Engine 93 Mustang GT, Code 41/91, KOER Cylinder ID shows 6 and not 8

79MercCapri93

Member
May 12, 2012
86
7
8
32
627669
 
  • Sponsors(?)


79MercCapri93

Member
May 12, 2012
86
7
8
32
U sure that's not connector grease?

Yeah, in person it has a ledge to it like something was there that was snapped off, and i dont want to try pulling that piece out and damage the harness. I sent them the picture and Kris said he was going to check and see what could have happened or if its something that im supposed to remove. I just dont want to try pulling that out and get stuck with a unusable harness and money down the drain
 

Window

Active Member
Feb 13, 2017
111
8
28
28
Yeah, in person it has a ledge to it like something was there that was snapped off, and i dont want to try pulling that piece out and damage the harness. I sent them the picture and Kris said he was going to check and see what could have happened or if its something that im supposed to remove. I just dont want to try pulling that out and get stuck with a unusable harness and money down the drain
Yea true I dont remeber enough off the top.of my head to say for sure cause it was about 2 years ago. I got mine from lmr as well.
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Yea true I dont remeber enough off the top.of my head to say for sure cause it was about 2 years ago. I got mine from lmr as well.

If i end up getting an email back today letting me know which way to go, im hoping to get it installed tomorrow since its literally like a 5 minute process lol
 
  • Like
Reactions: 1 user

79MercCapri93

Member
May 12, 2012
86
7
8
32
installed the new harness so well see what happens. But i think @General karthief might have been onto something with the IAC. When i drove home on Wednesday, every time i would come out of cruising speed for the toll booth or coming up to a stop, I would put the car in neutral and tap the gas once real quick and had no check engine lights come on at all. So its making me think that my IAC is getting stuck and causing issues.
 

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
27,461
2,794
234
75
Dublin GA
lowendmac.com
Recommended procedure for cleaning the IAC/IAB:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. Take the solenoid off the body and set it aside: the carb cleaner will damage some types of plastic parts. Soak the metal body in the carb cleaner overnight. There is a basket to set the parts in while they are soaking. When you finish soaking overnight, twist the stem of the IAB/IAC that sticks out while the blocker valve is seated. This removes any leftover deposits from the blocker valve seat. Rinse the part off with water and blow it dry with compressed air. The IAC/IAB should seal up nicely now. Once it has dried, try blowing through the bottom hole and it should block the air flow. If it doesn't block the airflow, there is still something that is gumming up the works. Reassemble and reinstall to check it out.

Gunk Dip type carb & parts soaker:
21hb0QWbOeL._SL500_AA300_.jpg


Setting the base idle speed:
First of all, the idle needs to be adjusted to where the speed is at or below 600 RPM with the IAC disconnected. If you have a wild cam, you may have to raise this figure 100-150 RPM or so. Then the electrical signal through the IAC can vary the airflow through it under computer control. Remember that the IAC can only add air to increase the base idle speed set by the mechanical adjustment. The 600 RPM base idle speed is what you have after the mechanical adjustment. The IAC increases that speed by supplying more air under computer control to raise the RPM’s to 650-725 RPM’s. This figure will increase if you have a wild cam, and may end up between 800-950 RPM

Remember that changing the mechanical idle speed adjustment changes the TPS setting too.

This isn't the method Ford uses, but it does work. Do not attempt to set the idle speed until you have fixed all the codes and are sure that there are no vacuum leaks.

Disconnect the battery negative terminal and turn the headlights on. Leave the battery negative terminal disconnected for 5 minutes or so. Then turn the headlights off and reconnect the battery. This erases the computer settings that may affect idle performance.

Warm the engine up to operating temperature, place the transmission in neutral, and set the parking brake. Turn off lights, A/C, all unnecessary electrical loads. Disconnect the IAC electrical connector. Remove the SPOUT plug. This will lock the ignition timing so that the computer won't change the spark advance, which changes the idle speed. Note the engine RPM: use the mechanical adjustment screw under the throttle body to raise or lower the RPM until you get the 600 RPM mark +/- 25 RPM. A wild cam may make it necessary to increase the 600 RPM figure to 700 RPM or possibly a little more to get a stable idle speed.
Changing the mechanical adjustment changes the TPS, so you will need to set it. Anything between.6 and 1.0 volt is good. There is no advantage to setting it to .99; that is a BOZO Internet myth, complete with red nose and big floppy shoes.

When you are satisfied with the results, turn off the engine, and re-install the SPOUT and reconnect the IAC. The engine should idle with the range of 650-750 RPM without the A/C on or extra electrical loads. A wild cam may make this figure somewhat higher.
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Thank you @jrichker

I purchased the can on Monday and let the IAC soak and cleaned it all out. I put it on the car today and due to poor time management decided to drive it without doing the base idle reset. :doh: Car ran great until about halfway to work when it start to buck and surge like crazy, so i know what i will be doing tomorrow morning before work. As well as riding with tools, a new IAC and scanner just to be on the safe side.
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Car ran great last night, no CEL or any issues whatsoever. Ran pretty good today on the way to work until about 7 minute out when it started surging again and trying to die when sitting
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
after doing some research, go figure all of the symptoms my car has been having over the last 2 days is common with the PIP sensor going bad
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Just to make sure I’m looking at this correctly. Since my RPMs drop at random when driving, especially when it’s hot out, and struggles to get out of its own way when this is happening because it’s bucking or stumbling so bad. I’m going to go out on a limb and say it’s just a coincidence and not IAC related... before I start messing with it. The car has done this before last year, but it’s been a while. And so far it’s only on the 2 days that it’s been in the 90’s, but on the drive home it has not had the same issues
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Well. Looked at the car. Found part of the problem. Radiator overflow had coolant in it, so now I’m trying to figure out what caused the car to overheat and praying it’s not a head gasket since the coolant was brown
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Finally had a chance to mess with the car.

Realized my key on power for my electric fan had somehow gotten disconnected which caused it to overheat and thus dump coolant. When i was looking i noticed that a timing cover bolt was weeping a little bit of coolant and so was the bypass hose. I replaced the hose, and put a 195 thermostat back in the car since I had to remove the thermostat housing to reseal the timing cover bolt. I pressure checked the radiator with the car cold and it held 16lbs without issue and no more leaks.

I put the new IAC on the car and did a base idle reset. I had the car set to about 750rpms with the spout and IAC disconnected. With them hooked backup and the TPS at .98 the car would idle at 1k rpms. Not sure why it would go up that high instead of idling at 750-800. I tried the IAC in both directions.

I test drove the car and seemed to run fine, but then I started to get that sputtering while cruising and during acceleration. I have a video of it, just have to upload it off my phone and see if i can get the video to compress enough to load. When the car sputters it drops roughly 500rpm or more and will either sputter once or twice or multiple times like its misfiring. I have checked all of my sparkplug wires and they look fine, and replaced the cap and rotor with Taylor, and kept my MSD cap and rotor since that appeared to make no difference. I also installed a new ACCEL coil after talking to some friends of mine who thought it might be failing given the sputtering and the RPM drop since the tach is coil driven. That made no difference to the car with the sputtering, but it did feel as though the car was pulling a little harder than it used to.

Today i installed a new PIP sensor and fired up the car and seemed to run fine. I redid my base idle reset with the IAC flipped in the normal direction and with everything disconnected, my idle was about 750 again and with everything hooked back up its at 1k, full load the car was idling at about 1100-1200. My tps was showing 1.58 and 2.19 when i connected my multi meter to the negative terminal on the battery. But any other ground on the car shows .72, whether its on the firewall, radiator core support, or somewhere else.

I have not had a chance to drive the car yet with the new PIP installed and plan to take it for a test drive sometime between sunday and tuesday.
 

Window

Active Member
Feb 13, 2017
111
8
28
28
Finally had a chance to mess with the car.

Realized my key on power for my electric fan had somehow gotten disconnected which caused it to overheat and thus dump coolant. When i was looking i noticed that a timing cover bolt was weeping a little bit of coolant and so was the bypass hose. I replaced the hose, and put a 195 thermostat back in the car since I had to remove the thermostat housing to reseal the timing cover bolt. I pressure checked the radiator with the car cold and it held 16lbs without issue and no more leaks.

I put the new IAC on the car and did a base idle reset. I had the car set to about 750rpms with the spout and IAC disconnected. With them hooked backup and the TPS at .98 the car would idle at 1k rpms. Not sure why it would go up that high instead of idling at 750-800. I tried the IAC in both directions.

I test drove the car and seemed to run fine, but then I started to get that sputtering while cruising and during acceleration. I have a video of it, just have to upload it off my phone and see if i can get the video to compress enough to load. When the car sputters it drops roughly 500rpm or more and will either sputter once or twice or multiple times like its misfiring. I have checked all of my sparkplug wires and they look fine, and replaced the cap and rotor with Taylor, and kept my MSD cap and rotor since that appeared to make no difference. I also installed a new ACCEL coil after talking to some friends of mine who thought it might be failing given the sputtering and the RPM drop since the tach is coil driven. That made no difference to the car.

Today i installed a new PIP sensor and fired up the car and seemed to run fine. I redid my base idle reset with the IAC flipped in the normal direction and with everything disconnected, my idle was about 750 again and with everything hooked back up its at 1k, full load the car was idling at about 1100-1200. My tps was showing 1.58 and 2.19 when i connected my multi meter to the negative terminal on the battery. But any other ground on the car shows .72, whether its on the firewall, radiator core support, or somewhere else.

I have not had a chance to drive the car yet with the new PIP installed and plan to take it for a test drive sometime between sunday and tuesday.
Have you looked at fuel pressure? I chased issues like you and never thought to look at my regulator because they are set out of the box. The bbk one I bought was messed with and the pressure was dialed down way too low.
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Have you looked at fuel pressure? I chased issues like you and never thought to look at my regulator because they are set out of the box. The bbk one I bought was messed with and the pressure was dialed down way too low.

That was actually one of the first things I looked at. Pressure was great and regulator seems to be intact with no smell of gas or anything. Besides trying to track down my 41/91 code issue, the car had been running great. Until my fan was disconnected and I didnt realize it. Unfortunately, I did not even think of that being an issue since my temperature gauge has been jacked up for as long as i can remember so i just ignore it, I have an autometer gauge to put in the car, but had not had a chance to do so. But ill probably end up putting that in here soon so i dont write off my gauge as faulty again.

Seems to be an issue only once the car gets up to operating temperature. When the cars cold, it runs great, so i am wondering if something is/was getting heat soaked. hopefully my new motorcraft pip sensor has fixed the issue, but I have not had a chance to drive the car since putting that in earlier today
 
  • Like
Reactions: 1 user

79MercCapri93

Member
May 12, 2012
86
7
8
32
I also cleaned and added new heatsink paste with diamond in it to the TFI since i had to remove it to install my new pip sensor as well
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
Was finally able to drive my car in a long time, having switched jobs and a million different things going on. Car seemd to be running a lot better with the new pip sensor. But the issue I am running into now is a hanging idle. Car never had any issues before, but the last 2 times I have driven the car, the idle will get stuck around 1500-2000 rpms and will not drop below that. The car also started doing this while idling in the driveway, when trying to set my base idle to rule that out, car would idle great and then all of a sudden jump up to 1200-1500 RPMs and would not drop, so it is definitely something computer controlled causing the issue from what i can tell.

I checked the throttle cable, and disconnected the cruise control from the TB to make sure it was not causing the issue since I have it un-hooked currently due to the sporadic cruise control.

I also checked the throttle body and discovered that the upper o-ring was missing which would explain why it was leaking during the smoke test, however everything else appears to be in check and without issue.

Through my research I think i have narrowed it down to either the speed sensor or the neutral gear switch/ neutral sensing switch. Learning more toward the latter. But when i just crawled underneath the car to look for broken wires or anything disconnected, i realized that the NGS/NSS has never been connected and in fact the plug has never been there since i owned the car. I always thought that the connector on the harness was for an automatic so its never been hooked up and has always just laid by the transmission cross member.

What im trying to figure out is (1) is the NGS/NSS switch needed, and if so why has there been no issue up until now? and (2) from what I have read it appears that this could be a huge issue for hanging idles or surging idle, so could this be the culprit?

I meant to run codes but without thinking, I disconnected the battery after I double checked the tps to make sure that the computer recognized the tps was in range.
 

79MercCapri93

Member
May 12, 2012
86
7
8
32
I also noticed I get different tps voltage settings depending on my ground. If I go to the post of the battery I get a really high reading, but if I go to a ground on the body, engine or the negative cable and not the post, I get lower readings


so right Now based off of the other grounds and not the negative battery post, the TPS is set at .88
 

Attachments

  • 25131715-559E-477C-A7C5-311430242511.jpeg
    25131715-559E-477C-A7C5-311430242511.jpeg
    345.1 KB · Views: 65
  • 74ECCCDB-9BB7-49C3-A60E-660D8E4EAE75.jpeg
    74ECCCDB-9BB7-49C3-A60E-660D8E4EAE75.jpeg
    369.5 KB · Views: 67

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
36,960
12,823
224
Massachusetts
An NGS not hooked up could cause a high/hanging idle.

My car doesn’t have it hooked to the trans but it’s hooked on the clutch pedal. If I slow down and slip the trans out of gear wen not under load, the idle will hang until I press the clutch pedal in

Clutch pedal and trans NGS are wires in parallel
 

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
27,461
2,794
234
75
Dublin GA
lowendmac.com
I also noticed I get different tps voltage settings depending on my ground. If I go to the post of the battery I get a really high reading, but if I go to a ground on the body, engine or the negative cable and not the post, I get lower readings
so right Now based off of the other grounds and not the negative battery post, the TPS is set at .88

You used the wrong ground to check the TPS voltage...


Why do the engine control sensors have a separate ground?
The computer pin 46 signal ground is a critical component: it provides a signal ground for the Map/Baro, TPS, ECT, EGR position and ACT sensors. Every sensor has to have a reliable ground for it to provide accurate and useful information to the engine control computer.

The more current that flows through a conductor, whether it is a cable or the car body, the greater the voltage drop. The ground on the car body and ground cable for the engine block may have different voltage drops. Some of the voltage drops change depending on electrical loads such as lights, A/C, and heater blower settings.

Under high current loads, there can be large changes in the voltage drop across the ground wiring that goes back to the negative battery cable. If the engine analog sensors ground is combined with power ground, the computer will see these changes in the ground as a change in sensor input. This voltage change is very undesirable for reliable computer operation, so the engine sensors all have a separate shared ground.

The engine mounted sensors all have outputs of 5 volts or less. Therefore, any small changes in voltage seen by the computer analog signal inputs can have a large effect in engine performance. Signal ground is used in many circuits that have analog inputs to eliminate the voltage drop across the engine block and body grounds when current flows through them. There is very little current flowing through the signal ground and the voltage drop across the signal ground is so small that it can be ignored by the computer.

The voltage output of any sensor must always use the signal ground for the sensor under test in order to eliminate any errors or variances. That way, what the voltmeter sees is what the computer sees unless there is a problem with the sensor wiring.

@Blown88GT
@Mustang5L5
@a91what
You guys have anything to add or modify here?
 
Last edited: