.
 

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If you have 12v between the power and ground on the MAF and its only putting out .34v. Then its a meter issue. You may try and clean the wire with some Mass Air cleaner. And make sure the contacts on the Mass Air plug are good and clean. If none of that works, look for a new meter.

The MAF SIG wire is what you are concerned with. Not the MAF SIGRTN. You have to be above .4v to not throw code.
 

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Discussion Starter #18
If you have 12v between the power and ground on the MAF and its only putting out .34v. Then its a meter issue. You may try and clean the wire with some Mass Air cleaner. And make sure the contacts on the Mass Air plug are good and clean. If none of that works, look for a new meter.

The MAF SIG wire is what you are concerned with. Not the MAF SIGRTN. You have to be above .4v to not throw code.
when you say it's a meter issue, do you mean the air sensor or the meter I am using to test the voltage with?
 

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The mass air meter. But that doesn't mean the volt meter can't be faulty. Any things suspect. But more than likely the volt meter is fine. The number look reasonable to be real.
 

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Discussion Starter #20
So I am sending the meter back to the company that sold it to me since it appears to be bad. They will test it out and give me a new one if it is bad.

But where would I buy these if I need a replacement in the future? I wasn't able to find it on-line. The part number for my meter is f2vf-12b579-aa-afh70-04
 
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