Hi. Im new here so idk if Im even doing this right. I have a mildly modded 90 5.0 tfs1 cam with explorer intake and gt40p heads. Crane hifire ignition a few bolt ons. Under normal driving you can run the rpms up to over 6000 and no problem. Its only when I downshift and nail on it, It revs and shuts off revs and shuts off if I hold the pedal down. I guess its not really shutting all the way off cause its still running but it sounds like im just revving and stopping when I have the pedal down. Any suggestions otber than pulling codes. Ive tried 3 different ways and nothing. My cel is not on either.
90 5.0 Bad Stutter When Downshifting To Pass
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mikestang63
SN Certified Technician
you are probably hitting the rev limiter and shutting off the fuel. The factory tach isnt that accurate and can be off a few hundred rpm.
That was actually my first thought but I can run it up to higher rpms than it cuts out at and hold it and its fine. Its only when I downshift or try to rev it up a lil and drop the clutch and launch hard. It will pull and cut off, pull and cut off, pull and cut off and if I hold the pedal down is like nothing is happening and im just coasting
Dump codes sticky.
Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. http://www.stangnet.com/mustang-for...codes-from-eec4-in-86-95-5-0-mustangs.889006/ I highly suggest that you read it and follow the instructions to dump the codes.
Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. http://www.stangnet.com/mustang-for...codes-from-eec4-in-86-95-5-0-mustangs.889006/ I highly suggest that you read it and follow the instructions to dump the codes.
mikestang63
SN Certified Technician
Dude, no need to shout at anyone. You'll get more responses that way. Jrichker is one of the most knowledgable members here- take it down a notch. If you can't run the codes check your grounds and your EEC.
Omg. Screw this. Ive read soooooooo many of these threads and had so much stupid stuff asked aand said Im wondering if anyone on here actually has a mustang and works on it themselves. Im trying to draw some info from someone who may have had this problem. Im beginning to think all these forums are a waste of my time. I WOULDNT HAVE TO SHOUT IF PEOPLE WOULD READ MY FIRST POST BEFORE SAYING SOMETHING STUPID. I SAID IN MY VERY FIRST POST I CANT PULL CODES!!!!!
mikestang63
SN Certified Technician
I've not been in admin for months now Mike.
mikestang63
SN Certified Technician
Noobz is your one stop shop for that service, but I still have a few "privileges" left over from days back.
He considers himself warned.
mikestang63
SN Certified Technician
Is that because they saw you with a box on your head,drinking with Dave? Haven't we all done that once or 100 times in our life @Noobz347
wow, I'm new to join in posting but not new to the site. just joined in because of this post and I'm also semi-retired so I have more time on my hands to beat on my '89 GT. That said, tbart77 needs to back it down and find another gear to operate in, I have been come'n here to get incite on a few issues that pop up on by vehicle for years and these guys (and gals if any) are the bomb (if that's the right term) when it comes to advice and tech on the finicky eec4 stuff.
As for my advice, if you cannot get any codes from your computer 'probing' that you likely need a computer replacement/repair. That's thinking you are getting nothing including an 11.
As for a rev limiter, I did not know there was one on this type system, eec4, as I have winged mine to 6500 with no issues. If there is one where does it cut off fun?
Also what is 'bump'? like fist bumping? Sorry, I'm kinda outta wack with modern terminology.
As for my advice, if you cannot get any codes from your computer 'probing' that you likely need a computer replacement/repair. That's thinking you are getting nothing including an 11.
As for a rev limiter, I did not know there was one on this type system, eec4, as I have winged mine to 6500 with no issues. If there is one where does it cut off fun?
Also what is 'bump'? like fist bumping? Sorry, I'm kinda outta wack with modern terminology.
Etiquette isn't your strong suit, is it sparky? If we're all such blundering idiots here, and the FREE technical advice offered to you isn't to your satisfaction, why don't you occupy your valuable time elseware? Better still, why waste your time at all asking questions on a Forum and just hustle your car on down to the nearest garage and pony up the $100+/hr diagnostic rate to have it checked locally?
....or, sit down, shut your mouth, get rid of that chip on your shoulder and pay attention to some of the invaluable advice being offered "FREE OF CHARGE" to you by members here and don't get your panties in a twist when your every whim isn't immediately catered to!
Then you need to turn down the volume and learn something new...
Computer will not go into diagnostic mode on 86-90 model 5.0 Mustangs
Disconnect the battery positive terminal before making any resistance checks.
The voltage drop in the ground cable will cause incorrect resistance readings.
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, ACT, ECT, & TPS sensors as well as the ground to put the computer into self test mode. If this ground is bad, none of the sensors mentioned will work properly. That will severely affect the car's performance. You will have hard starting, low power and drivability problems. 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 the test connector black/white wire 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.
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 on the computer wiring connector: 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 repaired or replaced.
See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix for the computer internal signal ground.
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 wiring connector: it is for an A9L, A9P computer.
Diagram courtesy of Tmoss & Stang&2birds
Check out the diagram and notice all the places the black/white wire goes. Almost every sensor on the engine except the MAF is connected to it.
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
See the graphic for the 10 pin connector circuit layout.
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