MSefi.com read only forum (Jan.15,2018)

Hi,

I've been running an old Version 1 board for 7 years now with no problems. Last fall as I put the car away for the winter it died. What I should say is it actually flooded the cylinders with fuel. I drained the oil, flushed the motor out then topped it up with new oil and filter and put it away as it was too cold to work on. With spring in the air, I pulled the board out of the car and hooked it up to my stim today. The injector 1 and 2 lights on the stim stay on steady. To me that means the injectors are wide open as soon as the key is turned on. Bad news.

I did build my own board way back but am not an electronics guru. I am not sure if the transistors at Q3 and Q5 of the board control the batch fire of each bank but I checked them with an ohmeter and they look okay. There is nothing obviously burnt on the board. Does anyone have any handy tips for checking for the cause of this problem?

Thanks,

Dan

First let me know what tools you have to troubleshoot this - multimeter? Stimulator? Oscilloscope? - and I'll go over what to check. You can use the V2.2 schematics as I'm pretty sure the injector driver circuit is the same.

Hi Matt,

I'm using a V2 stim and ohmeter. I've decided to move up to a MS II setup and have ordered the kit but still want to keep and repair the V1 board as a spare.

I looked at the schematic yesterday and am unsure of the purpose of the two transistors at Q3 and Q5. I checked them out with my meter and they seem okay. My meter has a transistor test function. It's not the socket type but just a switch position. I looked up how to test transistors on the net and am pretty sure they are okay. What else on the board controls the grounding of the injectors?

Thanks,

Dan

I'm not sure about MS1, but if it's the same as others there is an IC driver (U7?) between the processor and output devices which are not transistors but MOSFETs.

With the stim set to low rpm, you should see these switching using a DVM set to volts. Check the inputs and the outputs at U7, and that it has a 12v supply and ground.

MOSFETs are quite easy to test using a DVM for a work/don't work condition.

http://www.4qdtec.com/mostest.html

I read up on testing MOSFETs. I tried it on the board and it didn't check ok. I took it off the board and it did. I guess the problem is elsewhere. I don't plan on losing too much sleep over it. I ordered a MS 1 V3.0 kit today and put the MS II daughter board on it. If I see a really big difference I will probably get a second one down the road as a spare. I hear they have more circuit protection and therefore potentially more longevity. That being said, I did get 7 years out of the original board!

Thanks,

Dan