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4.0 with 2.9 electronics?


if your trying to avoid breaking the bank...whats wrong with the 2.9?

i just dont think trying to get the 4.0 to run on the 2.9 PCM is going to save you any time or money. the amount of time your going to spend trying to fool the pcm into working is going to be pretty high...and in the end you'll only have a mediocre product that gets crap economy (that'll cost you more in the long run than doing the swap properly).
 
if your trying to avoid breaking the bank...whats wrong with the 2.9?
c'mon, its a 2.9 - ive already got the 4.0, i just need to make it work

i just dont think trying to get the 4.0 to run on the 2.9 PCM is going to save you any time or money. the amount of time your going to spend trying to fool the pcm into working is going to be pretty high...and in the end you'll only have a mediocre product that gets crap economy (that'll cost you more in the long run than doing the swap properly).
i agree... like i said, just an idea i wanted to research a little. i never really thought about how the benefits of the 4.0 arent just from increased displacement, theres more to it than that.
 
Kunar

answer to your question;

yes it fits straight away.

Problem however is the inlet manifold for the injection

But the axle from oilpump is already there so the same way
as the older and smaller Ford V6 engines
(like 2.8 and 2.9)

Do you want to carburate is also??
 
sure but depending on the engine that oil pump spins different directions=distributor issues.
 
if the distributor truly does fit the way it should (i have no idea if it does), I think your best chance would be to convert your 2.9 efi system to mass air use 19 lb injectors and a mustang mass air sensor, as far as i know (correct me if I'm wrong) the 4.0 and 2.9 have the same firing order. so, assuming you have all the same sensors wired hooked to the same wires as the 2.9 did, your PCM would think it was running a 2.9. the mass air and larger injectors should be able to compensate for the increase in displacement. I guess this would be like having a stroked 2.9.
 
^ that would probably work.

but that doesnt save ANY trouble compared to swapping in the stock 4.0 electronics.
 
^ that would probably work.

but that doesnt save ANY trouble compared to swapping in the stock 4.0 electronics.

It may not but, i'd definitely be interested to know if it actually works.
 
if the distributor truly does fit the way it should (i have no idea if it does), I think your best chance would be to convert your 2.9 efi system to mass air use 19 lb injectors and a mustang mass air sensor, as far as i know (correct me if I'm wrong) the 4.0 and 2.9 have the same firing order. so, assuming you have all the same sensors wired hooked to the same wires as the 2.9 did, your PCM would think it was running a 2.9. the mass air and larger injectors should be able to compensate for the increase in displacement. I guess this would be like having a stroked 2.9.

Already suggested that. :D

IMHO, for the cost, might as well do it right the first time. My PCM was $80 from Subway truck Parts in California just by itself.

And FWIW, I suspect that it won't idle to save it's life. I used an IST Air Adjuster ($100) to "fool" the MAF readings to the computer on my 2.9L with 19lbs injectors. But I couldn't have my cake and eat it too, I had to run it a little rich at idle for better mixture result at WOT. It did run decently, but a lot of trial and error.

It may not even work at all, ever. That's another factor to consider as well, if that's the case, he is out that money.

Pete
 
well i talked to a guy that works for ford today (he also teaches at the local community college) and he seems to think that its definately possable. i picked up my engine today, but its staying in the bed of my truck, under the tarp till the rain stops. it does look like the distributor will fit in the block, with no issues there. the problem though, like has been said before, is making it fit around the intake. the intake isnt designed to have the distributor there and there just isnt clearance. what he suggested was making the 2.9 upper intake fit on the 4.0 lower. im sure they wont bolt up though, and thats just one more problem i dont need. now, if the entire intake will fit, upper and lower, is undetermined. i figure since the 2.9 and the 4.0 are basically the same engine, there isnt an issue with firing order or anything like that. the hard part will be making the computer understand whats going on.
 
your going to try and feed an engine with 38% more displacement through the 2.9's puny little ports? that thing is going to be a dog!

sounds like you could be well on your way to having the worlds slowest 4.0 :icon_thumby:
 
your going to try and feed an engine with 38% more displacement through the 2.9's puny little ports? that thing is going to be a dog!

sounds like you could be well on your way to having the worlds slowest 4.0 :icon_thumby:

lol... ive pretty much accepted the fact that this isnt the best way to go, but im curious now. i need to find out if it will really work... and hey, im gonna be using the bigger throttle body for the 2.9 if that helps any :icon_idea:

ill probably just search the yards around here for the wiring i need...
 
well good luck with it. From some of the swaps ive done i caqn tell you this. It will run but the AFs will be way off. At WOT the ecu has a pre-programmed trim for fuel. So at WOT the ecu will spray enough fuel for 2.9L of displacement. You will be runnibg 4.0ls and moving alot more air and you will most likely run lean eventually leading to things like cracked heads and blown HGs due to detonation and elevated EGTs. you can run some bigger injectors to try and fool the ecu at WOT and it may have a safe AFR however at part throttle the ecu may only be able to shorten the pulse width so much and it will run rich which will lead to poor economy, rough running for high load/low rpm conditions, fouled plugs, fouled 02 sensor, melted cat if you run one, more oil burn off, and if too rich washing the cylinder walls down leading to accelerated cylinder distortion/wear. Also with bigger injectors the idle will be choppy. you are running a speed density system so theres no MAf to tell the ecu that there is more airflow than theres supose to be. timing table issues can be a problem as well. The 2.9l electronics would be fine to use if you could tune it or have a dyno tuner burn you a chip but without tuning your going to have a bucket of problems.
 
i understand wanting to do it do be different... and if that is what you are trying to do, more power to you... but if you are doing this to save money, or make the swap easier, good luck. i swaped the 4.0 into my samurai, and found the wiring to be the easy part. i would imagine having a 2.9 in there before, would make this swap very very easy. it is going to be far easier to find the correct wiring harness for the motor, then it will be to put a distributer in it, change intake manifolds, and whatever else you will have to do.
 

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