1990 mustang 5.0 staring problem, i have a video of when it actually turned on but shortly after choked and turned off. Im new to the site so im not sure if i can post a video. If i can i will because its a way easier explanation of my problem. As of now the car cranks but doesnt turn over and is making a loud backfire type of noise. I was wondering if anyone could help me diagnose my problem?

 

Check for codes. Do a key on engine off test. could have a faulty tps, dirty maf, dirty iac, etc but it could be crap shoot at the moment. check for codes 1st to get a starting point. codes can be present w/o the light being on.

 

Im just waiting on the code reader to come in i order it off amazon. As soon as i get it, ill report back.

 

you can turn your key off and back on few times and get the codes that way

 

no problem. some things you can get that I like to have on hand CRC maf cleaner, CRC electronic cleaner, dielectric grease & CRC TB cleaner. you may need to clean some of the connections so the electronic cleaner and grease will come in handy. the others are pretty obvious.

 

I did the key on key off test. The codes that came up were Check Engine & Check Oil. I have cleaned the maf,iac,tb. I have the crc electronic cleaner,never used it not really sure how to.

 

There isn't a code for check engine or check oil, I don't know what you did or what the tool is reading. If anything you should have gotten code 11 for system pass.

I had you get the electrical cleaner to clean a connection. sometimes a code will come up and it due to a poor connection.

anyhoo lets start again. here is the procedure for both Key of and key on testing:

plug in the test into slef test port located on the drivers side by the behind the strut tower/ in front of the wiper motor area.

turn the key on but do not start the car, this will start the KOEO test.
It will take a few second sfor the codes to start to read then ther will be a pause for continous memory codes.

After the CM codes are read turn the key off for about 10sec. leaving the tester hooked up ( now going to do a engine on test). now start the car, the idle will rasie on its own has it gets ready to test, codes will read like the other test.

another area that causes idle issues ( and others) are the salt&pepper shakers ( two cylinder looking 10 pin connectors mounted on the intake facing the firewall) you may need to clean the connection and repack teh female side with dielectric grease( just the little female connectors not the whole plug). you may also need to clsoe them up a little or slightly open the male ends with a small pick to improve the connection.