My car wont stay running for more than 20sec give or take. I just changed the head gaskets but I had the problem before I changed them. I also cant pull codes(whole other issue there). There is a red/light green or light blue wire I cant really tell, it is between the drivers side shock tower and the battery tray. It is exposed and goes to nothing. Looks like its been pulled out of something but I cant see what. Ive never noticed it before. Where is the EEC relay, near MAF? if so the wires going into it have seen better days. Would this cause my problem? Or could it be Timmig? Please help my car has been down for like 3 weeks now and I just want to drive it,
Wont stay running.
- Thread starter AZNEAL311
- Start date
No info about your car's model year. Therefore no clue as to which wiring diagram you need. The wiring changed several times between 79 & 95
That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.
That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.
Glaze
New Member
Why cant you pull codes? It may indeed be related. If not still need to in order to make your life easier finding the problem.
Light blue wire with grey connector is also dangling on mine. Dont believe it is needed.
Id lean more towards fuel issue. But before you do anything try and get the codes if possible in order to save time diagnosing the problem. Search the forums for related issues.
Light blue wire with grey connector is also dangling on mine. Dont believe it is needed.
Id lean more towards fuel issue. But before you do anything try and get the codes if possible in order to save time diagnosing the problem. Search the forums for related issues.
poneypower89
Now everyone in the world will know I wanna bang t
when you say it will only run for 20 seconds.. how IS it running for that 20 seconds? Its a rough, chopping idle? Or does it just run perfect and then all the sudden die?
vacuum prob maybe?
mine did that when I had a bad egr valve.unless I fed it gas from the get go it would sputter and die.
mine did that when I had a bad egr valve.unless I fed it gas from the get go it would sputter and die.
The EEC relay is located on top of the computer, under the
passenger side kick panel. ON your 89, the relay under the MAF is
the A/C wide open throttle cutout relay. The wiring frequently gets
heat damaged from the close proxmity to the exhaust headers.
Computer will not go into diagnostic mode
How it is supposed to work:
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated
ground for the EGR, Baro & TPS sensors as well as the ground to put the computer into
self test mode. Since it is a dedicated ground, it passes through the computer on its way
to the computer main power ground that terminates at the battery pigtail ground. It should
read less than 1.5 ohms when measured from anyplace on the engine harness with the battery
pigtail ground as the other reference point for the ohmmeter probe. What sometimes happens
is that it gets jumpered to power which either burns up the wiring or burns the trace off the pc
board inside the computer. That trace connects pins 46 to pins 40 & 60. Only an experienced
electronics technician can open the computer up & repair the trace if it burns up and creates
an open circuit.
The STI (Self Test Input ) is jumpered to ground to put the computer into test mode. Jumpering
it to power can produce unknown results, including damage to the computer. The ohm test
simply verifies that there are no breaks in the wiring between the test connector and the computer input.
How to test the wiring :
With the power off, measure the resistance between the computer test ground
(black/white wire) on the self test connector and battery ground. You should see less than
1.5 ohms.
If that check fails, remove the passenger side kick panel and disconnect the computer
connector. There is a 10 MM bolt that holds it in place. Measure the resistance between
the black/white wire and pin 46: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem. If it reads 1.5 ohms or less, then the computer is suspect. On the
computer, measure the resistance between pin 46 and pins 40 & 60: it should be less than
1.5 ohms. More that that and the computer’s internal ground has failed, and the computer
needs to be replaced.
If the first ground check was good, there are other wires to check. Measure the
resistance between the STI computer self test connector (red/white wire) and pin 48 on
the computer main connector: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem
The following is a view from the computer side of the computer connector.
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine
passenger side kick panel. ON your 89, the relay under the MAF is
the A/C wide open throttle cutout relay. The wiring frequently gets
heat damaged from the close proxmity to the exhaust headers.
Computer will not go into diagnostic mode
How it is supposed to work:
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated
ground for the EGR, Baro & TPS sensors as well as the ground to put the computer into
self test mode. Since it is a dedicated ground, it passes through the computer on its way
to the computer main power ground that terminates at the battery pigtail ground. It should
read less than 1.5 ohms when measured from anyplace on the engine harness with the battery
pigtail ground as the other reference point for the ohmmeter probe. What sometimes happens
is that it gets jumpered to power which either burns up the wiring or burns the trace off the pc
board inside the computer. That trace connects pins 46 to pins 40 & 60. Only an experienced
electronics technician can open the computer up & repair the trace if it burns up and creates
an open circuit.
The STI (Self Test Input ) is jumpered to ground to put the computer into test mode. Jumpering
it to power can produce unknown results, including damage to the computer. The ohm test
simply verifies that there are no breaks in the wiring between the test connector and the computer input.
How to test the wiring :
With the power off, measure the resistance between the computer test ground
(black/white wire) on the self test connector and battery ground. You should see less than
1.5 ohms.
If that check fails, remove the passenger side kick panel and disconnect the computer
connector. There is a 10 MM bolt that holds it in place. Measure the resistance between
the black/white wire and pin 46: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem. If it reads 1.5 ohms or less, then the computer is suspect. On the
computer, measure the resistance between pin 46 and pins 40 & 60: it should be less than
1.5 ohms. More that that and the computer’s internal ground has failed, and the computer
needs to be replaced.
If the first ground check was good, there are other wires to check. Measure the
resistance between the STI computer self test connector (red/white wire) and pin 48 on
the computer main connector: it should be less than 1.5 ohms. More that 1.5 ohms is a
wiring problem
The following is a view from the computer side of the computer connector.
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds
(website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine
Ok i have a couple test results. Please help me desipher them and let me know where to start.
1. black/white wire on Self Test Connector to batt. ground pig tail.- 2.16 ohms
2. Black/white wire on Self Test Connector to pin 46- no reading
3. Pins 46 to 40- no reading
4. Pins 46 to 60- no reading
5. Pins 40 to 60- 0.000
1. black/white wire on Self Test Connector to batt. ground pig tail.- 2.16 ohms
2. Black/white wire on Self Test Connector to pin 46- no reading
3. Pins 46 to 40- no reading
4. Pins 46 to 60- no reading
5. Pins 40 to 60- 0.000
AZNEAL311 said:
1. black/white wire on Self Test Connector to batt. ground pig tail.- 2.16 ohms This reading is a little high, but it is good enough to provide a ground for the STI (self test input). I would probably check and clean the computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire. You'll find it up next to the starter solenoid where the wire goes into the wiring harness
Now for the others...
"2. Black/white wire on Self Test Connector to pin 46- no reading" Did you take this reading with one probe on the computer wiring harness connector and the other on the black/white wire on the self test connector?
"3. Pins 46 to 40- no reading"" Was this done on the computer or on the computer wiring harness connector?
4. Pins 46 to 60- no reading" Was this done on the computer or on the computer wiring harness connector?
Measurements 3 & 4 should be taken across the actual computer pins, not the wiring harness connector. When measured across the computer pins, it should be less than 1.5 ohms. This is the typical failure point that is due to internal damage to the computer.
I dont think it is a vaccum leak because when it runs it idles fine. Its almost like it just stops getting fuel. And come to think of it 20 secs is longer than it actually runs. Id say more like 10secs. It does seem to run longer if I prime the car a few times. Could my pump not be working after it primes? How long could it run with only primeing it? Would it still prime if the pump relay was bad?
#2. was done with a wire connected to the black/white wire at the self test connector to computer connector.
And I did test 46,40&60 on the connector but i checked it on the computer with the same results
#2. was done with a wire connected to the black/white wire at the self test connector to computer connector.
And I did test 46,40&60 on the connector but i checked it on the computer with the same results
As I have said before, fix what you know is broke and then chase other rabbits. Successful troubleshooting is best done when you take one system or problem at a time and work it until you have either fixed it or eliminated it as being the source of the problem. Chasing this rabbit and then that rabbit is very inefficent and will likely result in your missing the one thing that could help you find & fix the problem.
The key issue with no code retrevial is that the black/white wire used to set the computer in diagnostic mode is also the signal ground for the TPS, EGR & Baro sensors. They will not properly operate without a ground. If the Baro or TPS sensors are not working correctly, the engine will run very poorly.
The key issue with no code retrevial is that the black/white wire used to set the computer in diagnostic mode is also the signal ground for the TPS, EGR & Baro sensors. They will not properly operate without a ground. If the Baro or TPS sensors are not working correctly, the engine will run very poorly.
Im stuck between a fuel issue and a computer issue. I changed fuel filter and the fuel I drained out was pretty dirty, I let it sit in a cup and after a while the dirt in it settled and there was about a centimeter or real fine dirt on the bottom. from about 1 cup of fuel. However right before it started this issue I bought a code reader from checker due to my many failed atempts to pull codes with a test light. I hooked it up while I was waiting for a friend and I got nothing so when I went to leave it wouldnt stay running.
Also my MAP sensor is not hooked up to vaccum. With MAF conversion its not suppose to be right?
Also my MAP sensor is not hooked up to vaccum. With MAF conversion its not suppose to be right?
Glaze
New Member
I am wondering if somehow during you checking for codes with new scanner or using test light if computer got shorted. Any similar isntances ever happen anyone?
Thats good you found and fixed dirty fuel problem but i doubt that is what is keeping your car from running. Sounds if fuel pump is working with KOEO (key on engine off) but once KOER (key on engine running) it is disabled. Does anyone know if fuel pump is controlled by computer alone or just ignition switch?
Richker isnt his computer bad if he is not pulling any resistance what so ever across 46-40 and 46-60??
AZNEAL if your car's exhaust is loud nevermind but have a friend listen for the fuel pump running after you start the car.
Thats good you found and fixed dirty fuel problem but i doubt that is what is keeping your car from running. Sounds if fuel pump is working with KOEO (key on engine off) but once KOER (key on engine running) it is disabled. Does anyone know if fuel pump is controlled by computer alone or just ignition switch?
Richker isnt his computer bad if he is not pulling any resistance what so ever across 46-40 and 46-60??
AZNEAL if your car's exhaust is loud nevermind but have a friend listen for the fuel pump running after you start the car.
I am thinking it is my computer. I had a 87 Cougar do the exact same thing. Turns out when I installed a new battery I some how pulled that connector apart for the computer ground. Hooked it back up and ran fine. Im really hoping it isnt the comp. I have a A9L isnt there other comps that will work with a 5.0/T-5 w/ MAF conversion, if so what are they? And as for the loud exhaust I am running straight headers till Pacesetter swaps out my equal length headers that didnt fit. Even with my Flowmasters hooked up I wouldnt be able to hear it.
Glaze
New Member
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