MFI, points question
 

I have a 2.5 with MFI and points. Yesterday the car wouldn't start. This is after being more difficult to start since the colder weather has come. Now, everything on the engine is new and I have total confidence in it.
What I am curious about is:

can a coil fail out of nowhere?

is there a breakerless ignition set up I can buy for this engine?

can you fuel foul plugs with MFI?

I have changed the CD unit. I pulled a plug and found it to be wet so I am confident that I have fuel delivery. I let the car sit overnight and it wouldn't start this morning either. A low battery from lots of cranking maybe contributing to that also.

The cold start fuel line from the top of the fuel filter assembly to the MFI stacks is not hooked up. I plan to do so this weekend.

Any advice you guys have would be greatly appreciated. I will only have this engine for 6 months but while I do I want to understand such things to make sure it's a reliable one for me.

Thanks ahead

James, have you checked to see if there is spark? You can pull a plug wire and use an old plug grounded to the block. Watch out for fuel fumes.

If you have no spark you need to verify that the points are working. Pull the 3 pin connector at the CD unit and use a MM set to Resistance between the trigger wire and ground. rotate the engine by hand. Teh resistance should be infinite when the points are open and zero when they are closed. if this works you could have a bad coil or CD unit.

If you get always open or always closed your points are bad. I have used the Crane optical points conversion. It drops right into a Bosch dist and only has three wires to hook up. never worry about points again.

Make sure you clean ALL connections on the ignition system.

thanks Jamie. I will check after work to see if I have spark. I can't imagine the coil failing when it worked an hour before? I also changed the CD box to a known to be good unit. I inspected the points and they seem to be in good condition. I need to validate this also by turning the engine over manually and seeing if they open and close. It sux because I need a car to get the things I need to fix the car... :-D
I will change the coil to eliminate that issue. I also need to set the cold start thing up. The car has been getting harder to start over the last month. I attributed that to the slightly colder weather but what else could contribute to that?

If your plugs are wet, wait on hooking up the cold start fuel line. I hope that sucker is plugged off good. To be sure it doesn't work, remove the center fuse on the rear 3-fuse panel.

I remove the fuse on hot days if I'm going to restart and the motor is still hot. I plan on putting switch in the circuit if I don't hook the whole thing up to an activating button in the cab.

I'm with the spark thing. Weak or no spark is not good. Get that dialed in before tinkering wiht the MFI. If it ran before, then the MFI is not maybe a prime suspect. MFI doesn't change on it's own too frequently. It's more of a gradual process.

so you checked the points gap and it's ok ?

I have not checked the GAP will do tonight, I did have the cap off yesterday and the points "looked good" as in they were not burnt and they seemed new (everything else on the engine is new or rebuilt to my knowledge) .

Zeke, are you saying that I should not use the cold start thing? I have not to thus far.. but she has been getting harder to start when cold..??

James.... the others who have posted here are much more learned in this than I, so take this as only one person's experience... as someone who lives in a northern (cold) climate, a functioning cold start system has made a considerable difference in starting my car. My engine may very well have been out of tune at the time, but once I hooked up the system I went from many many cranks to just one.

Again, follow the others first… and I certainly don’t want to be responsible for setting your car in flames!

Good luck.

I live in FL and use the cold start. Do you have an inductive timing light? If so, you can check for spark without removing or disconnecting anything.

James,

If you follow this advice and blow up your engine don't come crying to me.

Connect everything up normally. Charge the battery OVERNIGHT.

Go to any gas station and buy a can of dimethyl ether starting fluid.

Squirt a SMALL squirt on the outside of your air filter. A SMALL squirt, like half a second on the nozzle. If you squirt too much, you will blow up the engine, cause voter fraud and lose the world series.

With a fire extinguisher handy, crank the engine over.

I disconnected the cold-start squirter on my '71 and the car WILL NOT start on its own when cold without the ether trick.

Good luck! Semper Fi.

James,

To answer your questions:
Yes, a coil can fail out of nowhere but is fairly unusual. Is there any sign if failure (oozing at the low voltage terminals?)

Yes, there are lots of ignition systems available. That is not where to go now.

Yes, you can fowl sparkplugs with MFI. I think the first MFI 911 built by Porsche probably fowled its plugs. Every MFI owner should have several sets of good clean plugs for diagnostic purposes.


On to fixing the problem:

Cold start problems are not easily diagnosed in downtown LA unless you have an environmental chamber. LA is not the same as Evansville/Louisville.
First, trickle charge the battery so cranking isn’t an issue.
All you need to do is verify that you have spark as BK911 suggests.
Install some new/clean sparkplugs.
Yes, reconnect the cold start system. Be aware of its potential problems (like not turning off or leaking.)
You will probably also need to check the thermostat operation.
With a fire extinguisher handy, you can probably start the car with starting fluid.
Once running, you know you just have a cold-start problem. Easy to fix.

The “art” of MFI is to have everything work properly without drowning the engine with fuel. Things work great with too much fuel but there are bad consequences. The most serious is diluting the oil with gasoline.

Here is my library of MFI info. I suggest you keep copies and study it.

Check Measure Adjust (CMA)
http://www.scatliff.mb.ca/pelican/MFI_Check_Measure_Adjust.pdf

“MFI Size Chart”
http://forums.pelicanparts.com/porsche-911-technical-forum/117171-mfi-induction-chart.html

“MFI thermostat spacers”
p. 1 end has CMA extension, p. 3 has nozzle, fuel flow, and fuel pressure.
http://forums.pelicanparts.com/porsche-911-technical-forum/169445-mfi-thermostat-spacers.html

“More Fun with MFI and LM1”
How to use protractors for correlation.
http://forums.pelicanparts.com/porsche-911-technical-forum/179707-more-fun-mfi-lm-1-a.html

“MFI Problems”
http://forums.pelicanparts.com/porsche-911-technical-forum/173700-mfi-problems.html

MFI tools
http://forums.pelicanparts.com/porsche-911-technical-forum/170242-mfi-tools-diyer.html

“Mechanical Fuel Injection” site with OK stuff:
http://www.my930.com/MFI/TipMFI.htm


Early_S_Man posted this” Here are several threads on the subject ...

Changes in Pelican's server have invalidated several links ... I suppose I need to go back and chart all of them, then edit and revise the links ...
Several people posted multiple threads on one problem, and that unecessarily complicated keeping track of the various threads!
http://forums.pelicanparts.com/show...ght=mfi+warning
http://forums.pelicanparts.com/show...fi+speed+switch
http://forums.pelicanparts.com/show...=rpm+transducer
http://forums.pelicanparts.com/show...&threadid=78685
http://forums.pelicanparts.com/show...mfi+speed+relay
http://forums.pelicanparts.com/show...tch+replacement
Good luck! Warren Hall
Pelican Tech article:
http://www.pelicanparts.com/techarticles/911_MFI/TipMFI.htm


Good thread on fuel pump, filter, tank on Early S Forum
http://d240157.u39.zeonhost.com/forum/showthread.php?t=4147&page=1&pp=15

List of MFI rebuilders/experts:
http://www.early911sregistry.org/Resource-MFI.html

“Any good MFI people out there” on EarlyS
Hot starting issues.
http://early911sregistry.org/forum/showthread.php?t=4355

I’m sure there are more.


Best,
Grady

James, I'm still fairly new to MFI myself. The folks on this board have been a great help in getting me squared away with mine. One thing I have noticed, and you will see some of the MFI gurus here alluding to, is that they do tend to run rich. As a result, they can foul plugs. There are a number of threads dealing with the correct plug to run in the older MFI cars; just search on "MFI spark plugs" or something like that. The consensus seems to be to run a bit hotter plug to help combat the fouling and to deal with today's gas. It made a difference in my car. I wish I had the number of the plug handy, but I'm at work so I can't check right now. Anyway, you didn't mention the color of your wet spark plug. If it was all black and sooty, in addition to being wet, you will probably never get the car started until you clean or replace them. Once in that condition, they can take days in a cold engine to dry, and even then the spark can be kind of weak. If everything else seems o.k., maybe take a look at that.

thanks fellas. I have the car on the charger. I think that I don't have a spark. The coil and points look ok. I don't have an extra set of plugs and doubt anyone local would have the ones I need. I sprayed carb cleaner in the aircleaner opening and with the charger connected and car turning over as normal she didn't start. I will verify in the am but I suspect I dont have a spark. Either that or the fuel pump failed? Is the fuel pump fused? I checked all fuses and they look fine. I sure do miss my 3.2! and can't wait for my 3.6! 5 months and counting!
Thanks guys and keep the advice coming!

Semper Fi!

(John you gotta earn the stripes to invoke that one!)

Thanks Jeff. Please post that plug when you can so I can order a set ASAP.

What I am saying is that if the hose does not go where it's supposed to go, take out the fuse.

When you get ready to hook the thing back up, make sure the hoses are in good condition and CLEAN. All stacks need to get the same amount of gas.

You can't call Tyson about this?

Here's one thread.

I have called him but he does this all day and heck if I can query you fine people for some ideas, all the better!

UPDATE

It is raining here and I dont have a garage yet so I can't do much until it clears. I was not able to yet get the correct "hot" plug info so if someone has it that would be a big help.

James,

Any local auto parts store should have an appropriate sparkplugs. You should query Tyson for the exact preferred plug. I would use NGK BP7ES for trouble shooting and in winter weather and BP8ES for summer and highway use. These are very common plugs.

Carb cleaner works ok for cleaning plugs. After cleaning, an hour in the oven at 300F helps.

Best,
Grady

thanks Grady, I will run out and get those now.

ok, got the plugs, thanks again Grady. Its getting dark now so I will check for spark and switch the plugs in the am. Would a fuel pump fail that suddenly?

pertronix
 

hi:
i do not have mfi but i had problems about 2 years ago...my points were ok but the black wire on the points was rubbing on the distributor cam and shorting out (just occassionally and especially when wet). After i found this out,,,took longer than it should have, i installed a pertonix breakerless point setup that i bought from pelican and it works great....some have had problems but i have not had any...

gary

thanks. I want to get one of those but I dont know what specific type of distributer I have. Is there an easy way to ID it?

BTW what should I gap the new plugs at?

Grady is the man on the MFI stuff. Milt is real good also. Both of them have helped me a lot troubleshooting my MFI

Im using the BPR8ES or BP8ES plugs in my car now and they have been great. Ive used the 6ES plugs before and wound up with detonation issues in the summer heat down here so I think they are a little too hot. I think the gap is around ~3mm, but I just make sure they are all consistent out of the box.

FWIW, ditching the points on my car and going to a Crane optical trigger was one of the better upgrades Ive done so far.

sherman, what was the specific crane part number? did you ditch the CD box with that upgrade?

http://forums.pelicanparts.com/uploa...1088540694.jpg

I bought the two bottom parts and kept the Bosch 3 pin CD box.

Dumb simple install

Black wire -> ground
White wire -> black/purple wire that used to connect to the points
Red wire -> switched 12V from the bottom fuse on the fuse panel

thanks Shuie, I really appreciate it.

OK. This morning, the sun is out and so I went out to the car. I pulled the black wire at the side of the distributer, attached a jumper wire, pulled the center plug wire from the rotor and placed it near where it could go to ground. I then turned the key into the start position and put the jumper to ground. NO SPARK!

So, what should I do fellas?

Is your CD box smoked? Does it whine with the ignition on? Ive got a good spare 3 pin Bosch box if you need one.

James,

To test the CDI unit and coil for good spark ...

1. Use a new spark plug with the body of the spark plug either laying on a good ground location or securely attached to a grounded clip ... attached to a known good spark plug lead inserted directly into the coil output terminal.

2. With the ignition switch on and CDI whining/whistling ... take the black wire from the side of the distributor and use it like a telegraph key ... repeatedly making and breaking contact with any nearby clean, bare ground locaction. You should see and hear a spark at the test spark plug each time the distributor lead is ungrounded.

For more information about the theory of operation of the CDI unit and how to test it ... see the Bosch test document posted in the following thread. It takes a long time to load all of the graphics, and hit the refresh button if any 'empty square' markers show up ... all of the links are good, but just slow loading at times, and Internet Explorer will sometimes time out before all are loaded!

http://forums.pelicanparts.com/showthread.php?s=&threadid=160537&highlight=bosch+ permatune

thanks Warren and Sherman. The CD box is working. It makes that humming noise. I don't have a spark. I did the test and no spark. I pulled the rotor and cap and bumped the car over by turning the engine over. I can't see that the points ever make a gap between that little block and the cam in the distributer. I wanna be sure that its not my eyes lying to me so I am going to find a match or piece of paper to make sure but at this point I think the points are not opening.

I have proper point gap. still no spark... I am at a loss here fellas. Any advice out there? I really need my wheels back.

thanks Shuie, it seems to be working and Tyson sent me on my way from LA with a spare. I guess it has to be the coil. But its brand new??

ARe you sure there is no break in the blak wire to the CD? have you tried cleaning the 3pin connector at the CD unit?

I dont think there is a break. I checked all connections and tighten/cleaned as appropriate. There doesnt seem to be any power to the coil (I know this is different than a normal system) SHould the green wire on the positive side of the coil be "hot"? I checked the ground behind the fuel filter, checked the wire from the CD unit to the coil for connectivity. I have used two different CD units to make sure that is not the issue. When I turn the car over it just cranks and cranks. I have checked and the fuel pump is working and fuel is reaching the engine.

There should only be power to the coil when the CDI sends a signal to collapse the field. You can test the coil. Remove the connections and measure resistance across the terminals. Here is an excerpt from Warren's coil tests.

>>>
The definitive test result for a bad coil is finding a secondary resistance lower than the limits ... meaning that part of the secondary winding is shorted out! Also, leaking oil is a sign that shorting out, even intermittent, had occured and resulting overheating caused the oil leak!

Coils for CDI-systems can be marked three ways:

Ealiest -- black finish
1 - 15 is primary ... 0.4 - 0.6 Ohms, 1 is ground, 15 is +
1 - 4 is secondary ... 650 - 790 Ohms

Mid years -- Bosch 0.221.121.001 ...

German-made are black; late Brazilian-made Bosch have a natural-finish aluminum case. Universal replacement for all CDI, including Turbo.

1 - A is primary ... 0.4 - 0.6 Ohms, 1 is ground ... marked '-', A is + ... not marked, though
1 - 4 is secondary ... 650 - 790 Ohms

Late -- Bosch 0.221.121.006 ... black finish
A - B is primary ... 0.4 - 0.6 Ohms, B is ground, A is +
B - 4 is secondary ... 650 - 790 Ohms
A & B terminals close together ... about 1" ... neither is polarity marked
<<<

You will need to determine which coil you have and measure the proper resistance measurements.

Things to check: continuity (zero resistance) between the coil + side and the output from the CDI. Good ground from coil to fan housing.

I can't imagine that both CD units are bad. Usually they are pretty reliable. I must admit that I had a 6pin CDI that had no output even with an electrical whine.

Don't worry, we will find the problem.

thanks for that info Jamie. I will check all that. At this point, with each day costing me no car, I am going to order a coil (spare if the one I have turns out ok) and breakerless points. With those installed and verification once again that the CD unit is plugged in correctly, etc. I can't imagine why it wont run. Problem for me is that I am a novice and I dont know anyone around here who I can get some help from. Thanks to you fine people I'll have a fighting chance!

James

anyone have any opinion on one of those CD/COIL combined boxes?

it would one less back-up part I'd have to keep around. I'd be very serious about the installed cooling ventlation and wiring.

Hey Ron, What do you mean about the wiring? Are you in favor of this option?