Starter problem

DEVONMAN · Post by **DEVONMAN** » Mon Sep 23, 2013 7:25 pm

I have just fitted a new starter to my RV8 and it spins the engine much faster thyan the previous starter.
The odd thing is that the engine used to fire up on the first attempt but now sometimes it needs 5 or 6 attempt.

I run a Megajolt, EDIS 8, wasted spark system.

Has anyone had a similar problem,

I suspect I am getting some spikes into the electronics from the new starter which is upsetting the EDIS

Up to now I have not needed the suppressors at the coils.
Maybe these would help ?????
The VR lead is shielded.

Thanks
Denis

DaveEFI · Post by **DaveEFI** » Mon Sep 23, 2013 11:30 pm

What have you got the cranking speed set at? Could it be it's now exceeding that and going on to the 'running' map?

I've got a similar on my SD1, and have had both types of standard Lucas motor and now a hi-torque geared type, and can't say I've seen what you report. I do, however, have the EDIS suppressor caps at the coils, but they (IIRC) are to help prevent ignition interference getting elsewhere rather than for the ignition itself

kiwicar · Post by **kiwicar** » Tue Sep 24, 2013 7:53 am

Hi
I have issues with starting using MSQ. I think they are down to not having a stable enough cranking speed for the megasquirt wheel decoder to be happy with, the plan is to go over to 24v starting next year and see if that sorts it out, I have fixed timing of 8 degrees advance for starting set to 800 revs (where the map takes over) and about 12 degrees in the first "box" I am considering upping both along with more advance in generally at the start of the table. . . I still think the issue is MSQ not being happy with the cranking stability and not starting to spark.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Tue Sep 24, 2013 8:21 am

I must admit my car doesn't start so quickly as I'd like. It always requires some churning - hot or cold. What I don't know is if this is down to EDIS, MS, or something else. I've not really worried as it does always start.

DEVONMAN · Post by **DEVONMAN** » Tue Sep 24, 2013 5:10 pm

Thanks Dave and Mike for your help.
I have now set the first box at 800 RPM instead of 500 RPM and touch wood it has fired up instantly since.

I'm not sure though how tthe Megajolt knows when it's cranking and not running or does it assume it's cranking when you are below the RPM set in the first box ???

Regards Denis

SimpleSimon · Post by **SimpleSimon** » Tue Sep 24, 2013 6:07 pm

DaveEFI wrote:I must admit my car doesn't start so quickly as I'd like. It always requires some churning - hot or cold. What I don't know is if this is down to EDIS, MS, or something else. I've not really worried as it does always start.

Hi Dave I do think this is an EDIS thing i.e your waiting for it sync up with MS & fire it's own coils, both myself and my brother use EDIS 8 and both crank a little not alarmingly but not a flick & fire system

DaveEFI · Post by **DaveEFI** » Tue Sep 24, 2013 10:47 pm

DEVONMAN wrote:Thanks Dave and Mike for your help.
I have now set the first box at 800 RPM instead of 500 RPM and touch wood it has fired up instantly since.

I'm not sure though how tthe Megajolt knows when it's cranking and not running or does it assume it's cranking when you are below the RPM set in the first box ???

Regards Denis

I'm not sure about MegaJolt, but MS has a settable rpm below which it is cranking - above running.

DaveEFI · Post by **DaveEFI** » Tue Sep 24, 2013 10:53 pm

SimpleSimon wrote:
DaveEFI wrote:I must admit my car doesn't start so quickly as I'd like. It always requires some churning - hot or cold. What I don't know is if this is down to EDIS, MS, or something else. I've not really worried as it does always start.
Hi Dave I do think this is an EDIS thing i.e your waiting for it sync up with MS & fire it's own coils, both myself and my brother use EDIS 8 and both crank a little not alarmingly but not a flick & fire system

Sort of confirms my suspicions. It obviously has to pass the missing tooth before it knows where it is - maybe even more than once. Unlike dizzy ignition where it will spark on each lobe.

Although my BMW starts pretty instantly with crank and cam sensors.

Wonder if wasted spark driven directly from MS is any better? I've got one waiting to be fitted when I get some tuits, so I'll try and remember to post back if it's better.

DEVONMAN · Post by **DEVONMAN** » Wed Sep 25, 2013 5:15 pm

The problem returned again today so further thought needed.

I will do some tests with the Megajolt disconnected to see if the problem is still there. If the problem persists then it's likely to be an EDIS hicup.

Thanks again for the help.

DaveEFI · Post by **DaveEFI** » Wed Sep 25, 2013 10:57 pm

EDIS is generally said to be bombproof - provided the VR sensor to wheel clearance is correct. But of course anything can have a poor connection.

DEVONMAN · Post by **DEVONMAN** » Thu Sep 26, 2013 8:02 am

DaveEFI wrote:EDIS is generally said to be bombproof - provided the VR sensor to wheel clearance is correct. But of course anything can have a poor connection.

Yes agreed.
I will check the VR and screened lead connection at the weekend.

I also need to check that the Holley injection system is squirting during cranking. It may not be getting the trigger pulse, or, the injection volume setting at the new cranking speed may be insufficient.

Thanks,
Denis

DaveEFI · Post by **DaveEFI** » Thu Sep 26, 2013 9:05 am

I don't know the Holley system - but as I said MS has a entirely different cranking 'map' to running which it switches to below certain revs. The tuning software TunerStudio tells you at a glance whether it's cranking or running, as would a log of a start. Although the difference in speed between cranking and idling rpm is usually so great that you'd not normally need to alter that figure. My max cranking speed is set to 300 rpm. But since it is a user setting I'd check it anyway. It's also possible a very different cranking RPM requires a different fuelling setting for cranking.

DEVONMAN · Post by **DEVONMAN** » Mon Sep 30, 2013 7:46 pm

I think the problem is gone.

At the weekend I checked out the shielded cables going to the VR and the PIP and SAW cable to the megajolt unit.

All seemed fine with the shields connected to pin 7 on the EDIS and not connected at the remote end.

There are some conflicting diagrams on line regarding this and one diagram I found shows the shield also connected to ground outside the EDIS in addition to the pin 7 connection.

I have added the extra ground connection and the engine now fires up first time every time and it even seems to fire up quicker.

So hopefully problem solved.

Thanks to all for the replies.

DaveEFI · Post by **DaveEFI** » Mon Sep 30, 2013 10:42 pm

It's normal to only connect the screen to ground at one end. Doing it at both ends could introduce currents flowing through it which isn't a good idea on a screen. Although like all these things it may not matter in practice.

Where is your EDIS unit grounded? My favourite way is to ground it to the engine block.

DEVONMAN · Post by **DEVONMAN** » Tue Oct 01, 2013 8:14 am

DaveEFI wrote:It's normal to only connect the screen to ground at one end. Doing it at both ends could introduce currents flowing through it which isn't a good idea on a screen. Although like all these things it may not matter in practice.

Where is your EDIS unit grounded? My favourite way is to ground it to the engine block.

You have possibly misunderstood what I have done.
The shield is connected to ground at ONE end only just next to the Edis unit. Pin 7 is also connected to the shield at this point.
There is no ground connection to the shield at the VR sensor end.
If there were, there would as you have said be a risk of stray unwanted currents flowing in the shield. The greatest damaging risk would be massive starter currents flowing through the shield if ever your engine block earth strap went bad.

My Edis unit is connected to earth with the original 6" long ring tag wire that was fitted to the edis connector at the factory. The megajolt and the other earths are all grounded at the same point under the dash.

My edis unit came from the USA and may have some differences to uk ones ???
From what I have read, pin 7 is grounded internally in the edis units and there should be no need to ground the shield elsewhere but some diagrams I have seen show an external ground connection also.

Regards Denis