Help please, can't get 10'

Rich550 · Post by **Rich550** » Sat Sep 12, 2009 4:30 pm

Alfa 33 4 cylinder, 1.7 8 valve boxer engine in Porsche 550 Spyder replica. (TPS)

Hi. This is my first post.

I've pretty much installed everything and have disconected the MJLJ to test that the EDIS is running at 10 degrees (just coil and VR connected to EDIS). The engine started up straight away (which was great because I've just totally rebuilt it) but it's not running smoothly. I tested the advance with a stobe (Gunson's basic Xenon timing light) and although the strobe is flashing properly, the view I get on the flywheel marks is eratic. When it does show a mark, it looks like TDC!

(I understand I might need to try a different timing light due to the wasted spark system, but I thought the basic, unadjustable light would work fine)

My main problem is that it looks like it's not firing at 10 degrees but at TDC!. (the fact that the idle is rough and the engine gets hot quickly would seem to verify this). BUT I'm positive I've set up the VR properly. When cylinder 1 is at TDC (I checked TDC with a DT gauge when I built it) the VR is pointing to the centre of the 9th tooth to the left (anticlockwise) of the missing tooth. ie The missing tooth passes TDC 90' before TDC.

Please help - I've got to get it running properly this weekend, so I can get it to the rolling road during the week ready to drive to the Goodwood Revival on Friday.
Thanks, Richard

alfa boxer · Post by **alfa boxer** » Sat Sep 12, 2009 7:35 pm

when i did my own boxer, I got cylinder 1 to tdc, undo the spark plug and check it.then fit the wheel as described and it should be at 10deg edis only you really need a modern timing light for wasted spark system. is your triger wheel running true?

NITROPIXIE · Post by **NITROPIXIE** » Sat Sep 12, 2009 8:52 pm

Your strobe light is fine. More expensive ones with adjustable advance can be more difficult to use as they see the wasted spark aswell as the noraml spark so then double the advance. Trust me yours will be fine.

It sounds like to me that you haven't located the trigger wheel correctly, hence the limp home mode is at tdc and not 10 degs advance. The reason for the scatter could be either an ill mounted VR sensor or interferance of the VR signal. Any chance of a photo of your VR sensor and do you have your VR wires shielded??

The reason engines tend to get hot is if there is too much advance i believe, not retarded as your is at the moment.

Ryan

Rich550 · Post by **Rich550** » Sat Sep 12, 2009 9:21 pm

The trigger wheel looks spot on, it was professioanlly welded on and skimmed true. The VR is, at most, a mm from it. I think the timing light is quite modern; it has the inductive pick-up and just an adjuster for sensitivity.

I can't help but think i've missed something or done something stupid! (At TDC, the missing tooth is 90 degrees clockwise of the VR, and the VR is pointing to the centre of that 9th tooth - that's right isn't it?) Perhaps the timing is ok, but it's just cold, running a bit rough and the timing light is not giving the correct feedback? Or perhaps that's wishful thinking.

Rich

NITROPIXIE · Post by **NITROPIXIE** » Sat Sep 12, 2009 9:27 pm

Is it welded onto a crank damper by any chance?? Get some picks up is best so we can see how it is setup. The idle should be bang on all the time with no scattering.

Rich550 · Post by **Rich550** » Sat Sep 12, 2009 9:35 pm

thanks Ryan. The VR wire is shielded, I used the intact part of the Ford loom, straight from the EDIS. I did take a picture of the VR install, I'll try and find it. The VR is very close to the trigger wheel and is adjusted by removing washers, I could try removing one.

Thinking about it, the only problem I can imagine is with the ground, I just grounded the single brown wire coming from connection 9 of the EDIS plug. This wasn't externally connected to the two brown shield wires as in the diagram, I thought as I was using the loom and EDIS plug intact I would not have to join the ground wires. Could this be the problem?

NITROPIXIE · Post by **NITROPIXIE** » Sat Sep 12, 2009 9:48 pm

According to this http://www.autosportlabs.net/MJLJ_V4_ve ... stallation you need pin 9 and 7 of EDIS connected to ground along with the shielding of the VR wires to a good earth. Make sure you have clean earthing points and use some wet and dry if need be to get bare metal.

The VR sensor was about 4 degs out when i mounted mine. Don't forget that 1 tooth equals 10 degs advance. Point the strobe light at the Triggerwheel and see where the VR sensor is in location to the missing tooth with the engine running. Like you said it should be on the 9th tooth, this should prove it better. You can take upto 5 degrees of error with the megajolt unit attached.

adsport69 · Post by **adsport69** » Sun Sep 13, 2009 9:20 am

Just a quick note - you have swapped plug leads 2 and 4 over, as your firing order is 1324 instead of the ford 1342.

Rich550 · Post by **Rich550** » Sun Sep 13, 2009 11:57 am

Thanks adsport, I've sorted the problem and it was partially related to firing order.

After checking grounds, double checking VR/trigger wheel set up etc, I worked out that the strode was picking up the wasted spark on cylinder 1 instead of the firing spark - not sure why that is - so I swapped leads 1&2 on the 'A' terminals on the coil and now the timing light is showing 10 degress spot on!!

(I've been viewing the timing marks on the flywheel through a hole in the bellhousing, so it was difficult to work out what degree the stobe was picking up, as there are no marks on the oposite side of the flywheel!)

(i think it just sounded 'rough' because it was the first time this engine's ever been run since the rebuild, it was cold and running on choke)

Job done, thanks for your help. I'll post some pics when I find my camera.
Rich