• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

LH 2.4 ECU info, BOV work or not? fuel cut @ what voltage?

thelostartof

unbalanced chemical
300+ Club
Joined
Jun 26, 2002
Location
Apache Junction, AZ
ok so i'm doing a bit of research on LH 2.4 ECU's to see what i can find out about them since many have a few varibles such as cold start and EGR. and then others will run BOV's and others won't and some have fuel cut higher than others.

so far this is what i've figured out

937 ECU - car came equipted w/o a EGR valve and w/o a cold start injector. can run a BOV w/o stalling. car will get check engine light but a BOV can and does work. has AMM fuel cut but not idea of voltage. anyone w/ this ECU can you measure the voltage u are getting @the AMM when you hit fuel cut??

939 ECU - car came equipted w/ a EGR valve and w/o a cold start injector. can not run a BOV as car stalls not matter how you shim the BOV. have yet to test for fuel cut and where it is

563 ECU- car came equipted w/o a EGR valve and w/ a cold start injector. do not know if can run a BOV as waiting to hear back from people. so far testing from a few have shown the stock AMM to be pulling over 5.4V's and NOT hit fuel cut yet. this is w/ the stock 13c @16psi.

560 ECU- car came equipted w/ a EGR valve and w/ a cold start injector. do not know yet if car can run a BOV, will test once i get the 91 running. from my previous driving i have run 16+psi w/ an open downpipe and not seen a fuel cut. i have had boost spikes to 22psi and not had any kind of cut because of to much air flowing past the AMM. once i get the car running w/ a 15g i will measure voltage and see where cut is

so far from the few guys i've talked to i've figured this much out

the 937 ECU was in a 93 940T
the 939 ECU was in a 92 940T
the 563 ECU was in a 90 760T
the 563 ECU was in a 90/91 740T


so far that's the little bit of info i've found ... i'd love for any more LH 2.4 guys to post here letting me know what thier ECU # is and what it came w/ be it EGR or cold start or not.. and if they can run a BOV and where thier fuel cut is if any. once we figure this little junk out we will see if we can swap ECU between these cars and see if LH can live w/ a wrong/different than stock ECU even tho it controlls the same things

thanks
mike
 
I agree about researching LH stuff. I think getting it to support higher hp numbers, and otherwise getting it to do what we want is very good. It might be a few years old, but don't underestimate the huge resources of the bigger companies compared to aftermarket companies. For reliability I think it makes a lot of sense. I have read posts from people that have tried aftermarket, ignitions, coils, fuel systems and they mention a lot of failures.

Where is the part number on the LH to check?
 
it is in the passenger side kick panel and then just pull back the metal a little and look @ the last 3 #'s of the #... this is a pic of my 560 ECU in my 91' 740T

sIMG_3954.jpg
 
Ok. I have the 563 ecu as far as i know. I think i have seen the number, but i forget. I have the 563 according to the above info (no egr, have cold start)


I hit fuel cut on my old AMM, but after replacing it I dont get fuel cut anymore. I need to check if I had the non turbo (015 little number)? or the turbo (816 little number)? on there before I swapped the AMM. Right now I am running a NA AMM. My car also backfires soemtimes and gets 17mpg freeway. Hey mike, you got a turbo AMM you can trade me?

As for the BOV, i get the TPS check engine light every once in a while. When this happens my idle goes to 1100 until i turn the car off. Restart the high idle is gone, but the light is still there. I talked to norcal745 at the show and he said he gets the light, but no idle prob. He also said at least one other guy gets the TPS code after BOV install. We both got the HKS super sequential BOV and we had the same amount of threads showing on the adjustment screw.
 
Also, my ECU seems to be really good at learning how to fix probs. When I first installed BOV the car would stall coming to stops on ocassion, but after a day or two it went to more of a stumble. Now it goes to idle just fine.


Also, with that used AMM i bought the car ran like crap at idle for a day or two then it went away....?

It sometimes gets an odd idle, but it always seems to fix itself. Which is good for driveablity, but a pain in the ass for diagnosing when/where you have problems.
 
u should of reminded me i could of brought my extra AMM's

but u bring up a REALLY good point. the 015(n/a) AMM is being used by toby on his 940 and his BOV works fine. yet i think my friends car is a 816(turbo) AMM so i think they might have different reading abilitys because of the little extra part inside that makes them different.

i will have to test both AMM's and see what the difference is. and i'll see if i can dig up a true turbo AMM (i'm not taking the brand new one off my 90)
 
on my car, w/ the T3 swapped in, and the Greddy Type-S in place, i will throw CEL's occasionally, and when under the CEL the idle while not in gear will hit about 2000rpm idle, and 1100 under load (drive or reverse). I had stalling issues when i 1st installed the BOV, since then the car has learned i guess, now it may stumble occasionally, but it doesn't stall... i'll pull my ecu to check it's number since i don't see my year/trim on the list..
 
so how long did it stall for before the ECU figured it out? you just drove around the block for a day and let it stall all the time till it started to keep the motor running and not die?

and well those ECU's show'd are just some of the cars i have seen them on .. volvo could of used them on any cars so we'll see
 
FYI....There was a TSB for cold start complaints on engines with LH 2.4. Both turbo and N/A and 700's and 240's. If you have had this epdate done to your ECU then it will probalbly have a sticker placed over the origional bosch label. The update was a PROM exchange.
Mark

Ok....just looked up on amazon.com Bosch fuel injection. Im gonna see if i can find some of these books locally. But ill bet there is a lot of good info in these books. I question the learining curve of LH 2.4 and how on these cars it seems to compensate for a lot and not change after. I know ECU's since the beginning of O2 control feedback carbs have had somewhat of a learning curve. But only to a point. (like the 99 chevy subarban i worked on that had a check engine light for a cam/crank sync error. the distributor was a whole tooth off!! the truck ran great, just threw a code.)
 
Last edited:
thelostartof said:
so how long did it stall for before the ECU figured it out? you just drove around the block for a day and let it stall all the time till it started to keep the motor running and not die?

and well those ECU's show'd are just some of the cars i have seen them on .. volvo could of used them on any cars so we'll see
mine took several days to "learn", and would only stall under light/part throttle then quick let off situations (i.e. stop and go traffic / stop signs / revving then let off) best i could figure, with the presence of the bov, the air was getting let loose out of the charged pipes when you'd let off, causing there to be an overly rich mix that would either stumble or stall the motor, and after enough time, the ECU learned to lean the mix out to compensate..
 
mike for more info,

My car was first sold in Texas, it has a build date of 04/92, it has the interior (dash and console) of the 93 build year.

More info we can get on this the easier it will be to draw lines of comparison.
========================================
740Turbo92Wagon:
on my car, w/ the T3 swapped in, and the Greddy Type-S in place, i will throw CEL's occasionally, and when under the CEL the idle while not in gear will hit about 2000rpm idle, and 1100 under load (drive or reverse). I had stalling issues when i 1st installed the BOV, since then the car has learned i guess, now it may stumble occasionally, but it doesn't stall... i'll pull my ecu to check it's number since i don't see my year/trim on the list..

I have this same problem (1-3-3 TPS adjustment colde), although I stopped clearing the CEL (check engine light) because it comes on every time i drive the car and dump a lot of air. This isn't exatally the topic for it ( I'll make one http://forums.turbobricks.com/showthread.php?p=148559#post148559 ) but is this what you described? Anyone else want to add their experance into that thread.

==============

Sorry to side track this thread, maybe when mike gets more info from many other ECUs we cna get an article done on it :)
 
Now that im thinkin about it...the one week I ran my home made BOV I did get a TPS code and that high idle problem, after climbing a hill in 2nd in boost and letting off after getting to the top. No help I know, but it just popped in my head.
 
i'll try it.

Hey thelostartof (Mike right?)

yeah I'm running the 937 on my 944t. I'll check the voltage at fuel cut for ya if you tell me which is the signal wire?

Mike (as usual)
 
runnign both a ssqv and a stock cbv on a 563 ecu. slight idle probs at first now just a high cold idle like described b4 2000 rpm and 1100 under load at adle till it warms up then idles fine.
 
heh....hey boosted, I *could* pull 5.4 volts stock with my 563 ECU, but i like my pistons to stay in their cylinders, and the rods being the internal type......dont think its a good idea to expose them to daylight :p just kidding:) (not gonna hit fuel cut with 226K)
 
Ok so i exposed some of the red/blue wire for the AMM to ECU about 2-3 inches away from the ecu. I hooked up the voltmeter and went for a drive. 2.7volts at idle, quickly goes into 4.xx range, and drives happily in the 5.1 and up range.

I got fuel cut at 5.55-5.57 v. I have a data hold feature on my meter and i hit the button when i got fuel cut. This was at about 5500 rpm and sometimes 5000rpm. I think this might of been what happened to me at the track the other night, but i thought I was running only 10psi then... Anyways today I was getting fuel cut at 16psi. The full three inch exhaust with no cat seemed to be what put me past the limit on the AMM.
 
Back
Top