Project Mickey Mouse - Build thread of 79 SC I bought on eBay

[Focker]

Originally Posted by Jonny042

By pauses I meant how the motor seems to come to almost a complete stop WHILE you are cranking. Like it's fighting an out of time spark.

I did see that you were pumping, but one or two pumps while cranking get "used up" and shoved out the exhaust right away.

It's worth trying to pump is 4 or 5 times before you even turn the key to create a nice slug of super-rich mixture that gets pulled into the intake port all at once during the first rotation.

OK, gotcha!

So to recap, I'm going to do the following:

1. Double Check plug leads go to the appropriate cylinder from the coil packs
2. Double Check Dip Switches on Xdi
3. Double Check pin out from Xdi to coil packs
4. Consider running engine in "single plug" mode just to get it to run

When I used the timing light, it was flashing on the 2 timing marks on the Rothsport pulley, but those flashes looked to be around 10 degrees to the right of center of the fan housing.

OH - One other thing of note. I bought the ignition second hand from Rothsport, and they sold me a new crank pulley with the timing wheel already installed. The ignition system was removed from a customer car.

It also came with a Clewett pulley that was part of the original kit, BUT there was an extra set of holes drilled and tapped on the backside.

So, using the KISS principal, I'm going to try the clewett pulley with the timing wheel in the original clewett location.

Thanks for all the help.

[Mr Beau]

Sure sounds like it has too much timing and the cylinders that want to fire are fighting against things. Or a firing order issue. You need to confirm with a timing light while cranking.

[Focker]

Originally Posted by Mr Beau

Sure sounds like it has too much timing and the cylinders that want to fire are fighting against things. Or a firing order issue. You need to confirm with a timing light while cranking.

I think changing the crank pulley will be a good place to start, or at least check where the missing teeth are relative to TDC.

For all I know, the toothed wheel was incorrectly installed by rothsport when I got it 18 months ago

[chrisbalich]

IDK about XDI. But with aftermarket ECUs, you account for that difference in the initial setup.
I had to change the value when I swapped from Megasquirt to ECUMaster even tho I didn't change the reluctor wheel. Hell, I didn't even take it off the engine. The ECUs calculate the offset differently so I needed a new value.

[Focker]

Originally Posted by chrisbalich

IDK about XDI. But with aftermarket ECUs, you account for that difference in the initial setup.
I had to change the value when I swapped from Megasquirt to ECUMaster even tho I didn't change the reluctor wheel. Hell, I didn't even take it off the engine. The ECUs calculate the offset differently so I needed a new value.

The Xdi is a basic b*tch with a 0-30 degree initial timing adjustment, a 3,000 RPM adjustment and an 8,000RPM adjustment all through individual dials.


Using the knobs, initial timing was set at 10 degrees BTDC. Towards the end of the video I changed it to 5.

When I use the timing light, the light flashes on the 2 timing marks on the Rothsport wheel at what looks to be around the 2 oclock position.

The more I think about it, the more I realize I need to check the installation of the toothed wheel.

[Focker]

Xdi adjustment

[Jonny042]

Originally Posted by Focker

Xdi adjustment

So there's no adjustment for trigger angle or delay? It just fires when it sees a missing tooth? Do the instructions say to have the missing tooth XX teeth before TDC? If it's a 36 tooth wheel you are going to need a missing tooth at least 4 teeth ahead of top dead center to get a trigger angle of 40 degrees. But with 72 degrees of possible timing advance on those three dials you are going to need a missing tooth 8 teeth ahead.

It sounds like you are shooting in the dark here.... not sure what you are seeing at 2 o'clock.... are these the total timing marks like on some pulleys?

You should see the TDC mark (which you should also, without doubt or hesitation, KNOW is your TDC mark)
"appear" 10 degrees before the timing mark on the fan housing when the motor is cranking (and running). The 10 degree BTCD would be about 10mm to the right of the TDC mark and line up with the mark on the fan housing when your timing light flashes.

Here's a pic of my crank pulley lined up with the 10BTDC timing mark lined up with the timing mark. The TDC mark is just to the left of the yellow paint band (this helps me find it). This is EXACTLY what you should see flash in stop motion when the spark fires on #1 cylinder if you're set for 10 initial timing. If you only have a TDC mark you can measure over 10mm and make a mark.



THEN you need to make sure you are getting another spark 120 degrees (there should be a mark at 120 degrees) around the pulley from there, and that it's happening on the #6 and #3 cylinders, and then one more check at 240 further and check and make sure THAT spark is happening at 2 and 5.

Only after you get all that right should you be trying to fire the motor.

[Mr Beau]

The video sounded like it was short on fuel and had way too much advance. I'd say the trigger wheel is not positioned correctly.

[Jonny042]

I couldn't wait - went looking for the manual (page 13):



In case it isn't obvious, the missing tooth look like they should be aligned with the TDC mark on the crank pulley. Your install should look like the diagram. Have you verified that?

(EDIT - FWIW this is a pretty neat ignition system. Great way to get dual plug on something for relatively little money. Yeah its basic but it looks like it should do the trick)

It's pretty easy to get lost in the manual with the whole A1 A2 B1 B2 stuff. From what I read you have two rows of three, dual-post coils. The first post of the first top row coil would go to the top plug of #1, and the second post of that coil to the top plug of #4. The second coil goes to the top plug of #6 and #3, and the last coil goes to #2 and #5. That way the order is right and each coil is only trying to fire one "active" cylinder and one "wasted" cylinder each time it fires.

The bottom row of coils will connect the same way, but to the bottom plugs, in the same (1/4)(6/3)(2/5) order.

[Focker]

OMG IM A F*CKING MORON.

I have the frigging firing order wrong!!!!!

I've read the instructions over and over and over, and the first set of coils even had the numbers marked for me.

6-3-5-2-4-1

But guess what hot shot? That's the order that they fire, not the cylinder numbers!

So the system was trying to fire 1/4 then 2/5 then 3/6, but it should be 1/4 then 3/6 then 2/5.

Too late tonight to swap and try firing, but that would explain the weirdness, right???

[chrisbalich]

Originally Posted by Focker

OMG IM A F*CKING MORON.

I have the frigging firing order wrong!!!!!

I've read the instructions over and over and over, and the first set of coils even had the numbers marked for me.

6-3-5-2-4-1

But guess what hot shot? That's the order that they fire, not the cylinder numbers!

So the system was trying to fire 1/4 then 2/5 then 3/6, but it should be 1/4 then 3/6 then 2/5.

Too late tonight to swap and try firing, but that would explain the weirdness, right???

This would exactly explain what Jonny was hearing.
I look forward to a video of this thing singing like a sewing machine.

[Jonny042]

Originally Posted by Focker

OMG IM A F*CKING MORON.

I have the frigging firing order wrong!!!!!

I've read the instructions over and over and over, and the first set of coils even had the numbers marked for me.

6-3-5-2-4-1

But guess what hot shot? That's the order that they fire, not the cylinder numbers!

So the system was trying to fire 1/4 then 2/5 then 3/6, but it should be 1/4 then 3/6 then 2/5.

Too late tonight to swap and try firing, but that would explain the weirdness, right???

YES!!!!! (as in fist pump triumphant lets get this show on the road YES!!!. not you are a moron, yes )

Don't feel bad. There are a lot of coils and plugs and wires and A's and B's and 1's and 2's in that system and it's pretty easy to get lost in it I bet.

[Jonny042]

I certainly hope you're faking some Covid symptoms and re-arranging your day so you can play with this!

I think the markings are wrong. Well, rather, they might be wrong for how they're wired back to the ECU. Somebody clever probably physically re-ordered the coils so that the wiring to the cylinders is more tidy.

I think you need to go back to the manual and step through the entire thing methodically and doubt everything you think you know, including what's been done before. The person that marked those coils might have had a different understanding of it than you.

According to the manual, the firing order of the coils is "A-B-C, A-B-C" for a complete cycle of the engine:



Since Coil "A" is 1/4, "B" is 6/3, and "C" is 2/5 that results in your entire 720 degree engine cycle (remember this is a 4 stroke!) firing order of:

1(4*),6(3*), 2(5*),4(1*),3(6*),5(2*)

* denotes the waste spark.

THIS IS ALL NEEDLESSLY COMPLICATED!!!! Which is the whole point of the waste spark, making it less complicated....

So if we take the above and add coil assignments to the horribly complicated sequence to make it even more complicated:

Coil A - 1(4*), Coil B - (3*), Coil C - 2(5*),Coil A - 4(1*),Coil B - 3(6*),Coil C- 5(2*)

Note the duplication. The good news is that's what simplifies it. For each turn of the crank pulley, it's "A-B-C". Simple as that. ABC ABC ABC ABC ABC ABC ABC till infinity.

Coil: A B C
Left terminal: 1 6 2
Right terminal:4 3 5

I hope you are less confused after reading that LOL.

[Focker]

They try to idiot proof it as much as they can, as the coils come mounted to the plate with wiring etc all encased with a plug mounted to the plate.

So the ignition controller fires coil A then 120 later B then 120 later C then 120 back to A.

Now that the light bulb has gone off, I can rearrange the plug wires and see where that gets me

[Jonny042]

Originally Posted by Focker

They try to idiot proof it as much as they can, as the coils come mounted to the plate with wiring etc all encased with a plug mounted to the plate.

So the ignition controller fires coil A then 120 later B then 120 later C then 120 back to A.

Now that the light bulb has gone off, I can rearrange the plug wires and see where that gets me

BUT - the plug from the ECU to the coils could have been re-arranged - best to double check everything - It would be easy enough to have the top set wired one way and the bottom another - I can only imagine how that would manifest itself!

[Jonny042]

I see what you're saying about the coil labelling being in the firing order.....yes that might indeed be it!!!!

[Focker]

If I didn't have client meetings today I'd be giving it a try right now!

I double checked the dip switches and they are all good. Also checked the pin out on the harness and it is good.

So looking from left to right on the coil packs (plug on the right), I want to go 5-2-3-6-4-1

[Hulley]

Oh boy, I can't wait to hear this thing fire!!! Thank God it's something minor!

[Focker]

My post yesterday didn't make it through, but...


IT STARTED! IT STARTED!

My eldest son had baseball last night, so I was on pick up duty. I got home around 8:30, moved the plug wires and reinstalled the XDi box. That took about 10 minutes.

I live in a typical suburban housing development where typical lot size is 4500 sqft, so I was getting close to being noisy loser neighbour.

I pumped the throttle about 5 times, did a quick hail mary and turned the key. Maybe 2-3 seconds of cranking and it fired right up. It was popping and spitting and didn't want to idle, but god damn, it was running.

I OWN A RUNNING PORSCHE! WOW!!!!

I didn't let it run more than a minute or so as I need to break in the cams and it was getting late.

I walked back in the house with the biggest ***** eating grin I've had in a long time, the weight of German disappointment lifted from my shoulders.

My kids who were already in pajamas ran down stairs shouting "THAT SOUNDED LIKE A THUNDERSTORM! WAS THAT YOUR CAR?"

Huge thank you to everyone on this forum that gave advice and support.

Thanks Jon for reading and rewriting the XDi instructions. Reading your post is what turned on the lightbulb. Not going to lie, I started reading that post with a "Yeah, I know, that's what I did!"

Then, to borrow a phrase my oldest son uses too often, I had the "Wait, what?" moment that highlighted the wrong firing order.

OMG you guys have no idea how good this feels.

[Joesmallwood]

Originally Posted by Focker

My post yesterday didn't make it through, but...


IT STARTED! IT STARTED!

My eldest son had baseball last night, so I was on pick up duty. I got home around 8:30, moved the plug wires and reinstalled the XDi box. That took about 10 minutes.

I live in a typical suburban housing development where typical lot size is 4500 sqft, so I was getting close to being noisy loser neighbour.

I pumped the throttle about 5 times, did a quick hail mary and turned the key. Maybe 2-3 seconds of cranking and it fired right up. It was popping and spitting and didn't want to idle, but god damn, it was running.

I OWN A RUNNING PORSCHE! WOW!!!!

I didn't let it run more than a minute or so as I need to break in the cams and it was getting late.

I walked back in the house with the biggest ***** eating grin I've had in a long time, the weight of German disappointment lifted from my shoulders.

My kids who were already in pajamas ran down stairs shouting "THAT SOUNDED LIKE A THUNDERSTORM! WAS THAT YOUR CAR?"

Huge thank you to everyone on this forum that gave advice and support.

Thanks Jon for reading and rewriting the XDi instructions. Reading your post is what turned on the lightbulb. Not going to lie, I started reading that post with a "Yeah, I know, that's what I did!"

Then, to borrow a phrase my oldest son uses too often, I had the "Wait, what?" moment that highlighted the wrong firing order.

OMG you guys have no idea how good this feels.

That's awesome news! And an awesome testament to the folks on this forum.