hello im new to the site.i have always loved mustangs how ever i have alway worked on classics. recently i bout a 87 lx 5.0 this past winter i did a b303 cam swap mass air conversion smog pump delete and pulleys.i start the car it runs good no miss, timeing is dead on,but after a few it slowly loads up i tried turning timeing back looked over all my work about a million times i dont have a computer to cheak for codes so i was wondering if any one could give me some advice or a direction to go thanks nickim lost
- Thread starter nicks87
- Start date
hello im new to the site.i have always loved mustangs how ever i have alway worked on classics. recently i bout a 87 lx 5.0 this past winter i did a b303 cam swap mass air conversion smog pump delete and pulleys.i start the car it runs good no miss, timeing is dead on,but after a few it slowly loads up i tried turning timeing back looked over all my work about a million times i dont have a computer to cheak for codes so i was wondering if any one could give me some advice or a direction to go thanks nick-
Sponsors (?)
what do you mean it loads up ?
Beasty306GT
Active Member
fuel pressure regulators are damned near useless....the computer compensates for changes made with the fuel pressure regulator.
The 87s came with speed density, not mass air.
A speed density system relies on a steady high vacuum signal to the map sensor on the firewall. The computer uses the vacuum signal essentially to know how far you have your foot buried into the gas.
See, a stock cammed 5.0 will put out on average 17-20 pounds of vacuum at idle. I've got the same b303 cam that you have, and I put out around 11 pounds at idle.
The stupid speed density computer is looking at the 11 pounds of vacuum that your engine is making at idle, so it's thinking you have your foot buried in the gas, and the computer is screaming, more fuel, more fuel!!!!
do a search on mass air conversion...this will fix your problem. It requires a new computer and some simple wiring and a mass air meter. It is a pretty simple swap
The 87s came with speed density, not mass air.
A speed density system relies on a steady high vacuum signal to the map sensor on the firewall. The computer uses the vacuum signal essentially to know how far you have your foot buried into the gas.
See, a stock cammed 5.0 will put out on average 17-20 pounds of vacuum at idle. I've got the same b303 cam that you have, and I put out around 11 pounds at idle.
The stupid speed density computer is looking at the 11 pounds of vacuum that your engine is making at idle, so it's thinking you have your foot buried in the gas, and the computer is screaming, more fuel, more fuel!!!!
do a search on mass air conversion...this will fix your problem. It requires a new computer and some simple wiring and a mass air meter. It is a pretty simple swap
you dont need a computer to check for codes. look at the stickies in the tech thread and it will show you how to check for codes with a paperclip and a test light. I do it all the time and it works perfect.
http://www.stangnet.com/mustang-forums/698148-help-me-create-surging-idle-checklist.html
this thread shows you how to pull codes. let us know how it comes out.
this thread shows you how to pull codes. let us know how it comes out.
