I just changed the heads, cam, and headers in my 93 F150, 302, and now it is not idling consistantly. It seams to be searching for idle, it drops to 600rpm, then up to 1200rpm. It goes back and forth and occasionally dies when it is at a low spot. I have tried advancing and retarding the base timing but it has not helped. I adjusted the idle up which keeps it from dying most of the time but it still is searching up and down.

I installed GT40P heads, MAC headers, and a Crane Compucam 2020, which I was told was speed density friendly.

I ran the codes and am getting EGR possition codes. Could this be the problem or do I need to make the switch to Mass Air?

 

Mass air is always better and I think that might be your problem.

when increasing the volume of air in your combustion chamber, the fuel must be exactly proportionate to maintain the exact balance your stock ECU had for your engine to handle. I do not believe that speed density ECUs can handle larger injectors though so this might be your problem.

Plus I guess another point would be: Does your new cam have the same idle RPM as your stock one, that might be another source. You may need to reprogram your ecu, that pretty much means you have to goto MAP. Don't worry though its just another computer and an extra wiring harness (ebay etc.).

You can convert your vehicle for about 250 bucks, and a case of beer.

 

what is the lobe seperation on that cam? if its less then 114 then the cam is your problem. after you installed this stuff and set the timing to 10*btdc with spout removed, did you disconnect the battery , let the ecu power down and reconnect. this will clear the ecu and then go drive it around for 30 mins it will help the ecu relearn. also you shouldnt mess with that idle screw put it back to its stock setting.

 

convert for 250 thats a good one lol

 

well i just looked up the cam you got and its lob sep is 112 so it wont idle for crap with a speed density system. who sold you the cam i would be screamin. sure its computer friendly if you had mass air. but that is gonna be way costly for ya. and in my mind not worth it.

 

Other than the cost, $630 for the plug and play Ford kit (5-speed) from Summit, I don't see any disadvantages to the MAF conversion. On the plus side it will allow me to do other upgrades that I was limited from doing with he SD.

 

go here and read www.fordfuelinjection.com

mass air isnt a fix all solution. speed density can run stuff as long as the cam is correct. now stroking a motor may require a bit more tuning but thats what a tweecer is for. lots of guys ive talked to that have lightnings went mass air thinking it was the way to go and get more power and have less computer issue . many have found that the speed density system produces more power if tuned properly using the tweecer system . its cheaper to. so what im saying is that cam in general just might not be whta your after . i can think of a lot of stuf i can spend 600 on ya know . putting the correct cam in will run ya what 150 at most.

 

I converted my 1989 lincoln towncar to from a non HO Speed Density to an H.O. MAP for about $250.


ECU = junkyard
MAP wiring harness w/ mass sensor = from a stripped '90's 'stang (junkyard)
Distributor = same stripped 'stang (junkyard)
H.O. cam = Junkyard
H.O. Heads = junkyard
Intake manifold upper and lower with injector harness, T.B. etc. ($150 EBAY)

I still have the flat top pistons since Im doin this without removing the motor

I got everything from a junkyard "all you can carry" for $45 (we have this twice a year at our local yard)

I spliced and lengthened the 'stang wiring harness with misc. wire I already had

Sorry, I guess including new gaskets and seals it cost me about $300 ($240 U.S.)

 

Kemicalburns, are you running Tweecer? Does it give you full control of the A/F ratio, idle, and spark timing? I have looked into a custom Superchip, and the cost of that by the time I run a few dyno runs is more than the Tweecer and approching the price of a Ford Racing MAF conversion.

Stinkinlincon, how long did it take you to do the conversion? Did you have any problems with getting it callibrated or anything at startup?

Right now I am just looking at my options, trying to figure out what to do next.

 

im not running a tweecer cuz my motor is still stock. but there are plenty of guys that are running them . yes you have full control. there is a slight learning curve but you get in contact with guys that have used it for awhile and they can send you a custom program .