Ouch. Good find. Justifies pulling the engine.
Cam timing OK to check in car - but adjusting is way harder.
Makes sense to check while you have it out. 2 steps foward - i backwards.
Sounds like a lot or P stories/rebuilds. Including my own. At times I swear it was 3 steps backwards.
But you plug on and eventually the reward is there.
Alan

Thanks everyone for the support. Was feeling pretty discouraged before, but I think I'm on the right track now. I picked up some beefier 10ga wire to feed the ignition system

The ring gear may have been a good fuse.

Might also want to double check that you don't have one of the cams 180* out, not that your symptoms indicate such an issue.

I bought my 930 over a live Yahoo auction in Japan. I am in New Zealand. Bottom of the world. Hard to get parts.
The car was advertised as good to go with freshly rebuilt engine. Perfect.
When it arrived it took me about 2 months to get the engine to fire. Hrs of diagnostics - jumped relays, burnt wiring under the dash, etc etc. Finally had to pull the engine - clutch was stuffed, no synchros in g/box. Turns out during a teardown, I discovered the rebuilt engine consisted of a 2nd hand P/C and about half a pound of RTV. Rust in part of the body - filled out with a recent edition of some Japanese newspaper and freshly painted over. Every job I went to tackle just identified more undiscovered issues. 3 steps backwards.
Lost count of how many times I pulled the engine out .
15 yrs on would not trade it for any $s now. Drive it like I stole it. Just back from 2 days racing this arvo. There was a time I wondered if I should just sell it for parts - could not see how I could get myself out of the hole I had dug.
Alan

The only thing that makes me question or second guess cam timing is that I have a rothsport crank pulley and the markings are kind of crappy.

You only need a TDC mark for cam timing.
Is that not clear on the pulley? If not, you can make your own mark - once you find TDC with a dial gauge. Not hard, with the engine out. Maybe worth doing anyway - put your own marks on while you have access. You can make 10-20 deg marks etc if you need.
Alan

I recently had a very similar issue. Had the gearbox rebuilt (was a 901 Gearbox) and installed a high torque starter, and got this:http://forums.pelicanparts.com/uploa...1652629150.jpg

Maybe those high torque starters are hard on the Porsche ring gear...

Bump for updates!

Not a ton to report - I did get the clutch back in after replacing the starter ring.

Kids sports and June filing deadlines are pushing back the completion date, but still hoping to at least get a few miles in this year. Hope to make some progress next week.

OH! I did run a fresh 10AWG wire from the starter directly to the relays for the ignition in case the hard starting was voltage drop.

Know what you mean. Feel for you. No rush buddy. At least you own a classic Porsche. Like a fine wine. It takes time to get there. Enjoy the journey!

Carved out a few hours for myself today and got the motor back in the car.

Engine cranks like a champ, great oil pressure, no funny noises.

I removed and cleaned all 12 plugs with the lower plugs looking a bit sooty.

I had run new power wires to the relays for the coils. The engine wants to start with some cough and stumbles but no start.

All 6 of the header tunes get warm, so no dead cylinders, but unfortunately no start.

Next thing I'm going to try is a more robust ground wire for the electromotive coils.

I get the odd pop back through the carbs, so it must be spark problems, right?

One thing that seems odd is that the engine has a harder time cranking with the throttle wide open. That's weird, right?

Anyway, back to work and kids until the end of the month.

Wish me luck, and let me know if you have any advice!

Maybe I should video it trying to start next weekend.

Just came across this thread and finished reading it. Great build by a fellow Canuck!
Looking forward to your updates.
Cheers,
Johan

Yay for that!!!!

I wouldn't read anything into the plug condition at this point. However, what plugs are you using and what are they gapped at?

As long as the ground is short and to the motor you probably aren't going to gain anything here.

Nope, that's going to happen, especially with carbs, and tends to happen even at idle when they are cold and can indicate a lean misfire I think - at least it means your getting some spark and isn't a cause for concern in itself. BUT it COULD indicate ill-timed or erratic sparks, or a spark timing isssue.

Normal, but only as long as it's not severe. More air getting into motor and takes more work to turn over. But is it possible your battery is getting low from all this cranking? It could still crank over but the voltage could drop to some pretty low level.

I would check, double check, and triple check that the spark plug wires go to the right cylinders, assuming you have triple coils with wasted spark, Cylinder 1 should be paired with 4, 6 with 3, and 2 with 5?

Also, check, double check, and triple check your spark timing with a good old fashioned "DUMB" timing light. A dial type thinks too much and will give erroneous readings due to the wasted "extra" spark.

I suppose if you have top and bottom plugs that the two systems are essentially redundant, it might be easier to fire up on just the top set of plugs for now - fewer parts and fewer variables.

PS - sorry for the weird post if you subscribe to this thread!

Last thing - PMO's have no cold start enrichment at all, correct? You are going to have to pump the accelerator like crazy to get that thing to start!!! I suppose some starting fluid might be fun to play with but is a last resort I'd say and isn't going to fix anything.

Last, but not least, welcome back!!! Hope things start (no pun intended) to go better. Something tells me that with a little forward progress you'll find it easier to carve out more time for the car.

All the best, Jon

Thanks so much for the advice!

I'll recheck the spark plug wires and try running just one set of plugs.

Plugs are NGK BR6EK. Chose those based on a post from Paul at performance oriented. Plugs are gapped at .035.

I don't have a timing light, was unsure what to get. Just buy the cheap non adjustable ones since it's wasted spark?

It's crossed my mind to switch to stock Bosch plugs just to get the car running.

Pop back through the carbs is lean, or ignition timing that is way off. Through exhaust is rich.

If you have a distributor with points, you could put crank pulley to 10* BTDC on #1 compression, pull #1 ignition wire and install a plug on the end, then move the distributor back and forth until you see a spark at this crank position. Not sure if there's an equivalent method with Electromotive.

But a standard timing light can be used to do the same. Disconnect all the spark plugs and verify #1 is firing near 10* BTDC while cranking. Might want to pull all the plugs to reduce load on the rod bearings and starter.

It's possible the manual for the system gives a firing order for a straight 6 or something in which case it would be wrong in the manual. Also then I assume maybe you have to program the electromotive system for firing order so double check that too? The default could be for a straight six or something.

Those are some kind weird plug that I've never heard of. Paul knows his stuff so he's maybe not wrong about them. BR6EK sounds like a non-projected tip to me (the "P" in BPR6EIX which I use) and the pics I found seemed like they are some sort of multi-ground electrode plug?

So the funny multi-ground electrode is good but I think the coil pack fires one plug at opposite polarity to the other (usually the centre is positive). From the NGK website:

Wasted spark ignition systems are a type of DIS, which uses one coil for every two cylinders. The coil provides the spark for one of the paired cylinders on the compression stroke and to the other on the exhaust stroke. Because the coil fires the spark plug on the exhaust stroke as well, it is appropriately named 'wasted spark ignition'. In effect, the spark plugs fire simultaneously and twice as often.

Ignition CoilOne of the two paired spark plugs is always negative polarity while the other spark plug is always positive polarity. Negative polarity means the spark plug's center electrode is negatively charged and its ground electrode is positively charged. Positive polarity is the opposite. Each time the plug fires, a rapid exchange of the protons and electrons occurs, called ionization.

The negatively charged electrons will be attracted to whichever side of the spark plug that is positively charged. The positively charged protons have much more mass than electrons, and thus cause more wear on the electrode they collide with. Hence, one plug will exhibit more wear on its ground electrode, while the other plug will experience more wear on its center electrode. If a spark plug with a precious metal on only the center electrode were to be used with this type of ignition system, there would be uneven wear on half the plugs. Although single precious metal or standard nickel plugs will still allow the engine to run, plug life will be greatly reduced.

Therefore, if a vehicle was originally equipped with dual precious metal spark plugs, replacement with a single precious metal or standard nickel plug may reduce plug life and engine performance.

So I think you need to delve into spark plug choice, find one with precious metal on the centre AND the ground. Bosch does 'em, no idea what the right number would be.

Last, but not least, how do you know what your timing is set at right now, if you don't have a timing light? When you do get one, it would be an idea to make sure the timing on 1 and 4 match and happen at the right time, 6 and 3 happen 120 degrees after (on the crank pulley) and then 2 and 5 120 after that.

THEN you'll have no doubt about the timing, and the firing order.

Hope that helps!

I'll double check the plugs, I likely misspoke as they are a single ground strap plug.

Wish me luck!

Jon are you using Iridium plugs?

Yes, BPR6EIX. Love 'em. Ran the first set for two full driving seasons of MFI tuning, 7 or 8 thousand KM's with some really RICH mixtures.

BUT!!! Not suitable for waste spark since you need iridium or platinum on both electrodes. Look for DOUBLE iridium.

Ah. Probably one of the BPR6E-something plugs, like a BPR6EY I bet. Nothing wrong with those but you'll get better spark (and plug life) with iridiums or platinum imo. Of course people have whole belief systems built up around spark plugs (same way they do with oils) so you'll get varying suggestions, some of them downright crazy, even from normally sane and intelligent people.

Thanks!

I just replaced the plugs on my M3. 3 years and 40,000kms and they were worn out. More power and fuel economy improved by 15%.

I got a timing light, and had my son crank over the car.

I confirmed all plugs wires are going to the right spot, but all I can do is get the car to stumble.

Starting fluid did not help.


I'm assuming that when the timing light flashes the mark before TDC should line up with the parting line?

After continually trying to start this thing I did notice fuel leaking out of the headers.

At this point I'm ready to either tow it to a shop, switch to EFI or burn the thing to the ground.

Is it possible to put the original distributor back in, maybe isolate the problem between the carbs vs ignition?

There's a mark at 10 degrees BTDC I think - which should be about 11mm from tdc. That's where you want to see a flash. You'll see it every time the crank goes to that position if you are on either the 1 or 4 plug wire. It's worthwhile putting some makeshift marks on the pulley at 120 from there and 240 from there to make sure the proper cylinders in the firing order are getting the fire at the right time. I know you've double checked but if you're double checking using some wrong information or assumption it won't get you anywhere else than where you already are.

PS - just confirming you got a fully non-computerized timing light, correct? And have you confirmed what plugs you've got in there?

Fully non computerized, correct. When I aim the light, it flashes at the timing mark that is pretty close to the Z1 mark.

Plugs are NGK BPR6ES

Part Number: NGKW0133-1641844
Part Name: NGK Spark Plug Standard BPR6ES NGK

I've reached out to Jeff Alton at Turn 3 (Jeff's a member here). If it isn't running by the end of the weekend, I'm towing it to his shop to get sorted.

Nothing wrong with getting a set of fresh eyes on the problem. We all get clouded by our past experience and sometimes can’t see the obvious.

You’ll get it sorted eventually and can direct all this frustration toward 6000 RPMs

You'll be in good hands with Jeff.

Those plugs are the standard copper plug. It would be worth trying a BRP6EIX which is the iridium version and has a fine tip electrode and will fire more easily.

Long term, you'll want to get a Double Platinum or Double Iridium plug to suit the waste spark setup.

6000rpm?

I thought this was a 911, not a John Deere.

Lol!

I’m in the farm league with my 2.7 so I’ll humbly exit stage left and leave the 7000 club to play ball.

If the spark timing is close enough (say 10* ATDC to 20* BTDC), it should fire if you have compression and fuel.

Firing order is 100% correct?

Pics and video might help.

I'll take a video tomorrow. Good chance I f*cked up the carb setup

Took a short video trying to start the car.

Ignition box was set at 10 degrees advanced, I rolled it back to 5 degrees advanced towards the end of the video.

I'm going to install a seat and some axles then send it over to Jeff to get it running.

Fuel pressure is 3.5 psi

https://youtu.be/jkfnvgq7Knc

Well that was a spectacular flame show! I assume you have a fire extinguisher handy.... I had 3 at the ready when I was first firing up Project Heavy Metal.

I was expecting to see you hop in and pump the accelerator 4 or 5 times to prime the intakes with a bunch of fuel. Not sure at any point in the video you pumped the carbs enough to give it a good starting shot. Not having a choke is really going to make it tough to get started without doing that.

The few times it did fire it sounds like its running like it should - although without those few instances to go on I would still swear there are at least two cylinders swapped in the firing order - my cue on that one is the odd pause in cranking that seems to occur rhythmically as you crank it over.

Also, the flame show out the cylinders.... oh my. I know you've checked the timing of #1 and 4, but have you checked the spark timing with the light against the pully 120 degrees from TDC to confirm those two cylinders are firing at the right time (and again at 240 for the last set?) just in case the XDI is doing something you don't realize swapping pairs on you in software? It's possible that the next two pairs in order have to be swapped at the coil pack (or a setting changed in software).

Also, that odd pause in cranking could indicate a poorly performing battery (or simply one low on juice) - the starter could be drawing so many amps at that very short moment it could be causing the XDI to reboot, in which case it might take a short time to come to life, and if it's like other systems it may need to see a few valid pulses before it will allow the spark to fire. Do you have a backup battery or one you could steal from another car and add to yours with jumper cables?

Last but not least, I'd make sure your timing curve is set to absolutely flat at first or at least quite conservative for the are between 0 and 2000 rpm, just in case the unsteady cranking is causing the XDI to advance the timing as it's cranking because it momentarily sees the engine speed spike up to a point on the curve where it's calling for advance. That might see the cranking smooth out a bit since the spark advance won't be fighting the cranking.

Sure behaves like a firing order issue.

Very interesting. The pauses in the cranking is me not wanting to crank it for 3 straight minutes.

I did pump it a few times each time.

I think I'm going to pull out the xdi and double check the pin out and dip switch setting.

Fire extinguisher was definitely at the ready.

Really glad I took a video.

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.