Tune BMW M30B35 correctly please help

[lummpy69]

Hello, everyone here in the forum.

Since my BMW M30B35 Turbo is now ready, it's time to tune it. I've driven around the block a few times too. The boost pressure is at 3200 rpm. A spring of 7 psi is currently used. According to the data, the 7 psi is fully on up to 5000 revolutions. At full load, the exhaust gas temperature measured just before the turbo is 820 Celsius.

Now to the engine:

M30B35 211 HP 9:1 compression year 1989
Turbo Holset HX35 and Wastegate 44mm
Original cylinder head gasket with ARP screws
Bosch 460cc injectors
Wasted Spark
Intercooler and Megasquirt MS3
Fuel pump 255 l/h
charge pressure control valve

Because there is a lot of experience in the forum, I hope to find answers to my questions.

My first question is how much boost pressure can an original head gasket with ARP screws withstand? It is clear to me that the ignition also contributes a large part. That's why I'm including my current ignition map. Of course I'm happy to receive useful tips.






Mfg

Tom

[turbodan]

The stock head gasket will not tolerate detonation, if that is avoided you'll be fine at 7 psi.

What does your actual air fuel ratio look like under boost? Are you using autotune for the fuel table?

The ignition map looks okay if you're running up to about 150 kpa. It would be a good idea to pull back more timing at higher boost, more than 1 degree per 10 kpa. Another tip would be to locate your RPM bins where they are most useful, at inflection points for the engine's VE curve. Your first five bins are below the RPM that I would sustain under load. One thing I do is switch ignition tables on the TPS signal, with the throttle closed it runs on an idle map which has excellent resolution at low RPM and manifold vacuum. As soon as the throttle opens, it switches to the main ignition map which covers the whole range of engine speeds and manifold pressures.

I would dial in some more vacuum advance and more some bins down to the sub-40 kpa zone. You don't need one every 10 kpa up above atmospheric, you could set them up with a bin at 110, another at 130 and another at 150. If you're running 7 psi, it should be running right on 150 kpa and you will definitely want to be able to tune that specific row.

[lummpy69]

Hello, first of all, thank you for the detailed answer.

Yes, I used Autotune and it hits the values pretty well. I would say that it already has an accuracy of 90%.

At full boost I have an AFR of 12.3 and I think that's not bad. I was thinking about the vacuum feed and unfortunately I can't get more than 35KPa when driving. When idling it is at 55 KPa, so I chose my KPa table like this.

I don't think the idea with the 2 ignition cards for the idle is a bad idea. Because the original M30 also has 2 ignition cards from what I've seen.

But since I'm new to tuning with Megasquirt I need more time. The MS3 simply has far too many settings and often overwhelms you.

I actually wanted to give more boost pressure, but from what I read, unfortunately it stops at 7 psi.

https://www.dropbox.com/scl/fi/7zkf1z19 ... hjus1&dl=0

https://www.dropbox.com/scl/fi/hzt858f8 ... fpe1z&dl=0

MFG

Tom

[turbodan]

Tuning standalone is like that. Lots and lots of things to set up, configurations to sort out.

I don't have experience with the M30 on megasquirt. The M20 is a bit different. With the M20B27 cam I would see idle vacuum as low as 24 kpa. With the M20B25 cam it gets down to about 33 kpa. Cruising can get down to the low 20's. You may be able to improve your vacuum with greater ignition advance at low kpa. Don't be afraid to dial in some advance in the idle region too, if the engine responds well and it boosts manifold vacuum then you know you're moving in the right direction. I know the M30 likes a little more timing than the M20 on account of the larger bore, I bet it would drop that idle vacuum quite a bit with 25 degrees of ignition advance.

Have you verified your trigger angle offset? If it's running you're not far off but it's always a good idea to verify that your timing is where you think it is.

[marc79euro645]

I've destroyed about 8 h/g's and a couple sets of pistons in the last 15 years of trying to tune a turbo m30. I can tell you what doesn't work. Your timing map looks scary to me. I've posted my timing map before but took it down after breaking another piston with it. I would recommend dropping to about 10* at 100 kpa and above and 11.5 afr. I also recommend a knocksense light to help you tune. Any Knock will kill these h/g's fast.
Good Luck!

[turbodan]

This is what I'm running with an 8.5:1 M20. It usually runs about 150-160 kpa under boost. Timing is very conservative on account of the undersized turbine. A bigger hot side would improve the intake/exhaust pressure ratio, raise the det threshold and allow significantly more timing.

It is my impression that the M30 head gasket is more delicate than the M20 has been for me. I ran 1.4 bar on a stock gasket with the last build, reliably. Premium pump fuel. It all comes down to detonation, nothing can prevent engine damage if it's pinging. Something will blow, head gasket or worse.

That said, 10 degrees btdc above atmospheric would probably be too conservative. EGT would be very high.

[lummpy69]

I've destroyed about 8 h/g's and a couple sets of pistons in the last 15 years of trying to tune a turbo m30. I can tell you what doesn't work. Your timing map looks scary to me. I've posted my timing map before but took it down after breaking another piston with it. I would recommend dropping to about 10* at 100 kpa and above and 11.5 afr. I also recommend a knocksense light to help you tune. Any Knock will kill these h/g's fast.
Good Luck!

Hello, if I pull out more timing above, the exhaust gas temperature goes towards 960 Celsius. I think that's just not good for my valves. I took out a bit of timing above before I posted the map. You immediately noticed more performance and improved torque. Then I went down even further and it subsided again so I added a little more. This is how the numbers came to be. It's also clear to me as soon as the boost pressure increases that I have to adjust the timing. Which tapping tool do you use?

[lummpy69]

I tried lowering the KPA today while idling. No chance of getting below 58 Kpa. The M30 doesn't pull as much vacuum as the M20. The system should be tight because the engine has been newly sealed.

[turbodan]

Here's an old thread on the subject, to supplement my lack of M30 experience:

viewtopic.php?t=82785

Reason I ask is because low idle vacuum can be indicative of ignition configuration issues, trigger angle offset for example. ~60 kpa is just not much vacuum. With megasquirt, the MAP signal is the load signal so you want to get as much range out of it as possible for driveability and fuel economy. Megasquirt will handle any vacuum leaks the same way as holding the throttle open, it'll see the manifold pressure and fuel accordingly. The only thing keeping RPM down would be retarded ignition timing.

What kind of vacuum do you see at a cruise or when revving the engine in neutral?

[lummpy69]

I have 2 links at the top where there are logs. We're currently idling at 15 degrees. Even if I set it to 20 degrees and turn on the idle speed control, it doesn't help. When I accelerate and let off the gas it drops to 30 kpa. I sprayed everything with brake cleaner and it didn't make a peep

[turbodan]

What is your trigger angle offset value?

[marc79euro645]

This is what I'm using.
https://www.viatrack.ca/

here's another option
https://www.diyautotune.com/product/ms3 ... odule-kit/

[tschultz]

Check your base timing against a timing light before messing too much with higher boost and advance. Sounds like you are on the right track though!

Here's a working B35 map that I have for reference, 91 octane. I notice a difference at the top end advance versus yours.

Code: Select all

200	9	10.2	11.4	12.9	14	14.8	14.1	15	15.8	16.5	17.7	19.5
180	9.2	10.9	12.5	15	16.5	17.4	16.8	18.1	18.5	18.8	19.8	21.4
150	11	12.2	15.1	18.8	20.6	22	23.4	24	24.1	24.3	25	26.2
120	14.6	18.4	20.2	22.5	25.3	28.5	28.9	29.3	29.7	30	30.3	31.2
100	17.6	19.1	23.8	29.7	31.9	34.4	35.8	35.7	35.6	35.4	35.8	36.3
90	18.6	22.4	26.5	30.8	33.2	35.9	37.6	37.4	37.2	37	37.3	37.4
80	18.4	24	27.7	31.6	34.3	36.6	38.3	39.2	38.9	38.7	38.9	39.2
70	16.9	23.9	27.2	32.2	35.2	36.5	37.9	41	40.8	40.6	40.6	41.7
60	17	23.2	27.3	33.3	36.1	36.4	37.5	40.2	40.2	40.3	40.4	41.5
50	14.5	21.9	26.8	33.2	36.3	36.3	37.2	39.4	39.7	39.9	40.2	41.3
40	12	20.3	25.4	32.3	36	36.2	36.8	38.6	39.1	39.5	39.9	40.9
20	12	17	20.5	26.6	32	36	36	36.9	37.9	38.8	39.4	40.4
	600	1000	1500	2000	2500	3000	3500	4000	4500	5000	5500	6500

I use excel and color code to my existing to compare maps if the scales are different...

[lummpy69]

Check your base timing against a timing light before messing too much with higher boost and advance. Sounds like you are on the right track though!

Here's a working B35 map that I have for reference, 91 octane. I notice a difference at the top end advance versus yours.

Code: Select all

200	9	10.2	11.4	12.9	14	14.8	14.1	15	15.8	16.5	17.7	19.5
180	9.2	10.9	12.5	15	16.5	17.4	16.8	18.1	18.5	18.8	19.8	21.4
150	11	12.2	15.1	18.8	20.6	22	23.4	24	24.1	24.3	25	26.2
120	14.6	18.4	20.2	22.5	25.3	28.5	28.9	29.3	29.7	30	30.3	31.2
100	17.6	19.1	23.8	29.7	31.9	34.4	35.8	35.7	35.6	35.4	35.8	36.3
90	18.6	22.4	26.5	30.8	33.2	35.9	37.6	37.4	37.2	37	37.3	37.4
80	18.4	24	27.7	31.6	34.3	36.6	38.3	39.2	38.9	38.7	38.9	39.2
70	16.9	23.9	27.2	32.2	35.2	36.5	37.9	41	40.8	40.6	40.6	41.7
60	17	23.2	27.3	33.3	36.1	36.4	37.5	40.2	40.2	40.3	40.4	41.5
50	14.5	21.9	26.8	33.2	36.3	36.3	37.2	39.4	39.7	39.9	40.2	41.3
40	12	20.3	25.4	32.3	36	36.2	36.8	38.6	39.1	39.5	39.9	40.9
20	12	17	20.5	26.6	32	36	36	36.9	37.9	38.8	39.4	40.4
	600	1000	1500	2000	2500	3000	3500	4000	4500	5000	5500	6500

I use excel and color code to my existing to compare maps if the scales are different...

Thanks for sharing the timing card. They pack even more ignition on it. How much boost do they run and which components? My trigger angle is 87. I checked it 3 times with the lamp. What I get is 98 octane or 100 octane. But it should be tuned to 98 octane.

[lummpy69]

This is what I'm using.
https://www.viatrack.ca/

here's another option
https://www.diyautotune.com/product/ms3 ... odule-kit/

https://nightmotorsport.com/link-g4-kno ... -114-2000/

The MS3 has a knock tool on board. Unfortunately, it's completely useless without the exact data. I actually thought of something like that when I voted.

[lummpy69]

I would like to post the entire map with all the settings, unfortunately you can't post them in the forum

[tschultz]

Thanks for sharing the timing card. They pack even more ignition on it. How much boost do they run and which components? My trigger angle is 87. I checked it 3 times with the lamp. What I get is 98 octane or 100 octane. But it should be tuned to 98 octane.

For reference, I believe 10-14psi (up to 1 bar), it is user Nosis with TCD turbo kit he installed onto a B35 engine he rebuilt.

[lummpy69]

So to solve the puzzle. The M30B35 Turbo simply cannot manage more than 55-60 KPA vacuum when idling. Idle is now between 850 to 900.

I completely pressurized the car today including a fog machine. The good piece ran for 1.5 hours today.

Spark plugs were also replaced with an NGK BPR7ES. Ignition cables will be new next week. Because I have a slight twitch when idling and it always comes from pretty much the same place.

Of course I will report further if anyone is interested.

[marc79euro645]

I'm interested keep posting
You have brought up an interesting subject. I have continued to retard my timing, plus I added a water injection kit, in an effort to stop the knock.
I've not been happy with the performance. Then I see the timing maps you and TSchultz are posting with such advanced curves. I don't know what to think.
My last build is already pooched, only 40# compression in one cylinder. Probably another broken or pinched ring. The car actually drives alright, except for smoking from blowby. If you didn't know what it was capable of you would probably be impressed with how well it drives. I'm really getting tired of pulling this motor out and apart. I don't really want to do it again. I've committed so much to trying to make it work with this motor, but it just won't let me enjoy the car. I really wish I had a v8 all motor, simple and reliable power.

I look at how this forum has dwindled through the years. You don't see anybody bragging about their satisfaction with performance or reliability. They just fade away...

[turbodan]

I'm interested keep posting
You have brought up an interesting subject. I have continued to retard my timing, plus I added a water injection kit, in an effort to stop the knock.
I've not been happy with the performance. Then I see the timing maps you and TSchultz are posting with such advanced curves. I don't know what to think.
My last build is already pooched, only 40# compression in one cylinder. Probably another broken or pinched ring. The car actually drives alright, except for smoking from blowby. If you didn't know what it was capable of you would probably be impressed with how well it drives. I'm really getting tired of pulling this motor out and apart. I don't really want to do it again. I've committed so much to trying to make it work with this motor, but it just won't let me enjoy the car. I really wish I had a v8 all motor, simple and reliable power.

I look at how this forum has dwindled through the years. You don't see anybody bragging about their satisfaction with performance or reliability. They just fade away...

Reliability with forced induction requires i's dotted and t's crossed, especially at higher boost pressures. A high level of mechanical intuition goes a long way as well.

You must have something set incorrectly. Sometimes it can be something as nonsensical as the tach output setting. I had an issue with the MSPNP where my tach output setting was configured to IGNOUT, which would ground the ignition coil with the tach signal and override the calculated ignition advance angle. It was audibly detonating and it did not respond to retarded timing. Setting the signal to TACHOUT resolved the issue and got the the tach working.

These motors don't die with no warning. Every head gasket I ever popped was due to detonation, which is audible. Can be drowned out by a loud exhaust but it's there. The only time I hurt anything more substantial than the HG was ring lands at the drag strip. That was the result of an increase in boost pressure that I knew I didn't have enough fuel injector for, which resulted in a quarter mile of the most severe detonation I've ever experienced. Had I lifted off of the throttle I could have saved that motor. This is usually the case.

I'm surprised that your knock sensing equipment isn't picking up the det. I have heard that these systems can be particular in how they must be set up. Sometimes engines like these produce enough mechanical noise that the knock sensor has a hard time distinguishing detonation from the ordinary amount of mechanical clatter. If your tune is good, your injectors are delivering the expected amount of fuel across all six, your compression ratio is appropriate, your IAT isn't excessive, your fuel quality is good and there are no issues with fuel supply, the engine will not be unreliable.

[lummpy69]

Hello, I haven't forgotten the topic.

Unfortunately winter has come to us. We are currently minus 8 degrees.

Therefore the BMW stays in the garage.

I replaced all the ignition cables.

The temperature made them soft like pudding.

I'm currently concerned with closed idle. It's not that easy, maybe someone has some tips.

I'll post my map as soon as I've come to a conclusion.

[turbodan]

Closed loop idle control is complicated to tune, I've played with it but I always go back to warmup mode. I switch ignition maps between an idle map and a main ignition table so as soon as the throttle closes it goes to the idle mode and keeps rpm in its little pocket. The idle pwm tapers down with coolant temp and the advance table stabilizes rpm.

[Panici]

At full boost I have an AFR of 12.3 and I think that's not bad.

To me this is WAY too lean under boost.
If you have an uneven injector or a bad tank of gas, there is no room for error and you'll melt a cylinder.


Two points of data:
--On my turbo miata (for which I have a spare engine) I run high 11s (11.5-11.9) at 10psi.

--On my M52B28 E30, I run 11.5 just getting into boost, down to 11.0 at 160kpa.



Extra fuel should help cool things down and prevent detonation.

[lummpy69]

Hello had some time to play again.

I took a look at the trigger log.

There is the falling and the rising.

Tried both settings. I get the nicer signal when it's falling. (I'll insert pictures.)

So now we have a little problem.

I flashed the trigger in the fixed ignition timing. The timing was fixed at 10 degrees and the gun was set correctly. The whole thing was set at 1000 revolutions. When I checked the 10 degrees with 3000 it fits 100 percent

To check, I set the ignition timing to 20 gard. Had to set the pistol at 30 degrees so that the TDC marking would fit.

That means it goes to 30 degrees instead of 20 degrees. Unfortunately it also does it when I switch on the normal ignition map.

Maybe or better said there is something wrong with the settings or I don't understand the system.








MFG

Tom

[lummpy69]

At full boost I have an AFR of 12.3 and I think that's not bad.

To me this is WAY too lean under boost.
If you have an uneven injector or a bad tank of gas, there is no room for error and you'll melt a cylinder.


Two points of data:
--On my turbo miata (for which I have a spare engine) I run high 11s (11.5-11.9) at 10psi.

--On my M52B28 E30, I run 11.5 just getting into boost, down to 11.0 at 160kpa.



Extra fuel should help cool things down and prevent detonation.

Thank you for your participation.

I'll take this to heart and make it a little fatter as soon as spring comes.

I am a beginner and completely new to the field. I'm glad to have gotten this far.

[Tiit]

Have you seen this yet?
https://youtu.be/3XEp3HnbFZ8?si=_qYSAgN-yKJROlW_

[lummpy69]

Hello, yes, I've already looked at it.

Unfortunately it doesn't help with my problem at the moment.

If I set the trigger with fixed timing to 10 from flashes and 20 from control, I have to set the gun to 30 so that it is back to TDC. I was also down with the dwell time and thought that the coil was discharging itself.


But it wasn't. It can't be the time lamp, I tried 3 of them.

I think there's something to do with the settings or I don't understand the system.

With 10 degrees fixed timing I can turn it up to 3500 and it holds the 10 degrees nicely. He just doesn't like the control.

[turbodan]

Are you using multiple ignition tables? Is table switching turned on?

[lummpy69]

No, just an ignition table. He also does it at the exact timing

[Panici]

Thank you for your participation.

I'll take this to heart and make it a little fatter as soon as spring comes.

I am a beginner and completely new to the field. I'm glad to have gotten this far.

Happy to help.
We all start somewhere, I learned to tune by myself on my E30 and have done three different setups now across two cars.

Better to take it conservative until you get the hang of it. I learned on an N/A engine, and then with 4psi wastegate springs for example.