04 V6 Engine Swap
04-12-2018, 01:46 PM
#1
Thread Starter
Join Date: Apr 2018
Location: CA
Posts: 5
04 V6 Engine Swap
My oldest son gave his younger brother an 04 V6 base convertible with 3.9L and automatic transmission that was in need of a new engine. Because my younger son is 18 and just got his license we decided he did no need more horsepower and we did a swap and put in an engine from an 01 V6 but is a 3.8L. In addition we also replaced the fuel pump. Now the problem we have is it cranks but doesn't start and found the fuel injector are not opening. What do we need to look for next? Is it an ECU problem because of the engine swap and change in size? Any help would be appreciated
04-21-2018, 07:04 PM
#2
1st Gear Member
Join Date: Mar 2018
Location: wa
Posts: 107
My oldest son gave his younger brother an 04 V6 base convertible with 3.9L and automatic transmission that was in need of a new engine. Because my younger son is 18 and just got his license we decided he did no need more horsepower and we did a swap and put in an engine from an 01 V6 but is a 3.8L. In addition we also replaced the fuel pump. Now the problem we have is it cranks but doesn't start and found the fuel injector are not opening. What do we need to look for next? Is it an ECU problem because of the engine swap and change in size? Any help would be appreciated
04-21-2018, 08:00 PM
#3
Banned
Join Date: Jan 2018
Location: Pennsylvania
Posts: 2,327
You must reuse your car's engine and transmission harness, MUST.
You will still get the same 190/193hp that all 99-04 Mustangs have, no increase with the 3.9 in the Mustang.
The switch to the 3.9 in 2004 was made mid model year, being that the 3.9 shares parts with the Windstar.
The stroke was increased by 2mm, pin to dome height was reduced by 3mm, along with a slightly different
cam; are the basic internal differences between a 3.8L and a 3.9L engine. Compression ratio remains at 9.4:1,
and by all intents and purposes, it should make approx. 5 to 7 extra hp over the 3.8, but the factory tune
keeps it at 190. These engines respond very well to mods and could produce very close to 200WHP with bolt on
mods. This 3.9 engine in the Windstar makes 200BHP.
The last 10,000 to 12,000 Mustangs made in 2004 came with the 3.9 engine due to logistics when re-tooling for
the 05 model. Rather than make or get more 3.8s, they used 3.9s they had.
Again, Any 01-04 Mustang 3.8 or 3.9 is a direct swap. You must reuse your car's engine and transmission harness, MUST.
FROM:
The stroke was increased by 2mm, pin to dome height was reduced by 3mm, along with a slightly different
cam; are the basic internal differences between a 3.8L and a 3.9L engine. Compression ratio remains at 9.4:1,
and by all intents and purposes, it should make approx. 5 to 7 extra hp over the 3.8, but the factory tune
keeps it at 190. These engines respond very well to mods and could produce very close to 200WHP with bolt on
mods. This 3.9 engine in the Windstar makes 200BHP.
The last 10,000 to 12,000 Mustangs made in 2004 came with the 3.9 engine due to logistics when re-tooling for
the 05 model. Rather than make or get more 3.8s, they used 3.9s they had.
Again, Any 01-04 Mustang 3.8 or 3.9 is a direct swap. You must reuse your car's engine and transmission harness, MUST.
FROM:
Originally Posted by taylor0987 @ V6Mustang Forums
umm some people gave some incomplete answers
I wouldn't bother trying to put a 94-98 3.8 in there.99-00 3.8 needs some important things done to make it work right.
1. always reuse your car's engine and transmission harness.
2. always reuse your car's engine and transmission harness. (it's that important I purposefully repeated it.
3. 01-04 Mustang 3.8 or 3.9 is a direct swap.
4. 99-00 Mustang 3.8 will swap in. You *must* use the harmonic
balancer and flywheel/flexplate off of the 99-00 engine unless you are 100% sure you have a late-build 2000
engine. for the simplest swap, move your 04 intakes over to the 99-00 engine. swap the cylinder head temperature
sensor over from your 04 engine to the 99-00 engine. if any sensors have a different connector on them, then
swap the sensors over from your 04 engine. if you try to use a 99-00 lower intake you MUST get your car retuned
or it will run VERY poorly because the 99-00 lower does not have IMRC.
5. 94-98 3.8 will swap in but you need to move your 04 heads over to it. by the time you pay for gaskets and head
bolts it's probably more worth it to spend the money to get a newer engine. 94-95 have known headgasket issues
even on a perfectly maintained engine.
6. 97-08 f150, e150, e250 4.2 will swap over. for the simplest swap, move your 04 Mustang intakes over to the 4.2 engine.
you will have to go through and swap the Mustang sensors over, and if the cam synchronizer is different you will have
to swap that over as well. you may need to use your 04 Mustang oil pan and some other related things on it to clear the
Mustang k-member. You may need to swap over your Mustang water pump.
windstar, freestar, monterey 3.8/3.9/4.2 won't work.
1. always reuse your car's engine and transmission harness.
2. always reuse your car's engine and transmission harness. (it's that important I purposefully repeated it.
3. 01-04 Mustang 3.8 or 3.9 is a direct swap.
4. 99-00 Mustang 3.8 will swap in. You *must* use the harmonic
balancer and flywheel/flexplate off of the 99-00 engine unless you are 100% sure you have a late-build 2000
engine. for the simplest swap, move your 04 intakes over to the 99-00 engine. swap the cylinder head temperature
sensor over from your 04 engine to the 99-00 engine. if any sensors have a different connector on them, then
swap the sensors over from your 04 engine. if you try to use a 99-00 lower intake you MUST get your car retuned
or it will run VERY poorly because the 99-00 lower does not have IMRC.
5. 94-98 3.8 will swap in but you need to move your 04 heads over to it. by the time you pay for gaskets and head
bolts it's probably more worth it to spend the money to get a newer engine. 94-95 have known headgasket issues
even on a perfectly maintained engine.
6. 97-08 f150, e150, e250 4.2 will swap over. for the simplest swap, move your 04 Mustang intakes over to the 4.2 engine.
you will have to go through and swap the Mustang sensors over, and if the cam synchronizer is different you will have
to swap that over as well. you may need to use your 04 Mustang oil pan and some other related things on it to clear the
Mustang k-member. You may need to swap over your Mustang water pump.
windstar, freestar, monterey 3.8/3.9/4.2 won't work.
Last edited by 08'MustangDude; 04-21-2018 at 08:06 PM.
04-26-2018, 01:01 PM
#4
Thread Starter
Join Date: Apr 2018
Location: CA
Posts: 5
Thanks everyone. We finally got it going. Turns out it was the "trigger wheel". There is a one tooth difference so the ecm was getting an I correct signal from the camshaft position sensor and wod not allow it to start. We swapped the one off the old 3.9 motor onto the 3.8 motor and started right up. I must say this cr is becoming kinda fun to restore. Just finished installing a new convertible top 2 days ago and it's starting to look like the beauty it is supposed to be
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