(Probably a stupid) MS2Extra Ignition Timing Issue

richardpope50 · Post by **richardpope50** » Wed Dec 26, 2012 6:51 pm

Having sorted out priming and other issues I tried to start my RV8 today. I almost made it but I have what appears to be a timing issue. It’s got to be a stupid setting but I cannot find it.

The engine almost starts but not quite. It fires whilst cranking but very hit and miss and not enough to keep the engine running. It kind of backfires occasionally but more of a ‘phut’, not a bang!
Just a couple of exhaust pipes are getting warm each side. Eg. Cyl 4 & 8, not 2 & 6. (it may be 4 & 6, not 2 & 8 but definitely cyl 2 is firing. Similar on odd bank so is this a clue?

It’s an RV8 Serp I am running an MS2 Extra with wasted spark and (two) coil packs – one per bank. I have fuel in the rail and it’s under pressure. I’m getting a strobe light off No. 1 cyl.

I am puzzled by one thing. I have a 36:1 trigger wheel with VR sensor and at TDC almost lines up with the 6th tooth (I can’t get the VR sensor directly over a tooth, it’s slightly out). Therefore the degree setting in TunerStudio calculates to 50 degrees but on cranking the strobe shows this way out at greater than 20 BTDC. I have to set it to 60 degrees to get somewhere between 10 BTDC and TDC. It seems to fire better when set around 62.5 degrees.

In ‘Engine Constants>(Standard Injection) pop-up the Engine Type is set to Even Fire. Is that correct?

Fuel is set to Speed Density

This may be a minor point but I had in TS a pop-up that allowed one to adjust the ignition with a large green / red + / - button feature. That was several weeks ago and it appears to have gone when I upgraded the firmware from 2.1.0 to the latest 3.2.4. I thus now have to alter ignition timing by changing the Trigger Wheel settings pop-up, burn and start another test.

Finally, could the timing be one revolution out with what I think is TDC being one revolution out (somehow) - I may check TDC again but I’m sure it’s OK.

DaveEFI · Post by **DaveEFI** » Thu Dec 27, 2012 12:01 am

I'm curious about your 'coil pack per bank' How have you paired the cylinders, wasted spark wise?

The timing can't be 'one revolution' out with wasted spark - that's really the point of it.

richardpope50 · Post by **richardpope50** » Thu Dec 27, 2012 10:05 am

Dave,

There are two coil packs each with four HT leads. One coil pack per bank

Of course, the dizzy could be one revolution out but wasted spark kind of wastes, I guess.

It's got to be something stupid.

DaveEFI · Post by **DaveEFI** » Thu Dec 27, 2012 11:07 am

When you say 'per bank' that suggests one coil pair does 2468 and the other 1357.
Here's the EDIS diagram which gives the cylinder pairing.

I'm also confused about your mention of a dizzy?

Cobratone · Post by **Cobratone** » Thu Dec 27, 2012 3:13 pm

On a wasted spark set up two posts of one coilpack go to the even numbered bank and two posts go to the odd, the same on the other coilpack therefore you cannot have a coilpack per bank, but two halves of two coilpacks to each bank as you can hopefully see from the picture below. HTH

richardpope50 · Post by **richardpope50** » Thu Dec 27, 2012 4:07 pm

I think my explanation is wrong ....

I have two physical packs each with two posts per side and all is wired as per
http://www.extraefi.co.uk/Drawings/PDF_ ... wasted.pdf which is what you are saying, I think.

What I was trying to get at is as there are two crank revolutions per one revolution of a distributor it is possible to get the distributor out by 180 degrees as No 1 may not be at correct TDC - i.e. at top of firing stroke. OK basic set-up mistake but easily done.

I do not have a dizzy but although I (think I) have set TDC for No. 1 cylinder, how does the ECU know when it is top of firing stroke and not at top after exhaust stroke. It presumably needs to count and so my thought is that the ECU is counting incorrectly because I have not set it at the top of the firing stroke.

Somehow I have to tell the ECU that it starts at TDC for firing stroke of cyl No. 1 and I am wondering if I have done that.

Cobratone · Post by **Cobratone** » Thu Dec 27, 2012 5:22 pm

Richard, the MS fires coil A first which is connected to plug numbers 1 and 6, therefore every time A fires both 1 and 6 plugs fire, one ignites the fuel in thge cylinder at compression the other is "wasted" by firing on the exhaust stroke. Therefore you cannot be 360 degrees out as long as cylinders 1 and 6 are connected to A! Hope that makes sense

DaveEFI · Post by **DaveEFI** » Thu Dec 27, 2012 5:37 pm

richardpope50 wrote:I think my explanation is wrong ....

I have two physical packs each with two posts per side and all is wired as per
http://www.extraefi.co.uk/Drawings/PDF_ ... wasted.pdf which is what you are saying, I think.

Yes, that is the same as the EDIS diagram. Did you make up the wiring yourself? If so double treble check the coil numbering (ABCD) against the pin on the MS plug, and the cylinder numbers that coil is feeding

What I was trying to get at is as there are two crank revolutions per one revolution of a distributor it is possible to get the distributor out by 180 degrees as No 1 may not be at correct TDC - i.e. at top of firing stroke. OK basic set-up mistake but easily done.

I do not have a dizzy but although I (think I) have set TDC for No. 1 cylinder, how does the ECU know when it is top of firing stroke and not at top after exhaust stroke.

It fires the No1 plug again after the exhaust stroke - that is the wasted spark.

It presumably needs to count and so my thought is that the ECU is counting incorrectly because I have not set it at the top of the firing stroke.

Somehow I have to tell the ECU that it starts at TDC for firing stroke of cyl No. 1 and I am wondering if I have done that.

You certainly need to set it to fire at the correct point. Some more recent power strobe timing lights don't work with wasted spark - my expensive Krypton one with dial in advance doesn't. Luckily I still had my old basic one which does. That works in exactly the same way as setting the timing with a dizzy

richardpope50 · Post by **richardpope50** » Thu Dec 27, 2012 7:27 pm

Thanks and I'll double check my wiring tomorrow but I'm sure it's correct..

Yes, but MS still has to know that cylinder 1 is actually at the top (start) of the firing stroke so I guess it assumes that if either 1 or 6 will be at this point then the other of the pair will be at the wasted spark point. If that's correct, then setting TDC and the degree offset of the VR sensor will mean the engine should fire )but it does not really fire).

I'm still puzzled why the calculated 50 degrees seems so far off from the 62.5 degrees that seems to work better - albeit only just.

I have noticed that the advance is set to Table timing and not Fixed timing so will try that tomorrow and see.

Edited to say my strobe is a very old (Zenon) one.

DEVONMAN · Post by **DEVONMAN** » Thu Dec 27, 2012 8:40 pm

When I first set my MegaJolt up I mistakenly had the missing tooth on the wrong side of the VR sensor when No 1/6 were at TDC.
This fired all cylinders about half way down the stroke and it was trying to start but understandably did not get going.

Worth a check.

Good Luck
Denis

richardpope50 · Post by **richardpope50** » Sat Dec 29, 2012 11:20 am

It does not now appear to be ignition as after a good few hours ……

When you start to crank the engine fires but does not continue. Looking at the (TunerStudio) datalog it seems it all works correctly until the injector hand-over from cranking to VE Table's fuel map.

The TS Pulse Width dials show zero until just before the engine fires, then they go to a reading of 5 and it fires. Once it fires they go to a reading of 11 and stays there but firing stops. Revs go from cranking to 480 when firing then drop back to cranking.

TS datalog indicator stages show:
Cranking = Y, Run = N @ 80rpm; PulseWidth = 0
Cranking = Y, Run = Y at 116rpm; PulseWidth = around 5
Cranking = Y, Run = Y as revs climb; PulseWidth = around 5
Cranking = N, Run = Y as revs still climb; PulseWidth = around 5
Cranking =Y, Run = N, ASE = Y, Warm = Y at 386rpm; PulseWidth = 11
RPM climbs to 481 and then the firing stops. Now Cranking = Y, Run = N, and revs fall to 80rpm; PulseWidth stays at 11

Question. What changes at this changeover point to make the injectors stop working (VE Table has values).

Is the initial firing of the injectors controlled differently during cranking to after changeover point?

I tried a non-conclusive test via TS injector test facility and I did not get any volts across injectors so maybe this is the problem. Could I have a problem with my injector circuit wiring? … but it fires / injects on cranking.

Any suggestions appreciated!

DaveEFI · Post by **DaveEFI** » Sat Dec 29, 2012 12:14 pm

There should be +12v present at the injectors at all times the ignition is on.
MS supplies the ground to each injector bank via its output drivers.

It also uses (effectively) a different map for cranking and running.

What MSQ file are you using? The base one for your software type should get you going once you've entered the basics.

Cobratone · Post by **Cobratone** » Sat Dec 29, 2012 1:24 pm

If the engine fires then doesn't run I'd first look at the after start enrichments. They should keep the engine running for the first 20 seconds or so before the warm up enrichments kick in. My ase coolant starts at -20 to 72 degrees and the % from 59% to zero both scaled down. Check yours and compare??

richardpope50 · Post by **richardpope50** » Sat Dec 29, 2012 2:38 pm

Thanks guys.

I'm sure it's not my map as I'm using Phil's MSQ file but made a note on above..

I'm now thinking it is the 12v side - I'm checking wiring at the moment.

DaveEFI · Post by **DaveEFI** » Sat Dec 29, 2012 4:00 pm

You've not fed the injector +12v from the pump relay by any chance?