Hi everyone,

After reviewing the wealth of knowledge regarding many successful conversions we’ve decided on replacing my blown 4.0 AJ27S with an 05 XKR motor and converting it.

for those that have used the 4.2 manifold and injectors instead of a swap over, what did you do regarding the pressure regulation? If we need to up the pressure to 65psi, is there no concerns regarding a vacuum setup to keep the pressure lower when not at WOT?

if someone has an aftermarket FPR part number or picture they have used that would be great. We are assuming consideration is needed with 4.0 idle/vacuum being 37.7, wot/disconnected 43.5 and 4.2 SC being idle 43.5 WOT 72.5

thanks!

 

I’m not entirely sure about this but, If you’re running a 4.2 engine with 4.0 ECM, you need to get the camshaft position reluctors located on the rear of the camshaft itself from the 4.0 and install them on the 4.2 cams unless you just swapped the cams over. I don’t know if the reluctors from a 4.2 are the same as a AJ27 4.0 engine. This is just something to look into.

About the only person I can think of who would provide you information regarding the electronic fuel pressure regulator is Avos. You may want to PM him and see. There is one other person but, they’re in such a secret squirrel land that you’ll never get any information other than silence.

 

4.0 does not have vvt with sc and 4.2 does. Much more is needed to be replaced too.

 

we grabbed an 05 xkr motor which doesn’t have the vvt

 

Just about there 😁

 

I bet that’s going to be fun after it’s up and running. Good job!

 

Thanks and Indeed! I’ve missed it since October when it said “I’ve given you 57,000 miles, all over the country 3 times and I’m moving on”


it was parked at 230,002 miles. We knew it was always coming, thing smoked barrels from bad nikasil wear for as long as I’ve had it. But, I drove it as it should be driven, was never scared of it letting me down and it started making a racket about 2,000 miles before going catastrophic. Took it out to Albuquerque from SC right before it started making a fuss and moved on during a hard run as it would want to go out, all In epic style! Didn’t even have to tow it home nor tow it to the shop so I could wrench on it comfortably (even with a lift at home, having room for engine rework is rough)! Smokey ride on the farewell to the shop though 😂.

maybe a proper burial is needed

 

im 99% sure the stock regulator bolts onto the aj34 rail

just run it at the stock 50psi

 

Unfortunately that is not the case but we are past it and good to go

 

How do you think it'll run with the 4.2 blue top injectors when the ECU thinks it has the side feed injectors? Same goes for the camshaft (rear mounted) reluctors. How do you think it’ll run?

 

the reluctors are the same

 

That’s good then. Thanks for that confirmation Xalty.

What did you do about the injectors and FPR? I would imagine the blue top injector ohms are different than the side feeds?

 

little something like that, apparently the ohms should be okay on the blue ones

 

That’s the fuel feed which I kinda forgot about. 😁 However, the fuel pressure regulator is what I was inquiring about.

 

 

This was a complete success. 2000 VDPSC runs nice and strong with this config. Fuel trims are near perfect (+-1) at 65 psi. All I can smell is old memories from the catalyst and some paint burning off the exhaust 😂

 

There were a few things we learned and a lot of chaos, doubling back on data, bugging Avos to death, etc etc but overall the car has been great after the conversion.

The only true thing I could gripe about that really (could be anything), is the gas mileage. When this thing was eating a quart every 500 miles with the 4.0 it wouldn’t get nearly as bad gas mileage. I’m lucky to get 14 combined now. Chalk it up to having fun over 6 months and the experiment, who cares. That old motor was loose and peppy, who knows.

some helpful tips for other people digging around on the idea hopefully:
Nothing special pre-existing on my 4.0 other than Bosch AMG (010?) intercooler pump and Mina intake w/OUT the cone, just the tube. They were moved over
05 XKR engine was the donor
grabbed a 1.5 upper pulley for it
used the 4.0 lower pulley, we didn’t want it to deal with the front cover
4.2 injectors moved over
My buddy and I didn’t realize there was no hole in the fuel temp sensor location, had to drill it. That’s our return to a Tomei S and works great. When I would adjust it, it wouldn’t seem to hold pressure after off when I locked it down. Had me in a circus for a bit on that issue. Eventually it would hold after some cycles. Very nice fpr.

After a LOT of stupid, Murphy got me good with the purge valve. It was messing up and throwing 0172 0175 in the middle of me testing pressures. Right in the middle of all this stuff related to things of course. That’s said and done - I run at 55base, long trims around 1-3+.

the intercooler temp sensor is from the 4.2 wired in to work. After looking at the charts and going crazy over it that’s what I went with.

Oh, and a catch can.

Other than the detail above the 4.2 conversion project going the 4.2 injector route worked fine with all the information compiled from here, obviously mostly from Andre. Other members had some good info and it became a huge bundle of a puzzle but it worked out.

It is a pretty special 2000 VDPSC now!