Hi I have a 1988 mustang 5.0. The problem is sometimes when I start the car the motor would raise up and idle around 2300 to 3000 RPM. I will click the key to the off position and back to the on position quickly and the car will idle normally. When I drive the car 5 miles and turn off the car and try to start it the car will not start it will crank and crank. I used my noid light and my spark tester and I was getting both. I took it to my trusted shop and they told me the reason why the car wasn't starting is because the engine would get flooded and they said they kept loosing communication with the PCM. I got my reciept. This is what my receipt says. (Engine will not start up once it is warmed up. Engine gets flooded when not starting, Technician experienced no communication to computer during this time.)11 pass10 SEP22 Map out of range35 RPM too low egr test 51 ECT input too high53 TPS input too high54 ACT input too highI was told to get a breakout box so I bought a Ford EEC-IV breakout box and plugged my 8LD in I tested every injector and I was getting 13+ DC volt. So I tested my throttle positon sensor pin 47 and it was at 97v closed throttle. When the engines is warmed up the the Engine coolant temperature sensor would be at .63 DCV pin 7. When the car is idleing at 3g the Idle air control motor will be at 4.17v pin 21. I will reprobe the ECT and it would be at 1.17 DCV a second after I shut the motor off and started back up. So far I changed the TPS, barometric pressure sensor and the PCM.
Country: United StatesMake: FordModel: MustangYear: 1988Engine: 5.0
Changed the Throttle position sensor, barometric sensor, Changed out the engine harness
Hello and welcome to JA, next to the throttle body, are 2 large connectors, the various engine sensors wiring all go through these 2 connectors...we used to have a TSB...technical service bulletin...to install a jumper harness between these two connectors because of high resistence, which will cause the signal from the sensors on the engine to be erratic, missing, etc...I dont know if the jumper harness is still available, but I would take the connectors and unplug them, clean them out with brake cleaner, blow them dry with compressed air, apply some dielectric grease and I am sure the problem will be fixed. We installed the jumper harnesses due to poor contact/high resistence, but in hindsight, we could have just cleaned out the corrosion in the connectors and acheived the same result...let me know how you make out.
the 10 pin connectors or salt and pepper shakers. I tried spreading the male terminals with a picking tool. That was my first suspicion. Is there any other sensors that would cause the engine to idle high. As far as I know the the engine coolant temperature sensor will bump up the idle when the sensor tells the PCM its over heating to work the waterpump and mechanical fan harder.
there are 2 large connectors just next to the throttle body, they may be what you refer to as salt and pepper as they are black and white, spread the male pins and clean them as I instructed you to...the IAC will cause a high idle also, try cleaning the throttle body yet?
no but the throttle body is aftermarket and is only a few years old but I can give it a try.
ok, let me know
I followed these instructions. "http://oldfuelinjection.com/?p=85." I used a pick tool to open the male terminals. It was hard to reconnect but I finally got it together. I still have the same symptoms how do I check for leaking injectors?
to check for leaking injectors, you need to pressurize the fuel rail, and block off the return line, so the pressure cannot bleed off to the fuel tank, the pressure should hold if the injectors are ok...but this will not cause your problem, so knowing I would go about trying to find someplace to obtain the jumper harness to install inline with the fuel injector harness...try a Ford dealer, ask them to check something called Vintage Auto Parts...this place purchases most of the dealership old inventory and old inventory from Ford...they are usually a good source for stuff like this.
does Vintage Auto Parts have a website?
no, it is a phone number that only the dealers have, they are the only ones authorized to use this service
So I ordered and installed the jump harness and it didn't fix my problem. Is there a way to check the connection using a DVOM or is there anyway to check the PCM to see if its bad?