Question for the MFI people out there...

[bbthomson]

Hey Guys,

It has been awhile since I provided an update. (Life has been too busy for me to get to playing with the car.)

I fabricated the heat exchanger restrictor tubes and also cut open a 30mm opening as per the Porsche workshop manual. I also aquired a thermocoupler gauge to measure temperature.

I think I found a significant source of my problems. I let the car run fro 15 minutes or so....I measured the air coming from the thermostat outlet and there was basically very little air coming from it and it was nowhere near being 240 degrees. (~100 degrees)

There was an incredible amount of heat coming from the car and although it was running well, I know that if I was to take it out for a drive that it would get that much hotter and begin the same symptoms of losing power etc...

So - this leads me to believe that I need to connect up my heat so that I can eliminate that as a potential issue and my thermostat is not working properly.

Are my initial conclusions correct?

Thanks,

Brent
_______
70' - 911

[Grady Clay]

Brent,

Remember this is designed to work under operating conditions – 3000 rpm and above. There will be very little heat/flow at idle.

The engine needs to be started and vigorously driven – not let idle to “warm up.” Horsepower makes heat. Heat turns off the thermostat.

Best,
Grady

[Clay Perrine]

Maybe that's why my 914/6 runs so crappy after it is driven for a while.. no flapper valve on the heat exchanger and just "warming it up" in the driveway before adjusting the MFI....


Hmmm.. I am going to have to correct that and see what happens.

[bbthomson]

Hey Guys,

Holy crap...I just got in from the longest drive since I started this project 18 months ago...The car is alive!!! Holy crap it is fast!

For those who have been following...I could not get my car to run properly at all. It would have a hard time starting, it stalled - it would not rev at high revs nor could I ever get it running in 3rd, 4th or 5th gear as there was no way to get to the speed required...

Here is what I have done since my last post. I listened to Grady and I took a step back and started to read, search and re-read posts.

-I decided to re-hook up the heat in my car
-I fixed the hand throttle
-I took apart and cleaned my thermostat thouroughly (It was a mess)

Once I cleaned the thermostat, I thought that I found my problem...

Took it out for a test drive and it was marginally better. I took another step back and was figuring that it had something to do with the fuel system. I did a search and found a great post that many of you participated in regarding the fuel system. (MFI fuel Starvation...out of ideas...help?)
MFI Fuel Starvation...Out of ideas.....help please

When I got my new engine I had the tank reconditioned, the fuel lines replaced and had a new pump installed but with everything that I had read I knew that there was something not right?!

I realised that the mechanic that I brought the car to used the Porsche manual to install the new fuel filter housing. He sent me a picture/diagram of what I needed to get before bringing him the car. Late last night, I was going over the previously mentioned post and remembered the picture my mechanic sent me...He was using the spec from the incorrect (older) manual...I compared the diagram to the one that Grady posted and realised it was wrong...!!! (Line from the fuel pump to the filter and the line from the MFI pump were reversed!)

I went out into the garage and confirmed that it was wrong and within 15 minutes, I made the switch.

Unfortunately, I could not drive the car until now....To my surprise it runs and runs well!!! Scary fast! Remember this is the first time with 3 different power plants where I have been able to drive my car...

Up until this point, every dime I have spent on this car was worth it as I have enjoyed learning, wrenching and basically just enjoyed knowing that some day I will get this figured out and it will be a great car. Wow!...Who would have known that driving this thing was fun too;-)

I am beside myself...Thanks to Grady, John, Warren, Bill & others who posted and helped me out.

Now on to my next set of questions:
1) Even after a half hour of some good driving the car still wants to stall unless I play with the hand throttle and keep the revs up. (~2000 to 3000rpm)
2) When I stopped the car and turned it off, I had allot of dark smoke coming off of the engine. (Could this be just because it is basically new?) It stopped within 3 minutes.

Once again, thanks guys...much appreciated! - this is a great forum comprised of some very solid, good people.

Brent
_______
70' - 911

[Walko]

Brent

The expert knowledge on this board will keep your MFI going and you will become its best friend

Michael

[bkreigsr]

Yes Brent, the MFI engines do fly like no others.
Nice catch on the fuel filter console.
Double check your dwell angle. I used to run 38 deg (+- 3 or 4 deg), otherwise I would have trouble keeping it running at idle.
Bill K

[Grady Clay]

Brent,

Thanks for the post. It is rewarding to hear of success. Congratulations finding the mis-plumbed fuel circuit.

Now for the fun part.

Your next step is to get some easy (not baby) miles on it. Find a set of conditions where the engine runs well and get some several tanks of fuel through it. Keep close track of your fuel and oil consumption. You are going to want to be skilled at removing and reinstalling your sparkplugs to diagnose the running. (Get this down pat so you don’t end up with a new problem.)

You are gong to want several oil changes at the same time. You have a “new” engine that hasn’t been running well and everything needs to get friendly and sealed up.

The rich running has left a lot of debris in the exhaust system. That needs to burn off. The only way that is going to happen is extended highway driving with reasonable (not rich) mixture. How long this takes will depend on how much gunk there is and how hot you can get the exhaust. As this burns off it will give a “rich” look to the tail pipe.

Don’t worry about the idle for now. Use your foot at a stop. Have the hand throttle off when driving.

After shutdown is this oil burning off something? Where is it coming from? If there is an oil leak it needs to be found and fixed. If there is a lot of oil residue in the heat exchangers, you need to be careful there isn’t a fire as you get the exhaust to normal (very high) temperatures. With the heat exchangers open prior, there could be a lot of accumulated oil from a leak.

Will the engine start with the cold start solenoid (on top of the fuel console) disconnected? If so, let’s leave it disconnected and plugged. Regularly check all your fuel connections for leaks. You don’t want a fire.

The next time you have been out driving and stop hot to check your oil level idling, please report how much fumes are coming out the open oil cap.

It would be useful to run a test wire from the overrun solenoid to the cockpit and a test lamp you can see while driving. This will let you evaluate the overrun circuit during these drives. Now is the time.

Is the evaporative emissions hooked up to the back of your air filter assembly? If so, make yourself a 3’ extension hose for diagnosing the mixture. In hot weather the fumes from the fuel tank can upset your mixture measurements. Speaking of fuel tank vent hoses; what condition are yours?

Great that you now have your Personal Reference Manual going. In your quest for information were you able to copy the Factory Workshop Manual Vol. I (p. SF11-SF45) section on MFI? You are also going to want the procedure for checking ignition advance, valve adjusting, checking cam timing, etc.

How is your progress with collecting tools? High on the list are the MFI adjusting tools (some are “of local manufacture”), exhaust gas (CO & HC) measuring, timing light, dwell meter, compression tester, cylinder leak gauge, air flow (Unisyn type), protractors, valve adjust, cam timing dial indicator and fixture, and the list goes on.

I, for one, are proud that you took on responsibility to make your MFI 911 right. Pass along the information.



Now that the 911 is up and driving there is going to be a series of other issues to address. Brake safety is paramount. Brake master cylinders don’t take kindly to sitting for long periods and will take it out on you by failing. Tires, ball joints, tie rod ends, shocks, CV joints & boots, clutch, linkages and many more will need attention. Some will only need an inspection or a daub of grease, others need summary replacement.

You are also going to want to collect some other “improvements.” Soon you will discover oil temperature. Find an excellent set of front oil cooler parts from a ’74-’89 911. Of course there is more – much more. That is part of the fun.

Best,
Grady

[bbthomson]

Hello All,

I had the car out again tonight and went for a good long run. It feels like the engine is getting stronger.

Bill: The dwell angle was set at 38 deg but I will have to check that it is still set properly.

Grady: With respect to fuel/oil consumption. I have been searching for a working set of gauges with no success. I have sent one of my sets of gauges to NH speedo to be refurbished...

At this point, I have a working gas gauge and speedo but the odometer on the speedo does not work...I will try to fix. Unfortunately, I don't know of a way to measure gas consumption other than mapping out a route and unscientifically looking at my gas level gauge.

On my trip this evening, I stopped a couple of times to check the oil. I had to stick my nose into the oil filler tube to get the smell of gas. Can I smell gas?...Yes. Is it strong?...no. That said, my oil level was very high. It read to the max and there was significant oil residue above the Max line. This leads me to believe that there is gas in the oil and that is what is raising the oil level. I have already changed the oil on this engine but I am going to do it again before I take it out so that I can get a more accurate reading. Just out of curiosity, how often should I change the oil?

With respect to the idle...it was still an issue when I was driving and stopping at stop signs. However, when I would stop to check the oil, I was able to slowly bring down the hand throttle and the car would sit an idle without an issue.

Just to clarify, outside of the idle issue...If I am in 3rd gear going 60 miles an hour and I press in the clutch and let the car roll to a slower speed the engine stops running. Basically, if I am asking for power it is giving it to me but if I lay off, it just seems to fall asleep for a lack of a better description.

When I shut off the car this time there was no smoke coming off of the engine. Some oil is dripping from the spine of the case and there is some drops coming from the front of the engine. (By front, I mean where the engine and tranny mate.) I will need to get under the car to see where that oil is coming from. There was no oil on the heat exchangers whatsoever.

My cold start solenoid is manual...I had them install a switch so basically it is only on when I press the button that squirts gas into the stacks. Yes, I seem to need this to start the car.

What will the benefit be of seeing the overun solenoid working during these drives give me?...if it is on would that be an indication that the car is running rich? Where would I find the overun solenoid?

I believe the evaporative emmissions is hooked up...I will have to hook up the hose as you suggest. The fuel tank vent hoses are supposedly new...I will check to make sure.

No - I do not have the factory workshop Manuel Vol.1 (p SF11-SF45) section on MFI....where can I get a copy? I would also like everything refering to the other subjesct you mentioned re: procedures for checking ignition advance, valve adjusting, cam timing, dial indicator and fixture...I realise that much of it can be found on this forum so if you tell me that all I have to do is search, I will do the work to find it. However, if you know where I can get my hands on an actual manual then I will gladly spend the money.

Tools I still need to get: Gas analyser, cylinder leak gauge, protractors, valve adjust, cam timing dial indicater & fixture...

I know that Innovate makes a very good air/gas analyser. I have heard of others that are cheaper. Is it worth biting the bullet and getting the Innovate setup?

Much of the projects you mentioned that are next on the list have already been done. I put on Carrera brakes replaced the master cylinder. To be safe, I have had 2 mechanics go through the suspension and brakes to verify that all is in good shape. All CV joints, tie rod ends, tires were either in good shape or replaced. The clutch is new so no issues there. 2nd gear is a problem but that will have to be taken care of at a later date.

I will am in need of an oil cooler setup. At this point, I don't think I need much oil cooling but I definitely will need something to bring the temps down. I have an RS bumper in front with the space for a front mount cooler. I am just not sure what setup to go with as prices range wildly for new and used can be a bit of a crap shoot. Any guidance anyone can provide in this area would be appreciated.

Once again - thanks for reading and providing great feedback and experience!

Brent
______
70' 911





A few things to report back

[bkreigsr]

Brent, is your microswitch adjusted correctly? The cut-off while rolling in gear sounds like what my car was doing before I fine tuned the switch. Do you have a microswitch?

[Grady Clay]

Brent,

Great progress!


“The dwell angle was set at 38 deg but I will have to check that it is still set properly.”

Good. Always check the timing at 6000 after setting the dwell. Dwell is the electrically measured result of physically setting the points gap.


”With respect to fuel/oil consumption. I have been searching for a working set of gauges with no success. I have sent one of my sets of gauges to NH speedo to be refurbished...

At this point, I have a working gas gauge and speedo but the odometer on the speedo does not work...I will try to fix. Unfortunately, I don't know of a way to measure gas consumption other than mapping out a route and unscientifically looking at my gas level gauge.”

Understand. This is where the entire 911 is a “system.” All the sub-systems need to work – part of the fun challenge here.


”On my trip this evening, I stopped a couple of times to check the oil. I had to stick my nose into the oil filler tube to get the smell of gas. Can I smell gas?...Yes. Is it strong?...no. That said, my oil level was very high. It read to the max and there was significant oil residue above the Max line. This leads me to believe that there is gas in the oil and that is what is raising the oil level. I have already changed the oil on this engine but I am going to do it again before I take it out so that I can get a more accurate reading. Just out of curiosity, how often should I change the oil?”

In the near term, change it often enough to insure having as little gas in the oil as possible. The original spec for the car was 3000 miles. During break-in, most recommend a change at 500 miles and again at 1500. This is to get any break-in debris out of the system.

I assume you have read my posts on the subject of oil dilution. It can have totally devastating effect on a 911 engine. Too many were lost.

Now that you have the 911 running (finally), the tank oil level at idle changes with temperature – hotter = higher. It is common for new 911 owners to overfill the system and have the oil overflow into the air filter assembly and then drip onto the ground just ahead of the engine. (hint)


“With respect to the idle...it was still an issue when I was driving and stopping at stop signs. However, when I would stop to check the oil, I was able to slowly bring down the hand throttle and the car would sit an idle without an issue.

Just to clarify, outside of the idle issue...If I am in 3rd gear going 60 miles an hour and I press in the clutch and let the car roll to a slower speed the engine stops running. Basically, if I am asking for power it is giving it to me but if I lay off, it just seems to fall asleep for a lack of a better description.”

There are a lot of things involved here. Foremost is engine break-in. Others include getting the thermostat off asap, the main mixture close and the overrun system properly functioning. There are also the issues of throttle body condition, linkage adjustment & correlation and idle air balance. You shouldn’t touch the idle until out of the “rich running and diluting the oil” mode. As things settle in and are adjusted it is possible the idle won’t need any adjustment. The good news is it is too low and not too high.


”When I shut off the car this time there was no smoke coming off of the engine.”

Good, you are over that hurdle.


“ Some oil is dripping from the spine of the case and there is some drops coming from the front of the engine. (By front, I mean where the engine and tranny mate.) I will need to get under the car to see where that oil is coming from. There was no oil on the heat exchangers whatsoever.”

Chase them down before they cause a mess or cause a problem.


”My cold start solenoid is manual...I had them install a switch so basically it is only on when I press the button that squirts gas into the stacks. Yes, I seem to need this to start the car.”

Excellent. Needing the cold start is an indication the thermostat cold setting isn’t so rich that the car will start on it. Where are you on the other two issues; clean shut-off of the cold start solenoid and aim of the “nozzles” in the air filter assembly?


”What will the benefit be of seeing the overun solenoid working during these drives give me?...if it is on would that be an indication that the car is running rich? Where would I find the overun solenoid?”

The Overrun Solenoid is located on the MFI pimp governor cover just below and to the left of the thermostat. CMA has a pretty good description of the settings. In short when you close the throttle it activates the Microswitch (left of #1 intake). The RPM Transducer (on relay panel) operates if the engine is above 1500 RPM and applies 12V to the Overrun Solenoid. The solenoid actuation forces the main rack in the MFI pump to the full lean (off) position. Once the engine speed drops below 1200 RPM, the system turns the fuel back on.

The purpose of temporarily wiring a test light is so you can evaluate the RPM vs. throttle position functioning of the overrun system while you are driving.


”I believe the evaporative emmissions is hooked up...I will have to hook up the hose as you suggest. The fuel tank vent hoses are supposedly new...I will check to make sure.”

Good. You will want to reconnect the system but for testing purposes we don’t want any complicating influences. The issue is that the MFI uses the fuel circulation to cool the MFI pump. In hot weather and low fuel quantity there can be significant vapors coming from the fuel tank. This will add fuel to the engine. The best procedure is to get everything finely adjusted with it disconnected and then readjust with the system connected. For your purposes right now, leave it on.


”No - I do not have the factory workshop Manuel Vol.1 (p SF11-SF45) section on MFI....where can I get a copy?”

These pages need good scans and be added to the pdf copy of CMA. My copy from ’69 has too many greasy fingerprints and tattered edges to be suitable.


“I would also like everything refering to the other subjesct you mentioned re: procedures for checking ignition advance, valve adjusting, cam timing, dial indicator and fixture...I realise that much of it can be found on this forum so if you tell me that all I have to do is search, I will do the work to find it. However, if you know where I can get my hands on an actual manual then I will gladly spend the money.”

All of the above. For what you are doing a new Factory Workshop Manual makes sense – GASP. You can find photocopies and used for sale.

It is a real challenge to accumulate the necessary technical info. It is worth listing this again.
Factory Workshop Manual – covers ’65-‘83
CMA (WKD.453.220)
Spec Book ’69-‘71 (WKD.421.020)
Spec Book ’72-’73 (WKD.422.020) since you have a 2.4 engine
Technical Information Model 70, 71, 72, 73 ….
PET pars CD (000.043.400.05)
Bentley 911SC manual
Haynes
Clymer
and more

The best additional resource is the on-line search functions at Pelican and others. Just the process of searching and evaluating the results helps a lot. The real benefit comes assembling your own personal manual.


“Tools I still need to get: Gas analyser, cylinder leak gauge, protractors, valve adjust, cam timing dial indicater & fixture...”

Careful, this can become as serious addition as Porsche. HeHe


”I know that Innovate makes a very good air/gas analyser. I have heard of others that are cheaper. Is it worth biting the bullet and getting the Innovate setup?”

I don’t know.




“Much of the projects you mentioned that are next on the list have already been done. I put on Carrera brakes replaced the master cylinder. To be safe, I have had 2 mechanics go through the suspension and brakes to verify that all is in good shape. All CV joints, tie rod ends, tires were either in good shape or replaced. The clutch is new so no issues there. 2nd gear is a problem but that will have to be taken care of at a later date.

I will am in need of an oil cooler setup. At this point, I don't think I need much oil cooling but I definitely will need something to bring the temps down. I have an RS bumper in front with the space for a front mount cooler. I am just not sure what setup to go with as prices range wildly for new and used can be a bit of a crap shoot. Any guidance anyone can provide in this area would be appreciated.”

Yet another area for a Pelican search and eventually start a thread.

For now it is break-in and MFI sorting. I am still very impressed how well you and the Pelican archives worked to find the fuel plumbing issue. That is a VERY obscure fact.

Best,
Grady

[bbthomson]

Hey Bill,

Is the Microswitch what sits on the top of the throttle linkage on the left side of the engine? If not, where is it?

Thanks,

Brent

[bkreigsr]

that's it. there should be a 8mm adjusting bolt and keeper nut sticking out the top. your description sounds like the switch is activating too early. once your linkages are spec'd out, the switch should barely contact the stop at full close, but with enough pressure to depress the contact.

[bbthomson]

Hey Bill,

Is it possible that the switch is activating too late? Basically if I manually, (from the back of the car) physically press down on the switch, I hear a 'clicking' sound.

While the car was running last night, I was able to get it to idle properly by physically making sure that there was a connection. It is almost as if it is not pressing down hard enough?...which, by your description is the opposite of what is happening?

My instinct, which could be very wrong, would be to adjust this where more pressure would be applied to the Microswitch.

Yes/no?

Regardless, I can play around with it and will document the changes that I have made as I go.

Thanks!!!

Brent

[bkreigsr]

yes, now that I recall, when I got my car back in 79, the adjustment bolt was not making contact with the shut-off. I was getting a lot of backfiring from unspent fuel when I lifted. I had to, like you said 'increase pressure', actually adjust the bolt closer to the contact.
so your engine cut-out when you lift at 60mph is probably not the switch adjustment.

[Early_S_Man]

!

Is it possible that the switch is activating too late? Basically if I manually, (from the back of the car) physically press down on the switch, I hear a 'clicking' sound.

Brent,

Yes! Your inclination is correct!

That Microswitch has 1/8"~1/4" overtravel designed into the spring-loaded plunger. So, feel free to adjust past the point where you hear the internal 'click' ... there is no danger of binding up the switch mechanism, as long as you don't overdo the preload!

[bbthomson]

Thanks Bill, Warren & Grady,

I adjusted the Microswitch and it appears and it is now connecting as described.

I changed the oil and it was incredibly dirty...surprising for a car that basically had probably just over a couple of hours use.

With fresh oil, I went for another good spin. The engine is acting the same: runs well, pulls hard but stalls if I don't keep it above ~2500 rpm.

Also - less oil leaked from the engine upon my return. Basically 2 oils spots on the floor, each the size of a Silver Dollar.

I will do as Grady suggests. Run it through a few tanks of Gas and monitor my oil.

If any of you have an idea as to why the car does not run unless under load let me know. At this point, I will just be doing research as I need to get some miles on the car.

Thanks!

Brent
______
70'-911

[bbthomson]

Hey Guys,

Here is an update on my car...things are not that good at the moment...?

I have been doing as you said. Trying to put some miles on the car. Of late, there has been increasing oil leaking from somewhere, I presume at the top of the engine. Basically it has been dripping onto the HE's and creating some blue smoke. (Minimal) I have been checking my oil regularly and it appeared low but still in the range. I cleaned up my engine top & bottom to try and help determine where the leak(s) are coming from.

Tonight, I went for a ride and noticed that there was an increasing amount of blue smoke behind me as I drove. The harder I stepped on the gas, the more blue smoke would appear...I was looking ahead to see where I could pull off safely and as I looked back noticed white smoke coming from the rear of the car? The oil level according to my oil gauge was somehere below half so I knew that there was at least some oil in the oil tank. I pulled over immediately and shut the car off. Plenty of blue smoke but I do not recall seeing the white smoke when I lifted the decklid. There was oil basically dripping at a rapid rate from the left HE and from the bottom front of the engine. Not good. I could also see that oil had sprayed inside the engine bay on the drivers side of the engine only.

I wanted to check my oil level so I went to start the engine. It would not start. I had battery power but the starter did not even try to turn over...no clicking...nothing...dead.

Once I moved the car - there was an oil spot that was about 6" by 18" long and it ran from the center of the car all the way inderneath the drivers side HE. It was not a pool but it probably would have been if I wasn't on broken pavement.

I checked the oil, albeit the car was stopped and not perfectly level, there appeared to still be oil in the oil tank.

So, at this point I have two distinct problems and I am hoping that they are not catastrophic...

...Help!

As always - thank you for your input in advance...it is appreciated!!

Brent

[Grady Clay]

Brent,

Well … sorry to hear that.

Clearly there is an oil leak. Based on your description the first place to look is for a rocker arm shaft loose and moving out of place. This can cause this kind of leak. Don’t drive it until you asses this possibility.

If a rocker shaft has moved, you should look at the shaft for damage and inspect the bore in the cam housing. It is also possible to have damaged a rocker arm. If OK, simply reinstall the shaft and tighten to spec. Check the valve clearance. To get the shaft in and out you need to have that valve with clearance. Some rocker shaft positions are not easily possible with the engine installed. In that case, inspect it in situ.

If it turns out to be a rocker shaft, you should torque the other 11. This would be a good opportunity to torque the heads also. Set your wrench slightly below spec (70%) first. If one moves at that – stop.

I would complete the oil leak issue and clean-up before you assume there is another problem. You may want to take the heat exchanger off for a through cleaning – there can be a lake of oil in the bottom.

Hope it is simple.

Best,
Grady

[bkreigsr]

just a long shot, but make sure that your adjustment screws on the mfi pump are fully seated against the outer case of the pump. they are spring loaded and occasionally hang up, partially seated, allowing oil to escape from the pump. (in mass quantities -especially on acceleration)
(ask me how I know)
Bill K

[Early_S_Man]

Brent,

There are only a few potential sources of oil on the left side of the engine:

Crankcase:

1. Oil return tubes ... fairly easy to identify or rule out!

2. Oval breather cover ... often warped.

3. Oil Pressure line from under oil pressure sender to MFI pump. Old lines often leak at the swaged/crimped rings.

4. Return overflow line [12 mm ID] from injection pump to breather cover. Old hoses tend to get 'smashed out' and ooze oil at both ends under the hose clamps.

5. MFI pump covers' rubber gaskets, all three of them, can leak and cause a terrible mess!

Cam towers/heads:

1. Forward cam tower plug ... complement to banjo bolt at oil supply line on rear of cam tower.

2. Banjo bolt -- either sealing ring missing can cause aleak!

3. Head to cam tower joints ... sealant flaw or gap.

4. Rocker arm ... six sources.

Good luck!