Hello everybody!

So I've been perusing around trying to find some pretty specific advise, and I am having trouble finding some real definitive answers.

I own a 1995 F150 that had a 5.0. I've just recently swapped it out for a 5.8. Some info to help fill yall in here:

The 5.8 came from a '94 F250. It originally was speed density. I kept the MAF on my '95 and will be using the stock computer to run the engine. I got lucky and picked a 5.8 that shared firing order with my previous 5.0. The 5.8 previously had an E4OD as a tranny, and is now bolted up to my current 4R70W. I did not switch flexplates. I came up in all my searching with no definitive conclusions for or against this so we'll see how that goes... The 5.8 is bone stock. No upgrades whatsoever. I even kept the EGR crap (I know so boring...)

So to my question. Should I get the computer tuned? I've read that the engine runs fine with the 5.0 computer, but does it really? I'm afraid of running lean mixtures due to the increased air volume. Or does the computer have the ability to account for that on its own? I want to run the engine safely and efficiently as an end goal to maximize reliability. So I'm not looking for performance gains. I just want it to run properly, not merely just "run" if you catch my drift. Thanks for any advice!

 

So you took all the wiring off the 5.8 and installed the wiring harness from your 5.0?

No you didn't.. the 5.8 firing order never changed.

I'll give you a definitive answer.. DO NOT fire that engine with that flexplate in there, you will destroy the transmission before the engine settles to a steady idle. You need a 28oz AOD/4R70w flexplate, it has a different front-back offset than the C6/E4OD flexplate.

Both of these motors wear the same heads, use the same injectors and make about the same HP, so while the fueling requirements for the 5.8 are a little different the MAF system will adapt to it over the course of a few days driving around.

 

Thanks for the quick reply! Ok so I'll go down the list here.

1. I kept the original 5.0 wiring harness and ditched the 5.8 harness. It all hooked right up with a few slight differences. I stole the knock sensor from the 5.0 and dangled it off the back. Bad idea? Let me know. I've read all sorts of stuff about keeping it or ditching it. I also stole an extra solenoid from the 5.0 for the EGR system (TAD or something. One if those). I plugged it in but didn't plumb it in to the vacuum lines. Just trying to avoid the CEL.

2.**EDIT** I think I may have just misunderstood what you meant. I believe you were merely telling me the 5.8s never changed, despite the 5.0 in fact changing its order to match the 5.8 at that time** Here is a Ford TSB that says in regard to firing order - TSB 94-04-10 for 87-96 5.0 and 94 - 96 5.0 and all 5.8.

1983 Ford Bronco TSBs & FSAs (Recalls) for '83-96 Broncos & F150s picture SuperMotors.net

According to that from 94-96 both the 5.0 and the 5.8 shared their firing order. But please correct me if I'm interpreting that TSB incorrectly.

My only real concern with firing order (aside from routing the plugs correctly) is having to possibly repin the injectors. If the order is different, is repinning necessary? Or are they batch fire and it don't matter? Not sure on that.

3. Thank you on saving my and my tranny's @$$ on this one. I'm ordering a new flexplate now and will install it once it arrives.

4. Alrighty, then in the end, I definitely don't have to visit a dyno or anything like that. Thank you!!!

Please let me know your thoughts on that TSB. I honestly thought that was a good, definitive answer when I had done previous research on firing order if indeed I am incorrect.

 

1. Yeah the 5.8 doesn't use a knock sensor so just leave the connector hanging.. no sensor in it.

TAD and TAB are not part of the EGR system that is the Thermactor(air injection) system and it is configured a little differently between 1/2 ton and HD trucks, that accounts for the extra solenoid. If the truck doesn't have the original cat and/or will never go through a smog sniffer test most of this system can be deleted, but for now just plug the solenoid in electrically.

2. Yes the 5.0 firing order changed in '94 but the 5.8 never did, so you never had to worry about matching anything

 

Hey loud41, how did you make out with the MAF 5.8 conversion?


I had a 1996 F250 5.8 that I converted to Mass Air but I took the expensive route and bought the stuff from a conversion site. I never got it running right as it had a vacuum leak that I couldn't chase down, so she ran rich as hell. I never had it tuned but looking back at it, I would have fixed the leak and had her tuned for sure.


Stock and even new, the truck was a pig with 9 to 9.5 mpg. She had 4.11s and 4wd...the MAF conversion sure didn't help. I lost my *** when I sold that truck.

 

I made out extremely well despite a bunch of idiotic things I did. I was in a hurry and skipped a few things that ended up biting me in the butt later on. For instance, I didn't change the valve stem seals while I had the heads off. They've turned out to be bad and so I burn oil as a result. Oops... I also learned that I have to allow the computer time to idle after the battery is disconnected for more than 5 minutes so it can relearn the engine and reestablish itself (allowing it to idle for 15 minutes with a/c off and 15 minutes with a/c on). Anyway I get 14-15 mpg highway with an old, clogged cat. A large improvement over the 8-9 I was getting from my old, worn out 302 it originally had. It also breathed new life and spark into the truck it never used to have. The 302 was unbearably slow. The 351w is fast (compared) with lots of torque. I've just driven it from Fairbanks Alaska to Salt Lake City towing a Uhaul 6x12 trailer fully loaded and had no problems at all. I had enough power to pull through the mountains of B.C. and averaged about 10 mpg throughout the trip. Couldn't be happier!

Just bear in mind that this was after about 4 months of troubleshooting and fixing miscellaneous problems the 351w originally had before pulling it. It wasn't smooth sailing from then to now. There's a problem with the EGR system that caused a misfire so it's blocked off for now. Clogged cat. Had to replace failing IAC valve and fuel pressure regulator. Had to remove and refurbish/clean all 8 injectors. Had to replace a failing TPS. Had to clean the throttle plates due to build up that caused a sticky gas pedal. Had to readjust the timing because somebody had adjusted it to about 14.5 degrees, causing pretty bad pre ignition. Had to replace the EEC's engine temperature sensor because it was failing, causing difficult startups when warm (outside temp, not engine temp) and bad fuel economy. It's been a loooong, drawn out battle, but I think I've finally won the war!

Btw - in the near future, I will be removing the engine once again to perform a proper rebuild like I should've originally done. New bearings, seals, rings, etc. Hopefully somebody can learn from this mistake and only pull the engine once. It's a pain...

 

Hi i know this is an old thread but its worth a shot did you ever figure out what was causing the egr to cause a misfire. I used a 1994 5 0 computer to convert my 95 5.8 to maf and its doing the same thing missfires with egr hooked up, runs fine with it unhooked. Thanks for any info

 

Sorry Devin I still drive my truck with the EGR blocked off. I thought about buying a new valve, but they are so expensive, I can't justify it. I also don't think I could get the valve off without causing other expensive problems. I just fabricated an aluminum plate that was the same size as the gasket and screwed it in place. I've since driven about 80k miles and have never had a problem related to the EGR. I'm not really sure why the truck runs so bad with the EGR hooked up. I suspect perhaps the vaccum signal is different, and so it opens the valve when it's not supposed to? Or maybe the exhaust gas chemistry is different? Perhaps there's a higher exhaust system pressure, causing more exhaust gases into the system than normal. I have no idea. The 5.8 has more displacement, so it pumps more air through. It will also have a different vacuum signal at idle. I'm just thinking out loud so keep that in mind. Your computer still thinks it's a 5.0, so I'm not sure if a 5.8 swap like this could run smoothly with the EGR hooked up. Perhaps someone else could chime in that has done this swap, only their EGR is hooked up and runs fine.