Hello, fellow smol (or big) brain E30 enthusiasts! I've been struggling with my E30 for quite some time and am nearly at my wits end.
Here are the specs of my E30 and highlights of my issue.
1989 325is (M20B25)
MSPNP2 ECU
AFM Delete (GM IAT in its place)
AEM UEGO X Series wideband in OEM O2 sensor port and wired directly to ECU 26 pin optional connector. Signal positive to pin 21 and signal ground to pin 22.
Siemens Deka 60lb/hr (630cc/min) injectors
Walbro 350lph fuel pump
As for my drivability issue, I've finally got the car running pretty decently. However, whenever the engine is at or above about 4800 RPM it starts breaking up pretty good. Almost sounds like an anti lag/2 step lol. If under load, the car will surge or buck because it momentarily loses power every second/half second or so.
Here's what I know about the issue.
-Fixed previous drivability and emissions issues by replacing, with genuine BMW parts, the timing belt, tensioner, distributor cap, distributor rotor, VR trigger sensor, and spark plugs. Spark plug wires were aftermarket and the Siemens deka 60's were also installed at the same time.
-REQ fuel has been updated with the new injectors.
-Datalog shows no loss in RPM or Sync loss
-PW stays even
-AFR has spikes within a couple hundredths of a second. For example, it will be say, 12.6 AFR at 4922 RPM and 0.06 seconds later will read 13.6 AFR then 0.06 seconds later back to 12.6 AFR.
-Tried Richening VE table in affected zones as well as retarding ignition timing. Base map was about 38 degrees advance. tried 32.
-Base timing verified with digital timing light. first tooth angle BTDC is set to 86 degrees.
-High speed tooth logger shows one bar approximately triple the height of the 57 short bars. (Did notice in the affected RPM zone, the short bar immediately after the long bar was lower than the other short bars. Also, the short bars appear to change in height in the shape of a sine wave once it hits the problem RPM range).
-Tried adjusting variable resistor for trigger Sensor in both directions.
-Noise filtering on or off made no change.
-Tried changing injector dead time. currently tuned at 0.9. Went up to 1.2 and down to 0.7. (Richened or leaned out fuel table to correct AFR for each change.)
-EGO control authority set to 0% (Off)
-Accel enrichment set to MAP dot of 1000kpa (Off)
Aside from what is listed above the only two things left I can think of to try, is to verify fuel pressure, and check the ignition coil and its wiring. Which I'm quite certain the fuel pressure will be just fine.
Thank you, generous wizards and or gurus of the mighty E30 and Megasquirt community!
MSQ: https://drive.google.com/file/d/1_QQ...usp=share_link
Datalog: https://drive.google.com/file/d/1JZd...ew?usp=sharing
Here are the specs of my E30 and highlights of my issue.
1989 325is (M20B25)
MSPNP2 ECU
AFM Delete (GM IAT in its place)
AEM UEGO X Series wideband in OEM O2 sensor port and wired directly to ECU 26 pin optional connector. Signal positive to pin 21 and signal ground to pin 22.
Siemens Deka 60lb/hr (630cc/min) injectors
Walbro 350lph fuel pump
As for my drivability issue, I've finally got the car running pretty decently. However, whenever the engine is at or above about 4800 RPM it starts breaking up pretty good. Almost sounds like an anti lag/2 step lol. If under load, the car will surge or buck because it momentarily loses power every second/half second or so.
Here's what I know about the issue.
-Fixed previous drivability and emissions issues by replacing, with genuine BMW parts, the timing belt, tensioner, distributor cap, distributor rotor, VR trigger sensor, and spark plugs. Spark plug wires were aftermarket and the Siemens deka 60's were also installed at the same time.
-REQ fuel has been updated with the new injectors.
-Datalog shows no loss in RPM or Sync loss
-PW stays even
-AFR has spikes within a couple hundredths of a second. For example, it will be say, 12.6 AFR at 4922 RPM and 0.06 seconds later will read 13.6 AFR then 0.06 seconds later back to 12.6 AFR.
-Tried Richening VE table in affected zones as well as retarding ignition timing. Base map was about 38 degrees advance. tried 32.
-Base timing verified with digital timing light. first tooth angle BTDC is set to 86 degrees.
-High speed tooth logger shows one bar approximately triple the height of the 57 short bars. (Did notice in the affected RPM zone, the short bar immediately after the long bar was lower than the other short bars. Also, the short bars appear to change in height in the shape of a sine wave once it hits the problem RPM range).
-Tried adjusting variable resistor for trigger Sensor in both directions.
-Noise filtering on or off made no change.
-Tried changing injector dead time. currently tuned at 0.9. Went up to 1.2 and down to 0.7. (Richened or leaned out fuel table to correct AFR for each change.)
-EGO control authority set to 0% (Off)
-Accel enrichment set to MAP dot of 1000kpa (Off)
Aside from what is listed above the only two things left I can think of to try, is to verify fuel pressure, and check the ignition coil and its wiring. Which I'm quite certain the fuel pressure will be just fine.
Thank you, generous wizards and or gurus of the mighty E30 and Megasquirt community!
MSQ: https://drive.google.com/file/d/1_QQ...usp=share_link
Datalog: https://drive.google.com/file/d/1JZd...ew?usp=sharing
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