MS3 Pro Injector A stuck ON

[svojohn]

I have a MS3 Pro running sequential fuel and spark. The ecu has worked flawlessly for the last 300 miles. Than Injector A output turned into a ground output all the time. Do I need to send the ecu back for repair?

John

[Matt Cramer]

Try reloading the firmware and a tune file from before it stuck on - there's a chance it's a corrupted tune. If that doesn't fix it, please contact us for a warranty repair.

[juansh2385]

I hope not but its sounds like the vnd are sometime still failing as reported in other post has any body tried a different omni mosfet rating? there are a couple options from the same company but I haven try them may be using a trough-hole omni-fet version instead of the sm one. Latetly I prefer the standar mainboard circuit with the with some modification to the circuit and parts non inverting driver mosfet pull to ground etc because it have been more reliable for me than the simpler vnd circuit.

[Matt Cramer]

I haven't seen nearly the same number of VND failures on the MS3-Pro as there were on the first round of MS3Xs. At this point, we believe that the problem was a reel of VNDs bought from a broker at a point when these things were hard. The MS3-Pro was designed from the get-go so that if we did have a problem crop up with VNDs, it could be switched over to other MOSFET designs at the drop of a hat - this is why there are a number of unpopulated slots on the board that would be used with some of the alternate parts. So far, we haven't seen anything to warrant such a switch.

[juansh2385]

Sounds good.

Great job guy ms3pro is a product worth of its name


Juan

[svojohn]

Try reloading the firmware and a tune file from before it stuck on - there's a chance it's a corrupted tune. If that doesn't fix it, please contact us for a warranty repair.

Ok I reloaded the firmware and a known good tune and same thing, Injector A outputs a constant ground. I'll send an email for warranty repair.

Thanks
John

[svojohn]

UPDATE: The MS3 Pro was sent back for repair and the injector driver was replaced. I now have the ecu back in the car and all works well again. Thank you for the product support.

John

[wes kiser]

Injector A (or it's wiring) didn't happen to be close to a secondary ignition lead did it? I had an A channel fail as well on a customer car, due to packaging the wiring was almost touching a spark plug wire.

[svojohn]

The plug wire is about 2-3 inches away from injector A. I can post a pic if you think that's the problem. The coils are mounted underneath the intake manifold and the spark wires run through (between) the intake runners.

John

[wes kiser]

I wouldn't consider 2-3 inches to be a "smoking gun" by any stretch of the imagination. The application I lost channel A on was a MSD box/distributor on a sbf with a very "unfriendly" IBV intake manifold. The plug wire and injector wire literally must touch. I sandwiched a piece of grounded AL between them as a "Hail Mary."

[svojohn]

Have some bad news, now injector B and D are stuck ON. We put just over 100 miles on it and made about 30 full throttle pulls before this without any issues. This happened during WOT around 5000 RPM. The ecu temp went from 169 to -3107.8 degf when the injector drivers failed. Also the RPM signal spikes up just before the failure but the VSS shows the same spike so that makes me think the tires may have spun. Don't know looking for answers.

John

[svojohn]

Here's some pics showing the plug wires and injector wiring:

[phoenix3d]

Sorry but this is probably a stupid question....

What is the Physical resistance measured across your Injectors? Take an actual reading..

If lower than 9->10 ohms then Low Impedance injectors - VND's Do Not Like Them!! fit Dropping resistors (Try 6.8 Ohm - 50Watt) in line with Each injector.
If Higher than above ohms... Maybe have a look at the Supply Side of the Injectors make sure they don't pick up any HT anywhere...

Remember VND's Die at >70V as per spec.

1 Dead VND ok.. maybe bad vnd... More than one...? Problem somewhere else...

Just my 2 cents worth...
G.

[wes kiser]

Phoenix, I sell a plug and play ecu that uses micro squirt modules (also uses vnd's). They have to "support" four cylinder low z. We recommend buying high z, but our way of doing this is a 3.5 ohm resistor inside the ecu . This is less than 6 ohms per vnd (still way below stated 5 amp max). We have seen 1 vnd failure that wasn't infant mortality (close to 200 sold).
I think it is a flyback spike in something exceeding 70v.
What ignition coils are you running, if inductive do the have a capacitor on their power feed?

[svojohn]

What ignition coils are you running, if inductive do the have a capacitor on their power feed?

The coils are the IGN1A sold by DIY. The coils do not have a capacitor on the feed but are on it's own feed with relay. Nothing else shares or is tied into the coil power feed.

The only thing I question is the connection of Pin B on the IGN1A coils. Currently that is connected to the signal return (blk/wht) wire on the ecu.

John

[svojohn]

What is the Physical resistance measured across your Injectors? Take an actual reading..

The injectors measured 12.2 ohms.

[nathaninwa]

I wonder if the spark plug wires are acting on the injectors and charging them like a coil in a welding machine?

[wes kiser]

Do you have a access to an oscope?

[svojohn]

Do you have a access to an oscope?

I think so. What needs scoped?

John

[wes kiser]

With engine running, scope the injector trigger wire from the ECU. When the injectors close, it is normal to see a flyback spike (50 ish volts). If you see near 70 that is bad. If something (like ignition system) is inducing something else in there, it can cause components to fail.

What type of spark plug wires are you running? Also, inthe harness does the ignition coil wiring (either its power or grounds) run parrallel to the injector wiring for any real period of time?