FIP Adjustment?

[garymand]

I invested a hour in explaining why you have the right to fear turning that knob.  Yes, you can send your Fuel Injection Pump to PA and let them have the fun of working with it,  They will adjust it aproximately to a facimily of our motors, and jest that it is only an approximation.  Yes, your motor will start.  yes, your motor will run pretty well and probably perform to the numbers published for your car.  

I called PA about 30 years ago.  They were incredibly nice, nearly exuberant to talk to a car owner.  Whoever i was talking to, it doesn't matter. What is important, is their love and enthusiasm for these German mechanisms.  Their only hope was that they could share their rare knowledge of these complex, yet simple devises.  

I understand your concert for turning that knob.  I understand the idea that no one is smart enough to comprehend the complexities of such a complex mechanism.  And, i understand that you would rather send your FIP or what ever other W113 parts to others to enjoy working on.  

Please understand that I, and a few others here, would rather do it ourselves.  We would rather learn, experiment, make mistakes, learn to measure, learn to adjust, remeasure, readjust and in the end, have the satisfaction of fine tuning our FIP to give us the unusually spirited performance that a much bigger motor can deliver.  

I really get a kick out of an Audi or BMW driver when they can't pass me.  I had a C300,( 2010 200 hp? )today, see if she could pass my 280 going up through a steep climb today.  At first, I thought she was just trying to get a closer look.  When I saw the kink in her smile, as she came up next to me and not slowing, I punched it.  What can I say, A W113 in 4th at 3200 rpms is not to be trifled with.  Especially when its FIP is really close to perfect for hill climbing...  I think she was happy, it was an old W113 that waxed her going up that hill. She smiled as I let her catch me.   I don't think we could have pulled on that 300 with a PA adjusted FIP, but that's just me, I want my W113 to perform the very best she can.  

[jeffc280sl]

Nice Gary,

I understand your sentiment and I'm one of those like you that likes to push into the unknown experiment etc.  It is indeed satisfying when you can feel the results of your efforts in the back of your seat at 3200 rpms in third or fourth gear.  Not everyone as the incredibly high frustration tolerance level needed to push through an issue when part of you is saying why did I take this on, why didn't I hire an expert.  But then few of us also know the personnel satisfaction of this kind of achievement.

Br,

Jeff

[ja17]

Much of the satisfaction is the "journey" not just the results.

[Cees Klumper]

Hear hear. I just managed to diagnose and replace a bad vibration in my Volvo drive shaft. Bringing the car to the dealer would have been the easy way out (and probably have cost close to two grand) but I found the failing part was just a 50 euro bearing. Swapped it out with a new one and although the job cost me about six hours, the satisfaction of having done it all myself will last for years!

[wwheeler]

Only having been involved with vintage Mercedes cars for about eight years now, I fully appreciate Jeff's remark about "high frustration tolerance". I had no idea what was in store for me when I started to restore my W111. I owe this site an incredible amount of gratitude for the straightforward tech help. Yes, when you have a problem, sometimes the fix doesn't come the first time. Or even the second or third..... So you just keep working at it and eventually some progress appears and you are on your way.

That is the way it is on tuning the FIP. I did send it off early on and as Gary said, it worked but not perfect. So for the last few years I have been educating myself on the operation of that incredible device. One step forward, two steps back sort of thing. I finally have the FIP running well hot or cold, starting well cold or hot. I am still in the process of tuning the warm start (above 95*F but below 140*F). It is getting better every time.
Just took a chilly test drive (it is 40*F here) with no cabin heat. Yes, leaky heater core and something else to put on the list.

It is very gratifying to fix your problem yourself but you have to be patient and persistent.

 

[garymand]

I'm at the teeter-totter place on the FIP: The low and high partial screws are balanced in that I get the same A/F reading.  That was a major break through.  I had the rod adjusted ball park and jumped into the WRD, oops!  It seems like the adjustments often work backwards, but it is really my thinking of how it works is backwards.  Or maybe its old age and CRS. 

I took one washer out of the fuel side of the WRD and it really bumped the fuel up.  I put the original back with 2 more washers about .015 to .020 in.  The mix at 45F is about right maybe a little lean.  But I'll have to wait for tomorrow morning the try again.  My A/F this moring climbing a hill was about 13, I'm thinking it shoud be richer.  I don't expect anymore cold mornings but I remeber the colder it is the more critical the WRD setting is. 

So after leaning out the wrd with the 2nd and 3rd washer the bottom and top were 6 clicks lean even with the air valve closed.  I was hoping the WRD had no effect once it reached 80C.  I was getting readings a little lean bottom and top coming down hill.  I'll give it 2 clicks on the rod before heading back up the hill.  That's how close it is, and the performance peak is noticable.  I think I'm 3 to 4 lean right now and the motor pulls very well.  Once I know where the peak is, I'll try changing octane and see the dif.  Then I have the correct distributor to put back in and try the different advance curve.

[jeffc280sl]

Hi Gary,

I went through this process several years ago so I'm a little rusty. What air fuel ratios are you tuning to?  Are you using the on road dyno specs as a guide?  What tuning device are you using?

[garymand]

I welded in a nut on one pipe and hooked up a temporary A/F ratio meter to an O2 sensor.  over the years, I tried three different tail sniffers, all simple balanced bridge type portable meters, they wouldn't repeat well on my SL. I got a hotrod 33 ford truck 4 barrel jetted and needles pretty well that way but, not the SL with FI.

I get really good repeatability.  I converted the bbb numbers to A/F ratio.  As the bbb alludes, it is a close approximation tuning.  And they don't go into what the ratio does in-between the tuning points.  When the FIP is far off, much adjustment gives little change, When you are very close, little adjustment gives big change.  My motor really likes gas.  Its highest output is in the 13 area, but its counter intuitive: mas you take your foot off the gas as in cruzing, the mix goes rich just below 11.  It just doesn't seem right to be at high end low load, low vacuum, and get an 11 A/F ratio. But that is where it is with a 13.5 at 300mm/hg and 3000 rpm. 

[jeffc280sl]

Thanks Gary,

I think the numbers sound very close to mine.  Like I sais it has been a few years since I was in deep on this subject.  Did you put a vacuum sensor on a blank threaded port on the intake manifold?  I did many test runs and found a set oh hills where I could, along with the emergency brake, approximate the engine load specs to match Tom's.  Then it was a matter of taking a ft readings at those points.  Then back to the garage for goo adjustments (white black) screws.  Tedious stuff but the end result was engine power that as you know can be felt in the back of your seat.