Jh Jetronic Vs Motronic

[VAVolvo]

My '94 850 is equipped with JH Jetronic (I'm assuming this is the name for it, correct me if I'm wrong), and '95 to newer come equipped with the Motronic systems? Just tying to get more info on it. But I have a couple of questions:

Is the Jetronic system a 'learning' system? In other words, if the signals to the ECU are modified, the Jetronic system will reroute and override back to stock. So little can be done as far as tuning this ECU? If so, is there a way to override the learning system and trick the ECU in accepting modded signals?

Another question: I heard there is a way to Megasquirt the 5 cylinders (or a similar stand alone system). Anyone have any details on that?

Thankyou!

[Guest Guest]

I belive you mean LH Jetronic and that is infact "motronic"

LH Jetronic mean Hotwire Maf

L Jetronic is Barndoor maf

D Jetronic is Map Sensor

K Jetronic is a CIS system.

I am the juggernaut B!TCH and I need more OCTANE!

[Fishey]

I belive you mean LH Jetronic and that is infact "motronic"

LH Jetronic mean Hotwire Maf

L Jetronic is Barndoor maf

D Jetronic is Map Sensor

K Jetronic is a CIS system.

I am the juggernaut B!TCH and I need more OCTANE!

The above is ME... by the way...

Also diffrence between Jetronic and Motronic is that on motronic has fuel and ignition controls in the same box.

[the underlørd]

I am the juggernaut B!TCH and I need more OCTANE!

:pizza:

[mAydAy]

LH Jetronic is different than Motronic. Very different.

One small difference, LH Jetronic has two seperate controllers - ignition and fuel, where motronic has one. Jetronic on these cars is very adaptive.

As is obvious here, there is very little knowledge about the Jetronic system used in the NA 850's.

[Jacob]

Another question: I heard there is a way to Megasquirt the 5 cylinders (or a similar stand alone system). Anyone have any details on that?

Yep, you can megasquirt but you will loose the ability to control the individual injectors. I'm not sure about an 850 but on an S40 the injectors follow the camshaft in when they fire.

When I switched the Audi from mechanical injection to electronic injection I used megasquirt on the 5 cylinder engine with no problems. Megasquirt comes with 2 injector channels, I had the 5 primaries on one channel and the aux injector on the second channel. I had to upgrade the FET on the channel with 5 injectors because I used low impedance injectors.

There is a way to control individual injectors by taping one of the aux out channels, but you would have to totally re-write the code. This is all megasquirt 1, I am not familiar with megasquirt 2. EDIT: or 3 :o

[javadoc]

I still miss the brutally simple CIS (K Jetronic) systems. :)

[Jacob]

I still miss the brutally simple CIS (K Jetronic) systems.

Those were the days, but the venturi-plate style CIS didn't like boost too much ;)

[mAydAy]

Just because its originally set up that way doesn't mean you can't batchfire it.....

[Fishey]

LH Jetronic is different than Motronic. Very different.

One small difference, LH Jetronic has two seperate controllers - ignition and fuel, where motronic has one. Jetronic on these cars is very adaptive.

As is obvious here, there is very little knowledge about the Jetronic system used in the NA 850's.

Read above, I explained that LH Jetronic has 2 seperate controllers and motronic controlls them togeather.

There is alot of information on High Performance LH Jetronic systems but the problem with the system as far as I know is its inability to measure large amounts of airflow without moddifications since it uses a total flow sensor (as far as my information says). The only lead I really have about it is that Dennis Wray of Wray Electronics in Seattle has used it to some sucess by moddifiying the system to a partial flow sum.

[mAydAy]

I forgot to add:

Not true about MS not controlling individual injectors. It all depends on how its set up. You are talking about setting up Megasquirt on Batchfire --- which I might add, was used on whiteblocks up until ME7 was introduced -- but they can be set up for sequention injection allowing fuel to each injector to be trimmed. With MSII its easy to set up, just not worth while.

[Jacob]

I forgot to add:

Not true about MS not controlling individual injectors. It all depends on how its set up. You are talking about setting up Megasquirt on Batchfire --- which I might add, was used on whiteblocks up until ME7 was introduced -- but they can be set up for sequention injection allowing fuel to each injector to be trimmed. With MSII its easy to set up, just not worth while.

Not worth while to MS it or BatchFire it?

[mAydAy]

Not worth it to set up sequential injection, seeing as the OEM fuel injection was batchfire. Only way you can truly take advantage of sequential injection and fuel trim for individual cylinders is when you have an EGT probe in each runner for each cylinder.....

[VAVolvo]

Yeah, this is good info...I'm trying to understand stand it, some of it is still over my head at this time. But I've heard the same thing about MS in a 5 cyl. It can be done but it's complicated.

I'd like to know someone who is running a stand alone right now in their 5 cyl. and I'd like to know how they did it, what they used, and what problems they are facing, or one would expect to face when setting up one. Since I've never used MS before, it's hard for me to visualize exactly what's going on in setting one up.

Thanks for the info though, keep it coming!

[EricF]

Not worth it to set up sequential injection, seeing as the OEM fuel injection was batchfire. Only way you can truly take advantage of sequential injection and fuel trim for individual cylinders is when you have an EGT probe in each runner for each cylinder.....

Motronic used sequential. Why would you think otherwise? Try swapping injector leads around a whole bunch and see how it works out

I agree batch fire is fine though for sure.