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LH2.4 update using an LH2.2 EZK from a 740

dl242gt

The world of the smiling Dogo
Joined
Jun 21, 2002
Location
S NJ, a suburb of Phila.
I noticed there are quite a few LH2.4 swaps now. If I recall corectly a few years ago one of the Buchka brothers mentioned that you could use the LH2.2 ezk with a LH2.4 fuel computer. I am making this thread because I would like some help verifying that. It seems like if you are doing an LH2.4 swap it would be great to not have to pull the engine to add the crank sensor and instead could use the distributor with a hall sensor. I don't have diagrams to compare wiring and signals. Can anyone help with this?
 
I noticed there are quite a few LH2.4 swaps now. If I recall corectly a few years ago one of the Buchka brothers mentioned that you could use the LH2.2 ezk with a LH2.4 fuel computer. I am making this thread because I would like some help verifying that. It seems like if you are doing an LH2.4 swap it would be great to not have to pull the engine to add the crank sensor and instead could use the distributor with a hall sensor. I don't have diagrams to compare wiring and signals. Can anyone help with this?

I've often wondered the same thing.
 
I will look around for some diagrams and see what I come up with and post about it. I couldn't find the thread with the comments in it. So that's why I started this one.

Thanks for the reply.
 
Hmmm I have to put a trans in my 88 240 I'm interested as well now would be the time to 2.4 swap it...but is there a reason to of its just a n.a. Driver? Is 2.2 bad I think 2.4 idled smoother but that's the only difference I could tell.would a dave barton harness be the thing to use?
 
Lh2.2 is arguably more reliable, the hall sensor has a stronger signal than the VR sensor in lh2.4. I'm pretty sure 2.2 computers are more robust too, but this is anecdotal from browsing TB.
 
I compared the connections for signals between the two fuel ecus and the ezk. The LH2.4 uses an extra output signal. However, outputs are the same it seems if the ezk thinks it's communicating with an LH2.2 turbo.
for example.
LH2.2 has pin 8 input signal from pin 24 fuel ecu
LH2.4 has pin 8 input signal from pin 25 fuel ecu

2.2 has pin 15 output to pin 12 (B230FT only)
2.4 has pin 4 output to pin 28 fuel ecu

2.2 has pin 17 output to pin 1 fuel ecu
2.4 has pin 17 output to pin 1 fuel ecu

So it seems when it's a turbo version it uses the same extra signal output to the fuel ecu just different pins on the connectors. If any of you have diagrams and can double check that but it seems like it's compatible.

The other possible issue is the coolant sensor. I've never owned a 2.2 car But I may have a sensor around to check. Will post back.

Writing this made me realize I skipped a whole generation of LH2.2 240s and 740s. Never owned any. I went right from Kjet, to kjet turbos, to LH2.4 cars.
 
Dont forget that 240s never came with lh2.2 ezk... just the christler ignition box AFIAK... they only got EZK ignition in 89 with the lh2.4 change.
 
I haven't gone through the details but looking at a wiring diagram for an early 740T with LH2.2 ECU and a EZ117K versus a '93 240 with LH2.4 ECU and a EZ116K, they look similar. The pin numbers on the EZK box aren't quite the same.

For LH2.4/EZ116K, there are 3 wires between the ECU and EZK
- EZK-4 to ECU-28 Knock signal from EZK to ECU, grounded by EZK to enrich fueling
- EZK-8 to ECU-25 Load Tq from ECU to EZK, pulse width modulated, selects row in ignition advance map
- EZK-17 to ECU-1 RPM or tach signal from EZK to ECU, one pulse per spark.

For an old post on using LH2.4 without a EZK box, see:
http://forums.turbobricks.com/showthread.php?t=288874
 
Thanks for clarifying what those signals are. If the cars are turbo LH2.2 with ezk then all three signals are used with LH2.2. But the diagram I had read that it was B230FT only that had pin 15 ezk to pin 12 fuel ecu. I'm thinking you would tie pin 15 on the 2.2 ezk to pin 28 on the LH2.4 fuel ecu. Providing the same knock signal as pin 4 on the LH2.4 ezk.
 
Just a bit of background is that I'm considering changing my kjet 82 turbo to efi. I have enough parts to do an LH2.4 swap to it. Saving me the effort of adding the crank sensor would be nice. I'm thinking a tuned LH2.4 fuel ecu triggered by a hall sensor ezk with a chip might work out well for that.
 
OK, I looked at a '87 740 greenbook and see what you mean about the 3rd wire.

For LH2.2/EZ117K (turbo), I think the 3 wires are
- EZK-15 to ECU-12 Knock signal from EZK to ECU, grounded by EZK to enrich fueling ???
- EZK-8 to ECU-24 Load Tq from ECU to EZK, pulse width modulated, selects row in ignition advance map
- EZK-17 to ECU-1 RPM or tach signal from EZK to ECU, one pulse per spark.

For non-turbo LH2.2 ECU-12 is WOT switch (grounded at WOT). I have a turbo EZ117K box in my pile of extras, but I don't have a good way of generating a suitable knock sensor signal to see what the EZK-15 output signal actually looks like. The Ignition Systems greenbook (TP31397-1) does say that EZ117K knock enrichment is only for B230FT. (EZ116K knock enrichment is all engines).

I know what you mean about the CPS bracket. I ended up making a custom one to drop the sensor down ~1/8" of an inch from the non-bumped B21FT bellhousing. If I had a mill, it wouldn't have been too bad, but all I had was a hacksaw and a file. I'll see if I have pictures somewhere.
 
Thank you Bob. This is looking promising. If the circuit boards are similar to the ezk116 then it may even use the daughter board and wasted spark updates. I wrote hopefully as I haven't ever looked inside the ezk117 box.
 
Sorry, the wasted spark board is LH2.4/EZ116K only. It uses the conditioned signal from the 60-2 CPS and counts out which half of the revolution the crank is on. If it's the upper half, then the spark from the normal EZK circuits is directed to wasted spark output 1; if the lower half, then the original spark goes to wasted spark output 2.

Here's pictures of the B21FT bellhousing with no bumpout, a B230 bellhousing with bumpout and holes, and the custom bracket I needed to make. (BTW, I rebuilt a 83 block, but when I pulled the original 84.5 B21FT block, it had the bumpouts on the bellhousing, but un-drilled.)
LH2-4-CPS-vs-B21-FT.jpg


custom-CPS-bracket1.jpg
custom-CPS-bracket2.jpg
 
Just adding this for future reference.

I did this hybrid swap and it works fine.

My application is n/a 16v swapped B21.

fuel: LH2.4 ECU for B234 (571)
ignition: EZ-117K (B234 mapped box from sbabbs)

LH2.4 pin 25 to EZ-117K pin 8
LH2.4 pin 1 to EZ-117K pin 17
splice in TPS signal to LH2.4 pin 2 / EZ-117K pin 7
7.5v signal to LH2.4 pin 28 (otherwise triggers 3-1-2 code/CEL...turbo applications would connect to EZ-117K pin 15)
VSS signal driven by Dakota Digital SGI-5E / T5 VSS (pin 34)
 
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