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View Full Version : Changing from LH3.1 to 2.4


derosa
12-18-2006, 12:59 AM
Items needed:
LH 2.4 computers
5 wire amm from a 91 and later volvo
TPS from a lh2.2 or 2.4 car, swiping the whole throttle is easier.
The plugs, just cut them out when you take the amm and throttle.
New connections from eagleday.com they are called JPT or Junior Power
A crimping tool, pliers will work but not as well.
A roll of 16 gauge wire, preferably in an odd color.

Note: As always when dealing with electrical disconnect the battery.

Step one:
Unplug the tps, and remove the old throttle.
There should now be enough room to move the wires so clip them from the plug. You can use the old plug as a pigtail but I prefered pulling the connections and using new ones.
Looking at the plug so you can see the numbers 3 18 2
3=blue/white
18=brown/black
2=white/yellow
The reason I prefer new connecters is if your pigtail from the JY is from anything other then a 240 it will have different color wires from your harness, using the one you just clipped could be confusing because the pigtail wires are the same colors in a different order.

Edit:
If you use the stock 3.1 plug it will be numbered differently and the wires will be as follows
240driver
1=white/yellow (this wire goes to ECU plug position 2)
2=brown/black (This wire goes to ground)
3=blue/white (depends on whether you hook it up or not, you clearly don't need to)]
the number 3 wire does need to be connected if you are using NA computers but doesn't need to be (possibly shouldn't be) for turbo computers.


Step two:
Remove the old amm and clip the plug off, this one is useless since it won't fit the new amm.
The new plug is numbered 1-6 while the old is numbered 1-4, I'll try to fill in the colors later.
for the new plug 1 is from wire 2, 2 comes from wire 1, 3 comes from wire 4, 5 comes from wire 3. That deals will all the existing wires, 4 has to be added, here is where the odd color wire comes in, try to use something that doesn't match everything else.

If you want to turbo the car it is a good idea to pull the wires out of the harness before they have been installed in the new plug. Simply slice a decent gash in the loom covering near where it enters the firewall and you can see them all. Carefully you can pull them through, remember there are cuplicates so if a wire doesn't pull through see if there is another. The brown/black ground wire will not pull through, it is actually wired to the intake manifold so when you move the amm to the other side for the turbo hoses you should install a new wire.

Step three:
the ECU and EZk wiring. First unwrap the harness from its miles of extra sticky electrical tape.
Here is where things can get confusing.
Pull out ECU 10 and plug into ECU 3, this should be a blue/white wire.
Pull out ECU 2 which is yellow/white, Pull out EZK 7 which is yellow, clip off the old connecters and put the two together on one connector, plug them together back into EZK 7
Pull out ECU 8 and plug into ECU 2, this should be yellow and simply connects the 2 computers (This is the wire from EZK 7)
Plug into ECU 8 your new wire from the amm.

That is all the wiring that needs to be done, I don't know for certain but I believe the ECU has to be grounded so screw that back into place, if going with NA computers the EZK are numerically the exact same so I would assume you don't have to change it, I switched to turbo computers so I honestly don't know.

Notes:
Pulling the connecters from the plugs is a pain in the ass, use a thin metal tab to make it easier.

All total you need 12 JPT connecters, buy extra, they're small and easy to loose, worse 3 of my connections didn't crimp well and I will be buying the proper crimper and brand new plugs for when I add the turbo, the wires to the amm are way to long and need to be shortened considerably when you switch the amm to the other side.

All total to leave it in a NA setup with turbo computers took 3 hours, if I was turboing at the same time getting the brown/black amm wire out of the loom to move it would require removing the intake so prepare with a new gasket.

Buy loom material, why leave it looking like ass? Mine does at the moment, I thought 1/2" loom was big enough for the rest of the harness and it wasn't. 1/4" seems perfect for just the amm wires.

The rubber boots that protect the plugs, remember to put them on the wires before putting the wires in the plug, I put the old amm plug cover on, it doesn't fit so that plug is unprotected for now.

Results:
Ahh the scary moment.
Once I discovered the TPS was no good and replaced it you would think everything should be perfect but it isn't.

First start-The engine surged to 2500rpm and dropped to almost stalling with all lights flickering on. Car didn't want to stay running but with some coaxing it made a victory limp around the block, note: quite a bit of cranking was required to make it work. At this point check the OBD for a code, if there is none your wiring is probably sound.

Second start-the drive to work, made it 8 blocks out with the car lugging badly at every acceleration, didn't want to run at all, turn around to get my bicycle and 2 blocks from home the idle smooths out and it runs fine continues to do so for the rest of the trip to work with some hesitation at accelerations that may be due to flooding from using a turbo ecu without a turbo.

Third start- the trip home, Again surging idle at start and really bad bogging on acceleration attempts (won't dignify it by calling it an acceleration success). This time it goes on for 10 blocks, not 14, again idle smooths out and runs fine for the 12 miles home.

Fourth start- surging idle and bogging lasting 4 blocks. Drove fine afterwards.

At this point the car still surges to 2000rpm on initial start up and holds it for roughly 30 seconds, maybe it has something to do with cold start?
Once it is done with the high idle it now idles smoother then 3.1 did, driving is fine but power seems diminished and if I press the gas too hard on acceleration is hesitates then surges quickly, again possibly due to turbo comps in a still NA computer, don't have any NA comps to check against, also hindered by a badly leaking exhaust.

All in all the results came out well, the car drives ok and idles smoother, just expect a rough learning curve for the computer's first few drives and you'll be fine.

blarf
12-18-2006, 05:41 AM
Turbo computers, but what kind of fuel injectors?

derosa
12-18-2006, 11:58 AM
Currently running stock injectors with 3bar fpr, when the turbo is introduced I will use ford red tops which flow same as stock turbo, didn't desire to flood the car.

blarf
12-18-2006, 01:58 PM
Try some turbo injectors + resistor pack.

derosa
12-19-2006, 09:08 AM
Try some turbo injectors + resistor pack.
No need to do that, the resistor pack just lowers the power going to the injectors so the low impedence won't be stuck open and burn out quickly, the red tops are the same flow rate but don't require the resistor pack. With either option I would assume not havingthe turbo attached would cause the car to run richer and flood.

blarf
12-19-2006, 02:22 PM
Why would it flood with no turbo? The AMM measures how much air is going through.

volvostud
04-14-2009, 03:18 PM
I'm looking at doing this shortly, but have a problem with your write-up.

At this point the car still surges to 2000rpm on initial start up and holds it for roughly 30 seconds, maybe it has something to do with cold start?
Once it is done with the high idle it now idles smoother then 3.1 did, driving is fine but power seems diminished and if I press the gas too hard on acceleration is hesitates then surges quickly, again possibly due to turbo comps in a still NA computer, don't have any NA comps to check against, also hindered by a badly leaking exhaust.

All in all the results came out well, the car drives ok and idles smoother, just expect a rough learning curve for the computer's first few drives and you'll be fine.

Doesn't sound like good results to me. Is there a way to do this without the idle problems? I'm doing the 3.1 to 2.4 swap at the same times as a +t, so I'll be using T computers and the system will be turbo'd. So that might help.

Any updates on this?

DNAsEqUeNcE
04-14-2009, 06:16 PM
Folks, any input would be greatly appreciated.

Paperjam
04-14-2009, 10:53 PM
if you use turbo ecus with no turbo injectors, it idles and bogs really badly. although this is on 2.2, the same may hold true for 2.4. My car was quite happy after receiving turbo injectors + resistor.

or just get na ecu's

240driver
04-22-2009, 07:49 PM
I'm getting ready to try this as well in the coming weeks. I'll try and do a decent write up with plenty of pics. Still curious how it turned out for the OP.

240driver
05-02-2009, 08:45 PM
I did the switch and it runs like total poop. I get the exact same symtoms as posted by derosa the OP. I think I will wire in the resistor pack and stick in the injectors from the 940T donor and see if that helps.

derosa
05-02-2009, 09:23 PM
The initial issues were due to a bad computer, I had a 563 or 561 computer, can't remember which and at this stage I had not yet turbo'd the car. I discovered the issue when the car suddenly started to sound like it was trying to run backwards and threw a crank sensor code, when a new sensor was installed it still wouldn't run right, swapped computers and everything was ok. Know that the computers came from a good running car to start with. I also had initially installed the ford red tops when doing this and it took time for the computers to adapt to these. The car did have a turbo tossed on shortly after and has been running fine since and I've had about 30k miles added on since.

240driver
05-02-2009, 10:01 PM
The initial issues were due to a bad computer, I had a 563 or 561 computer, can't remember which and at this stage I had not yet turbo'd the car. I discovered the issue when the car suddenly started to sound like it was trying to run backwards and threw a crank sensor code, when a new sensor was installed it still wouldn't run right, swapped computers and everything was ok. Know that the computers came from a good running car to start with. I also had initially installed the ford red tops when doing this and it took time for the computers to adapt to these. The car did have a turbo tossed on shortly after and has been running fine since and I've had about 30k miles added on since.

All of the LH2.4 stuff that I've swapped in came from the same running car. I drove it into my garage before I parted it out, it ran strong, so I know the parts are good.

I suspect the stock 3.1 injectors aren't up to snuff because it seems to be starved for fuel.

derosa
05-02-2009, 10:10 PM
If you've added the turbo while doing this swap the injectors are probably the issue. Keeping the stock 3.1 injectors will only work if you switch to 2.4 and keep it N/A. N/A injectors are 18lbs while turbo are 30lbs, not nearly enough.

240driver
05-02-2009, 11:53 PM
I didn't install the turbo bits yet. That was supposed to be tomorrow's job but it looks like I'll still be messing with the engine management swap.

I tried wiring in the resistor pack and using the green top injectors from the donor car and it wouldn't even fire. Maybe I did it wrong, it's hard to tell. Screw it I'm going to bed.

EDIT- Turns out I had a bad connection. and the TPS wired wrong... keep reading.

derosa
05-02-2009, 11:59 PM
Are you running the turbo computers or NA computers? Even if you're running the turbo computers without the turbo you need the turbo injectors or something similarly sized. If it ran poorly before and now won't with the resistor pack you may have wired it backwards. My understanding is that it can go in to either wire, power or neutral, but that it is directional, not really sure of the facts on that though.

240driver
05-03-2009, 01:00 PM
Everything is from the same running 940T. I had a loose connection and now that it's fixed the car runs. It doesn't want to idle well and cuts out at WOT but pulls very strong at 98% throttle position. The K cam is loving the LH2.4 or the bigger injectors because it pulls harder than it has in the past with the 3.1 bits. I am guessing the idle and cutting out problems have to do with the TPS being out of adjustment or something along those lines.

Anyway, I thought I would add some pics and a short description of what I did.

I think I simplified the ECU rewiring ordeal. Rather than mess around with EZK wiring and what not I accomplished the same thing by cutting and splicing two wires. The yellow wire at pos 8 gets cut off and spliced in with the yellow white wire in position2. The yellow wire stub left sticking out of the ECU plug in pos 8 gets spliced to the new AMM wire. Then it's just a matter of moving the blue-white from position 10 to position 3. The pics illustrate it better.

Wiring change on ECU plug:
http://farm4.static.flickr.com/3397/3497046263_df30d5b883_o.jpg

Here's what I used to release the connection from the ECU plug:
http://farm4.static.flickr.com/3356/3497862244_916feac650_o.jpg

Here's how it's used:
http://farm4.static.flickr.com/3303/3497045873_23c19e7678_o.jpg

Ready to be snapped into place:
http://farm4.static.flickr.com/3537/3497862658_a9f0449b36_o.jpg

The TPS wires get switched around a bit after you change the TPS. You leave the yellow white wire alone and cut the other two and switch their positions. EDIT----I eventually discovered this is incorrect, read on for instructions on properly wiring the TPS.



I didn't take any pics of the AMM wiring, but it's pretty straightforward. You're just cutting off the old 4 wire plug and installing the 5 wire one from the donor. You use that wire you connected to the ECU plug position 8 in the number 4 position on the 5 wire plug.

The wiring schematics should help too. http://pliki.mojevolvo.pl/schematy/volvo_240__1992.pdf

volvostud
05-04-2009, 04:37 PM
Alright, so for my swap I need computers, Throttle (or just the TPS?) and AMM from the same car. It sounds like new injectors would be best too. Which color?

Start is a 91 240 with 3.1. End is a 91 240+t with 2.4.

All can happen at once, or I can do the computer first and run the system on an NA for a week or two. Thoughts?

derosa
05-04-2009, 09:50 PM
Alright, so for my swap I need computers, Throttle (or just the TPS?) and AMM from the same car. It sounds like new injectors would be best too. Which color?

Start is a 91 240 with 3.1. End is a 91 240+t with 2.4.

All can happen at once, or I can do the computer first and run the system on an NA for a week or two. Thoughts?
Basically you will need computers, from experience if you're going to run NA for a while get NA computers if going straight to +T get the turbo computers. The turbo computers run like crap without a turbo attached. Just get the whole throttle, it is easier to remove the 3 nuts to pull the throttle then to try to transfer the tps, injectors if you are going +T immediately, you can leave in the stock injectors in staying NA, a 2.4 amm, and a couple of wiring guides or the directions above if you can follow them. Despite doing the write up I still needed the diagrams and the directions I wrote in advance helped me keep track of what I was doing. Swap over the plugs for the amm and tps, use pigtails, it was easier in the long run and get the small inserts for doing the computer wires.

240driver
05-04-2009, 11:59 PM
Basically you will need computers, from experience if you're going to run NA for a while get NA computers if going straight to +T get the turbo computers. The turbo computers run like crap without a turbo attached. Just get the whole throttle, it is easier to remove the 3 nuts to pull the throttle then to try to transfer the tps, injectors if you are going +T immediately, you can leave in the stock injectors in staying NA, a 2.4 amm, and a couple of wiring guides or the directions above if you can follow them. Despite doing the write up I still needed the diagrams and the directions I wrote in advance helped me keep track of what I was doing. Swap over the plugs for the amm and tps, use pigtails, it was easier in the long run and get the small inserts for doing the computer wires.

I'll have to disagree with you on the NA vs. Turbo computer thing. My car now runs quite well with the LH 2.4 from a 940T and no turbo. The only thing that I still need to sort out is the cold idle. It doesn't have any problem once it's warmed up, but when cold it doesn't idle well, but I doubt that has anything to do with the injectors or turbo computer. (since the turbo donor idled just fine with the same amount of boost... none;-))

I will say this though, you can't run the LH2.4 computers with the stock orange top injectors. At least I couldn't. I mean it will run, but only barely and it runs like total crap. I swapped in the resistor pack and green tops and it runs great. Pulls harded than ever too.

I think you can do the swap by just buying the computers and AMM and the TPS (if you don't take the whole throttle body you will at least need the backing plate off the TB the TPS bolts to-it's different on the 3.1 TB) and the injectors. (and resistor pack if using low impedence injectors) I'd try and use whatever injectors came on the car you took the computers from. You can buy the wiring bits like Derosa did, or not. I really didn't find it necessary, but to each his own. Also don't bother switching the blue white TPS wire to the no. 3 position. You really only have to cut and splice two wires and you're done. You just need a length of wire and some good heat shrink connectors (blue and red) and some QUALITY crimpers. (I only use the ratcheting kind) Good luck!

240driver
05-05-2009, 08:05 PM
OK I just had my Eureka moment. I looked up the wiring diagram for the 940 Turbo I got my LH2.4 bits from and had a breakthrough. Turns out the reason the car wouldn't idle cold and cut out at WOT was I had the TPS wired incorrectly. I remembered when I was reading the directions at the beginning of this article I noted that while they said to move the Blue white wire to position 3 on the ECU terminal, (since that's what the LH2.4 Volvo 240 diagram shows) there was no such wire in the 940T donor car's plug. (that spot was left empty) So me thinks I should wire it like a 940T and I did so, by moving the yellow white wire from position 3 on the TPS plug to position 1. That's how it's shown in the 940 diagram, and that's how it was wired in my donor 940T, so no big suprise when it worked. I'm just an idiot for not trying it sooner. So when you go to rounding up bits for the swap remember it always pays to get the used connectors with the computers if possible so you can verify wire routing. (as it was on the other car)

So to summarize, when adapting the 240 from 3.1 to 2.4 you need to wire the TPS as such:

TPS connector plug position 1 wire (color dosn't matter) gets spliced into the wire that was formerly in position 3 on the 3.1 connector. (so wire from connector position 1 regardless of it's color, ends up tying in with the wire that connects to ECU position 2- on my car it was yellow-white and had been on TPS plug position 3 on the old 3.1 system)

TPS connector plug position 2 wire goes to ground. (on my car it was blue and white and was spliced to the brown and black wire that formerly occupied position 1 on the LH3.1 TPS plug)

So to summarize my summary after changing the TPS sensor, you need to cut all three wires on the plug. Take the one that was in position 1 (bn/blk) and hook it to the wire stub sticking out of the plug in position 2. Take the wire that was in position 3 (yellow wht) and connect it to the stub of wire sticking out of the plug in position 1. That's it. Leave the other wire disconnected, you don't use it. (turbo models don't utilize the WOT switch)

So, sorry for the confusion. I'll edit the original posts after I get some miles on this setup to verify it works flawlessly. All indications so far are that it will.

sbabbs
05-05-2009, 10:55 PM
Yeah the turbo lh 2.4 TPS hookups are different then NA 2.4 or 3.1 and needs to be changed if using a NA harness and going turbo. Good write up.

derosa
05-05-2009, 11:01 PM
That's why in my original post I stated that the numbers are based off of the numbers on the plug hence the 3,18,2 that I list for which wire goes where. The 3 is not the third position, I believe it is actually the 1st position based on looking at the plug with the numbers up. Since I ran mine NA for a while I hooked up all three wires and have never bothered to unhook them. My car was WOT all the way to 6k rpms twice today and has done it easily a hundred times since the swap with the turbo and turbo computers so I don't believe there is any significance to the one wire being connected or not with turbo computers.

240driver
05-06-2009, 08:28 AM
That's why in my original post I stated that the numbers are based off of the numbers on the plug hence the 3,18,2 that I list for which wire goes where. The 3 is not the third position, I believe it is actually the 1st position based on looking at the plug with the numbers up. Since I ran mine NA for a while I hooked up all three wires and have never bothered to unhook them. My car was WOT all the way to 6k rpms twice today and has done it easily a hundred times since the swap with the turbo and turbo computers so I don't believe there is any significance to the one wire being connected or not with turbo computers.


Ahh, I think I see he reason for my confusion.
Here is the quote from the original write up:
Looking at the plug so you can see the numbers 3 18 2
3=blue/white
18=brown/black
2=white/yellow
I reused the plug that was already on the car. The plug doesn't have the numbers you list above on it. The plug from the original 240 harness has the numbers 1,2,3 on it. (so does the plug from the 940T) And it needed to be hooked up as such:
1=white/yellow (this wire goes to ECU plug position 2)
2=brown/black (This wire goes to ground)
3=blue/white (depends on whether you hook it up or not, you clearly don't need to)

You may want to revise your write up a bit so other easily confused people like myself who don't buy new connecters aren't led astray. I don't mean to be critical, I applaud you for taking the time to write it up and likely would never have undertook the project had you not.

derosa
05-06-2009, 02:10 PM
You may want to revise your write up a bit so other easily confused people like myself who don't buy new connecters aren't led astray. I don't mean to be critical, I applaud you for taking the time to write it up and likely would never have undertook the project had you not.
I'll make the addition, it must be they numbered to plugs for 2.4 and 3.1 differently to keep the people wiring them from getting confused and putting the wires in the wrong order.

240driver
05-10-2009, 10:42 PM
I finsihed the +T conversion this weekend. Works great.. Thanks Derosa.