Backfiring/Hesitation/Powerloss
- Thread starter Jeff7477
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CBZGT50
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Every car I have owned that was fuel injected would eventually run kinda "puttery" after about 50K miles. I learned that removine the the throttle body, TB gasket and sometimes the upper intake will help. What needs to be done is to have the back side of the TB sprayed with brake cleaner or laquer thinner. Spray a little in the intake to get the crud off. It's just like the old times when you had to spray carb cleaner in the intake of the carb to get it running better. I did mine tonight. My 93 Cobra would stumble at 5200 rpm and spit and bounce like it was the computer rev limeter. I knew better. So I removed the TB (which only had two of four bolts on it) and removed the old gasket and cleaned the TB with some brake cleaner. Hit the idle solonoid hole and the back of the butter fly. I had some gloves on and just wiped all the black carbon deposits off. I stuffed a rag in the upper intake to remove any liquid cleaner. I bolted the TB on with four bolts, cleaned the MAF and put the tube and filter back on. I can hit 6300 rpm and break tires in first and second just by appying the gas.
So try cleaning the TB. I have done it four times on four cars and had positive results every time as far as drivability.
One thing, DON'T USE CARB CLEANER. It leaves a residue and eats a film off of the TB and it will rust.
PE C
So try cleaning the TB. I have done it four times on four cars and had positive results every time as far as drivability.
One thing, DON'T USE CARB CLEANER. It leaves a residue and eats a film off of the TB and it will rust.
PE C
Jeff7477 said:
Codes 94 & 44 - AIR system inoperative - Air Injection. Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve. The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.
The two electrical controlled vacuum valves mounted on the rear of the passenger side wheelwell turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.
Remember that the computer does not source power for any actuator or relay, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.
The computer provides the ground to complete the circuit to power the solenoid valve that turns the vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel & the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin 32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Starting the engine with the computer jumpered to self test mode will cause all the actuators to toggle on and off. If after doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38 and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin 38 & Solenoid valve #1.
If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation. Power & ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif
I have the same problem and I've changed most everything as well.OK well I ordered a new distributor today overnight. Will get it tomorrow. I have a gut feeling that its a spark problem not a fuel problem because of the way it feels.
Was going to just replace the PIP but I guess you need to have something pressed off to replace one so I figured I would just drop some coin on a good MSD.
Heres to hoping.
Was going to just replace the PIP but I guess you need to have something pressed off to replace one so I figured I would just drop some coin on a good MSD.
Heres to hoping.
Fuel pressure OK, the injectors are not firing, OR one or more injectors stuck open
Do a cylinder balance test: Warm the car's engine up to normal operating temperature. With the Engine Off, Key OFF, use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 99 or the number of the failing cylinder such as 22 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure
The red wire on each injector is powered up whenever the ignition switch is in the Run position. The computer provides a ground to complete the circuit and fire the injector. The injector must have a ground to squirt fuel on command. A short to ground in the injector return wiring can cause one or more injectors to be continually open or triggered
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help
Using the above diagram, check the resistance between the injector and the computer. Clean and check the 10 pin connectors since they are a potential trouble source. Any resistance greater than 1 ohm between the injector to computer wire and the matching pin on the computer connector is a problem.
See http://fordfuelinjection.com/?p=6 for more help
Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. You’ll need it to do the cylinder balance test
See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html
Do a cylinder balance test: Warm the car's engine up to normal operating temperature. With the Engine Off, Key OFF, use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. The engine RPM should exceed 2500 RPM's for a brief second. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 99 or the number of the failing cylinder such as 22 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures. Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure
The red wire on each injector is powered up whenever the ignition switch is in the Run position. The computer provides a ground to complete the circuit and fire the injector. The injector must have a ground to squirt fuel on command. A short to ground in the injector return wiring can cause one or more injectors to be continually open or triggered
A.) A Noid light available from Autozone, is one way to test the injector wiring. If the light stays on constantly, either the wiring has a short to ground or the computer has failed
B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles An injector stuck open will release a continual stream of bubbles. Cheap if you have the stuff laying around, and works good too. The same trick works great to find leaking injectors too.
The wiring for the injectors may have some bare spots in it causing the injector to computer control wire to ground out. This would cause the injector to remain on anytime the key was in the Run position. Remove the injector wiring connectors from the injector. Note that each injector has one red wire for power and a non red wire (wire some color other than red) for computer controlled ground. With the key off, disconnect the computer connector from the computer. Use an Ohmmeter between the non red wire and ground. You should see more than 100000 (100K) ohms resistance.B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles An injector stuck open will release a continual stream of bubbles. Cheap if you have the stuff laying around, and works good too. The same trick works great to find leaking injectors too.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help
Using the above diagram, check the resistance between the injector and the computer. Clean and check the 10 pin connectors since they are a potential trouble source. Any resistance greater than 1 ohm between the injector to computer wire and the matching pin on the computer connector is a problem.
See http://fordfuelinjection.com/?p=6 for more help
Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. You’ll need it to do the cylinder balance test
See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html
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trents99
Founding Member
I kinda feel like I did after watching Dances with Wolves.While mildly entertaining I'm glad it's over 
That might be my problem too. Congrats on not giving up and breaking something.
That might be my problem too. Congrats on not giving up and breaking something.
When the car was cold did it feel like it had more power? When my car is cold it feels like a monster, when it warms up when I take off it feels like ****!
I'm thinking about replacing the:
PIP
MAP
TFI Module
and if that doesn't solve it, ill start looking at the fuel section. Does my problem sound like an ignition or fuel problem?
I'm thinking about replacing the:
PIP
MAP
TFI Module
and if that doesn't solve it, ill start looking at the fuel section. Does my problem sound like an ignition or fuel problem?
Do some thinking about how things work before you start throwing parts at a problem. That approach just makes you broke and frustrated. Start you own thread and describe your car, model year, mods & problem.Synned said:
Here's a book that will get you started with how the Ford electronic engine control or "computer" works.
Ford Fuel Injection & Electronic Engine Control 1988-1993 by Charles Probst :ISBN 0-8376-0301-3.
It's about $20 from Borders.com see http://www.amazon.com/ . Select boo...have to count flashes or beeps.. Cost is $35.
I have the same problem with backfire through intake on acceleration. More so when cold and gets much better when warm or over 2500-3000 rpm. Replaced plugs-wires-cap-rotor-ignition coil-module-pickup coil-whole distributer-timing chain-fuel filter-alternater(Was bad)-took off throttle body and cleaned it-took off egr valve and made a plate for it-pulled codes and only got different egr related and emissions codes-check engine light is not on-put a cold air intake on it-timed it all over the place to see if i can get rid of it but its still there. I read that plugged cats could cause this problem. Has anyone heard that???? I have new bbk headers and h-pipes coming.I loosened the collectors 2 let it breath and seemed like it ran great. im in a non DEQ area so guna eliminate all cats and cross fingers it will go away. if nothin else it should sound bad ass. I have an 88 so its SD and not MAF. HELP
Did you ever figure this out this is exactly what my 87lx is doing I've replaced fuel filter,plugs,wires,cap,rotor,coil,negative battery terminal and nothing has worked so I was thinking Tfi or map
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