mfi idle on max, still lean on idle?

[svandamme]

it just won't deliver at idle if i lean out the main, both the thermostat or the main adjust, if i lean those , the idle is lost... i can only maintain idle with the hand throttle, and even then , it's very, very rough , and my main is still too rich, it's drivable, sort off, but it's no fun... lm1 calls 10:1 at best under load... without load... 17 and sometimes more... not good.... coughs and spits way to much so as soon as i figure out which kidney i'm going to sell, left or right one ... the pump goes to Koller for a rebuild...

[cmcfaul]

Good call on the rebuild. Do it while there are still people who know how to do it. It will come back properly calabrated and should be good to go.

Chris

73 911 E

[svandamme]

just went to the garage, yanked the pump and injectors of
was a little tempted to go for a little drive, the weather is so nice, it's almost like a mild summer...

decided not to drive, no use heating things up when i want to get those injectors out and stuff, besides, it's cramped working space as is , with a warm engine, it's just like an oven...

dripp dried the pump, then pulled the solenoid and panels off and was amazed how much oil still was in there... all out now, stuffed the whole thing in a box, some isolation foam... got some collegues who work in our Nurnberg office, so no shipping cost to Koller, i'll ship it from office to office till it arrives in Nurnberg

"anyone going to Dusseldorf?" then "anyone going to xxx??"
practical benefit of working in a multinational company

[Grady Clay]

Stijn,

What is the condition of the throttle bodies? It would be appropriate to have them flow calibrated at the same time.

What are you going to do about the thermostat? It would be best for them to install it on the pump, properly set. I would recommend you get a new left (at least) heat exchanger and the correct air tubes to the thermostat.

While the pump is off, set the engine to Z1 #1 and pull the distributor. Take it to someone with a good old distributor machine. Get everything set and run in. Have them make you an advance chart of the actual measured advance curve and vacuum retard. This will be very useful when you get everything back together. You will be able to set the timing static and be very close at 6000.

Remember to take your batteries out.

Good for you. I know it is expensive but you will have this fixed and properly running for many years to come. Fun driving ahead.

Best,
Grady

[svandamme]

my TB's are fine, they seem to be rebuild before, no plastic bushings, no play either, they were dirty though , the bores for the screws and the vacuum were clogged so i cleaned them and flowed them with a vacuum cleaner
i have good throttle correlation , no problems there

as for heat exchanger/thermostat, i'm planning to ask Koller if they can rebuild mine with the enrichment solenoid... they have been quite strict on prior emails, when i was asking about changed engines ( before my rebuild) and they answered with "no! we only rebuild according to ze Bosch spec" ... but can't hurt to ask about this enrichement thing... paying customer with pump in their shop , might get different answer than someone just firing an email in their mailbox... i'll see what happens...

the Dizzy is fine as far as i can tell, advance and retart behaves according to the factory manual , allready over budget so i'll leave it at that for now
believe me , if i had the cash , i would ave just dropped car and engine and the whole thing off at some restoration shop, with a note saying :

"please strip nekkid, and rebuild concourse state, don't forget the radio and all the little stickers, i'll be back in a month to pick her up..., K?thx!"

i just don't have the bankaccount to do that...

[sballard]

Stijn,

If you are considering Grady's suggestion about installing a conventional thermostat, you could just have a local welder attach a short length of stainless tubing on the heat exchanger to connect up to the new thermostat. I did this and it was a lot cheaper than buying a new exchanger. You can see the location of the factory tubing and hose on an MFI engine in the recent thread of the early 911 assembly line.

Steve B

[Peterfrans]

Steve,

Stijn has no heat exchangers on his car, fabricating something to feed the original setup with warm air is not so easy.

[svandamme]

fyi , just received my delayed xmas present by UPS

my pump , all nice and rebuilt by Koller
fresh thermostat&shutoff solenoid, the idle adjustment thingie is fixed and 6 brand new injectors

looks almost brand new

just ordered a new mfi belt , and some little things
and should get the pump installed soon-ish...

i'll make some pictures when i get it home

[svandamme]

cheapo digicamera , flash is no good, and no flash ain't to shabby either...

Grady , came up with an idea for the thermostat
not sure if it will work , but it's well worth a try

here goes :

i plan to use the low pressure in the engine bay , created by the fan and the intake

so i'll attach the hose to the thermostat and the engine tin , as would normally be attached

then i'll fab up something below the engine tin , so it pulls air from some hot area headers or lower valve covers, not sure which ones yet ,as i'm not sure how much heat i need to make the thermostat tick..

then i'll check if the normal engine bay has low enough pressure to draw air from down there

i'm no expert, but it's just the reverse from the stocksetup ( fan blowing air into the HE's, and from there , to the thermostat
it's no direct source either , so i don't think it needs much air movement to work...

does anybody know , at what temperature the MFI thermostat is supposed to click?

[Peterfrans]

This won't work as there is no significant pressure difference between the engine bay and the area below the engine bay at standstill. When driving it even could be the other way around.

The easiest way around this is the supertec solution as this enables you to manually adjust the enrichment. Another option would be going back to at least the left head exchanger in stead of the headers you are now using. Also still possible is Grady's solution with the screw.

[Peterfrans]

or, you could rig a hair dryer to the thermostat and it is just a click of a switch on the dash

[Grady Clay]

Stijn,

Great that you now have all ready to go back together.

First let’s talk about the thermostat. Am I correct there isn’t any tin heat exchanger on the left headers? If there are just the bare headers, find some tin and make yourself a small “heat exchanger” just for the thermostat. It should be at the “bends” in the headers toward the front as they are the hottest. Make it too large; you can always waste the extra heat. Use the standard supply ducting behind the distributor and below the tin you can make an adaptor to reduce the hose to a smaller size. From your custom “heat exchanger” use the OE air plumbing to the thermostat.

Part of this effort is to maintain the original warm-up characteristics of the system. Having too much heat results in the thermostat turning off sooner; preventing gasoline diluting the engine oil. This is easy to modulate by simply wasting some of the excess hot air. If the thermostat turns off too soon, all that happens is you get a little “lean rough running” during warm-up. No big deal. If too rich and too long, you get oil dilution that can be catastrophic.


OK, on to the next issue.

How long did you run the engine after the rebuild before you pulled the MFI pump? Kilometers, hours, liters of fuel? What service did you do? Change the oil? Torque the head nuts? Check the cam timing? Adjust the valves? Check the ignition advance curve and set the timing?

Right now you are at a critical CMA point.

When you have all these “little” details attended, you want the engine to start and run satisfactorily. You will then need to do some brake-in both from the fresh engine rebuild and the setting all winter – very important. You should try and not adjust your fresh pump unless absolutely necessary. If you do, keep perfect track of your adjustments. As the engine, MFI system, ignition and other all settle in, you want to chase the adjustments with full knowledge.

I posted on someone else’s thread (Canada?) about MFI brake in. Find that link.

There is a lot to do before you first crank the engine. There is a lot you shouldn’t do when it is first running. You are not permitted to take Peter for WOT runs. Hehe. Some careful running is necessary.

Let’s devise a carefully thought out plan.

Best,
Grady

[svandamme]

i didn't run it to much , max 1.5 tanks of gas probly less, maximum 150 kilometers (many WOT runs and very rich , obviously)
and 2 oil changes (1 after initial 20 minutes, another one after i needed to pull the tank to fix the bracket)

nothing torqued yet, no cam timing or valve adjust yet
did check the curve and timing , that was fine

i spoke to the rebuilder, he said drive it 1000 clicks, then valve adjust, no need to torque anything, i trust him , he restores a historical 911 racer for Porsche finland, and does mostly early 911 racers


Koller did not mention any special instructions for running the pump , i told them it was for immidiate use, so i assume they did not do any special storage treatment
in fact, the pump is capped off all over, the fuel connectors still smell like fuel from testing

i figure i'll put the pump on , prime it with oil, time it
and then spin the engine with the lm1 & synchrometer at hand
while at the same time keep an eye out for everything as one would during the first startup of a fresh rebuild...baby steps so to speak...

for now , i'll just use a manual heat gun to control the thermostat untill i decide on a final solution , Koller installed the thermostat, and laquered the bolts for warranty check , so i'de be stupid to pull it off and mod it , untill at least i know the pump checks out otherwise...

agreed on not messing with the settings, if everything is as one would expect from a by the book rebuild, it should run pretty close to perfect out of the box...and definately a hellofalot better then when i pulled it off a few months ago


PS , i don't think Peter is up for another WOT run anytime soon

[svandamme]

ñews from the fronline :

pump is installed, major cursing and swearing during the belt install phase...

key to on
left it to build up some pressure
then cranked

no joy
took about a minute and a half worth of cranking , in short bursts, till it fired, while i made sure i had spark (carbcleaner)

then it went , sounded great, nice steady idle
revved nicely , no popping or hesitation

after about 3 minutes, used the heat gun to switch on the thermostat, rpm went down , but was a bit to soon as it hesitated when i pulled the control rack
'
but LM1 confirmed, AFR of 14 ish

checked for leaks, none, checked the oil , bit low, topped it up

now i'll pull it from it's parking spot , get some fresh air and maybe do a short drive

[Peterfrans]

Great news! Glad you decided on the rebuild route for your pump. Still enough time to dial everything in, fix some details, sort out the thermostat issue and be ready for summer and classic le mans

[beepbeep]

AFR 14:1 @ idle sounds promissing. Please post your AFR findings, (I never fiddled with MFI. It would be nice to see how fresh MFI works AFR-wise.)

[svandamme]

well, didn't do much fiddling yet, had some vibration in the wheels i wanted to take care off, so i took my fronts off, and decided to get all the brake dust off them , and all the lead, and redo it

by that time, rain and gusts, so no more driving

LM1 , before the pump rebuild :




LM1 , after the rebuild , no tuning so it's not perfect yet
shutoff not connected yet, and thermostat operated with heat gun :



there is a clear improvement, and i'm sure it will get better with some effort


next time, i'll go through the procedure , as last time with the throttle bodies, they're now setup from last time, when the pump was way to rich, so the idle isn't strong when warmed up , need handthrottle to keep it running... but i know how it works now

disconnect all linkage, and configure everything like that
then reconnect the linkage, and make sure the linkage does not open the valves when it should be at the stops...
tedious , but it works really well, with the pump working fine, it should be an open and shut case

just been comparing the xy plots in logworks...
the old one was all over the place, no clear concentration of plot points.. but the new one , there's allready a concentration of points in the 13/14 region , for the mid range RPM
i'm confident i'll be able to get that looking more like a fat line of plotting points as i get the throttle bodies setup for the new pump output...

[beepbeep]

Stijn: best way to get consistant AFR vs. RPM plot is to do one long WOT pull on straight road, in 4:th gear. Start with full throttle from 1000 RPM and let it accellerate to 6000 RPM or so while logging.

Scatter-diagram is also good statistical tool but you need to log lot's of data. You seem to have data dropouts on AFR chanell on last diagram, do a smoothing on them.

[svandamme]

yeah i know , but the car had been not driven for 2-3 months
so i was still beeing carefull , checking things over and doublechecking again for fuel leaks and what not

since i had the shaking in my wheels, high speeds in 4th gear were not really a safe thing to do... let's hope the rebalancing of the wheels fixes that, so i don't have to chase suspension/bearing gremlins

[Peterfrans]

Also check if your front wheel bearings are tight