Engine 88 mustang gt, random stalling?

Comp Cam · Jan 11, 2019

I'll probably get flamed for this but whatever. So I have a 88gt, mind you this car runs fine. But I have this issuse that just started. Sometimes the car will stall but I'll be able to get it back up and running and it'll run fine. There's no other way to explain this. Sometimes when I'm leaving my apt. It will stall in first and I'll have to start it back up again. It will start and run fine. Like it kind of sputters out then it dies. Then I start it back up again and it runs flawless. There was one day however I couldn't get it back started for awhile. It just cranked and cranked and cranked until I decided to leave it. This happened at idle. Then I come back later and it starts right and I'm able to drive it. There was also one day where I shifted to second and it literally stalled mid drive and then came back on. I hear the fuel pump prime so I'm thinking it's not the fuel pump. Maybe a bad regulator? Or could it be a clogged fuel filter? Or maybe the dreaded TFI module? Any input would be nice. My check engine let is also on so I'm going the check for codes as soon as I get and obd1 scanner

RaggedGT · Jan 11, 2019

Any codes? Any modifications?
Get a little more info outta ya, and I’ll (as well as the rest of the community) will try and help ya..
Welcome to Stangnet

RaggedGT · Jan 11, 2019

And... just in case you need to know how to dump codes-

jrichker said:
@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it...

Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.[/B]

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.

The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see www.midwayautosupply.com/Equus-Digital-Ford-Code-Reader/dp/B000EW0KHW Equus - Digital Ford Code Reader 3145.
It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.

And-the surging idle checklist,though long and a bit overwhelming-is chocked full of extremely useful diagnostics for sorting out pretty much any running issue
https://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/

Mustang5L5 · Jan 11, 2019

'88 with a check engine light....mass air car I assume?

The speed density versions didn't get the light.

If the light is on, start there.

Good code reader to buy
Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW

Comp Cam · Jan 11, 2019

RaggedGT said:
Any codes? Any modifications?
Get a little more info outta ya, and I’ll (as well as the rest of the community) will try and help ya..
Welcome to Stangnet

It has a
Comp cam
30lbs injectors

RaggedGT said:
Any codes? Any modifications?
Get a little more info outta ya, and I’ll (as well as the rest of the community) will try and help ya..
Welcome to Stangnet

-Comp cam
-75mm throttle body
-306 GT40 heads
-GT40 lower intake
-Cold air intake
-MSD Ignition
-4:10 Gears
-Aeromotive 340 fuel pump
-Lifters and pushrods
-BBK longtubes
-X-pipe to flowmaster mufflers
-King Cobra clutch
-tubular rear suspension
-subframe connecters

Comp Cam · Jan 11, 2019

Comp Cam said:
It has a
Comp cam
30lbs injectors

-Comp cam
-75mm throttle body
-306 GT40 heads
-GT40 lower intake
-Cold air intake
-MSD Ignition
-4:10 Gears
-Aeromotive 340 fuel pump
-Lifters and pushrods
-BBK longtubes
-X-pipe to flowmaster mufflers
-King Cobra clutch
-tubular rear suspension
-subframe connecters

Mustang5L5 said:
'88 with a check engine light....mass air car I assume?

The speed density versions didn't get the light.

If the light is on, start there.

Good code reader to buy
Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW

I will buy but I have to witch parts store has one the one I went didn't have one. And yes it has a mass air flow I'm guessing it was converted.

Mustang5L5 · Jan 11, 2019

Comp Cam said:
I will buy but I have to witch parts store has one the one I went didn't have one. And yes it has a mass air flow I'm guessing it was converted.

No idea. I haven't bought anything in a store in years.

You really want to find out of the car is converted or an original 1988 mass air car. Given that the check engine light works, I think it's original unless someone wired it in. Reason I ask is because converting to Mass air incorrectly can cause some of your issues, for example is the Vehicle Speed Sensor isn't wired in, the car tends to stall when coming from a stop.

But given that you have a check engine light, I don't think this is the case. Reread post #3. If you want to do this quick you can just use a paper clip and count the check engine light blinks. Perfectly fine way to do it if you can't get a code reader ASAP.

Steel1 · Jan 12, 2019

MSD ignition ?
What ignition components are MSD ?

Comp Cam · Jan 12, 2019

Steel1 said:
MSD ignition ?
What ignition components are MSD ?

Don't know, I bought the car already modded the way it is. It does however have an msd distributor

Steel1 · Jan 13, 2019

MSD distributor "could" be part of your issue, in my experience non Ford electronics
don't play nice with these cars.

Comp Cam · Jan 13, 2019

Steel1 said:
MSD distributor "could" be part of your issue, in my experience non Ford electronics
don't play nice with these cars.

Maybe so, I got an obd1 scanner that should be here Tuesday. So I'm going to pull for codes and start there. Any idea on why the msd distributor would cause such a problem?

Steel1 · Jan 13, 2019

Pull codes first and see what shows up.
The non oem electronics in the MSD could cause signal issues or aftermarket tfi.
I've had problems in the past with aftermarket distributors, good thing is you can run an
aftermarket housing and replace the guts with Motorcraft parts.
But let's not jump to conclusions start by pulling codes and post what you get, there are a lot
of members on here that know their stuff.

Comp Cam · Jan 15, 2019

Steel1 said:
Pull codes first and see what shows up.
The non oem electronics in the MSD could cause signal issues or aftermarket tfi.
I've had problems in the past with aftermarket distributors, good thing is you can run an
aftermarket housing and replace the guts with Motorcraft parts.
But let's not jump to conclusions start by pulling codes and post what you get, there are a lot
of members on here that know their stuff.

Well I went to pull for codes today and I got nothing. It just said 000 the whole time. Did I not doit right or does this mean there's no codes?

Comp Cam · Jan 15, 2019

Steel1 said:
Pull codes first and see what shows up.
The non oem electronics in the MSD could cause signal issues or aftermarket tfi.
I've had problems in the past with aftermarket distributors, good thing is you can run an
aftermarket housing and replace the guts with Motorcraft parts.
But let's not jump to conclusions start by pulling codes and post what you get, there are a lot
of members on here that know their stuff.

So I went back outside and did it right this time it's throwing just one code and it's code 31,c for egr valve

Comp Cam · Jan 15, 2019

It's actually throwing 85,10,31

Steel1 · Jan 15, 2019

I'm sure jrichker on this site will chime in, seems to be the authority on resolving trouble codes.
I believe code 10 is just a separation code, not an issue.
31= EVP below voltage
85= purge solenoid

If you use the search function on this site for those codes I'm sure you'll get plenty of info.

jrichker · Jan 15, 2019

Did you get the engine running codes or just the stored in memory codes?

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit.
Revised 06-Aug-2016 to add clarification of the 10 pin connector possible problems
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections. The 10 pin connectors are especially prone to connection problems, If the voltage checks at the EGR sensor are good but not at the computer, the 10 pin connector is suspect.
See the graphic for the 10 pin connector circuit layout.

Code 85 CANP solenoid - The Carbon Canister solenoid is inoperative or missing.

Revised 11 –Jan_2015 to add warning about vacuum leaks due to deteriorated hose or missing caps on vacuum lines when the solenoid is removed.

Check vacuum lines for leaks and cracks. Check electrical wiring for loose connections, damaged wiring and insulation. Check solenoid valve operation by grounding the gray/yellow wire to the solenoid and blowing through it.
The computer provides the ground for the solenoid. The red wire to the solenoid is always energized any time the ignition switch is in the run position.

If you disconnected the carbon canister and failed to properly cap the vacuum line coming from under the upper intake manifold, you will have problems. You will also have problems if the remaining hose coming from under the upper intake manifold or caps for the vacuum line are sucking air.

Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.

Connecting the gas tank vent line directly to the intake manifold will result in fuel vapor being constantly sucked into the intake manifold. There is unmetered fuel that the computer cannot adjust for. The result is poor idle and poor fuel economy.

It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?

The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

The purge valve solenoid should be available at your local auto parts store.

Purge valve solenoid:

The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:

Comp Cam · Jan 15, 2019

jrichker said:
Did you get the engine running codes or just the stored in memory codes?

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit.
Revised 06-Aug-2016 to add clarification of the 10 pin connector possible problems
Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections. The 10 pin connectors are especially prone to connection problems, If the voltage checks at the EGR sensor are good but not at the computer, the 10 pin connector is suspect.
See the graphic for the 10 pin connector circuit layout.

Code 85 CANP solenoid - The Carbon Canister solenoid is inoperative or missing.

Revised 11 –Jan_2015 to add warning about vacuum leaks due to deteriorated hose or missing caps on vacuum lines when the solenoid is removed.

Check vacuum lines for leaks and cracks. Check electrical wiring for loose connections, damaged wiring and insulation. Check solenoid valve operation by grounding the gray/yellow wire to the solenoid and blowing through it.
The computer provides the ground for the solenoid. The red wire to the solenoid is always energized any time the ignition switch is in the run position.

If you disconnected the carbon canister and failed to properly cap the vacuum line coming from under the upper intake manifold, you will have problems. You will also have problems if the remaining hose coming from under the upper intake manifold or caps for the vacuum line are sucking air.

Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.

Connecting the gas tank vent line directly to the intake manifold will result in fuel vapor being constantly sucked into the intake manifold. There is unmetered fuel that the computer cannot adjust for. The result is poor idle and poor fuel economy.

It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?

The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

The purge valve solenoid should be available at your local auto parts store.

Purge valve solenoid:

The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:

Sorry for late reply didn't get your message. But no I didn't check engine running codes. I did KOEO only.

Comp Cam · Jan 30, 2019

Sorry to revive this thread guys but I need to know the location of the evp sensor

General karthief · Jan 31, 2019

If you are talking about the charcoal canister purge valve that is located on the right frame rail, there is a vacuum line from the upper manifold and it gathers up a pair of wires around the heater hose area and together the travel down to the valve then to the canister. If you car is a 94-5 it is located behind the right shock tower and the canister is in the fender well behind the splash shield.

Engine 88 mustang gt, random stalling?

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Been here over a DECADE and still no CT

Been here over a DECADE and still no CT

That is…until I whipped out my Bissell

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That is…until I whipped out my Bissell

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wonder how much it would cost to ship you a pair

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