Being I have an AOD transmission I was informed by several posts on many forums that it didnt matter. The engine also ran well up until the wrong dizzy gear sheared my cam gear off hense the rebuild. I am not trying to blow off any Ideas because right now I am struggling with any myself but If the computer does matter then there are several posts and posters giving wrong information.

 

Hey all I pulled codes again and am now confused as to the first code. I never got this one to begin with.

KOEO codes:
56(?) MAF or Vain air flow? I don't have either of these. The computer I purchased at Oreilly Auto was for a 351W with C6 I thought Ill pull it and get the numbers off the ECM

67
85
91
92
93
94
99

 

The problem here is the motor is capable of enough HP(moves enough air) to need 24lb injectors but the computer is programmed for 19lb, so the idle will improve with 19's but it'll be lean under load at any kind of rpm and won't be safe to drive. A 7.5 PCM for an older truck with a manual or C6 would be an option but it still won't run as well as it should because the fuel requirements for the larger displacement are different, the 7.5 would need more fuel at idle and low rpms but the built 5.8 will need more fuel at higher rpms because it should make more HP than a stock 7.5.. ie: move more air.

Like I said the best option is to get it converted to MAF and add a tuner, then you can give the computer the correct data on engine displacement, injector size, and the MAF transfer function and it can make accurate calculations for fuel requirements... instead of constantly correcting itself based on O2 sensor feedback alone.

 

It matters if you have a computer designed to run an elec trans with no elec trans there to control. I guess we just assumed you are using one for an e4od since you never specified.

If you're throwing codes for mass air, there's your issue.

 

Alright, I don't have the money for the MAF conversion and am needing the truck on the road by the coming up weekend so I am going to pick up a ECM for the 7.5 with manual for the time being and I will re-install the 24# injectors. During which I will save up and research for the MAF conversion.

In the moment though the MAF code is a bother due to the fact I have a computer for 351W 1989-1990 and a manual trans with federal emissions. Why on gods green earth would I retrieve a MAF code did Oreilly give me the wrong ECM? My ECM # is 784436

Guys I due thank you for all the help if anyone is in my area please hit me up I already owe Conanski a beer.

 

No that is a mis-read of the codes on his part, code 56 can also be a TOT(trans oil temp) sensor issue or it could just be that the codes were pulled on a cold engine when all temp sensors are often out of range and temp sensor codes should just be ignored. It's also important to note that there are truck and car specific definitions for the same code numbers so you have to make sure you have the correct code definition list to reference.

 

Conanski that would be why I didn't get any codes yesterday while the truck was warm thank you very much. Am I the only one who thinks this speed density crap is... well just that CRAP.

I know there are a millions topics on the MAF conversion I WILL READ THEM ALL but while im on here just asking what is the best and most descriptive thread for the conversion in your opinion?

 

There is no one complete guide to MAF conversion. Best thing to do is read them all and piece together what you'll need to do.

FWIW, I don't think the 460's idle and "around town" fuel requirements are really that much different than the 351, especially a mildly built one. It'll probably be close enough that the O2 sensor will compensate.

 

Should run great with 460 ecm for manual trans, 24# injectors, and all sensors functioning. No, speed density is not crap. When they run *right*, they run well.

 

Maybe.. maybe not. I think a 7.5 PCM would do better but the PCM only looks at the O2 under low load conditions, anything more than about 1/4 throttle and it switches to open loop and relies 100% on tables.. which aren't gonna be correct for a healthy 351 that should make upwards of 100hp more than a stock 7.5EFI.

 

Not true. Closed-loop fueling changes are committed to the KAMRF memory, which is the long-term adaptive fueling correction. KAMRF corrections are applied when in open-loop mode, but they only get updated in closed-loop.

 

Well I have re-installed the 24# injectors. The computer is on the way picking it up in an hour. When I was ordering the computer one of the guys at the auto part store told me of a mysterious wizard who can cut a chip and reprogram my computer to fit my needs. He stated he has several mustangs and trucks on speed density that has been modified and tuned this way. I was under the impression that the ecm in these vehicles was not programmable or am I wrong?

That being said I will post the results of the computer swap shortly.

 

All of these PCMs are technically programmable, the issue is that the memory map for most of the SD PCMs have not been sorted since they are seldom used for performance applications so the programmer has to figure that out first if he can before he can put new values in. If you do have a guy local to you that can build a chip for the PCM you get then consider yourself lucky, definitely worth having a little chat with him.

 

As Conaski said, all EEC-IV computers have the ability to be tuned, the trick is finding someone who can tune your specific computer. The Mustang computers are pretty different compared to the truck computers.

 

Well then as far as the tune then there is a silver lining to this story after all.

Ok, I installed the 24# injectors and placed an ECM from a 1989 f250 with the 7.5L and manual trans. It now runs like it did when the 19# injectors were in with the old computer which means this is good but I now have a idle and light smoke issue.

Pulled codes again and received: KOER
12
13
33
41

When I look them up all I get is 12 idle too low and ,13 idle too high, motor not idling correctly(

33, EGR not opening properly. I then blocked the EGR off with piece of an aluminum can and nothing changed.

41 System lean fuel control. I pulled the vacuum line off the regulator and the engine slowed the idle down a small amount and evened out a little.

When I removed the EGR valve from the truck I plugged the hole and ran the truck, no difference, but i then pulled the plug from the EGR hole and found the motor Rev-ed up quite nicely. Is this normal of a large Vacuum leak I always kinda figured the truck would die out.

I know its a Frankenstein but what in the world could be wrong with this truck. All sensors are new and replaced within three months aside from the MAP sensor and O2 sensor which appeared to be new when I bought the truck.