mfi pump- which one do I have? How to adjust?
 

Hi
I have just got my 2.7RS spec engine running after a long engine building process. The engine is fitted with an mfi pump which was on and engine with a green shroud I thought it was a 2.4E The pump was rebuilt in America about 14 years ago and then put into storage.

The car idles great and accelerates well except through second gear.

I know it is most likely the wrong pump for a 2.7RS spec engine but, is there any thing which can be done to improve the problem of starvation at low speeds. The car absolutely rips above 3000RPM but doesn't like driving in second gear when cornering at slow speeds. splutters a bit. very embarrassing.

I'm at the stage of ditching the whole system and looking for carburettors. It would be a real pity because every thing inside the motor including all the injectors are new.

Pump number is 42123579, type number is 0408 126 019

i'll go out and see if I can get some more info off the pump.

Any help would be good.

thanks

Terry

hi can't see any more numbers through the mfi stacks but the distributor number is JFUD-6 0231 184 004

Is this the right distributor for RS cams? and pump?

Thanks

terry

You have a 019 pump which is the correct pump for a 2.7 RS. There is a lot of information on this board on MFI. This link should get you started:

http://forums.pelicanparts.com/porsche-911-technical-forum/269190-ultimate-mfi-resources-thread.html

Read become familiar with and use CMA as it is written to set up your MFI. If you have access to AFR meter you can use that to help. On my car after we had it running well we used a high temp gun to check each exhaust primary, and found a variation on one one bank. Ed Mayo was then able to adjust the individual pistons on the pump to get that bank balanced. The car has run great since, that has been over 3 years ago when I switched to a sport muffler. Once you get MFI set it will be very reliable. Changes seem to come with component wear over time or if you are starting with worn linkage or throttle bodies.

Good luck getting it tuned and hope you are enjoying it soon.

How are you able to adjust pistons in the pump?

I have not done it personally but did watch Ed do it. You have to take off the side cover and the pistons are exposed. You can then turn them which will adjust them up or down and change the volume. This will either richen or lean that cylinder. I think this would be a final, very fine tune after everything is set and working well. We did not have EGT for each port so we used a Temp gun at the port to spot a variance port to port. This was not done by using an absolute temp target. It was done to balance a bank.

Terry - Don't ditch the MFI - it is superior to carbs (power, throttle response, cold-starting, automatic altitude compensation) for a 2.7RS motor when working properly, imo. Since it seems you have the correct pump (and presumably space cam), it is certainly well worth the effort to tune it properly. Use the resources on this board (the adjustments are quite easily made, if the pump is in good general repair).

Good luck!

Tezza,

As Grant said, try and stick it out! I felt the same way about MFI because I didn't fully understand how it worked... only that it was awesome. However, I debated between MFI and EFI. Carbs have their own headaches too, while initially simpler to deal with, fine tuning for power across the rpm range and longevity they are no match against MFI.

As boba said, start reading the CMA front to back, several times. THEN start asking questions on
the board, save posts and links to posts you find valuable... Your in a great spot mate, there are very knowledgeable guys on this board who are extremely generous and helpful with that knowledge.

I'm getting close to having my pump dialed in, and I gotta say its an awesome and very gratifying feeling. throttle response, sound, dude, mfi is soooo worth it!

Heres my thread, sound familiar? http://forums.pelicanparts.com/911-engine-rebuilding-forum/499548-how-long-did-take-you-dial-2-8-mfi.html

Cheers, d

Mfi
 

OK
so I was up half the night reading mfi posts and it seems pretty logical to me but as my pump was rebuilt in the USA I don't want to mess with it too much. I will start by measuring all the linkages.

the throttle bodies were also reconditioned but i didn't buy new linkages. best I can do is to try and check every thing.

If my cams are right and the pump is right can the dizzy be wrong?

I bought the motor in 1996 in Belgium from some crazy Flemish guys who operated out of a barn. I went there because these guys could get new old stock Porsche parts. Initially I wanted stock mahle E pistons and a engine rebuild kit for the original 2.2 which is in the car.
I left with a newly rebuild 2.4 ( I thought) in 2.7 RS spec. The guys wife was diagnosed with cancer right in the middle of the rebuild and I was due to leave the country so I just wrapped up the motor and left.

Got back to Australia, put the motor in the car and it leaked oil. Took it out again and sent it to my Ozzy mechanic ( now retired). Pump and throttle bodies went to the USA for overhaul.

Alls back together now only had one minor problem with a leak in the oil cooler.

So being in Australia and far away from any one who knows much about mfi it is going to be a long haul in getting this right.

Option 1 drive the car 1000 miles to Melbourne to the only Porsche dealer who apparently can work on the mfi.
option 2 let the Bosch injection guy give it a go, he's old so i know he has some knowledge, Told me he would have to read up a bit as its been a while since he has had to look at one.
Option 3 Puddle through it.

Funny thing is I have mfi on my old 2.2E and it has always fired up and run perfectly with out any fiddling. pitty about the worn rings.
Anyway thanks for the encouragement, looks like the mfi will stay. Got some work to do.

thanks

Terry

Afr gauge
 

I would highly recommend a good AFR instrument. That is what really helped me sort out my 2.7 MFI. Our host sells the Daytona Sensors Wego IV and the Innovate. I have the Daytona sensors and love it. I am now involved in the distribution of the Wevo IV now so I may be a little biased, but check it out. Logs 2 hours of AFR and RPM data.

You can get a chart to convert CO to AFR as well.

Good luck. Good running MFI is worth the bother.

+1,000,000 on that! I've been borrowing my friends Innovative... the pure definition of an educated adjustment to the MFI.

feelin dizzy
 

Hi
I'll look into it.
Can any one tell me if im using the correct distributor before i mess with the mfi?

Terrance,
You might want to contact Mark Yung (356RS) regarding your MFI questions. He, in my opinion, is an expert.

Regards,

al

I think just about any reasonable advance curve will work with MFI. I ran a couple of different spec distributors on my 2.4 T motor, from its stock unit, to an S unit, and finally a Barry Hershon recurved unit that had full mechanical advance come in at 2,000 rpm. I initially ran my 3.0 (when it was still single plug) on a similar Barry Hershon worked distributor, with full advance coming in at 2,000 as well. Now that it is twin plugged, I run it with an Electromotive unit set up with a very simple curve - 12 degrees initial and 25 total, which comes in at 3,000 rpm.

That's kind of a long way of saying I don't think your distributor can be "wrong enough" to cause the problems you describe. I would begin by going through CMA in its entirety. Don't skip anything, no matter how inconsequential it may appear. Be exacting and precise.

Once you are through that, do what these guys suggest - get a quality A/F meter and use it. I have an old LM1 that I swear I could no longer live without. The information it provides is absolutely invaluable in tuning one of these systems.

And, above all, keep the faith - once sorted, there is nothing more fun to drive. The throttle response offered by this system is still unmatched by anything else.

Terry,

I think the dist # you listed may be a Bosch #, the Porsche # is 911 602 031 06.

231 184 004 is the Bosch # as found on this Bosch document, second item down.



http://www.automotive-tradition.de/download/ausruestungslisten/mf1644.pdf

Terry, Your getting great information hear. Also reading the Ultimate MFI Threads put together by David Clark is a wealth of information. BTY you have a very good source of MFI information in Australia. Look up John "jcge" on this board.
Jeff Higgins and others have mentioned getting a quality A/F meter, and I must agree.
This would be the best way to find out what is really going on during your possible fuel starvation when corning.
Keep the MFI.

mfi starvation blues
 

Hi
I have read a whole bunch of the posts now and have a better understanding of how the mfi pump works.

I also took the car out today for another drive. It purrs along in mid range and top end with out any apparent issues. Acceleration is quite awsome but with a 110 km speed limit its not ideal testing. It's been so long since I drove the damnd thing that I inadvertantly put it in a gear too high for the speed I'm travelling. That is just my stupidity. long legs in the 5 speed 901 box.
I checked all the linkages, they appear tight with little play. The micro switch to the shut off solenoid appears to be working. When coasting down hill fuel doesn't seem to be dumped into the motor, no back fire and only a little rummbling and minor popping when really slowing down for corners.

I can't tell if the cold start thermostate works correctly or not. Can it be shutting off too much?

The cold start thermostate came off the old 2.2 motor. I don't know how many disks there should be in there for the 2.7


I'm not going to touch anything at all untill I can get some info on the correct measurements for all the external components.

I need to write a dot point list of procedures and work out all the measurements for all the external components. I have found one shop that preps GT3's the guy said he has some experience with mfi. He's 250 miles from my house so its getting better.

The car will idle smoothly at about 600rpm with the throttle handle off. Is that about right?
Can I disconnect the shut off solenoid ? Is that a valid test to see if it could be the cause of the starvation?---Or will i get the massive fuel dump and back fire? Can that cause a fire? I thought this might be the issue?

Test equipment is on the cards --if i can sneek it past the wife--I'll be in the dog house soon.

Thanks for all the advice I am not as freaked out as last week when all I could see was a huge bill looming.

cheers

Terry

MFI should idle around 850; Measure the linkage that connects from the main rack down to the pump as it should be 114mm.
What kind of plugs are you running and what do they look like, is the car in good tune-new points adjusted properly, new cap and rotor, plug wires, valves adjusted, etc.. Does it have the heater hoses connected from the HE to the pump? Make sure the car in in perfect tune before you start futzing with the mfi-pump wise.

Every thing new, built by a Porsche trained technician, had the new motor in storage for three years prior to fitting. The mechanic has since retired. The motor started first go after priming with fuel and oil. Every thing was set in the shop but the guy who built the engine has never seen it running as he move away after retiring.
the fact that it runs almost perfectly is a testament to how well he put it together on the stand.

I'll measure the rod in the morning .

thanks

Terry

Terry,

You are getting a lot of great advice here. I know what you are up against, I have been down the same path. I have had my 2.7 1973 RS clone for 11 years and put over 100,000 miles on it. Did not do too much with the MFI in the beginning. I was afraid to mess with it. My mechanic had it running pretty well, so I did not touch it. With the help of this forum and the CMA I started to get more familiar and more confident in tuning.

Again the AFR was a real breakthrough. CMA refers to CO measurements and the use of an early, now very crude instrument and road testing. We are very lucky that we now have the wideband AFR sensors from Bosch and others that give us such great data. I am biased, but my research showed me that the Daytona Sensors Wego IV is the best value for the money. Retails for $440.00 USD from our site sponsor. Best thing is on a Porsche, the RPM portion is an easy one wire hookup. Also data logging is a must. You can log 2 hours of running data. I can't emphasize enough how valuable it is to be able to sit at your computer and analyze what happened on the run. It is just like a dyno run.

Here is a chart of a recent run of mine. This is a one minute slice.

http://forums.pelicanparts.com/uploa...1274539490.jpg

This charting gives you the ability to see what happens as the engine warms up and runs under varying conditions. I know other AFR instruments will do charting, but I don't know of a package in the $400 range that includes data logging, software, Bosch wideband sensor, wiring, and extreme accuracy for this price.

You can also download all data on a spread sheet and read it that way.

Good luck with your MFI journey. There is lots of satisfaction when it all works well, and you know that you did it.

Looking at your post had me looking at the MFI posts again, and I decided to recheck the linkage to the MFI pump. Not sure who the last one to check it was, but not me. It is supposed to be 114mm center to center. I removed the linkage and checked it several times and it was 111.7 which is of course a bit too small. I adjusted it to the 114 spec and retested the car on a 15 mile drive.

Idle is now spot on at 869 rather than too high, and the MFI stays nice and rich through the acceleration range, where is was a bit on the lean side before. Makes sense. The pump is more rich because of the longer rod.

I will tweek the idle mixture later.

Hi can any one tell me the exact lenth the rod protrudes from the thermostat in a 2.7RS spec at running temp?

Oh, and how may bimetal washers and in what order?

thanks

Terry

Hi dicklague

I measured all the linkages, the one from the pump is about 13mm at 14 it doesn't want to run very well. I took the old linkages off the 2.2 from the throttle bar to the bodies and put them on the 2.7. the car runs 100% better but idle has dropped to about 200 rpm, if that.
It will stall without the hand throttle.

good news is it is drivable at low speed , bad news is I don't have the tester to measure and balance each throat of the stack.

tail pipes also gone fron beige /camel brown to sooty black--bad news I guess.

Fix one thing and a host of others opens up.

Test equipment would be good but if i don't know what I'm doing with it I'll just go round in circles.
Time to take the car to the local Bosch injection guy. He's old school but hasn't worked on mfi for a long time. A few weeks ago he suggested I just drive it a while let the new motor settle in and then check and measure and adjust as needed. At least he's got the right approach.

I filled up with the third tank of gas today but didn't add any octane boost--maybe thats also why I 'm getting darker deposits.
If the linkage from the mfi pump is supposed to be 14mm what are the other two lengths supposed to be?

Cheers and thanks for the help.
Terry

Terry, I would like to help you out on some of your questions but I,m out of town right now and some of the specifications you requested need to be more accurate than my memory can provide. I have the data on the thermostat rod length for the 019 pump back at the shop but I can tell you there are 25 bimetal disc pairs in the thermostat. More important is the number and size of the solid discs on the end of the rod. These other discs set up the amount of fuel needed for a cold start on the 019 pump for the 2.7 RS engine which is a little different than the other pumps.
The rod length of 114mm connected to the pump throttle lever is very important because it sets up the proper throttle angle relationship between the pump and throttle bodies. Of course the linkage on the throttle bodies has to be set up correctly before this can all work correctly.
I'm sure there are many on the board today that can answer your questions. Lots of great help on this board.

Thanks 356RS

I will plod along, I'll ring the Porsche dealer see if I can get the parts guy to give me the right number of discs fot the thermostat.

the fuel shut off solenoid might be Ok as that was on the pump when it went for a rebuild, I would have expected them to set the rod lenth if it needed it.

Cheers

Terry

MFI fine tuning
 

been plodding along

raised the idle to around 850-900. The screws were all over the place some went two turns to match the others. The car absolutely powers. I used a flow meter to try and match the stacks. got the right set ( thats facing the engine from the back) all pretty balance but the air srrews have almost no effect on the left side. They are all pretty even but don't match the right side at all.

Turn the screws in and it falters, turn them out and not apparent effect. They would bave fallen out if I kept going.

Still a little popping and the odd gurgle.

The left side you can hear an obvious ff-t ff-t ff-t sound. Injectors are all new , tank new, lines cleaned and new filter.

I want to get the left running like the right side as it's smooth not faltering.

Still looks a bit rich at the pipe.

Time to go to the shop I think. hook up to the test equipment.

Any more ideas would be good.

Thanks

Terry, Glad to see you have a flow meter and you have the right side set. How much of a difference in flow meter readings is there between the left and right? When you are checking the flows do you have the linkage arms, left & right, removed from the main crossbar throttle arm?

Hi 356RS
Flow meter is a bit primitive, borrowed it from a young guy with a bastardized 912come 911 around the corner. The meter only has three divisions.
I have ordered a new one.

First
Three stacks on the right are spot on in the middle of the gauge, at level 2. The indicator jumps around a bit but you can clearly see they are all even.
Other three are barely at level 1.

Second
No--didn't disconnect the linkages, should I? Ill try that this morning.

I guess, what you are going to say is, set it when the throttle bodies are in a relaxed state and then re adjust the linkage on the bad side to match the good. I'll try that too.

I pulled four of the plugs yesterday front cylinder right side was camel brown colour looked textbook excellent the next four were black sooty. I didn't pull the last two as it was getting dark but they are on the bad side so I suspect they are a bit fouled as well. Think I also need another bottle of octane booster.

Also pulled apart the thermostat. 25 bi metal disks, two thick and one thin spacer. All works perfectly. Came from a 2.2E but compares with the 2.4 specs when you heat it up rod shortens to 17 mm, It appears to work properly.

Attached are two photos. The one good plug and the motor as its set up.

Whilst running it without the filter it also seemed to run better. i do have some K&N filters but for some reason the filter element has never sat properly in the groove, also the element fowls the barometric regulator plus does not have the cold start fuel circuit. Might drag them out today and look at them.

http://forums.pelicanparts.com/uploa...1275174849.jpg
http://forums.pelicanparts.com/uploa...1275174943.jpg

Your on the right track Terry. Let us know the outcome with the linkage removed. Reading plugs from an engine that has been at idle will not give you an accurate reading but I guess at least they should be all the same color. Mine are close to black with the MFI I run.

Air flow all pulls pretty even
 

Hi 356RS
back again.
Well after a few hours in the shed tinkering I have now managed to get all the air flows at about the same level.
I disconnected the linkages to the throttle bodies and let the engine idle on its own. as soon as you tried to in crease the idle on the left bank it stalled, that was odd because it was the side which appears to be spluttering. I was trying to just open the butterflies a bit---didn't work.

I wound all the air screws in. some went more than eight full turns others only four. it was obvious they had no effect at all on the enginee. I then wound them out about four full turns each, thought that was about right as i had read it in a post.

I tried to re attach the linkages but idle went up to 1500. disconnected and lengthened the rods. then took it for a drive and experienced the lag at 2500-3000 2nd gear.

Turned the linkage end one full turn each and reconnected again the car is drivable again with a small hesitation. I'm not sure if this is due to the fuel shut off solenoid, i did have to readjust the micro switch stop because is wanted to back fire a bit on deceleration.

It is such a fine line between a total cock up and absolute power that is in quite unbelievable. i can see why many people get the sh-ts with it. luck i never give up.

Tail pipe is back to camel brown now, hope it's not too lean, I'll see how rich the exhaust looks on start up this morning.

Might have to wind in one linkage end one full turn again. also think another set of throttle bodies and brand new linkages are on the cards. There does seem to be about 2mm play across the tree butterflies
all in all I'm very happy

Big Thanks

Terry

Does my one light coloured plug look too lean?

No, but idling is not the way to read plugs. Put new ones in, go for a spirited drive and shut off after accelerating hard for a second or two, coast to a stop, and pull plugs.

White would be too lean. Light Brown is just right. Darker brown than yours would be rich. Black is probably oil.

Hi
mondat here and about to go to work.

You can go from brown to black on the plugs with just a few mm of adjustment in the linkages from throttle bar to the butterflies. Unless you motor is really worn the black is just really rich isn't it?

My motor is new so can't be the oil when black or iIwoouldn't be able to obtain light brown with the minor adjustments.
does that sound right?

Next week end for more adjustments--must order the Co meter to really know whats going on.

cheers

Terry