My 92 LX Auto 5.0 would not start. A9P computer was sent away to be repaired and when it came back runs fine except when it hits 3500 RPM's and above. Feels like it is coughing, choking, just plain cutting out. Any gear or just sitting still. Can there still be a problem with the computer? Plugs have been changed along with the cap, rotor button, plug wires, fuel filter etc. Never did this before in my 25 years before the computer was sent away. Car is a convertible with only 16000. miles on it and it looks brand new. Tired of this problem and just trying to find out if there could be a problem with the rebuilt A9P computer. I know I received mind back, because we marked it. Any helpers out there?????? Thanks.
92 Lx 5.0 Engine Chokes At 3500 Rpm
- Thread starter mleg
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I'm gonna guess you have not checked for codes, there is a thread in the tech/how to section, it will show you how to check for codes, also check fuel pressure.
This is figuring that the fuel tank is clean and fresh gas
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This is figuring that the fuel tank is clean and fresh gas
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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
Thanks for all the replies. I'm not sure I'm Mustang smart enough to figure dumping the codes. I have read the thread on dumping the codes around a dozen times and still not sure I want to take it on. Will talk to my mechanic and see if he can help. Thanks for all your replies.
mikestang63
SN Certified Technician
NO need for a mechanic
Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW
One of these days I'm going to make a YouTube video on using this thing. It's easy
Amazon product ASIN B000EW0KHWView: https://www.amazon.com/INNOVA-3145-Ford-Digital-Reader/dp/B000EW0KHW
One of these days I'm going to make a YouTube video on using this thing. It's easy
I'll see if I can get one done over the weekend but don't wait for me. Hectic enough over here with kids that it might have to wait.
mikestang63
SN Certified Technician
You are the man. Ordered mine yesterday and hope to have it Tuesday. Maybe now I can find out why it will not run at 3500 RPM's. Thanks for your help. You are pretty damn good on TV.
Pluged in my new Innova 3145 tool today and out of all those codes in the book I only had one when it was running. No codes when the ignition switch was on. The only code that was pulled was 21R. The book states that the cooling Temp. sensoe is out of specified range OR ECT out of range. Does anyone know if either of these would cause it to choke and cough at 3500 RPM's? Got my doubts.
Did you run the codes with the engine hot or cold? If cold, let the engine warm up and try it again.
Also, after the engine running codes, blip the throttle and do the cylinder balance test.
And yes, a bad coolant temp sensor will cause issues
Also, after the engine running codes, blip the throttle and do the cylinder balance test.
And yes, a bad coolant temp sensor will cause issues
Ran the codes with the engine hot. Not sure what blip the throttle is and will have to read up on the cylinder balance test. Thanks for the help.
Basically at the end of the engine running codes, when they've repeated twice, the code reading will stop. At that point, give the engine a healthy rev. The input from the TPS will trigger that start of the cylinder balance test which is a primitive way of testing for misfiring cylinders.
And yes, engine hot and you got a code 21...bad coolant temp sensor. It will give you issues
No code
High speed miss on a warm engine
Revised 7 Nov-2016 to add PIP sensor as possible problem and dumping the codes to help determine if it is the TFI or PIP.
The TFI module mounted on the distributor is one of the culprits for a high speed miss on a warm engine. The other suspect is the PIP sensor inside the distributor. If the problem does not occur when the engine is cold, the TFI module or PIP is definitely suspect. Dumping the codes may help determine which one it is. You may need a special socket to remove the TFI module, but most auto parts stores will have one for $5-$7.
Be sure to use plenty of the heat sink grease on the new TFI and clean the old grease off the distributor.
See Automotive Tools Specialty | Auto Mechanic & Technician Diagnostic, Testing Equipment | Thexton
diagram courtesy of Tmoss & Stang&2Birds
High speed miss on a warm engine
Revised 7 Nov-2016 to add PIP sensor as possible problem and dumping the codes to help determine if it is the TFI or PIP.
The TFI module mounted on the distributor is one of the culprits for a high speed miss on a warm engine. The other suspect is the PIP sensor inside the distributor. If the problem does not occur when the engine is cold, the TFI module or PIP is definitely suspect. Dumping the codes may help determine which one it is. You may need a special socket to remove the TFI module, but most auto parts stores will have one for $5-$7.
Be sure to use plenty of the heat sink grease on the new TFI and clean the old grease off the distributor.
See Automotive Tools Specialty | Auto Mechanic & Technician Diagnostic, Testing Equipment | Thexton
diagram courtesy of Tmoss & Stang&2Birds
No more codes. Replaced the coolant sensor and ran the cylinder balance test and that came back with a code of 90 which by the book means all cylinders are OK. The code 21 I had for a bad coolant sensor is also now gone. Code tester comes back with 10's and 11's which means all engine test are normal. WELL, it still starts missing badly at 3500 to 4000 rpm's. Not a small miss, but the tack will dance back and forth from about 2500 to 3500 rpm's. Thanks for everyone's help. Not sure which way I will turn now. Still believe it is the computer that I sent off and had rebuilt. Never, never had this problem before it was sent off.
Next step I would say is to mount a fuel pressure gauge where you can watch it like maybe on a windshield wiper arm, it's only temporary, watch the pressure as you drive.
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