Degreed Cam in an EFI 5.0 problems...

Malibutommy

New Member
Jun 15, 2008
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I posted a question a few days ago and got a bunch of good responses and I checked everything and my 5.0 still won't idle correctly. I have the cam advanced 2 degrees with the kit from Summit and I'm wondering if anyone knows if this would cause my truck to not idle correctly? I'm new to EFI performance (I have done lots and lots of carbed engines)... Would the computer not read things correctly and cause the truck not to idle and surge under steady load when trying to drive???

Background: 1989 F-150 4x4 5-speed 5.0 with a larger than stock cam (204/214 @ 0.50/ 0.448/0.472 lift) MAF conversion out of a 91 Mustang GT, long tubes and hours and hours of diagnostic work...:mad:

Any responses or help would be greatly appreciated. Thank you in advance
 
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It has the firing order for the non-HO 5.0 and the injectors are wired as such. I called Summit today to double check the cam firing order and it is the same as the non-HO... I ran the KOEO self-test the other day and used my test light to read the codes and I got 31 (EGR- expected since I removed it and haven't gotten the simulator yet) 67 (Neutral Safety Switch- Clutch Switch works fine) and 85 (Canister Purge Soilenoid circuit failure-wouldn't cause it to not idle)

I'm at a loss... I have checked everything else and the TPS is fine, IAC is good and clean, MAF is working properly, both oxygen sensors are wired in correctly, MAP has the vacuum line removed and line is plugged coming from the intake, firing order is correct on injectors and the plug wires. Any help would be great. Thank You
 
It has the firing order for the non-HO 5.0 and the injectors are wired as such. I called Summit today to double check the cam firing order and it is the same as the non-HO... I ran the KOEO self-test the other day and used my test light to read the codes and I got 31 (EGR- expected since I removed it and haven't gotten the simulator yet) 67 (Neutral Safety Switch- Clutch Switch works fine) and 85 (Canister Purge Soilenoid circuit failure-wouldn't cause it to not idle)

I'm at a loss... I have checked everything else and the TPS is fine, IAC is good and clean, MAF is working properly, both oxygen sensors are wired in correctly, MAP has the vacuum line removed and line is plugged coming from the intake, firing order is correct on injectors and the plug wires. Any help would be great. Thank You
 
The cam part number is SUM-3600 from Summitracing, I have wired the injectors for SEFI and wired them to the NON-HO firing order and the plug wired are also for the NON-HO order. I broke in the cam but couldn't get it to idle before or afterwards. The TPS has 1 volt at closed throtle and 4.4 V at WOT and continuous 7.5 V from the computer (A little high but I don't think it would cause any problems???). The IAC has 12 ohms resistance (within limits) and is getting 12 V. The MAF is wired in correctly and is getting 12V+, 12-, and C and D terminals are hooked up to the correct pins in the computer and there is a .6 V difference in them at "idle" and it rises to within specs as the RPMs go up. I have the second O2 sensor wired in correctly but haven't tested it yet. The MAP (now BAP) sensor has the vacuum line removed and the line to the manifold is plugged. I added long-tube headers and have the O2 sensors in the collectors, but haven't gotten the chance to add the rest of the exhaust yet (possible back-pressure issue???). The distributor is in the correct way and ear-timed as best as I can get it. The EGR and the smog-pump are removed as well as all the ports for each are plugged and not leaking. I don't have the EGR simulator yet (another possible problem???). I also moved around pin 51-38 and 11-32, both for the smog pump (Useless but I did it anyways because the computers had different locations for them) and also 8-19 for the fuel pump (I didn't find anyone else who did that but according to the wiring diagrams, thats where it goes on the 91 Mustang computer...)There is probably some other stuff but I have done so much to it, I really can't remember it all.

The MAF had a bunch of numbers on it so here they all are
TOP:F1ZF-12B579 AA
MIDDLE: AFH55 03B
BOTTOM: OG24

Apparently its a stock MAF out of a 91 Mustang GT 5.0 ???

The only number I could see on the computer is A3M1, I know there are other numbers on it but I have to take it out to get those. My friend who I bought it from said that they put in his friend Mustang before he bought the computer just to make sure it worked and it did and then he stored it in his room so it never got wet or anything else like that...

Hope thats what you asked for. Thank you in advance for your help.
 
I just re-double-checked the wiring for the fuel injectors and just like it was before I put it in, its all ok. I checked the ohmic resistance on all the injectors and it was 16 ohms on all of them (good. Spec: 11-18 ohms). I also pulled out the injectors and rails and turned the engine over and all of them sprayed fuel all over my intake. So all of the injectors and wiring are operating correctly. I'm about out of ideas on what it could be... PLEASE HELP
 
A3M1 is a Mustang MAF ECM that uses the 351w/HO firing order. It doesn't matter if you rewire the injectors harness, the system expects a change in one bank of injectors, but it is "correcting" on the other bank. The firing order is also a scalar value in the ECM, not only to fire them in their correct order, but to also establish the HEGO it will use for feedback and fuel trim corrections. Check the information at http://fordfuelinjection.com/?p=92