For any discussion not specifically related to your project
User avatar
By tobbera
#35062
ric355 wrote: Sat May 25, 2019 6:16 pm
LPG2CV wrote: Sat May 25, 2019 3:15 pm Just a couple of random thoughts.

Two reasons I can think of, off the top of my head for a kick back. Sparking at the incorrect time for that cylinder, and a weak mixture.
The OP needs to re-post his tune and the log, as the tune originally posted does not match the image shown shortly afterward (req_fuel is different for example, as is the number of injectors).

The previous log posted is showing a gamma enrichment of 116 when cranking. I suspect that is not enough cranking fuel although I do not know the engine. The reason for this number is that the IAT is showing 200 degrees, and so the Gamma Air is reducing the fuel to only 76% thus reduing the fuel by a fair amount. The IAT needs calibrating. If this is already done, then this demonstrates the importance of posting the latest log & tune as earlier stuff will throw people off.

To answer the earlier question about rpm variations throwing off the timing. I suspect what you are seeing is an effect not a cause. i.e. the rpms are varying wildly because the engine is trying but failing to start with it occasionally catching.
I would check the following:
1. Calibrate your IAT.
Done. It was just disconnected at the moment.
2. That you know where TDC is on your crank, and that your timing mark matches it. Take a plug out and check it that way (either using the piston stop & divide approach, or a screwdriver or other object that you can visually identify TDC with)
3. As a result of (1) that your trigger angle is correct.
Yes, I did this with a timing light and I think I'm roughly on. As mentioned before, it has a hand drawn mark on a small diameter axle, so hard to get very accurate.
4. That the spark is reliable when cranking. If it drifts, this points to other issues - I see you're having problems with the VR sensor and you need to get to the bottom of this otherwise all bets are off. tbh it beats me why people persist with VR as they seem to cause no end of problems.
VR is stock on my engine and I would like the Speeduino to be as plug and play as possible. Please see my attached scopes and logs.
5. That you have fuel when cranking - does the fuel pump prime at key on and does it run when you crank it. Just verifying your plugs are wet will probably do if you have no means to check the pressure. After all this cranking, if your plugs are wet, dry them out. There is limited chance of it starting otherwise. This can be a frustration after fixing issues and it still not firing up - I've been there.
I have deliberately removed fuel, or added very little to not send my starter gear out of the crank case when kicking back.
6. That you have enough fuel during cranking. I note earlier it was mentioned that "some req_fuel was added" (paraphrasing). Question is was enough of it added. I echo the comments about weak mixture and kickback.
See above.
7. That your throttle is open enough to allow it to start, through either the throttle plate adjustment or whatever idle bypass arrangement you have.
Haven't gone that far to have it fire up properly. Want to make sure its not kicking back and destroying thing first.
8. The earlier tune has the injector close angle set at 80 degrees. That seems like an unusual number given the default is 355 and described as "suitable for most engines" (it can be tuned in due course). This may not stop it from actually starting but might mean you need to chuck more fuel at it before it does, and given the earlier gamma stuff I've mentioned could be having an effect. I'd reset it back to 355 myself.
I set the injector angle to fire fire when the valve is open. (And the other pulse just opposite ofcource, since I don't have phase input.)
User avatar
By PSIG
#35065
I didn't check your msq, but do you have dwell corrections for your coils? Is your over-dwell limiting also on? Any chance you are hitting dwell limiting, which cuts coil power, firing the coil at an unknown crank angle? Of course I'd suggest setting corrections for a good healthy spark, but a quick check with over-dwell limiting off may be worth an answer.

David
By LPG2CV
#35067
Hi
I'm not familiar with scopes and guess I really should get one. But from what (I think) I understand, and looking at your images. I see the VR signal with the varying voltage. I can see VR Condition Out, but I would have thought this would then equate to the 24-1 trigger wheel with the teeth evenly spaced and 2 missing!
User avatar
By tobbera
#35069
PSIG wrote: Sun May 26, 2019 4:48 am I didn't check your msq, but do you have dwell corrections for your coils? Is your over-dwell limiting also on? Any chance you are hitting dwell limiting, which cuts coil power, firing the coil at an unknown crank angle? Of course I'd suggest setting corrections for a good healthy spark, but a quick check with over-dwell limiting off may be worth an answer.

David
Very valid thought you have there. The thing is that my boards runs "smart" ignition drivers that, if over dwelled, shuts down softly not to cause a spark.
User avatar
By tobbera
#35070
LPG2CV wrote: Sun May 26, 2019 6:22 am Hi
I'm not familiar with scopes and guess I really should get one. But from what (I think) I understand, and looking at your images. I see the VR signal with the varying voltage. I can see VR Condition Out, but I would have thought this would then equate to the 24-1 trigger wheel with the teeth evenly spaced and 2 missing!
The first scope shows all the 24-2 teeth outlined with lines and dots.
User avatar
By PSIG
#35071
tobbera wrote: Sun May 26, 2019 8:13 am The first scope shows all the 24-2 teeth outlined with lines and dots.
True, but notice the rotation before only shows one missing tooth. Also, the VR input appears to be inverted on the conditioner output (going high on falling VR signal). This appears like an inverting VR conditioner (MAX, LM1815, etc) and that means your Trigger Edge should be set to Rising, not Falling. In any case, it's your trigger that needs attention, as in your last log I looked at it lost sync 6 times while cranking. :shock: That would likely explain your odd ignition timing and kick-back.

David
User avatar
By tobbera
#35074
Thank you. yes I can see the sync loss now.

"Also, the VR input appears to be inverted on the conditioner output (going high on falling VR signal). This appears like an inverting VR conditioner (MAX, LM1815, etc) and that means your Trigger Edge should be set to Rising, not Falling."

Do you mean the red dots I have put in the scope picture bellow? When there is no teeth on VR the output of conditioner stays high. When there is a tooth, it goes low.

Also, when you say "True, but notice the rotation before only shows one missing tooth. ", how do you see that on the scopes?


6.png
6.png (26.4 KiB) Viewed 6933 times
2019-05-26 20.19.54 1474x807.png
2019-05-26 20.19.54 1474x807.png (40.04 KiB) Viewed 6933 times
User avatar
By tobbera
#35077
I have looked closer att the scope trace and I assume the bellow is what you are refering to as "Also, the VR input appears to be inverted on the conditioner output (going high on falling VR signal). This appears like an inverting VR conditioner (MAX, LM1815, etc) and that means your Trigger Edge should be set to Rising, not Falling."
7.png
7.png (28.96 KiB) Viewed 6931 times
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