Volvo 760 B23ET engine managment (in 244)

[Scuby]

Hi

I have a 244 I've been tinkering with on and off the last two years. Thanks to a forum member here or elsewhere I got the thing from not running to running pretty ok on 4 cylinders. It's been a bit of a battle involving taking most everything apart save the longblock itself.

I have decided to sell the 244 but keep the b23ET due to their potential and rarity, even in Europe (where I live).

Here's my problem/question:

This thing now starts, runs and idles. Doesn't idle smoothly. But it idles.

It starts to break up under load around 3k rpm, sometimes 4k rpm.

Fuel pressure is set to 3 bar and. It's got green injectors (stock?)

The turbo is a T3 Garrett.

Other than breaking up around 3k, sputtering and so on, it's slow. I can feel boost just starting to build and then it get's unhappy.

When checking the timing belt it seemed to be a tooth, maybe two teeth off. This wasn't comparing crank to cam gears (pulleys still mounted in the way) but by putting it at true TDC. The cam seemed a bit advanced dot on pulley b4 mark on housing)

I've had a motor start and run 1 tooth off so I know that's possible. I'm building boost although yet to measure how much.

The Motronic unit in this (only used for 84/85) does ALL the timing so adjusing manually does nothing.

Could it be that my timing belt is just off a little, do Redblocks still run? I measured compression as it's setup now and it seemed high if anything. I measure around 13 bar per cylinder!

Thoughts?

 

[nordmaschine]

13 bar is an ok, healthy engine.

Redblocks are known to start more than a tooth off. I recently had an lh2.4 car that started and drove almost fine, it was 2 teeth off on the cam and one hole off on the flywheel - so, cca 40? off on the ignition side. And the damn thing ran.

Remove plastic covers, check everything. Later (B230ET) Motronics use 2 VR sensors on the flywheel. Is B23ET setup in the same way? If so, is your flywheel oriented correctly?

Measured MAF, seems ok, wasn't tampered with?

 

[dl242gt]

Sounds like a description of spark blowout under boost. I would suggest new plugs that are set to the proper gap or at least check the plug gap. I don't know those engines but it is probably happy with the .028" or .7mm gap on the plug.

 

[Scuby]

13 bar is an ok, healthy engine.

Redblocks are known to start more than a tooth off. I recently had an lh2.4 car that started and drove almost fine, it was 2 teeth off on the cam and one hole off on the flywheel - so, cca 40? off on the ignition side. And the damn thing ran.

Remove plastic covers, check everything. Later (B230ET) Motronics use 2 VR sensors on the flywheel. Is B23ET setup in the same way? If so, is your flywheel oriented correctly?

Measured MAF, seems ok, wasn't tampered with?

Thanks for this. I'll pull the pulleys and get a good look at the timing then.

The b23et, at least mine, does have two flywheel sensors. how would I go about checking if the orientation is correct? If I swap them (plugs are the same) then it won't run at all. So it's in the ballpark. The way this thing runs is so poor and so rich and irregular that knowing it's not compression it has to be timing. If I didn't know better after going through it twice I would swear it had a burnt valve at least.

I've never had a redblock run this poorly. How do I check the flywheel orientation? It has an m47 (mechanical speedo drive) gearbox so I'm thinking that isn't original to the engine. So a flywheel swap/resurfacing could have been done messing with the orientation...

 

[Scuby]

Sounds like a description of spark blowout under boost. I would suggest new plugs that are set to the proper gap or at least check the plug gap. I don't know those engines but it is probably happy with the .028" or .7mm gap on the plug.

Even at idle? Either way it's a good thing to have set correctly. cheers

 

[dl242gt]

Oh well, I read it that as soon as you tried to make boost the breakup happened. Missing at idle is another issue. Probably a bad speed sensor or tdc sensor.

 

[Scuby]

Oh well, I read it that as soon as you tried to make boost the breakup happened. Missing at idle is another issue. Probably a bad speed sensor or tdc sensor.

My wording wasn't concise. You are right.

It idles ok, it's a bit high and hunts a little. Not rock solid.

Anybody have the part numbers for the flywheel sensors. One senses speed and the other tdc?

 

[Scuby]

So the timing belt was off by a few teeth.

But it hasn't changed a thing. It just starts a little better now.

If anything it idles worse. It has an prety extreme lope to it audibly similar to how you'd expect a high rpm cam to sound in V8

it has better throttle response so I'm concluding timing was an issue. However it hasn't fixed much.

This thing has two sensors on the flywheel.

When I pull on of them it doesn't change a thing. Pull the other it dies.

What can a Motronic live with/without? I'm assuming the RPM sensor which in turn could explain it breaking up at 3k? I'm assuming with out a TDC reference it won't run.

The other thing is: where to get these parts? 2 year only run on these motors with this managment system. Are the two sensors the same?

 

[DET17]

Are you allowed to run aftermarket ECU in The Netherlands?

If YES, I'd strongly suggest you convert the car to MS2 Megasquirt. Build a new harness, and the battle will be reduced to the occasional "skirmish". Cam & spark timing must be correct, but that is irrelevant to engine management. How is the cold cranking compression, all within 10% or closer?

Buy a Tuner Studio license...... and tune the damn thing with your laptop (hell, probably soon a phone!).

Good luck & mfG.

 

[Scuby]

Are you allowed to run aftermarket ECU in The Netherlands?

If YES, I'd strongly suggest you convert the car to MS2 Megasquirt. Build a new harness, and the battle will be reduced to the occasional "skirmish". Cam & spark timing must be correct, but that is irrelevant to engine management. How is the cold cranking compression, all within 10% or closer?

Buy a Tuner Studio license...... and tune the damn thing with your laptop (hell, probably soon a phone!).

Good luck & mfG.

Thanks!

I have about 10 other projects and have more time than money although not so much of both. The motronic, in working condition will suffice for me power goals.

Compression is 13 to 13.5 across the board.

Turbo is spooling. No boost leaks.

I'll probably ditch the motronic for LH at a later date but I want it to run on motronic as I'm stubborn. It's all there. It should work.

 

[Scuby]

Although looking at the MS2 I'd like to tinker with it.

I have a supercharged Jag thats going in a 1978 series 2. Mightbe a good candidate

 

[Scuby]

No one have any feedback on the issue of the two sensors on the flywheel on this Motronic system? I believe an RPM sensor and a TDC sensor.

Any idea without which one it would still run so I can order the other as I unplugged it and it kept running?

 

[J2_]

You are correct.
One sensor (above flywheel ringgear) for rpm and the other for tdc.

Motronic used in the volvo's are quite misterious.. what some oldschool ecu guru told me is that it uses the rpm sensor for letting the ecu knows its cranking so it fires up and tdc is for ignition timing.

If it's running and you unplug the tdc sensor it will go into some sort of limp mode IIRC. (I have ditched motronic in my '85 long time ago..)
If it doesn't change a thing if you unplug one the sensor is faulty.
I should have set laying around somewhere... (I live in the Netherlands too).

 

[Scuby]

You are correct.
One sensor (above flywheel ringgear) for rpm and the other for tdc.

Motronic used in the volvo's are quite misterious.. what some oldschool ecu guru told me is that it uses the rpm sensor for letting the ecu knows its cranking so it fires up and tdc is for ignition timing.

If it's running and you unplug the tdc sensor it will go into some sort of limp mode IIRC. (I have ditched motronic in my '85 long time ago..)
If it doesn't change a thing if you unplug one the sensor is faulty.
I should have set laying around somewhere... (I live in the Netherlands too).

if you could have a look for me that would be great and I can send you my 06. Whatever other Motronic stuff you might have lying around I'd be interested in, if not just to prove to myself I can get it running. Where are you located?

 

[J2_]

Send me a PM, I will be in my beunschuur tonight so I'll look for the motronic stuff.

I'm in randstad area (near Rotterdam).