Bosch LH-Jetronic 2.4 specifics

TerryA · 2017-03-04T09:46:05+00:00

88 = lh2.2 89 = lh 2.4 Swapped from using the sensor on the distributor and having the chrysler ignition module near the washer fluid tank to having the c...

Anthony

If a LH2.4 starts up instantly its not a LH2.4 its still a 2.2.

We need to be careful when giving advice when doing conversions on just about anything.
The 'she'll be write' all you need is this, is often proved insufficient as overlooked are things such as:
the connector is different, the mount is different, the manual version is different to the auto version, a trigger wire is needed on this model, the relay also needed to be changed and then you find out the connector also, the wiring colours changed. You put in a newer steeing rack and the hose connections changed location... all the things that can trap people.. and we initially implied it was a piece of cake........

Slowbrick

Boy this is confusing. Having done each flavor of the swap here is the deal. Both swaps are going to require a level of competency with wiring and both will require you to pull wires out and put wires in. If you are going to be swapping in a B230FT into the 240 then you are removing the trans anyway, it makes little to no sense to not do the swap for this reason of having to change the flywheel.

Ok lets get to it: LH2.2
The wiring for LH2.2 and LH2.4 in a 240 is NOT the same. If you are going to be sticking with LH2.2 in your 240 then you will need to extract the EZK (ignition system) wiring from the 740 donor car. This job to be honest is a huge PITA as the wiring is bundled together with the body wiring. You will need to cut and shorten bits and pieces although this is not a huge deal. Then you need to remove the old Chrysler ignition out of your 240 and fit the EZK. Then you need to extend the AMM meter wiring to go to the drivers side. After that is all done you cut the blue tps wire to turn off the WOT map and you plug in your TURBO LH2.2 computer and TURBO LH2.2 EZK and away you go. As you can see it still requires a fair level of rewiring.

I have taken this approach in my first 240 turbo build and tbh...i wouldnt do it again. Yes LH2.2 is good and yes you can make it make decent power but to get it there its a PITA. It has a very narrow window of what its ok with and what its not. You can trick it with resistors and bigger injectors and a big MAF but at the end of the day you end up with a car that might make 250whp. LH 2.4 will do 300whp in stock trim with bigger injectors and the other supporing mods. Also LH2.2 parts are harder to come by and the wiring harnesses are for the most part junk and are riddled with shitty plugs and connectors.

LH2.4.
Back in 2014 I did a Kjet to LH2.4 conversion. I embarked on this journey thinking it would be super difficult but tbh the wiring diagrams made it really quite simple and it was for the most part as simple as pulling out the old Kjet stuff and laying in the new LH2.4 stuff, plugging it all in and go go go. The beauty of the LH2.4 swap is that you can get any ordinary 89+ 240, pull the entire harness, separate it down to just the fuel and ignition harness and lay it into your car. Obviously with your 88 240 you will need to remove the old LH2.2 harness but this isnt a huge deal with the dash out of the car. This then gives you everything you need to connect up to your new engine without the need to cut and shorten things had you taken it out of a 240. It also means you dont need to splice in connectors to make your EZK talk to your LH2.2 which is what you will need to do if you stick with LH2.2. The last piece of the puzzle is to get yourself the flywheel and you are done. If you are so inclined you can grab the diff from the donor car to get the speed sensor as LH2.4 uses it for road speed and without it you will have a hunting idle .With this all done you just need to source yourself some LH2.4 turbo computers and away you go. The computers can easily be had in the states from many popular members on turbobricks.

So what are they like to drive? I found LH2.4 to be far smoother and offers a much broader power curve as opposed to LH2.2. LH2.2 doesn't offer any learning so it does the same thing everytime you mash the pedal...dump fuel. I found LH2.2 always seemed to have a dead spot off boost and no amount of timing adjustment helped. LH2.4 just works. It makes good power, adjusts itself to the fuel I put in it and doesnt really complain. Hell even one time the wastegate hose broke loose and the needle pegged at 20psi...pulled like a rocket and not one hint of an audible ping. Had the same thing happened in a LH2.2 car it probably would have roasted.

All in all its your choice but if you are chasing the stock fuel system dragon and you are going to be spending any amount or time in doing the swap it makes little to no sense to stick with LH2.2 when LH2.4 is not much more work but far superior.

Anthony

Couple more LH2.2 to 2.4 differences
- ~~Fuel pressure regulator (might mean fuel rail update as well)~~ (see below comments -mod)
- Coolant temperature sensor change to dual thermistor type (The LH 2.2 temp sensor is coloured blue and is NOT grounded via its body and the LH2.4 is black and grounded via body. They will physically interchange as both use the same two male spade lugs and will also thread into the block. But if you use the 2.2 into the 2.4, then the ecu will see a permanently cold motor, and perhaps over-rich, backfires, and high fuel consumption.)
- Two wire idle motor
- Power stage for late EZK
- pray old sensors output levels can be managed by the self-adjusting feature of LH2.4

Philia_Bear

Fpr runs the same pressure and does not need to be changed (lh2.2 vs 2.4)
The fpr is different from na vs turbo motors
Lh2.2 cares about this lh2.4 does not

jamesinc

From what I've seen, turbo 2.2, NA 2.4, and turbo 2.4 all use the same 3 bar FPR (part #3517064). NA 2.2 is the only one that doesn't use it, and instead uses #3517063 (which is 2.5 bar)

Anthony

Thanks for Fuel pressure reg update.
I sourced via Bosch - B23/230FT - Bosch #0280160 226

Philia_Bear

jamesinc;102707 wroteFrom what I've seen, turbo 2.2, NA 2.4, and turbo 2.4 all use the same 3 bar FPR (part #3517064). NA 2.2 is the only one that doesn't use it, and instead uses #3517063 (which is 2.5 bar)

US spec LH2.4 has 2.5bar for NA and 3.0bar for Turbo
Because of how flexible LH2.4 is its not really material which one your using as long as the o2 sensor is working

I've seen aus spec cars with LH2.4 NA motors using both

IIRC 16v were all 3bar

Slowbrick

When I did my swap I just went onto FCP and ordered one of every sensor I would need. That way I could be sure it was going to work the first time and not be hampered by a questionable sensor.

Major Ledfoot

My 2c, FWIW? (may be overvalued at that...)

The FPR on LH2.2 turbo is the same as LH2.4/16V and LH2.4/turbo but IIRC the LH2.4/NA is different again.

@Slowbrick 's brilliant post above ought to be stickied.

TerryA

Thanks all
Now more confused what to do.
Would be great if you were all in Perth
Cheers
Terry

Slowbrick

bgpzfm142;102718 wroteMy 2c, FWIW? (may be overvalued at that...)

The FPR on LH2.2 turbo is the same as LH2.4/16V and LH2.4/turbo but IIRC the LH2.4/NA is different again.

@Slowbrick 's brilliant post above ought to be stickied.

Correct. The NA FPR is 2.5 bar and the Turbo is 3.0 bar.

Terry, basically either route you take will require you to do a fair bit of wiring. Staying with LH2.2 will require you to integrate new wiring into your old wiring. It looks like its half the work but getting the required wires out of the 740 harness and then integrating it makes it just as much work. The LH2.4 route requires you to tear out your old ECU/Ignition harness and laying in a whole new one. Sounds like more work but only requires you to lay down a new harness that is made to go together as is. If you are doing it then get yourself new sensors and FPR from FCP. Also the NA and turbo LH2.4 AFM is the same from what I can work out and will end with 016.

You can then use 850 orange top injectors with either LH2.2 or 2.4 and these will flow as much as the greens but dont require a resistor pack. The LH2.4 dizzy is also different from the 2.2. Main differences from my observation is: fixed mounting point as timing is not adjustable, no hall effect built in and 10 mm shaft.

A good starting point would be to find an LH2.4 240, familiarize yourself with what its wiring looks like and then lift that and fit that to yours. The diff sensor is not mission critical but without it you will need an LH2.2 throttle body as you cant set the idle without the diff sensor as it gives the ECU road speed.

Any further questions just ask :)

Philia_Bear

You can use lh2.2 dizzy on 2.4
You just dont use the hall effect sensor at all

jamesinc

I see 3 bar FPRs on NA 2.4 cars all the time (in fact, I've never seen any 2.4 car with a 2.5 bar FPR). VADIS also says the 2.5 bar FPR was only used on some 7xx chassis. I've only had a look at a handful of 2.2 engines (all turbo) and they also use the 3 bar FPR.

So based on VADIS, and on my own observations, which are consistent with what VADIS is reporting, nearly everything runs 3 bar and if you find a car running 2.5 bar it's rare, it's certainly NA, it's probably LH-2.2, so you can say "(RARE)" when you put the car up for sale.

Vee_Que

The important point of the lh2. 4 is getting the drilled flywheel, whereas you don't need that for lh 2.2, and if you're going to an aftermarket ecu down the track, 2.2 is fine. But you can get chips for lh 2.4 so it will make more power.

Anthony

Philia_Bear;102782 wroteYou can use lh2.2 dizzy on 2.4
You just dont use the hall effect sensor at all

Good point, as the hall effect sensor was moved being relocated to the bell housing, and the front mount 240 dizzy simply distributes the spark as per normal.

Slowbrick

Anthony;102808 wrote
Philia_Bear;102782 wroteYou can use lh2.2 dizzy on 2.4
You just dont use the hall effect sensor at all
Good point, as the hall effect sensor was moved being relocated to the bell housing, and the front mount 240 dizzy simply distributes the spark as per normal.

Not quite true. The LH2.2 dizzy had the provision for you to advance and retard the timing. The Lh2.4 dizzy does not. Now im not sure because I havent tried it but I would imagine if one were to install the LH2.2 dizzy in the wrong orientation because of the lack of locating bolt hole that this would throw the maps off for LH2.4 as it is expecting to see the dizzy at a specific angle (e.g 10') instead the many possibilities of the LH2.2 dizzy. Havent tried it but could see it causing problems.

EDIT: I stand corrected and it seems LH2.4 just dont give a shit
http://www.turbobricks.com/forums/showthread.php?t=270830

Philia_Bear

Slowbrick;102813 wrote
Anthony;102808 wrote
Philia_Bear;102782 wroteYou can use lh2.2 dizzy on 2.4
You just dont use the hall effect sensor at all
Good point, as the hall effect sensor was moved being relocated to the bell housing, and the front mount 240 dizzy simply distributes the spark as per normal.
Not quite true. The LH2.2 dizzy had the provision for you to advance and retard the timing. The Lh2.4 dizzy does not. Now im not sure because I havent tried it but I would imagine if one were to install the LH2.2 dizzy in the wrong orientation because of the lack of locating bolt hole that this would throw the maps off for LH2.4 as it is expecting to see the dizzy at a specific angle (e.g 10') instead the many possibilities of the LH2.2 dizzy. Havent tried it but could see it causing problems.

EDIT: I stand corrected and it seems LH2.4 just dont give a shit
http://www.turbobricks.com/forums/showthread.php?t=270830

Lh2.4 does not care
Lh2.2 cared because adjusting the dizzy affected the reading of the hall effect sensor (same as kjet)

Lh2.4 runs the dizzy at about the 1/3rd point in the slot

Vee_Que

I've seen them moved and it makes no difference.

Major Ledfoot

With regards to the speed sensor on the diff and LH 2.4 -

Is there an aftermarket tone wheel and sensor available that can bolt up to the tailshaft flange and/or a speedo drive? Does LH 2.4 need the 48 pulses per revolution signal, or is it 96 pulses per revolution?

FWIW, if you want to run LH2.4 without using a LH2.4 specific flywheel/flexplate, KL Racing sell a 60 -2 tone wheel that bolts to the crank pulley, plus a suitable sensor and bracket.

Philia_Bear

Lh2.4 does not use the spedo in the diff in any way shape or form until 1996 and then its only used as a speed limiter in the japanese market

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