5.0-5speedgt

hey guys i have been working on this car for over a month now and because it was someones project before mine there are things im not sure about. i know it has 289 heads and an ho firing order, 75mm tb, new msd distributor, new plugs and wires, smog delete and ac delete. while idling if i punch the throttle it will pop/backfire into the intake and in the low rpms while driving it will do the same. with the motor cold all of the cylinders are between 120-125psi on the comp test

when i ran the codes i got 63,96 koeo
and 13 koer
the balance test seemed like it sent out 77 2x but im not sure it was actually performed correctly

the car also ran a little better and with less backfiring with the o2 sensors unplugged

also brought the motor back to 10*btdc

sorry for the randomness of this post im kind of just thinking of things as i type. any help with this problem would be appreciated

5.0-5speedgt

No? No love shown? Please...

mjr46

check firing order........you say it has 289 heads? how did you confirm this? what year block is it and how do you know it has an h.o firing order?

5.0-5speedgt

I know it has 289 heads because of the auto light 45s I had to replace and I'm pretty sure it is a 302 block because the older firing order makes it run like complete ****. The car is at the point now that I'm pretty sure it just has a vac leak or bad sensor. If I punch the throttle in neutral it will pop then Rev up and if I drive it it will pop and bog down anywhere below the 2500rpm range and the car feels sluggish. The sluggishness might be the gear ratio but I'll be checking that our today. I've had other mustangs and this is by far the slowest. Once I check the rear end it will give me a better idea of the acceleration I should have. The car seemed to run a little better once I unplugged the o2 sensors. That's leading me to believe this is an air/fuel ratio problem like a vac leak or some other sensor. Any thoughts?

mjr46

try unplugging the maf and see if issues go away....if so try cleaning the maf

5.0-5speedgt

All it does is die. I tried also unplugging the TPS and IAB with no change. I might pull the upper intake tomorrow to check any vac lines under there. I've searched everywhere I can and can't find a leak anywhere.

It's so annoying g that this was someone else's project and they obviously didn't know what they were doing. I'm almost willing to swap the heads to gt40s and start fresh from the deck up

5.0-5speedgt

So today I decided to pull the upper intake and see if anything was wrong with the vac lines under the upper manifold. Once I touched the longer bolts (replace with threaded rods and nuts) I noticed they were loose. Once I pulled them I realized they were completely stripped/crossthreaded. After the upper was removed the lower bolts were not much better. The torque required to remove each one was completely different. Once I removed the valve covers I also found out that the heads are 351w I believe. (351 cast into the head) I managed to get a stock 50 intake manifold and once the gaskets and egr spacer come in I'll be putting it all back together. I'll post back in 4-5 days with any updates. Hopefully there was maybe a leak in the manifold that the spray just wasn't getting to and the car will be good to go by the weekend.

Anyone have any luck with the afr top end kit? Advertises 360hp and 370 torque with heads, intake,cam,rockers but on a 306 motor. Just want to know if anyone dynoed that kit or any others on a stock 302 block.