lh2.4 fuel cut solution

[ZVOLV]

I need to get past the AMM based fuel cut on my 1990 740 turbo. This is not overboost switch as used on lh2.2.

I did about an hour of searching tonight and came up with: "yeah, the fuel cut is 5.1v" and "go ems/megaquirt" I am not going ems/megaquirt, but rather looking for a 5 dollar homemade voltage regulator solution.

I found that on my ecu i get fuel cut at around 5.5v. I got 5.55/5.57 to be specific.


I am looking to make a low cost voltage regulator so that the computer only sees 5.5v. Does anybody know how to make a contraption like this? Apparently eric s. was working on one but had probs with the resistance across the unit. I can see how that would be a problem because I am working on one that uses diodes and a variable resistor and I can see how if i put it inline with the AMM signal it would interfere with the voltage the ECU sees. Here is a quote from one of his threads,

Fuel Cut:" Many people running 15Gs and larger turbos have started reaching a stumble in their WOT adventures. This is caused by maxing out the AMMs sensing abilities and thereby 'jumping' off the fuel map. The ECU responds to this by cutting the fuel injectors off completely. This point is around 5.1vdc. I am currently working on a solution to this problem using a 'magic black box' but I'm having trouble keeping the voltage drop across the box from interfering with the normal AMM operation. More on this soon."


So does anybody wanna help me make a budget box that will bypass the AMM based fuel cut?

[davidmacq]

Can't you trick it into thinking less air is passing through the AMM? Some try to swap out a larger AMM, but without the internal electronics being the same, that is problematic. Couldn't you get a 2nd hand AMM and bore it out so it will give a lower voltage?

Think it might be a hard problem to lick adding electronics to it. From the electronics side I would think you could reprogram the ECU to react differently to the AMM.

[frostburner]

well i dont know if brickers have tried this but i did it on my turbo dodges and it worked perfect.. using a zener diode taht is at a set voltage u put inline with the signal and ground and they also have adjustable zeneer didoes so you can be more exact.. cost range about 50cents or less for teh regular one to 5$ i tinhk for an adjustable.. not sure on prices but it tricked the map sensor on my other cars into never seeing above 4.7v which was about boost cutout on those cars..

[pbonsalb]

One of the aftermarket electronic performance parts companies, perhaps Split Second, makes a device that does exactly what you want. Probably costs $150, so you might want to discuss it with an electronics expert to see if one could be made for less. Essentially, it is a voltage clamp.

Note that you have to independently add fuel above that point since the stock EMS will be tricked into seeing only 5.1 volts (or whatever) levels of airflow. Extra injectors are one way, but you have to do some experimenting to figure out how to set them up to work only when needed and which ones to use to get just the right amount of fuel -- unless you are using a computer controlled extra injector system that can be adjusted/tuned.

Philip Bradley

[frostburner]

if you just need to keep teh ecu from seeing above 5.1 a zener diode will do it just fine.. ive done and tested it on other cars and it worked perfect.. and can be done for less than 1$.. or u can go fancy and spend alot for teh same thing. and for addign extra injectors is very easy.. just get a pressure switch.. give the injector power but not ground.. pressure switch grounds teh injector at set psi when you start to laen out.. very very easy can also be done for dirt cheap.. both things i have done many times and worked flawlessly..

[Jess]

A lot of guys are using diodes (known as "clamps") on their VW 1.8T engines. Basically you are clamping the signal from the mass air sensor (or air mass meter) to the ECU. The only problem is you end up running a little lean if you don't compensate the fuel system a little bit. Do you know what the stock fuel pressure is? What about the stock fuel injector size?

Check out this link for more info.

http://forums.vwvortex.com/zerothread?id=1308960

[TerribleOne]

Temporary solution to a permanent problem.
Go EMS.
You do want performance dont you? Your stock fuel system odviously isn't up to the task of making your car go as fast as you'd like it to. save your money and live with what you've got.

[bmessina]

Is the fuel cut behavior similar to what it's like when you hit the rev limiter in LH 2.4? In a few WOT adventures I've had so far in 1st gear(AW71), I swear my car has been stumbling well before it hit 6k rpms.

[volvorod85]

Is the fuel cut behavior similar to what it's like when you hit the rev limiter in LH 2.4? In a few WOT adventures I've had so far in 1st gear(AW71), I swear my car has been stumbling well before it hit 6k rpms.


What kinda boost are ya running?

[ZVOLV]

I bet that the problem bmessima is experiencing is different than my problem. Stumbling at high rpms isnt the same as this abrupt cut out. This is stronger than the rev limiter.


Ok, here is the link to a box I made, but never installed due to lack of knowing how to put it in correctly. I dont know how to make sense of where the wires each go. I am reluctant to cut the signal wire to my ECU.

Let me know what you guys think of this rig and how you think it should be hooked up in the volvo. I know the red/blue wire is the signal from MAF to ECU. So does this rig get put inline with the signal wire to the ECU? www.fwdmopar.com/sites/dennis/howto.html

Here is a link to one of the best wiring diagrams I have found for my car. When I did a voltage test on the MAF wires I never found a 5v+. I only found 12v wires. http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm

[Magnum TE]

Here is a link to one of the best wiring diagrams I have found for my car. When I did a voltage test on the MAF wires I never found a 5v+. I only found 12v wires. http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm
if that goes down, or you want something faster, i mirrored it in my referance section.

www.unce.org/volvo/referance/

[the poi]

well i dont know if brickers have tried this but i did it on my turbo dodges and it worked perfect.. using a zener diode taht is at a set voltage u put inline with the signal and ground and they also have adjustable zeneer didoes so you can be more exact.. cost range about 50cents or less for teh regular one to 5$ i tinhk for an adjustable.. not sure on prices but it tricked the map sensor on my other cars into never seeing above 4.7v which was about boost cutout on those cars..
bwahaha... i was talking to kenny a couple weeks ago about this, and i was thinking "sheesh, sounds like a job for a damn zener"... never had a guinea pig to try it on though. good to know that it really IS that straightfoward tho. common votlages that would work for us is 4.7 and 5.1... i'd try a 5.1 first. but as was said before: something needs to richen the mixture once you go over that voltage, cause the ECU will still think its only flowing the 5.1v airflow....

[volvorod85]

Zener diode sounds like the answer. So now I think the question is where should it be wired, id have no problems trying it on my car, thouygh Im not close to hitting 5v fuel cut :P. Like it was said before, you want to put it with the ground and signal return wires. Now am i correct in saying it should be Ground (->|) Signal in terms of wiring?

Blue red pin 3 on AMM pin 7 on ECU signal return.
Blue green Pin 2 on AMM pin 6 on ECU Ground.
Pin 1 on AMM (brown?) chassis ground
Blue and yellow pin 5 AMM Pin 9 on ECU 12V
Blue and White pin 4 AMM pin 8 on ECU. Brun off signal? signal comes from ECU


Info VIA Alldata
Mark

[frostburner]

bwahaha... i was talking to kenny a couple weeks ago about this, and i was thinking "sheesh, sounds like a job for a damn zener"... never had a guinea pig to try it on though. good to know that it really IS that straightfoward tho. common votlages that would work for us is 4.7 and 5.1... i'd try a 5.1 first. but as was said before: something needs to richen the mixture once you go over that voltage, cause the ECU will still think its only flowing the 5.1v airflow....
yes i have guinea pigged alot of my cars just to see if it will work..lol.. hey someone has to.. but yea zeners work great.. never had a problem and they come in alot of voltage ranges.. its real easy takes about maybe a max of 2 min to install... and i used it before to stop cutout and aded fuel with extra injectors setup with pressure switches to come on when my car started leaning out.. so adding fuel is a no brainer also.. pretty straight forward also..

[frostburner]

Zener diode sounds like the answer. So now I think the question is where should it be wired, id have no problems trying it on my car, thouygh Im not close to hitting 5v fuel cut :P. Like it was said before, you want to put it with the ground and signal return wires. Now am i correct in saying it should be Ground (->|) Signal in terms of wiring?

Blue red pin 3 on AMM pin 7 on ECU signal return.
Blue green Pin 2 on AMM pin 6 on ECU Ground.
Pin 1 on AMM (brown?) chassis ground
Blue and yellow pin 5 AMM Pin 9 on ECU 12V
Blue and White pin 4 AMM pin 8 on ECU. Brun off signal? signal comes from ECU


Info VIA Alldata
Mark
yes.. pretty sure athts where it goes in at least tahts where it went on my other cars..

[Boosted2003]

get 563 ecu and chip it. Not to be an ass. But people stop temporaryly fixing the problem and chip the car. For the price of chip and 563 ecu you can get your self MSnS.

[TerribleOne]

get 563 ecu and chip it. Not to be an ass. But people stop temporaryly fixing the problem and chip the car. For the price of chip and 563 ecu you can get your self MSnS.

I know you guys like to modify stuff and all, but boosted03 is right.
Take off your dress and buy EMS.

[ZVOLV]

Obviously EMS, chip, MS is a solution. I am not interested in those solutions. Please dont suggest it any more.

" I did about an hour of searching tonight and came up with: "yeah, the fuel cut is 5.1v" and "go ems/megaquirt" I am not going ems/megaquirt, but rather looking for a 5 dollar homemade voltage regulator solution. "

This is the wiring diagram that shows exactly which wires do what on the AMM. http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm

I found this: http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=276-565

It is a 5.1v zener diode, but I am getting cut closer to 5.5v according to my tests. Other people suggested they got up there too in some other thread. I found some other sites with the diodes, but I dont know which one to get.

[davidmacq]

get 563 ecu and chip it. Not to be an ass. But people stop temporaryly fixing the problem and chip the car. For the price of chip and 563 ecu you can get your self MSnS.
What is the deal with 563? Could you explain a bit. Isn't the ecu the chip? I assume you mean swap your ecu out, and get it programmed? I thought chipping either replaced your ecu or reprogrammed it. Is the 563 the best ecu? Do you need to swap AMM's too, or anything else?

[TerribleOne]

if my memory serves me right, the title of the thread has ..fuel cut solution in it.
seems more like youre looking for temporary hack.
sorry for pointing out the odvious. ;-)

[frostburner]

I know you guys like to modify stuff and all, but boosted03 is right.
Take off your dress and buy EMS.yea i was just explaing the quick fix for it , but for myself im going ems.. dropping about 1k on a very good ems system with a laptop.. :cool:

[the poi]

Obviously EMS, chip, MS is a solution. I am not interested in those solutions. Please dont suggest it any more.

" I did about an hour of searching tonight and came up with: "yeah, the fuel cut is 5.1v" and "go ems/megaquirt" I am not going ems/megaquirt, but rather looking for a 5 dollar homemade voltage regulator solution. "

This is the wiring diagram that shows exactly which wires do what on the AMM. http://www.autoelectric.ru/auto/volvo/740/1989/740-89.htm

I found this: http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=276-565

It is a 5.1v zener diode, but I am getting cut closer to 5.5v according to my tests. Other people suggested they got up there too in some other thread. I found some other sites with the diodes, but I dont know which one to get.
well, since you probably won't be moving more than 5.1v of air in closed loop mode, then a 5.1 ought to do it. when the amm stops increasing, turn on whatever auxillary fuel injetion you're using (the obvious solution is MS controlling additional injectors. Set your VE to 0 until you get up to the RPM and MAP levels that coincide witha 5.1v amm output...)

[ZVOLV]

Well I just did another test drive on the turbo maf I just got from lostartof. Thanks for sending me a second MAF to try without expecting a deposit or shipping.

With the turbo AMM I was getting 5.1v at 3500-4000rpm with 10psi on my 16g. Fuel cut at 4500-5000 rpms @ 16psi with 5.6-5.7v. I dont think I was even in closed loop yet when I was hitting 5.1v. I need to double check.

With the non turbo AMM I was getting fuel cut way up at 5500 rpm and 16psi, but the A/F meter was showing leaness all the way to fuel cut. With the turbo AMM it was in the green till fuel cut. Which was a good 1000rpm sooner. Still at 5.6-5.7v Hmmm. Not to throw a spin on the whole thing. This is only two AMMs and so it could just be the difference between the two. The turbo one looked quite a bit more fresh than the non turbo.

On my test drive i droped by radio shack and bought the 5.1v zener diode. I am gonna put it in soon here and see what happens.

I am gonna be tuning with a wideband here in the next few days and I will see if the ECU is still adding fuel past 5.1v. That diode might be the 1$ solution I am looking for.

[the poi]

I am gonna be tuning with a wideband here in the next few days and I will see if the ECU is still adding fuel past 5.1v. That diode might be the 1$ solution I am looking for.
the ecu wont be able to add any more fuel all by its lonesome...in fact, it'll lean out real fast. Id configure your secondary fuel system to run it rich around the dead spot, and then lean it down to where you want it. ecu has no way to determine fuel needs without the correct signal at the AMM, clamping it wihtout any extra fuel could be pretty bad

[ZVOLV]

Ok, I guess I kinda confused you. Since I am getting the cut at 5.6v I want to see if the ECU is adding more fuel between 5.1 and 5.5v. That way I can decide if I wanna use the 5.1v diode or if I need to go hunting for a 5.5v diode. If I have .4v worth of ECU controlled fuel I want to use it.

[thelostartof]

the ecu wont be able to add any more fuel all by its lonesome...in fact, it'll lean out real fast. Id configure your secondary fuel system to run it rich around the dead spot, and then lean it down to where you want it. ecu has no way to determine fuel needs without the correct signal at the AMM, clamping it wihtout any extra fuel could be pretty bad

he can always just run injectors that are just to big (like 46lb CFI's @ 3bar) so when he does get over that 5000rpm its dumping so much fuel u hope its the right ammount(or u can sit down and calc the perfect oversized injectors to use that would make it to to rich for the lower RPM's and almost perfect @ redline


and the reason taht turbo(816) one looks better is because i cleaned it out big time before i send it(sorry about not doing it to that n/a one). just get some qucik drying elec parts cleaner and really spray out the AMM and wire.

[Boosted2003]

What is the deal with 563? Could you explain a bit. Isn't the ecu the chip? I assume you mean swap your ecu out, and get it programmed? I thought chipping either replaced your ecu or reprogrammed it. Is the 563 the best ecu? Do you need to swap AMM's too, or anything else?

With the 563 ecu. This only works for lh2.4 guys. but you can get chip that made for 15g ot 16t turbo running at 1.3 bar.

http://www.volvonet.org/tpc/performance.html

[volvorod85]

A temporary fix is only temporary if you dont plan on leaving it there :P hehe anywho, Ya know the voltage difference everyone is getting with fuel cut voltage can have a lot to do with a ground issue (we are only talking hundredths of a volt) and the varance in the calabration in DVOM's. It seems LH 2.4 cuts fuel when it sees reference voltage coming back into the ECU, period. No mattter what the ECU#...So if your reference voltage is 5.5 your fuel cut is at 5.5. 5V is a standard reference voltage. And the 5.1, 5.67, 5.25 whatever it is, its a varance on where people are measuring the voltage, how "intune" your volt meter is, and how good the connections and wiring is in the car. So its not that it hitting at a higher voltage, is that no two of the same cars are exactly alike.
Mark

[linuxman51]

Frostburner seems to think it'll work (And indeed on his other cars it did), so not to be an ass here on this one people, but we're discussing, what $5 tops in parts? SOMEONE GET OFF THEIR ASS AND GO TRY IT! He did (on another car but the differences cant be that great), and hes saying that it works.. gaa, its not like its a big deal, if it doesnt work or has abnormal side effects, you take it out. This is why most of you foolz stay slow, you debate the snot out of something and talk yourselves out of doing it before you've even tried. Be a man... go try it out, and tell us what happens


Also, just getting rid of fuel cut isnt going to solve the magic power problem, you're going to run out of fuel if you havent already, and you're going to need to address this. One way is a series of injectors(or one really big one, bet that would be fun to tune eh) on a pressure switch, this worked well for isaac until his switches left him for another dimension (yes, isaac has achieved inter-deminsion travel with his f+t ;) ).

Or you can get an aditional injector controller. split second makes one, i believe doug used it? for a while and thought it worked well
or you can get a megasquirt, flash the dual table code and set the map up such that it does nothing until the boost level/rpm range where the maf gets maxed out and tune it as such. and with the other part of it you can have electric fan control, water injection control (i think, I was reading about it last night, theres an attempt at boost control as well), or whatever.

So for $160 bucks you can have stock driveability, switch the hi boost switch and have a fully tuned system. Next thing you'll get to address is igntion timing, and here it goes again: at that point you'll have spent close to what it costs to get a haltech system, more than what it costs to do megasquirt with the edis setup, and your car will still just be a series of balanced hacks (not that that doesnt work, it just generally requires more attention).

Sorry guidom, fuel on a turbo car is NOT the place you want to cheap out, esp when there exists a plethora of options that don't break the bank. I'm with terribleone on this, and I disagree with boosted2003 *unless* the chip allows you to run a bigger maf, cause after a point the maf will stop reading anyway, and you're back to square one.

[volvorod85]

linuxman51 <-What he said. I agree, its only 5 bucks in parts, so what do ya have to loose? Just dont run outa fuel. (like i said, id do it, but i cant run the level of boost yet) Ya pay to play. Youve gotten your answer to the fuel cut question. What you choose to do with it is up to you, aaaaaaand im spent
Mark

[Boosted2003]

Frostburner seems to think it'll work (And indeed on his other cars it did), so not to be an ass here on this one people, but we're discussing, what $5 tops in parts? SOMEONE GET OFF THEIR ASS AND GO TRY IT! He did (on another car but the differences cant be that great), and hes saying that it works.. gaa, its not like its a big deal, if it doesnt work or has abnormal side effects, you take it out. This is why most of you foolz stay slow, you debate the snot out of something and talk yourselves out of doing it before you've even tried. Be a man... go try it out, and tell us what happens


Also, just getting rid of fuel cut isnt going to solve the magic power problem, you're going to run out of fuel if you havent already, and you're going to need to address this. One way is a series of injectors(or one really big one, bet that would be fun to tune eh) on a pressure switch, this worked well for isaac until his switches left him for another dimension (yes, isaac has achieved inter-deminsion travel with his f+t ;) ).

Or you can get an aditional injector controller. split second makes one, i believe doug used it? for a while and thought it worked well
or you can get a megasquirt, flash the dual table code and set the map up such that it does nothing until the boost level/rpm range where the maf gets maxed out and tune it as such. and with the other part of it you can have electric fan control, water injection control (i think, I was reading about it last night, theres an attempt at boost control as well), or whatever.

So for $160 bucks you can have stock driveability, switch the hi boost switch and have a fully tuned system. Next thing you'll get to address is igntion timing, and here it goes again: at that point you'll have spent close to what it costs to get a haltech system, more than what it costs to do megasquirt with the edis setup, and your car will still just be a series of balanced hacks (not that that doesnt work, it just generally requires more attention).

Sorry guidom, fuel on a turbo car is NOT the place you want to cheap out, esp when there exists a plethora of options that don't break the bank. I'm with terribleone on this, and I disagree with boosted2003 *unless* the chip allows you to run a bigger maf, cause after a point the maf will stop reading anyway, and you're back to square one.

Agreed. But supposly the 563 ecu AMM runs up to 6.5 volts.

[frostburner]

Snipit
agreed.. it sonly 5$ at max in parts.. ive been a guinea pig alot and alot of stuff has worked because i wanst scared to try it..something messes up.. oh well then you cancel that as an option.. itll let you learn what you can an cant do to your car.. it *should* work the same only diff is the voltage.. and yes adding fuel where it starts to lean out is very important.. as in my other cars it would lean out at about 15 psi so that is whne i had extra injectors turn on via pressure switch.. its real easy to do just a matter of trying it out to see if it works for you..

[thelostartof]

linuxman51 <-What he said. I agree, its only 5 bucks in parts, so what do ya have to loose? Just dont run outa fuel. (like i said, id do it, but i cant run the level of boost yet) Ya pay to play. Youve gotten your answer to the fuel cut question. What you choose to do with it is up to you, aaaaaaand im spent
Mark

how about when your new motor is ready to go in we test your setup and run 20psi on that T3(u need a new compressor anyways) and open downpipe and see what kind of voltage you get on your setup ... figure if ya blow the motor oh well you have one ready to put in

[volvorod85]

Heh...its a good idea, but i need to use that turbo on teh new motor, so i cant trash the turbo if i blow the motor and get metal in the oil :P. We'll figure something out
Mark

[thelostartof]

that turbo has a compressor leak(@least you say it does) so just pick up a .60/.63 off a turboford for $50-90(1/2 off weekend) and be set w/ that

[BERTONE ALLEY]

Why not use the walbro 255lph high pressure pump, with the stock FPR it will run 53 psi at the rail at WOT. At 18 lbs of boost w/tdo4-13c you get into a rich (-10 A/F ratio) condition causing loss of power about midway through the rev range confirmed on a Dynojet. A larger turbo is a must at this point.

As for rev limiter, my tranny (AW-72L blue plate special) shifts at 5,800 rpms at wot 1st to 2nd, 2nd to 3rd, then 6,300 rpms from 3rd to 4th never any shut down! I have found the tach is about 50 rpms off across the scale.

Clip the cooling fins on the AMM!

The car is a 1991 780 Turbo.

[ZVOLV]

I am running a tdo5 16g. 18psi on the 13c.....that is some really hot air.

Interesting how I get fuel cut way earlier with a different MAF. With the 16g I can push enough air at 3500 rpms and 16psi to get fuel cut. This is with the stock exhaust. When I put my race exhaust on (full 3 inch w/ no cat or mufflers) I get fuel cut even earlier.

[volvorod85]

If I mix and match the parts though, wont i have a balance problem with the turbo? (sorry kinda offf topic)
mark