V12 M73 to Audi trans, with Proteus in Lamborghini Replicas

[Lambo97]

Update crossover tube installed. It's 0.6 Inches in diameter. It's brought the banks closer together around 1 point difference in AFR.

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Now Time for Tuning to get the AFR closer to Stoich.

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[mk e]

Did you get #4(?) running? That will make that bank read lean...or should anyway.

[Lambo97]

Yes I changed the coil cable and plug. This reading is after the change in pulling all the plugs again tonight to see if there are more issues.

[mk e]

Yes I changed the coil cable and plug. This reading is after the change in pulling all the plugs again tonight to see if there are more issues.

Excellent news and getting them all lit!.....I think a new video is in order

Does the ecu give you any way to change adjust the TB positions independently? That would be a great feature if it doesn't...syncing the TBs is really the best way to sort this kind of issue before going to fuel tables to deal with the affects of the issue.

[mck1117]

Does the ecu give you any way to change adjust the TB positions independently? That would be a great feature if it doesn't...syncing the TBs is really the best way to sort this kind of issue before going to fuel tables to deal with the affects of the issue.

It doesn't now, but I think he's going to get a second MAP sensor so we can play with it!

[mk e]

It doesn't now, but I think he's going to get a second MAP sensor so we can play with it!

ahh.

I guess where I was going is you do have 2 O2 sensor support so he has the information he needs to "tune" or sync the second TB. A TB sync feature to let the user alter the tb position for bank 2 relative to bank 1 seems like a good approach to balance the banks. I have 12 TBs but only 1 actuator so altering fuel is my only option in the ECU, but I have a mechanical adjuster of each TB....for 2 actuators a %offset of maybe 4 or 8 point table would probably help a whole lot.

[bill]

Have you tried measuring the ETB while they are operating on idle??
the Jag v12 recommends the (mechanical) throttle body butterfly be open .002 inches... which is almost nothing...
so the electronic throttle body is gonna have a hard time making that kind of a tight tolerance .

also, did you put some carb balancing gauges on the two intake manifolds?
while idling or while revving up.
see if the crossover pipe cleared up the vacuum difference?

crossover pipes are strange beasts-- the jag v12 in the 70's had a ½" pipe,
then in the 80's they went to a 1" pipe, along with the standard ⅛" vacuum line also ...
not sure why, but the crossover size changed

below is kind of gauges for manifold balancing
https://www.amazon.com/ALPHA-MOTO-Carburetor-Synchronizer-Motorcycle/dp/B004MSJ7C8/

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[AndreyB]

How is the yellow m73? There was some drama with compression was it resolved?

[Lambo97]

Hey there, I was frantically testing last week before we had a family vacation planned for this week. I found a dead cyl 8 this time, plug was wet. Ran 2 compression tests to make sure it was an issue and was only getting 60 pounds. I ran air into the cyl and I could heard a hiss in the intake and exhaust. I plan to gently lap the valves in place. Next post this Friday I'll update with hopefully good news the compression is holding and that should get the AFR closer than the 1.2 point spread I have right now.

Thanks for the info Bill I've never seen carb balance guages. If I don't get the AFR numbers closer after getting cyl 8 back I'll look into getting some.

[mk e]

Stupid 12 cylinders, it seems like something is always wrong...

With a cylinder leaking you're manifolds pressures will not be equal so best to get that sorted before doing any more EFI related trouble shooting.

With no known mechanical issues I was going to suggest let it idle with the MAP on bank 1 then restart with it in bank 2....not as good as 2 MAPS at but something. I measure and report all 12 because I have 12 TBs and HW that lets me, but I also have a manometer I can move move around, that was like $30 I think and helpful.

Edit: I wasn't clear, the manometer measures the difference between 2, then I move it around to get all 12 but if you only have 2 its all the info you need i 1 shot

[Lambo97]

So bad Cyl aside I can't seem to find the reason it sprung an oil leak inside one of the cylinders. Oil smoke is the reason I moved away from an old Carbureted V8 and this is pathetic. Working until 2:00am most mornings for months on end and it comes to this.

So I took a week off so I could loose some of the anger at the hunk of junk and will get Rob the Black car's owner over here next weekend to pull the motor. Head gasket and bolts are coming. Off to the machine shop in a few weeks, back together and maybe a run before it snows. So frustrating because there was no smoke a week into testing and then poof oil leaking into a cyl somewhere. Plus I've manually lapped the dead cyls valves from above and still little compression. 30 to 40 more hours and a 3 angle valve grind, here I come.

[mck1117]

Is it worth getting the car together enough to go for a drive (even if down a cylinder and the injector unplugged) to try and get some heat and pressure in the rings?

[dbh97]

Hook up your air compressor to the spark plug hole and listen for the hissing. That will tell you if it's the exhaust valve, intake valve, rings, or head gasket. If it's the rings, there's all kinds of potions people put in their cylinders to try to free up the rings. Sometimes they even work.

[mck1117]

If it's the rings, there's all kinds of potions people put in their cylinders to try to free up the rings. Sometimes they even work.

Unless it's a broken ring (been there, done that), perhaps the most effective potion is horsepower. A friend of mine fixed an oil consumption problem on his miata with a track day.

[Lambo97]

So there are 3 problems. Cyl 8 is 60 pounds under testing. Cyl 11 is 170 where all other cyl are 205 to 210. And an Oil leak making nasty plume behind car on that bank. I took the springs off and spun them with a drill for a few minutes. They seems to seat nicely but the intake based on the position of the valve would either be kind of quiet to hissing like crazy.

So I can't trust this valve wont spin when running. The Oil issue being my bigger issue because it looks like hell and smells like hell. The problem popped out of no where a week after I started testing before I found the bad cyls. I did an inspection of each stem seal with a camera they are al good. Cyl 7, 10 and 11 have relatively black plugs compared to the others so I might quickly take off the springs to check those first.

In any case with 2 low cyls and an oil leak, best option would be to send it in to get done properly. I got a quote $650 for one head so I'll see if I do 1 or both. Lots of money for a car I won't be driving this year but at least if I get the motor back together in a month or so. I'll post updates from the machine shop to see what they find. I don't know if BMW uses Steel valves seats in the aluminum head. My guess is they do.

[mck1117]

The Oil issue being my bigger issue because it looks like hell and smells like hell. The problem popped out of no where a week after I started testing before I found the bad cyls.

This almost sounds like a stuck ring.

[mk e]

The valves do rotate in normal operation, every time the spring is compressed there is a small rotation that occurs or at least can occur and this helps the parts wear evenly so picking a specific location for the valve is not going to work as you suspected.

It sure sounds like you have bent valves in at least cylinder 8, the question is how did they get bent? Do you have a camera you can get into the cylinder?...or I guess if the heads are coming off you'll see then.

Can you disconnect the crankcase breather and see if there is also smoke coming out that? Smoke out the breather means you have piston/ring issues which would be good to know. Normally rings sticking only happens in engines that are sitting and doesn't pop up once the engine has been running a while again....so I worry that whatever bent the valve also damaged the bore or the piston.

[Lambo97]

Ok the Motor is out and the heads are at the machine shop. 3 angle grind, deck, resizing of the valve guides to match the valves. Perfect AFR here we come.

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In this picture of the lean side, we can clearly see oil leaks. I marked the 3 cylinders that had dark plugs. Cyl 8, second from the left was the 40 to 60PSI cylinder also has a pool of oil on the piston. Cyl 9 also has oil, and cyl 11 which had 150psi instead of the normal 205 to 210 was also dirty and had oil.

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The other rich side as I like to call it was dry and sooty like a rich bank would be. The head gaskets were Victor Reinz so the motor has had the original ones replaced (I think BMW recommends head gasket replacement with every oil change) Every BMW I've owned needed a replacement.

This is the rich side. The middle cyl is a little rad fluid that fell on the piston but there's no oil just dry soot and carbon on the piston tops.

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[Lambo97]

Update:

Heads are back, Was waiting for Gaskets from the only place on earth that seems to sell parts for M73........Latvia

Should be pulling the engine from under the cover and starting the reassembly. Machinist resized the stem guides, 3 angle grind, all looking clean and no more air leak! Should have some photos next week.

[bill]

yea, why are there no head gaskets in usa?? weird...
and why does a "complete head gasket set " NOT have a head gasket?!?

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[mck1117]

FCPEuro has head gaskets in stock in the US.

https://www.fcpeuro.com/BMW-parts/750iL/Cylinder-Head-and-Components/?year=1998&m=20&e=191&t=5&b=5&d=72&v=

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[Lambo97]

I ran through a $350 set from Latvia for the first rip and strip. So this time I only bought the gaskets I didn't couldn't use RTV for. I got the head gaskets from Ebay both Victor's so at least I got them . The ones I really didn't want to make were the upper to lower front case gaskets that are a certain thickness and have a neat cut out to go around the chain.

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End of summer trying to get all the yard work done but into the garage I will go soon to focus on the rebuild.

[Lambo97]

Finally an update, after a few months working on a 460 Ford big block. I had to finish this motor and transmission for a friend. All done, but too bad there won't be any EFI on this motor.

460 Ford Big Block

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Finally cleaned the block surface and installed the head gaskets. Set TDC, new chain, installed the cams and triple checked alignment of the chain pullies. Picking up a M12 x 1.5 tap for the new Bosch temp sensor matt recommended. Goal is the engine back in this weekend with the ancillaries being attached next week to possibly do a run up in a week or 2. I'll run a new compression test to see how the valve job is and just glad to get back to where I was 6 months ago.

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[AndreyB]

Happy New Year! I was wondering

[Lambo97]

Update 36.857

Motor is in and run up once 2 days ago. Lots of raw fuel coming out the back, even though I leaned the crap out of the VE table at idle until the engine starting a slow up and down pulse. Running through a new compression check to make sure all is well after rebuild. Checking plugs tonight and off to trying to get the AFR decent at Idle. This is what the Diablo engine looks like now.

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The black car has also been moving forward, Engine is in and we are on the last of the wiring. Hopefully in a few weeks we will run up that motor also.
This is the coil setup using 2 Toyota igniters.

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We are going for a more old school look on this motor so the coils are front and center.

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Also I designed a throttle control box so I can mount the Toyota throttle in my car and add a spring to increase the pedal pressure. Our Cars have a cable that used to go back to the original engine so this made sense.

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[Lambo97]

Ran up the Diablo's car motor last week, idles great. AFR is a little off still. I guess due to the side to side differences between the intakes. So I continued to look for a crossover tube solution to equalize the vacuum across the intakes. I purchased new PCV's, drilled out the location of where the M70 used to have it's IAT sensors on each side. The used a 3/8 NPT tap and some nylon NPT 90s with 1/2 inch barb to connect the 2 sides.

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Engine bay almost done. Waiting for weather over -10 to open the garage door and set the idle parameters. Things are looking good for a test drive in a few week when they stop salting the roads!

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[AndreyB]

Do you have any relevant lambo replica meets this summer? Checking for what dates I should book my ticket

[mk e]

Looks great!

Idea. On the bank that is rich, change the TB closed position to tell the ECU 0% TPS is actually just a little open on the TB so it will never close quite as far. You can balance the idle mixtures this way and the error should go away as the TB opens so I think between this adjustment and the balance tube this should sort the issue...I think.

[mck1117]

Looks great!

Idea. On the bank that is rich, change the TB closed position to tell the ECU 0% TPS is actually just a little open on the TB so it will never close quite as far. You can balance the idle mixtures this way and the error should go away as the TB opens so I think between this adjustment and the balance tube this should sort the issue...I think.

I'm (slowly) working on adding a small table to adjust throttle-to-throttle trim instead of a hack like that.

[mk e]

No doubt that's better and more flexible, I was just thinking about what knobs could be turned today not suggesting it was anything beyond a possibly functional solution for this very specific case where an idle/low power mismatch is occuring.