BMW no spark, quadspark and ms3pro evo

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Tim C
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BMW no spark, quadspark and ms3pro evo

Post by Tim C »

Working on a 91 525i bmw for a friend. It has the m50 engine (2.5l I6). We are installing a ms3 pro evo ecu with the diybob adapter, quadspark modules and stock bmw coils.

Ive been following the steps in the manual pretty much and last night we got to the testing phase. I have injector pulsing in the test mode, all the sensors appear to be reading correctly, and it shows sync while cranking. I cant get the coils to spark in output test mode or while cranking, using a spark tester inserted into the coil boot. I have verified there is 12v at the coil at all times the key is on (key on engine off, and key on cranking). The quad spark modules are mounted to the inner fender and the grounds are attached to the back of the cylinder head. I have verified there is continuity between the megasquirt plug and the quad spark input wires on 3 channels per quad spark (with one channel unconnected on each quad spark) I have verified continuity between the quad spark heavy gauge output wires and the coils. I have verified the input and output wire colors match, so I dont have the coils all cross connected. There is no output on any coil when checking one or sequence.

I have to bring my snapon graphing meter home from work tomorrow to check for an actual signal from the computer, but with a cheap digital multimeter I have here at home, I saw a voltage change from 0 to around 0.5 volts when activating the test mode for coil a while the meter was connected between ground and the quad spark input and it would drop back to 0 when deactivating the test mode so I believe the ms3 is putting out a signal but not 100% sure yet.

This is my first time using megasquirt so if someone with some experience could at least look to see if I've missed checking something in the tune I'd appreciate that.
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billr
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Re: BMW no spark, quadspark and ms3pro evo

Post by billr »

Disconnect the Quadspark and check the voltage at the MS spark outputs. I think those are "logic level" and should be 0-5V, not 0-0.5V
Matt Cramer
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Re: BMW no spark, quadspark and ms3pro evo

Post by Matt Cramer »

billr wrote:Disconnect the Quadspark and check the voltage at the MS spark outputs. I think those are "logic level" and should be 0-5V, not 0-0.5V
Yes, although a normal multimeter won't be able to get an adequate read on the voltage. An oscilloscope or graphing meter will.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Tim C
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Re: BMW no spark, quadspark and ms3pro evo

Post by Tim C »

Ok, so at lunch I took home my old snapon vantage (brick) graphing meter. With the quadspark module unplugged I was getting a 5v 3ms spike with test mode activated. I could increase the frequency of the spikes by playing with the duration setting ( going from 200ms default, 600 rpm to about 40ms around 3000ish rpm) so the ms3 is signaling the quad spark.

That means i have a wiring issue or something not set up correctly I assume. The car was driven to my house January 2nd. The stock bmw coils are getting a confirmed 12+v key on, cranking, and while running the output test from the original bmw green wire that powers the ignition coils and triggers the main relay, which is also working as it powers the injectors and they work. This wire goes to pin 1 i believe on the coil, which was not modified from stock at all. Pin 2 on the coil goes to ground on the head which is the secondary coil winding ground. Also as stock. The black ground wires from the quadspark module all go to a large 8ga wire attached to the back of the head. Each quadspark has its own 8ga ground wire.

To simplify things here ill just describe cylinder #1 coil. The spark out A from ms3 goes to the blue 20ga quadspark wire, the violet 16 ga quadspark wire goes to the #1 coils negative terminal through the stock harness through the diybob 88 pin ecu adapter. I have confirmed there is continuity from the violet wire to coil connector pin number 3, which is the pin the original ecm fired the coil directly with.

Unless ive misread the quadspark instructions that should cause coil 1 to fire. Im reasonably sure its wired correctly. The quadspark nor the coils are getting hot. Is there something in the tune I didn't check off that could cause this?

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billr
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Re: BMW no spark, quadspark and ms3pro evo

Post by billr »

Sorry about my bogus advice about checking the 0-5V output; for some reason I was thinking the OP was using output testing to toggle the spark outputs on-off, not the spark test-mode.

No, I don't think there is anything in the tune settings that will prevent test-mode from firing coils. Although the "going high/low" may cause coil over-heating that doesn't seem to be a problem here.
Tim C
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Re: BMW no spark, quadspark and ms3pro evo

Post by Tim C »

billr wrote:Sorry about my bogus advice about checking the 0-5V output; for some reason I was thinking the OP was using output testing to toggle the spark outputs on-off, not the spark test-mode.

No, I don't think there is anything in the tune settings that will prevent test-mode from firing coils. Although the "going high/low" may cause coil over-heating that doesn't seem to be a problem here.
Im going to go back over my wiring again tonight. See if i can find something I got messed up. Right now im at a loss.

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billr
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Re: BMW no spark, quadspark and ms3pro evo

Post by billr »

"The spark out A from ms3 goes to the blue 20ga quadspark wire, the violet 16 ga quadspark..."

I can't say this is your problem, but why are you confusing things by connecting the MS3 spark A to the QuadSpark D (the BLU/PPL I/O)?

Can you get a coil to fire by momentarily touching its QuadSpark input to 5V? Do this with the MS disconnected from the QuadSpark, just to be sure not to damage the MS spark out by "backdriving" it with that momentary 5V.
Tim C
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Re: BMW no spark, quadspark and ms3pro evo

Post by Tim C »

billr wrote:"The spark out A from ms3 goes to the blue 20ga quadspark wire, the violet 16 ga quadspark..."

I can't say this is your problem, but why are you confusing things by connecting the MS3 spark A to the QuadSpark D (the BLU/PPL I/O)?

Can you get a coil to fire by momentarily touching its QuadSpark input to 5V? Do this with the MS disconnected from the QuadSpark, just to be sure not to damage the MS spark out by "backdriving" it with that momentary 5V.

That was just luck of the draw when we wired it up. We have an 8 pin connector on each quadspark with two rows of 4 pins. The four pins nearest the lock tab (or the top so to speak go to the inputs a, b, c, d. The lower row is the outputs a, b, c, d. There for each driver is going to a pin in the same column so to speak. In other words, top left is quad A in, bottom left is quad A out. Second pin from left on top is quad B in, etc. The car side of the harness only has 3 wires on each row since theres only 6 cylinders, leaving the unused pins blank. Both quadspark 8 pin connectors are wired symetrically so either one can be plugged in to either car side connector to keep things simple in that respect. Actually quad A is unused on both quadsparks. The grounds do not use a connnector at all, they are attached directly to the 8 gauge wire that runs directly to the back of the cylinder head.

I just temporarily touched 5v from a power supply to the quad input for coil 1 and it doesnt fire. I also temporarily used an old canister coil from my 67 Fairlane in place of the bmw coil and it doesnt fire either.
Tim C
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Re: BMW no spark, quadspark and ms3pro evo

Post by Tim C »

Heres the wiring we're working with. ImageImageImageImage

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billr
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Re: BMW no spark, quadspark and ms3pro evo

Post by billr »

OK, it sounds like the problem is somewhere in the coil/QuadSpark arrangement, no need to worry about the MS or TS settings right now. The chances of two QuadSparks being identically bad seem slim so let me ask for a couple of more checks:

Does the 12V supply to a coil stay up at 12V when the QuadSpark is turned on with 5V, charging the coil? You can leave that on long enough to get a steady reading, several seconds, without cooking the coil.

Similarly, the coil negative that is connected to the QuadSpark output should be at 12V when the QS (I'm tired of typing "QuadSpark") is not turned on, and should then go to near 0V when the QS is turned on. Is all that happening?
Tim C
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Re: BMW no spark, quadspark and ms3pro evo

Post by Tim C »

Matt sent me a pm earlier. Apparently they had a bad batch of quadspark modules and recalled them but we slipped through the crack and didnt get the notification email, probably a spam filter on my friend's end. Anyway we had two bad modules and theyre sending us replacements. That should take care of things, but I'll update this once I get the new modules with the outcome.

Thanks for the help guys!

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billr
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Re: BMW no spark, quadspark and ms3pro evo

Post by billr »

Ooh, I didn't know about that...
Tim C
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Re: BMW no spark, quadspark and ms3pro evo

Post by Tim C »

That was it. Wired up the new modules, it tested good in output test mode, then the car fired right up.

Now on to tuning!

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