Bad idle and dies at lights
 

I was searching the Mustang forums but I did not find exactly what I was looking for. I believe some of my bolt ons may be causing problems.
I'm a BMW tech but I'm spoiled with top of the line scanners and diagnostic tools that obviously don't work on an old Mustang motor.
Anyways, I just got my 5.0 on the road. Drove it home from the shop about 7 miles. Loads of power but at red lights it dies every time. Any help on what direction to go in will really help. I have no experience with old mustangs.
What I have: balanced 302, freshened GT40 heads/intake, TFS stage 1 cam, stock T5, 8.8 3.27, diy build with MRM wiring and A9L.
New parts: TPS, MAF (stock sensor in 76mm housing), CAI (cheap cone filter located in bumper), MSD dizzy, TFI, and Coil.
Junkyard parts: O2 sensors, baro meter, explorer throttle body and 19 injectors.
Egr is disconnected and blocked off at intake.
Timing set at 12 btdc

I was having a similar issue on my car. I ended up replacing all the used parts with new ones trying to eliminate things. For me, it ended up being the throttle position sensor. That's a sensitive little bugger. You can also check for vacuum leaks by spraying some starting fluid around the hoses and see if engine surges. Pay close attention to intake gasket.

Good tip Gunpilot. I will re adjust my TPS for fun.
I just pulled codes and I got alot of EGR codes like 31 82 and 83. These are to be expected because it is not hooked up.
I also got 85 that means excessive fuel flow. I'm using the stock Miata pump and the stock mustang rail with 19# injectors.

Do you have idle surge? If so that would suggest a vacuum leak. Code 85 is the canister purge valve - probably not there and not an issue.

You may simply want to do a base idle adjustment. Get the engine up to temperature, pull the idle air bypass connecter, adjust to desired idle, install connecter, turn engine off, start again, verify, repeat if necessary, etc. Once idle is set, adjust TPS voltage if necessary (like to around .98 volts).

Excessive fuel? Did you test your junkyard injectors? You can pull and bench test pretty easy. Plenty of info on YouTube. Seals could be bad and stuck open. I ran carb cleaner through mine both directions to clean them out while actuating them with a battery.

Thanks for the suggestion Miatamike. I Googled code 85 and you are right that it's the canister purge.
I have an injector bench tester with a flow meter at work and the injectors checked out fine a year ago when I got them.

Set the base idle. Be sure that the idle bypass valve is not full of carbon & crap.

I set the TPS at 0.97 vdc. Idle control valve is clean. Smoked it for vacuum leaks and found a leaking egr. It is not in use so I'm building a block off plate. I siliconed it shut for now.
So after that it seemed to idle good but once it reached operating temp the original symptoms came back.
When I'm between gears the rpms drop slowly like they should. But when the car is stationary or moving very slowly the rpms drop very quickly. The ecu trys to bump up the idle but the motor dies after a hick up or two.
I will bump up the base idle as a band aid for now.

I would run a KOEO and KOER test and see what codes it spits out. Sensors you want to be new are the coolant temp sensor, the O2 sensors and the throttle position sensor. All three play vital roles in giving the ecu the information it needs to make fuel ratio decisions and go into closed loop operation. Sensors like the baro and air charge temp sensors are not as vital and can be used.
I'd put money on the coolant temp sender being out of range ... A KOEO test will confirm or deny my speculations.
Good luck,
-Jason

I have pulled codes and i have egr and purge valve codes. I expected those because they are not installed.
I have a new ect sensor but no change. I am working on getting new O2s.
I belive part of my problem is the throttle does not return all the way back to idle everytime. I probably messed up the springs resistance when i tacked on the new bell crank. So... do i try to add another spring or say its trash and spend the money on a bbk unit? Do yall think new O2s or a throttle that returns correctly is of the highest priority?

I would first correct the mechanical throttle body operation, then set base idle (by adjusting the butterfly opening).

I have the Explorer TB as well and made/attached the bell crank. The only return spring I have at the moment for the throttle cable is the TB's return spring and it is working fine. If the spring is shot, a new TB may be in order. I have no EGR or spacer so it is very close to the valve cover and heater tube. Is it rubbing on any of that kind of stuff?

I installed a carb return spring to mine.

I also have a stronger return spring on mine. The Miata cable has to take a pretty sharp turn to the right just after the firewall and the Ford Explorer throttles were never meant to be heavy.

-Jason

Ok... i have all new sensors except the MAP/BAP. I have been adjusting timing, base idle, and TPS all weekend." Idle" (doesnt really hold an idle) fuel pressure 39lbs. Timing turned down to 12btdc. The new 02s didnt seem to help. Still so very rich. It makes my eyes water there is so much gas in the air.
The idle sucks in cold starts now that i have been adjusting everything. It wants to idle up then bogg and die unles im tapping the throttle. Once its warm it does better but still dies at red lights.
Starting to think i have a stuck injector... maybe?
I am thinking about drilling a bigger hole in the explorer butterfly.

JASON! This is for you. I dont know what bank to plug the 02s to. I looked through the book you sent with the harness and it does not mention left or right on the 02 plugs. Does it matter? My thought is i have a stuck injector and the ecm is trying to lean out that bank BUT my 02s are backward and its leaning the wrong side. Does that make any sense?
I work on Bimmers and if you swap the 02s the computer will lose its mind. Is this the same on 5.0?

Oh yeah... forgot to add that i fixed the returen spring issue. Too tight of an adjustment at the petal and i added a carb style spring to the throttle.

I would not make the hole in the butterfly any bigger. You should be able to "open" the butterfly if needed but and the idle air controller has a pretty wide range to add air if the base idle is adjusted good.

got the same problem, found it's was the PIP so i change the complete distributor.

richporter sell one for cheap.