Klickmania

Ok so a bit of background info on my bastard-child of a Mustang. It's got a '92 GT body, '71 Fairlane/Torino block converted to EFI with an AOD tranny. None of that was my choice, unfortunately. The car came that way when I bought it. Anyway, I just rebuilt the motor with an f-303 hydraulic roller cam. I have the right length pushrods and the conversion kit came with a spider for the lifters, so all that isn't an issue. Keep in mind, I didn't upgrade the springs just yet. I've quadruple checked the firing order (I'm using the older 5.0L / H.O. firing order to go with the cam AND the older style block/rotating assembly). I've restabbed the distributor probably a dozen times between last night and tonight, set it up at 10 degrees BTDC, took the spout out, and finally got it to start. Now that I've got it to start, it won't idle and the brake pedal doesn't drop any once the motor starts.

That's making me think I've got an issue with my vacuum somewhere. Now, is this because of the cam I chose, or because of a vacuum leak somewhere? I know flat tappet cams with a lot of lift are notorious for causing idling/vacuum problems, but I didn't think I'd run into a problem like that with the f-303 since it's a hyd roller and it's not that agressive of a cam. Should I upgrade my valve springs, or should I start hunting down a vacuum leak (which I'm dreading).

Thanks for any replys guys. I really appreciate it.

- Spencer

AdderMk2

your F cam DOESNT have alot of lift.. You have a vac leak... find it

Klickmania

Thanks for the reply man. I figgured as much though. I just hate that the previous owner hacked up some of the wiring and the vacuum lines when they rebuilt it.

The vacuum diagram that's in my Chiltons manual is kinda hard to read too. I can't really make heads or tails out of it since I'm not 100% sure what some of the stuff on there is. I guess I'll go do some searching for a good vacuum diagram, unless there's one here I haven't found yet.

Thanks again man.

- Spencer

Klickmania

Ok...So, I just replaced the upper intake manifold gasket and I'm still having the same basic problem. The car still won't idle, but it doesn't seem as bad as it was before. Also my brake pedal will now drop when I start it, just like it should. But my vacuum gague still says intake manifold gasket leak/late valve timing. Still have my timing set at 10 degrees BTDC with the spout out. I've got all my vacuum lines hooked up right and sealed well, lower intake was torqued correctly as well as the upper intake. Gaskets are all in place. It'll run like crap below 1000 rpms and it will die out at around 500 rpms. I also have to basically floor the gas pedal in order to get it to start. Could it be a fuel delivery problem as well?

I also forgot to mention that the car had hypertech stickers on it when I got it, as well as the hypertech badge in the door sill. Would the entier PCM be replaced with one from hypertech, or can you just send your stock computer in to get it flashed? I don't know much about the computers on OBD-I cars. I'm just wondering if the car has been tuned to run with a flat tappet cam like the one it had, and not a hydraulic roller. Would getting a tune help fix my problem? Thanks again guys?

- Spencer

Klickmania

Anyone??? I'm kinda lost and I don't know what else to check. I'd really appreciate some replys.

- Spencer

AdderMk2

checking to see if it has a chip would be a good start... then remove it

Klickmania

Thanks man. How exactly do I go about doing that?

- Spencer

pete88gt

pull out the computer and unplug it, where the computer connects at there will or won't be a chip

Klickmania

Thanks a bunch. I'll be sure to do that sometime this week, if not I'll get to it on the weekend.

- Spencer

Klickmania

No chip in it, like I thought. Got a new battery in it today, which helped with the start up, but it still won't idle. I'm gonna try to reset the idle tomorrow, and double check for vacuum leaks.

I also have to pump the throttle in order for it to start properly. Kinda just like a carbureted car. Could it be a fuel delivery problem? Don't think I have a fuel pressure gauge.

- Spencer