Help me troubleshoot an M20b29 replacing an M20B27.

[Tinkerer007]

I don't. I gave them away with the engines, I think.

[3seriersD]

By chance, do you still have the old harness for the b27?

[Tinkerer007]

So, the M20B29 still had the cut out after re-installing it.

Last week my son gapped the plugs, and that seems to have resolved the cut out. He set them to .28, not sure what they were before... :-( Boy do I feel silly.

[hasa]

If you found a broken rocker it likely needs proper valve springs.

[Tinkerer007]

So, my son was sporting around in the E30 with the "stock" engine, and it "stopped working".
Found a broken rocker arm.

I need to get the car to pass a smog test
, so I put the stroker engine back in.

After chasing miscellaneous leaks, loose hose clamps, unseated throttle cable (high idle), new battery, I got to go for a drive today.

Wow, the car drives great, and pulls hard to redline at full throttle (originally would cut out at 4K RPM).

I did buy a rebuilt set of M50 injectors.

And this was on a stock chip.

Pretty exciting. Now, fingers are crossed it will pass smog.

[digger]

I usually set zero lash measure open and close at

(0+cl = 0.25)
(0.1 +cl = 0.35)
(1+cl= 1.25)
(0.050”+cl = 1.52)
(0.200”+cl = 5.33)

or put another way set clearance at 0.25 and measure open and close at fhe following lift points

seat
0.1mm
1.00mm
1.27mm
5.08mm

[Tinkerer007]

So, I have replaced the engine with a stock I engine.
My boys have been learning to drive and one of them got his drivers license.

I have the stroker engine in the garage, and measured the valve lift with a degree wheel and dial indicator (.001").

Intake open @ .020" 347 Intake open @ .050" 3
Intake peak of .433" @ 113
Intake close @ .050" 223
Intake close @ .020" 235
Max lift .433"

Exhaust open @ .020" 133
Exhaust open @ .050" 146
Exhaust peak of .419" @ 249
Exhaust close @ .050" 2
Exhaust close @ .020" 15
Max lift .419"

Advertised duration 274/274
Lobe separation: 136 (?)

Any other measurements I should get? .005"?
I didn't measure valve clearance (seems like this could affect numbers).

[Tinkerer007]

bmwman91 Thanks for the comments.

It is still lean. And cuts out ~3800 RPM at WOT. If I accelerate with moderation, it will pull well to 6k RPM.

I have reached out to SSSquid.

[bmwman91]

Assuming that there are TDC marks on the cam, set it to TDC (or whatever is indicated on the cam, it is not intended to me manually advanced or retarded since the tune in the ECU will only be optimal for one position of it). Ignition timing is controlled by the ECU.

If the thing is pinging, it is probably because of the hotter cam and increased compression. I assume you are running 91 octane gas? Pinging with a stock set of ignition timing values is a red flag for sure.

As far as "learning", the M1.x ECUs are very limited. The main thing they do is take O2 sensor feedback and store basic adjustments based on that. The "short term" adaptation occurs nearly constantly once the engine is warm, and ends up looking like ~1Hz oscillation in AFR. It is an additive correction. The other one, which is "learned" is the "long term" adaptation. That one basically determines an "average" deviation from stoichiometric, so if you put in larger injectors it would determine that there is a global rich condition. It is a multiplicative term, meaning it will serve to scale all fuel calcs by the reciprocal of the determined deviation. In my experience logging AFR, this "long term" correction takes maybe 15-20 minutes to fully settle when driving with the engine fully warmed up. You want to disable both the short and long term corrections when trying to tune fuel.

There are some other adaptations pertaining to idle control as well, which do seem to take a little longer to settle, probably because most of the time spent running is not at idle.

Are you still experiencing any intermittent power loss or other abrupt changes to behavior while driving, or is the issue now just pinging and general lousy running? If it is just poor running with no major hiccups, then it is probably the case that this non-stock engine plus a stock tune is not a great combination. Digger and ForcedFirebird have way more experience with built M20's, so they would know how well it should run (or not) on a stock tune. Assuming there are no other red flags form them that indicate electrical or mechanical issues, I am standing by my recommendation in your thread in the tuning subforum...Sssquid tuning.

[Tinkerer007]

I got an exhaust gas analyzer today.
The AFR is good on the freeway.




If I accelerate hard it goes very lean (over 20). (I guess I have to stop that until I can figure out how to address.)

I also have a ping on hard acceleration or acceleration from less than 2K RPM. I think retarding the timing would help?
I installed another computer with a Dinan chip, and it pinged worse. (I assume they advance the timing to take advantage of higher octane fuel.)

How long does it take for a computer to learn when you change it? At what point does it not learn any more?
(Edit: E30wiki says -- 11.Go for a drive, the car will run a bit “rough” for about an hour while the ECU learns the new chips settings.)

I have a Nuke adjustable cam gear. Does this adjust both cam timing and ignition timing? How much should I try retarding it? I was thinking 3 degrees would be a good start.

I will order an Ostrich 2.0, and see what I can do with that. (Thanks for the pointer ForcedFirebird.)

[ForcedFirebird]

Do some research before purchasing WAR, we have removed a few of them at work to replace with MS. It's nothing more than a preloaded emulator which you can get from Moates.net for $175.

[Tinkerer007]

what tune are you running?

Just the stock ECU.

I think I want a W.A.R. chip to be able to keep the OBC functional. But I don't understand how I would tune it. What tools can I use, and what inputs do I need to track?
CPS (TDC)
AFM (Is this engine load?)
Temp (Operating tempature)
TPS ( Idle / normal / WOT)
Is there a signal for the #1 spark plug wire? (Would this show timing?)
O2 (Feedback on fueling)
AC (Show additional load on the engine for increased idle speed)

Are there any other inputs that drive the ECU?

[digger]

what tune are you running?

[Tinkerer007]

I changed the injectors a week ago. It was not conclusive that it improved the running. Although after moving the wheel on the AFM, I don't need octane booster.

It passed smog today:
15MPH @1645RPM CO2=14.6 O2%=0.1 HC=13 CO%=.05 NOX=0
15MPH @1724RPM CO2=14.7 O2%=0.1 HC=11 CO%=.01 NOX=0

It still has a hesitation at 3800 RPM under load, and then power picks up again after 4100 RPM and pulls well past 5K RPM. This is not exhibited if revving in neutral.

On the gas analyzer, it is rich at idle, but then leans out at higher RPM. He adjusted the AFM to have 14.7 CO2 at higher RPM (and then idle is rich with CO@~1.23%)

Here is what was done to try to resolve hesitation:
Resistor to temp sensor. (To richen it up)
Added adjustable fuel pressure regulator. (To increase fuel pressure)
Tried another ECU.
Adjusted wiper on AFM.

What tools can I use to diagnose this?
Speculating that the crank sensor needs to be replaced.

Could this be seen with an oscilloscope on the CPS signal?

Is there a data logger that can see relevant info?

I still have the e tach installed. Could this be affecting it? Is this where the redline is on the ETA cars?


Any comment on Faucet CPS vs Genuine BMW? ($40 vs $160)
https://www.autohausaz.com/pn/101227...iABEgICMPD_BwE

Oh, and here are the specs for the motor:

2.9 Mahle motorsport stroker

10:1 Compression ratio

M52 Crank ( 84mm stroke)

85mm Bore

Super sport head with performance valve springs and 274 cam

S50 Connecting rods

ARP Rod bolts

ARP Main studs

ARP Head studs

Nuke adjustable cam gear

Pistons have two of the proprietary coatings for smooth operation total seal rings

brand new pan

The head and the intake manifold have both been polished and ported

[Tinkerer007]

BINGO! (I think)

I went and measured the resistance of the CPS on ECU pins 47, 48 and got 545 Ohms.

When I moved the car to the shade, it was in barely run mode.
I changed the coil to the one from the wreck.
And, went for a 35 mile highway drive and did not have any engine cutting out.

Earlier in the day, the mechanic used the exhaust gas analyzer and it is running rich.
RPM HC CO2
Idle 3000 130 - 300
3000 9.2 6.8 - 7.0

Looks like I will be changing to to the M50 injectors I had installed in the 325is.

Thank you so much for all advice.