View Single Post
Old 03-04-2011, 05:08 AM   #1
<Master Tech>
ZVOLV's Avatar
Join Date: Nov 2002
Location: California
Default LH2.4 Install/Conversion. Just a few wires to make it run

Right click dead links and open in a new window to view pics.

Do you want to know how to install Bosch LH2.4 EFI in your Volvo? Fantastic! It's very simple and only takes a few wires. We installed a 1994 B230FT and LH2.4 into a 1984 240 Turbo and this is how we did it.
-LH2.4 240 wiring harness.
-B230FT Engine OR drill/tap block for RPM sensor if attempting on a B21/23. If you don't drill/tap PERFECTLY the airgap will be wrong and it won't run at all/well.
-LH2.4 Fuel Computer and Ignition Computer
-LH2.4 Flywheel or Flexplate and RPM sensor
-Complete rear axle or differential from electronic speedo 240
-Electronic speedo cluster
-LH2.4 Idle air motor
-LH2.4 MAF
-LH2.4 Coolant temp sensor
-Greentop injectors and resistor pack OR high resistance injectors like 850 Turbo orangetops
-2 small Custom fuel lines if converting from Kjet OR fuel lines from an EFI car


-First remove old engine bay harness

-Install B230FT and transmission of choice

-Install electronic speedo rear axle with gear ratio of choice.

-Install LH2.4 engine harness, run it thru firewall, and hook up computers.

-There is a wiring pigtail that goes from the computers and across the dashboard. Updated Nov 2015. Colors may vary slightly by harness year. Make sure you do your homework! But here are the basic few wires to make the thing run. Again, this is using a 1989/1990 wiring harness. Dash pigtail is different on the later models. SLIGHTLY. Don't be a bonehead. Get out a multimeter and wiring diagram and figure out the differences.

Wire 1: Thicker (12ga?) Red/Yellow- Power OUT TO Fuel Pumps.
(Wire 2:) Thinner (16ga?) Red/Yellow: Power FROM fuse to Heated 02. (Vehicle will start without this wire connected)
Wire 3: Blue: Ignition ON signal.
Wire 4: Blue/Black: Signal fom back Speedo (optional. You will get high idle after freeway runs without it. No big deal.)
Wire 5: Power up ignition coil with switched 12v. ( i suggest adding it to 2 wire plug. One wire is yel/red. Other is blue. By adding 12v to this wire, you are powering up the coil and the powerstage)
(Wire 6) entire LH System/Fuel Pumps gets power from a RED fused wire from the battery. At least on 1989-1990. Later model wiring harness is different. Sort thru other guy's posts or look at wiring diagrams to figure it out.

- Relocate the MAF wiring to the other side. This was easy. We pulled all of the wires, except the brown/black ground wire, out of the harness carefully and moved them to the other side. For the ground wire (that black/brown) you cant pull it out because it grounds other things. You need to pull it out as much as you can and then attach it back to your MAF plug.

-Plug in 4 wire connector in your new 2.4 harness into the old firewall connector. Its grey.

-There are a few other wires that need to be hooked up for AC, ABS function, and Check Engine Light but the above wires are all it needs to RUN! Pink one is for Check Engine light BTW.

-For fuel lines you can either get a complete set of EFI fuel lines from a donor car, or you can have a custom feed line and return line made. We went to Parker hose fittings and got hooked up with both for about $20!

-SPEEDO. Considered optional. If you do NOT run a speedo signal, you may have moments of high idle. For the speedo signal you just need to install a electronic speedo rear axle, or attempt to install just the diff and diff cover in your existing housing. You will also need to install a electronic speedo cluster. There are two wires coming off the differential. You run the black wire to the same ground point with the black wire coming of the speedo. The blue wire from the diff cover goes directly to the instrument cluster. Then you need to hook up the red/black wire from the ignition switch to the back of the cluster. This will power the whole cluster up. Use the old wire that powered up your instrument cluster.
No Start Thread

Last edited by ZVOLV; 10-23-2017 at 07:21 PM..
ZVOLV is offline   Reply With Quote