Old school pontiac-Noise or crank signal issue? SOLVED!

[LAV1000]

Can you post a msl log ?

I still think sensor is fine.
I think problem starts at a faulty plug or distrubutor mis alignment
When there is a misfire the high voltage kicks back and the weakest circuit (rpm sensor/circuit) sees it as a signal.

When you make a msl log you can check on Afr, Dwell, and spark advance.
And see wich one or what is related to the misfire.

[opnwide]

Lav,

Interesting idea about a misfire kicking back voltage. I hadn't considered this idea exactly quite like that. Sat, I already pulled 6 of 8 plug wires to check for excessive resistance and I've been checking the plugs. Plugs are generally a little oily, but new. They're a couple of clicks colder than stock due to the turbos, and gaps have been tightened up a hair. I probably need to install something in the middle of the two heat ranges. It ran good with the carb with the same plugs. I will try to pull the last two plug wires Monday and measure those (I need to pull wheels off to get to those:(

I've been keeping noise filtering off because I feel I shouldn't need to filter noise if everything is wired/working properly. However, any suggestions for settings? Going to try settings for the curve 150 microsec @500rpm and 11.3 microsec@6500rpm, assuming that TDC is happening once every 200 microsec and 15 microseconds respectively. Am I calculating this right?

[opnwide]

SOLVED!

Thanks for all your help with this issue. Here is how it played out:

I read an old post about someone that had a sprint car and a microsquirt V3. He was having some crank signal issues with his hall sensor as well. This guy solved his issues by wiring his signal wire to the VR+, not the VR- like it says to do in the manual. He also ran a 10,000ohm resistor to boost his signal.

Before, my engine would miss horribly at 2200+rpm unless I had the noise filter on. I didn't accept this, believing that I should be able to run without the noise filter turned on.

First I tried a resistor, 8700 ohm, even though my hall sensor was supposed to have a built in pull-up circuit . I wired the resistor to shunt power from the 12V source wire to the signal wire. Car seemed to rev OK with the noise filter on. I turned the noise filter off and I could STILL rev it to 3000 + rpm without misfire. I was happy. I checked all my logs and my tooth log showed that weird pattern where there is a 2nd small signal after the long missing tooth signal. It looks like a "bounce", and I knew it was characteristic of a VR sensor being hooked up backwards.

So I moved my signal wire to the VR+ wire to the microsquirt. Tooth logger became SOLID and still no miss at decent revs (3000-3500 rpms) once my #1 tooth position was adjusted in the tune. I feel that there needs to be a change in the instructions for the Hall sensor and the microsquirt V3. Anyone else favor this?


I feel like I can finally start tuning my car again. Hopefully I won't have any of those driveability issues that I had when I was running fuel only. I'll be moving in the next week or so, but I'll get tuning as soon as I get settled in.

Wish me luck!

thanks again to everyone!

[jsmcortina]

I feel that there needs to be a change in the instructions for the Hall sensor and the microsquirt V3.

That will probably depend on the specific sensor in use.

Are you using "Rising" or "Falling" for input capture?

James

[Mr Gadgets]

Just read through this post, kind of painful! So happy you found a resolution! I am thinking of using a Hall sensor instead of my VR sensor on the crank. I need to find a Hall sensor for the cam.
I know the feeling of being stuck trying to find the solution, so I am happy everyone was helping you to find it. Great work everyone!!

[opnwide]

James,

Rising edge capture, as generally recommended for 36-1 wheels and hall sensors.