1990 Mustang GT Supercharged
Well, been having this Code 91 problem also have a Code 12. Raised idle and the Code 13 went away. New Plugs were white in center for two months. Today, I go out for further testing ... start it up and run it. First, it cuts out immediately like 4 times. Get it running but it is chugging and not responding to my foot on the gas too well. TPS and IAC have been checked numerous times nothing is saying they are bad. IAC replaced 4 times in two years just to be sure. Measuring .97 Volts on TPS. Anyway, run it for a while and do a KOER Test and only the Code 12 shows up and nothing was fixed. Run it longer at 2,000 but hear a lot of gurgling in exhaust under drivers seat and worry a bit. Run KOER Test and now Code 91 re-appears as it has been for 2 months now along with Code 12. Also have a Code 31 but have EGR removed and blocked off to take this out of the equation. Las time I ran it, I noticed unplugging hose to FPR made it run a bit better but this time it did not. Went on and did a cylinder balance test and came up with Code 9 (PASS). While it was idling a bit more, hear a strange noise (don't know what it was) thought since things have been lean, I have been real cautious cuz I do not want to do damage. Turn car off let it coll a minute and re-start car ... everything sounds okay but I do not run it up to 2000 rpm too long because something doesn't sound right underneath in the exhaust. Then, I shut it off not identifying anything once more.
I then pulled all the plugs and did a compression test and got 120 psi (+/- 5 psi) on all cylinders so that seemed okay. Went back and did a wet test and got anywhere from 150 psi to 180 psi depending on how much oil was put in the cylinder. Every Ford I have ever owned had about these same numbers so only having 85,000 miles on the car, the compression seems acceptable. But, this time when I pulled the plugs, both banks were black unlike the last 2 months since they were installed and i got the Code 91. Nothing was changed just ran the test on a different day. So, w/o changing anything how did my nice lean looking spark plugs all of a sudden change to being black ... looks like carbon not oil. When they were white, the base metal to 1st thread was always black but the center porcolean was always white ... now in one running both banks turned black! WTF is going on??? If the passenger side or drivers side suddenly showed up black or stayed white, I would understand this better! And, I am only getting a Code 91 which is the drivers bank. Any good ideas on all of this??? I am so tired of chasing down and doing things that turn out to not solve this problem ... this is simply crazy! Next Spring, I want it fixed and have the time over the Winter ... but do not want to tear into the motor if nothing in the motor is showing up or even with the sensors. This is crazy and no one believes this could be happening!!! And, I am great with cars ... just so fed up!
I know it needs a water pump cuz its weeping out the weep hole just a little ... need to replace that but wanted to do it when I found what this other problem was ... doubt this is affecting this situation though.
KOEO only shows 31 but I have EGR blocked off for now.
Any good suggestions would be appreciated before I pull my hair out!!!
Well, been having this Code 91 problem also have a Code 12. Raised idle and the Code 13 went away. New Plugs were white in center for two months. Today, I go out for further testing ... start it up and run it. First, it cuts out immediately like 4 times. Get it running but it is chugging and not responding to my foot on the gas too well. TPS and IAC have been checked numerous times nothing is saying they are bad. IAC replaced 4 times in two years just to be sure. Measuring .97 Volts on TPS. Anyway, run it for a while and do a KOER Test and only the Code 12 shows up and nothing was fixed. Run it longer at 2,000 but hear a lot of gurgling in exhaust under drivers seat and worry a bit. Run KOER Test and now Code 91 re-appears as it has been for 2 months now along with Code 12. Also have a Code 31 but have EGR removed and blocked off to take this out of the equation. Las time I ran it, I noticed unplugging hose to FPR made it run a bit better but this time it did not. Went on and did a cylinder balance test and came up with Code 9 (PASS). While it was idling a bit more, hear a strange noise (don't know what it was) thought since things have been lean, I have been real cautious cuz I do not want to do damage. Turn car off let it coll a minute and re-start car ... everything sounds okay but I do not run it up to 2000 rpm too long because something doesn't sound right underneath in the exhaust. Then, I shut it off not identifying anything once more.
I then pulled all the plugs and did a compression test and got 120 psi (+/- 5 psi) on all cylinders so that seemed okay. Went back and did a wet test and got anywhere from 150 psi to 180 psi depending on how much oil was put in the cylinder. Every Ford I have ever owned had about these same numbers so only having 85,000 miles on the car, the compression seems acceptable. But, this time when I pulled the plugs, both banks were black unlike the last 2 months since they were installed and i got the Code 91. Nothing was changed just ran the test on a different day. So, w/o changing anything how did my nice lean looking spark plugs all of a sudden change to being black ... looks like carbon not oil. When they were white, the base metal to 1st thread was always black but the center porcolean was always white ... now in one running both banks turned black! WTF is going on??? If the passenger side or drivers side suddenly showed up black or stayed white, I would understand this better! And, I am only getting a Code 91 which is the drivers bank. Any good ideas on all of this??? I am so tired of chasing down and doing things that turn out to not solve this problem ... this is simply crazy! Next Spring, I want it fixed and have the time over the Winter ... but do not want to tear into the motor if nothing in the motor is showing up or even with the sensors. This is crazy and no one believes this could be happening!!! And, I am great with cars ... just so fed up!
I know it needs a water pump cuz its weeping out the weep hole just a little ... need to replace that but wanted to do it when I found what this other problem was ... doubt this is affecting this situation though.
KOEO only shows 31 but I have EGR blocked off for now.
Any good suggestions would be appreciated before I pull my hair out!!!
