More fun with MFI and LM-1

[analogmike]

HI,

I had my 2.7 RS engine rebuilt again after another missed shift at Watkins Glen. (Wevo is ready to install now!). We put in a lot of new parts and really messed up the pump calibration getting the new engine to run. So I got an Innovate LM-1 after reading all the threads about them on this forum.

We added headers so no more heat to the thermostat...
I pulled off the thermostat and made up a thumbscrew manual thermostat as shown on other threads, for now I have it screwed in all the way.

Engine is running pretty well now but it's a little weird... at part throttle, cruising around on the highway etc it's very rich about 10.5 : 1. Exhaust is very black. At full throttle, I logged some data through 3rd and 4th and into 5th gear and it got a little too lean at higher RPMS, 14 - 15.

I am wondering if anyone knows how the various adjustments ACTUALLY work - part load and thermostat adjustments.

1) Does part load adjustment change full throttle much?

2) Does the thermostat adjustment change full throttle more than the part load? If so, I can richen the thermostat adjustment and lean out the part-load.

Any other ideas?

THANKS!

[Wayne 962]

Innovate LM-1:

http://www.pelicanparts.com/catalog/shopcart/TOOL/POR_TOOL_CAT447_pg1.htm

-Wayne

[Zeke]

Have you done the measurements and the geometry with the protractors on all the linkage?

[Ceder2.4S]

Hi,

As far as I know and have experienced:

1) With the part load screw you adjust the pump main rack. Hence also the mixture at full throttle.
2) The thermostat is only for use at coldstart and warming up. When at full operating temp it should be max out all the time.
3) The relation between part load and the idle mixture adjustment seems to have a lot of influence on the 2500-3000 rpm range.

First make sure the throttle correlation is correct. If it is, then in your case I would properly try to give it 2 clicks counter clockwise (more rich) on the part load and two clicks counter clockwise on the idle mixture (lean).

Hope this helps.

Where in the exhaust have you positioned the O2 sensor?

Carsten

[jluetjen]

Another question that can have an impact -- what is the space cam in the MFI pump? Adding headers apparently often messes up the mixture on an MFI'd engine since the MFI cam doesn't take into account the extraction affects of the headers.

But if the engine was running fine previously, before you messed around with all sorts of stuff, I'd go back to the start of CMA and work through the process.

[Grady Clay]

Mike,

What are all the components – cams, stacks, throttle bodies, heads, pump?
What headers? What do you have for mufflers – SuperTrap? Other?
How is your LM-1 sensor(s) mounted? Where?

Also, on your manual thermostat always carefully screw it in all the way but never firmly bottom it and back it off 1/16 turn or so. You don’t want to load the linkage. If you screw it in hard, you can bend the linkage.
With your LM-1 you can start backing the screw out and see where the thermostat action starts. The last ½ to ¼ turn should have the thermostat off.

John, Carsten, and Milt are right on.

You are going to have to set the main mixture for your proper WOT track use and adjust the idle mixture for best part throttle and idle. The part throttle probably will never be great without a stock OEM muffler.

Best,
Grady

[analogmike]

HI,

THanks for the replies!

I already have the LM-1, purchased from Pelican Parts.

I have not done the protractor measurements, they were OK before but someone may have messed some up.

THe weird thing is that the right side of the engine is running much hotter than the left. I check with an Infrared pyrometer, at the fuel injectors (screwed into the heads) and the headers near the heads. The left side is coooler on all 3 cylinders... maybe the cross bar is off calibration.

Rims and tires - this is a combo that should not work, but works for me!
Turbo rear fuchs front and rear, front '76 930 8x15 with 225/45/15 and rear '86 930 9x16 with 245/45/16. Hoosier radials.


>> 3) The relation between part load and the idle mixture adjustment seems to have a lot of influence on the 2500-3000 rpm range.
First make sure the throttle correlation is correct. If it is, then in your case I would properly try to give it 2 clicks counter clockwise (more rich) on the part load and two clicks counter clockwise on the idle mixture (lean). <<

That is something I have not messed with much, could do the trick!!

this helps.

> Where in the exhaust have you positioned the O2 sensor?

the LM-1's sensor is on the driver's side collector on the header, on top.

I believe I have the correct 2.7RS space cam in the MFI pump.

> What are all the components – cams, stacks, throttle bodies, heads, pump?

All stock RS parts, but metal stacks from a 71S and K & K dual weber filters with no rain shield.

> What headers?

not sure, RSR style 1 5/8"

> What do you have for mufflers – SuperTrap? Other?

I was using a factory sport muffler for dialing on the street, will use megaphones for the Lime Rock Fall Vintage Festival in a week and may have to richen it up for that.


>> Also, on your manual thermostat always carefully screw it in all the way but never firmly bottom it and back it off 1/16 turn or so. You don’t want to load the linkage. If you screw it in hard, you can bend the linkage. <<

Thanks, I saw that in a previous post so I did that.

>> With your LM-1 you can start backing the screw out and see where the thermostat action starts. The last ½ to ¼ turn should have the thermostat off. <<

good idea.

>> You are going to have to set the main mixture for your proper WOT track use and adjust the idle mixture for best part throttle and idle. The part throttle probably will never be great without a stock OEM muffler. <<

I see, I will try to lean out the idle and richen up the part and try
to get it close enough. Actually only full throttle matters as it's a race car but I dont like the plugs getting fouled driving around and nice to be able to idle smoothly before the races to warm up.

Here is my engine last year, looks the same now except I painted a new fan yellow and no more thermostat or air ducts going to the heat exchangers.



thanks!

[Grady Clay]

Mike,

Conda Green?

It is a big deal if the engine is running differently left-to-right. That should be your number one priority before you adjust anything else.
High on the list are the butterfly correlation and cam timing.

You have a situation where you should follow CMA and more.
Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf

I added some important stuff to CMA here:
“MFI thermostat spacers”
p. 1 end has CMA extension, p. 3 has nozzle, fuel flow, and fuel pressure.
MFI thermostat spacers

Don’t skip anything in the CMA and extension, no matter how sure you are.


I would recommend you get a second bung, O2 sensor and extension cable so you can monitor both banks. For your purposes it will be invaluable. Make some protection from rocks for both sensors. Make sure both sensors are in the relative same location in the headers.

You said the pump is 2.7RS. I assume that means it was recently rebuilt by a Bosch builder.
Do you have access to ALL the MFI tools and measuring instruments?

What P&Cs? How is the condition of the throttle bodies?


Cool 911.

Best,
Grady

[Wil Ferch]

Mike...welcome aboard....another Rennlist member defector ( or add'l member).

You'll find the guys on this board know their stuff and the ability to post to individual threads ( with Pics!) sure has Rennlist beat in the most of these areas....although John Dunkle is a great guy who has done much with that page.

Nice to see Kermit (?) in better shape following the Watkins Glen Excursion and such. Just missed seeing you again at the Glen during the Porsche clash in June...I was entering the grounds as you were trailering your car out !

Regards,
Wil

[tobluforu]

One of the reasons your car could be giving different readings from the left and right bank is Cam timing. I found that the right bank was leaner then the left. After mucking with the car for god knows how long, I decided to check cam timing. And it was off. Just a heads up.

[analogmike]

Grady,

Thanks for the reply.

>> It is a big deal if the engine is running differently left-to-right. That should be your number one priority before you adjust anything else.
High on the list are the butterfly correlation and cam timing.

You have a situation where you should follow CMA and more.
Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf

I added some important stuff to CMA here:
“MFI thermostat spacers”
p. 1 end has CMA extension, p. 3 has nozzle, fuel flow, and fuel pressure.
MFI thermostat spacers

Don’t skip anything in the CMA and extension, no matter how sure you are. <<

I have the CMA but I think my mechanic adjusted the throttle body stops and it does not cover that :-(

All is OK up to the point in the CMA where I will try to balance the idle screws at 3000 RPMS. Will try that today and see if it helps.

>> Do you have access to ALL the MFI tools and measuring instruments? <<

I don't have the protractors or know how to attach them. But the linkages should be OK as they were not messed with.

My mechanic says the cam timing is right on, it only has 300 miles on the rebuild and he says the dyno numbers show that it must be correct. Dyno #s are VERY strong :-)

>> I would recommend you get a second bung, O2 sensor and extension cable so you can monitor both banks. For your purposes it will be invaluable. Make some protection from rocks for both sensors. Make sure both sensors are in the relative same location in the headers. <<

That would be a good idea.

>> You said the pump is 2.7RS. I assume that means it was recently rebuilt by a Bosch builder. <<

Not very recently, talked to Gus and he said it should be OK. Will try to clean one of the nozzles as you recommended in another thread, as one cylinder seems to be idling worse than the other 5.

> What P&Cs?

Brand new 2.7RS P&C and Cams.

> How is the condition of the throttle bodies?

Quite poor I think, but it's a race car so full throttle is main importance, and keeping the engine running OK during warmup to not foul the plugs is good enough.

I made a vaccuum retard connection to the middle left stack yesterday as the idle was too high and advanced. It pulled the timing back to TDC and idle speed is fine now. But the vaccuum actuator is banging a lot at idle as the vaccuum is not smooth, each revolution of the engine it bangs. I will try to attach a fuel filter or something in the vaccuum line as a small vaccuum reservoir to try to smooth out the pulses.

> Cool 911.

thanks!!

These are the cars I will be racing next week #8-0

[Grady Clay]

Mike,

I will disagree; idle and part throttle are big issues with a race situation. How you beat that “big iron” is not on the straights but with finesse in the corners. That is where the great throttle response of Porsche’s MFI comes into play. The ability to modulate the throttle in the 0-10% and 5-60% range is critical. Full throttle is a no-brainer.

The MFI 911’s performance at the limit of traction is greatly enhanced by the very precise correspondence between accelerator pedal position and power delivered to the wheels. This is particularly true in a temporal sense; no hesitations.

You will need to pay particular attention to that mid-range, part-throttle mixture issue if you want to win.

I am concerned about your description of the throttle bodies. When you have been off the gas, braking into a corner, and need to have some power to control the car, you don’t want any hesitation or mixture difficulty. That is a mixture issue and the throttle body condition is a significant part of that at low throttle position.


There should be someone in your area with a Bosch nozzle tester. That is an easy (and inexpensive) test and can spot a potential problem without throwing money at new nozzles. BTW, I would test new nozzles and confirm the sealing, pattern, and opening pressure.

The throttle body idle stops are the first step in idle air flow measurements and correlation. You have the CMA, do you have the Factory Workshop Manual? Do you have access to protractors and air flow measuring?


As the saying goes; “The Devil is in the Details.” MFI has plenty of details.
I want you to embarrass that “iron” with your 911.
BTW, what are the other cars and who are the owners?

Best,
Grady

[analogmike]

Howdy,

I found the right side throttle bodies were a little off, possibly from strapping my engine down inside my truck for transport. I balanced them and now it's pretty even on the air flow synchronizer.

I also leaned out the idle, idle is now steady and good mixture.
Full throttle is also good. But normal driving (just TOUCH the accelerator pedal on a 2.7RS in normal traffic or you will rear-end the car ahead of you or get a ticket) it is still running very very rich, about 10 - 11:1.

With 1/3rd throttle or more it gets fine. I guess this is a correlation problem. But I had the same problem last year early in the year UNTIL they changed over from winter gas to summer gas. Now, in CT, all gas has ethanol in it. I am thinking that my MFI does not work well with Ethanol. I may try to buy a barrel of gas in another state that does not subsidize the farmers...

anyone else have problems running ethanol laced gas with MFI?

[RoninLB]

Originally posted by analogmike

anyone else have problems running ethanol laced gas with MFI?

have you tried disconnecting the dizzy vac ?

[lateapex911]

Ahhh...Analog Mike pays a visit.

Just to fill you guys in, Mike is a long time 911 owner, back when his first 911 was only a dozen years old! I think that Mike was the last guy to win the Solo II Nationals in A stock in a 911, in his case the "swimming blue pool" 72 (or 3?) 911S targa. Thats right, a targa! The kid could drive! Beat a solid field to!

His racing skill is very high as well. Clean smooth, and often wins, beating the big iron handily. Always a pleasure to watch. I look forward to seeing him at Lime Rock!

Hey Mike...is your mechanic as good as your body man?

[Grady Clay]

Mike,

Sorry for not posting sooner. I’m still recovering from our little Colorado Pelican Technical Camping.

Sounds like you are getting closer.
Where does the mixture go rich? What is the idle mixture? Full throttle?

Adding an alcohol (ethanol, methanol) to the gasoline leans the mixture. Try it, you’ll like it.

If you have suspicions about fuel, many local drag strips sell spec fuel. There are independent fuel suppliers all over. Our local VP suppliers (4) sell 112 octane in 54 gal lots for about $230. They also sell in 5, 15, and 30 gal drums and deliver. They sell many octane ratings, leaded and unleaded.
Here is the VP site: http://www.vpracingfuels.com/vp_01_fuels.html?mgiToken=0C15B7C83F4F75C06#leaded

While the fuel issue is worthwhile to pursue, you need to complete the details of CMA first. Have you found access to protractors?

Is there still an exhaust manifold temperature difference left-to-right with your IR thermometer?

Best,
Grady

BTW, I like the 30 gal size drum (19” dia, 29” high.) Two strong men can pick up a full drum and set it in the back of a van or pickup. One person can handle it on the ground or ramp it into a trailer without any other equipment. A full 55 gal drum needs a drum dolly and a loading dock or lift gate.
Steel drums are the absolute best for storing, transporting, and dispensing fuel. You will need a proper bung wrench and a mechanical pump. Be very careful handling fuel.
G.

[analogmike]

Hey Jake!

Thanks for the post and helping me out in the race today.
I couldn't quite pass that Ferrari 512S or Bobby Rahal or the other guy in the Chevron but beat all the production cars




>> Sounds like you are getting closer.
Where does the mixture go rich? What is the idle mixture? Full throttle? <<

It is rich with no load and any throttle position, about 10:1.
With part load it is very rich, about 10:1 or 11:1 in normal driving.
At low idle it's not too bad, just very lumpy. At full throttle it's OK but a little lean. I fear the pump took a dump and needs a rebuild as their failure mode seems to be running rich like this.
Pump is leaking oil too, really needs help

I was going to try race gas but the LM-1 sensor might be destroyed by the lead


Still no protractors, will see if I can get an urgent rebuild on the pump before my big PCA race in 2 weeks.

>> Is there still an exhaust manifold temperature difference left-to-right with your IR thermometer? <<

It was improved a bit by balancing the air metering but I have
not checked recently, I should have done that.

Also installed a new Permatune I got on Ebay a day before the race, runs the same.

[lateapex911]

Yea....don't 'cha love when Bobby drops in in his little car?

The video of you wasn't too bad. I'll make a copy and bring it up to the PCA race if I can make it.

Congrats on the drive...if I am not mistaken weren't all the 911s behind you running more displacement?? Good thing that Prescott Kelly guy got hung up behind the Pantera...your mirrors would have been pretty filled !

[ttweed]

Originally posted by analogmike
I was going to try race gas but the LM-1 sensor might be destroyed by the lead

Mike-
The leaded race gas will shorten the life of the 02 sensor, but it will still work for quite awhile. The replacement sensors are fairly inexpensive so you can carry a spare for when it goes south.

TT

[Grady Clay]

Mike,

The fuel suppliers offer unleaded fuel, including high octane to 109 octane. They also offer spec race fuel for SCCA (PCA, POC, vintage.)

Best,
Grady