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A K-Jet to LH-Jet conversion?

2

242DL

New member
Joined
Oct 13, 2005
Location
Oregon
I know this might sound insane, but is it possible to convert a normally aspirated B21F with K-Jetronic injection to LH-Jetronic injection? I drove an '84 wagon that got really good mileage but was sort of a dog in other respects in that it ate starter motors and had a host of electrical problems. My '81 242 is a superior car (except for its stock 'L' cam) and the fact that it has a B21F that has K-Jet fuel injection.

I have seen this type of conversion done before on a B21FT block but I would like to know if this is as simple as getting LH-Jet injection components and the ECU/wiring harness? And if this conversion is possible, would it improve fuel economy even if it's using the smaller B21F block?

I'm replacing the cam, bypassing the a/c (which doesn't work) and planning on removing the cooling fan and utilizing an electric one for the sake of reducing the work that the eingine has. And I thought while I was at it, whether or not to upgrade the FI system if possible. Any ideas?
 
Sure, it can be done, but it's not easy. Each system has different schemes for connecting to the various sensors and relays. It may be a little better if you only deal with 240s. I took 760 wiring and 240 wiring, took everything all apart and made one harness. It took WEEKS.
 
did it on my car, it's prolly best to know what your doing with the wiring,but that was the only hard part, finding a good 700 series harness
 
If you're going to go through swapping FI systems, consider swapping the whole engine too - preferably one with a turbo. :badboy:

Anyways ... L cam - you in Cali? Or did your car just come from there?

-- Kane
 
My car came from California...got a nice sticker that says "This vehicle was manufactured in accordance to the specifications for the State of California for 1981 model year vehicles." And we thought something was wrong with the ECU that was keeping it from going more than 3500 rpm in 4th gear with OD (4500 rpm with no OD).

Yes the logical conclusion would be to take a B230FT and drop it in but that's money and time that I don't have to work with.
 
Personally, I'd not bother with the hassle of swapping TO LH from K-jet. If you're wanting to go EFI, do something more interesting than 'stock'. Do a search here (or on google) for 'Megasquirt'. If you're assembling the parts to do LH, it would be a shame to not go fully programmable. You wouldn't save any money due to the cost of MS itself vs LH computers/harness, but you could get the peices on a budget and put it all together in a couple of weekends (or less, depending on skill level and help from the EFI forum here).

That's just me though, others have swapped to LH and are happy with it.
 
The thing is I can get LH-Jet ECU's and wiring very easily and cheaply -- and I have a very competent mechanic. I am assuming I would need an B23F/B230F intake manifold in addition to the ECU/wiring harness. What other parts would be required?
 
In addition to the ECU you'll need the block mounted distributor with hall effect sensor, EZK ignition box, power stage, knock sensor (you'll have to drill and tap an M8x1.25 hole in the boss under the intake manifold for the knock sensor), I believe the Coolant temp sensors interchange, fuel pump relay and radio suppression relay, you'll need the o2 sensor, AMM, intake manifold with tps, fuel rail, fpr and injectors, you'll need to make fittings to go from the fuel filter to the rail inlet, and from the FPR outlet to the tank return line, plug the holes where the k-jet injectors are or leave them there. I know i'm forgetting stuff, but its late and i'm tired.

Its a real pain in the ass. I did it to my 242tic when I swapped a b23F+T in. I dont regret it, but I wouldnt do it again.
 
It'd be easier to get the K jet running right. When it's set up right, K jet is a damn good system.
 
I would tend to agree...my mechanic also suggested switching to LH-Jet wouldn't be worth it with the 2.1L displacement. The system as far as I know is running well -- even the cold start problems I had when I first got the car have vanished. Odd though my fuel economy has gone down recently and it can't be the switch from high octane to mid octane (89) gasoline. the K-Jet system really has less to go wrong with it because it is simpler. Now I want to figure out how to make my fuel economy a bit better with a car that is in quite good tune.
 
If it is in fact running good, you can probably tune a few miles a gallon out of it with just a proper tune and CO adjustment. There isn't going to be much of a difference in milage from K jet to LH if they're both set up right.
 
My station wagon (the dog) got decidedly superior gas mileage than my 2 door does...I'm having the cam replaced and the a/c bypassed this weekend...so maybe we will look into the CO adjustment while we're at it.
 
ask ye shall recieve

Volvo 240 Series cars built from 1975-1982 (plus Turbos all '81-'85) were built with Bosch K-Jet fuel injection. 240 series cars from 1983 (excluding turbos) to 1993 were built with LH-Jet fuel injection. Back on topic...I was actually wrong about the cam in my car...it has a B cam in it. But it still says it was built for California spec...so whether some B cams were ground to L or whatever...So now it has a 'V' grind in it -- and it did make a difference though I haven't been driving it too hard since it needs to be broken in. We're going to finish dialing it in tomorrow afternoon...
 
242DL said:
Volvo 240 Series cars built from 1975-1982 (plus Turbos all '81-'85) were built with Bosch K-Jet fuel injection. 240 series cars from 1983 (excluding turbos) to 1993 were built with LH-Jet fuel injection. Back on topic...I was actually wrong about the cam in my car...it has a B cam in it. But it still says it was built for California spec...so whether some B cams were ground to L or whatever...So now it has a 'V' grind in it -- and it did make a difference though I haven't been driving it too hard since it needs to be broken in. We're going to finish dialing it in tomorrow afternoon...
Click to expand...

hmm...my 79 244 with K-jet has a B cam and its peppy as hell. revs hard almost to 6K and could to 4500 rpm in OD no problem. one of the best running B21F engines i've seen. untill the HG blew that is...
 
I think the original question was hey give me some help lets convert this car. Im in the same boat. 81 kjet 240 just got all the parts from an 85 240, even the distributor and ignition box. Im doing it cause I want to run a turbo and eventually switch to ms. If you have the initial parts for electronic fuel injection it definetly makes it easier to go to the final round which would be ms
 
Its going to be a pain in the butt to switch over to LH, You are definetly better off tuning Kjet to run well. Im pretty sure Kjet should get about the same mileage as LH, Injection is injection..

As for Kjet not running well. Vacuum leaks (Gaskets, Vacuum tubing), if you have Lambda, replace the single wire O2 sensor. Re-do your wiring harness for Kjet, check ignition timing and optimize it for what gas your using. Im pretty sure if you just change your L cam to something like an A cam you should pick up mileage AND pep!~
 
You say to change the single wire O2 sensor on the lambdas. Am I to assume there exist 2 wire or other O2 sensors? And I assume of course that they're better?
 
rossi240 said:
I think the original question was hey give me some help lets convert this car. Im in the same boat. 81 kjet 240 just got all the parts from an 85 240, even the distributor and ignition box. Im doing it cause I want to run a turbo and eventually switch to ms. If you have the initial parts for electronic fuel injection it definetly makes it easier to go to the final round which would be ms
Click to expand...

I just did this a few weeks ago (minus the +T)....

used the LH2.2 and EZK boxes from an '88 745Ti as well as the wiring harnesses...it wasn't too bad, luckly I bought the harnesses already pulled from the donor car, made life much easier.

the wiring is pretty straight forward and the car starts and runs great....
 
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