MFI Pump - Open Heart Surgery

[jeffc280sl]

dicklague,

If I'm not mistaken your WOT run starts at 7650 seconds and ends at 7660. During that ten second period rpms went from 2000 to 7000 and afr ranged between 13.5 to 16. If I were you I would richen the high speed screws 2 clicks and take another test run. Do you know where you are in the adjustment range?

[dicklague]

I want the part throttle cruise to be 12 or above and not 10.5 to 11. How to you make it richer when you first get on the throttle?

[jeffc280sl]

When you first get on the throttle the space cam immediately rotates 90 degrees or so. As you know we have an idle, partial load and full load adjustment screws which effect the forwards and backwards read location of the stylus on the space cam. At wot the space cam is rotated approx 90 degrees CW to the extreme edge of the space cam undulations or grooves. At this location you want the stylus to read a different spot forwards or backwards on the space cam. As discussed in this lengthy post these adjustments are inter-related. If you make a change in the full load (white screws) you may very well have to change the partial load and idle range.

This is why I suggested you make a 2 click CW change to the white screws and then take data. You may find the this change has effected the partial load afr and if so an additional adjustment will be required for that range. Tuninmg this pump involves trial and error, repeatable tests and accurate data.

Don't forget the rack adjustment which I consider to be fuel volume. As you approach the adjustment limitation of the white screws to richen the mixture at wot you may find a CCW rack adjustment appropriate. Basically I can't get to where I need to be with the white screws alone because I'm near their adjustment limit.

This is why I asked where you stand in the adjustment ranges of the black, white, idle and rack adjusters

[dicklague]

I have never touched the white screws at all. I have leaned the idle about 5 clicks since adjusting the pump arm. I have gone 5 clicks leaner on the part throttle.........I will have to check back on all my notes on these 2.

Maybe I will try the 2 clicks rich on the white screws and see where that brings me.

[jeffc280sl]

You've seen the springs the idle, black and white screws interface with. I think adjusting the white screws is considered verboten because of the impact it has on the stylus. As you richen the white you may have to wean the black and idle. This is why its important to know where you are in the adjustment range. My car is on the rich side at idle and that's a compromise I live with in order to meet partial and full load specs.

You will love your car when you get the full load afr in spec. Power and the exhaust note will confirm it.

[dicklague]

Ummmm I now don't know what direction to head. I guess I should not mess with the white screw.

I have never had my pump apart, and the last time I had it serviced, it cam back so lean that once the warm up stack was fully extended it would not run at all. So where am in the the range? I could take out my log and add up all the adjustments since the pump was resealed and reset 6 years ago.

I just know that idle and part throttle are in a decent range, but the 2000 to 3200 RPM range on suddenly opening the throttle has a big lean spot. Once the RPM is up to 32k 34k, it all goes away.

[jeffc280sl]

I didn't mean to unnecessarily scare you away from adjusting the white screws. It's a pain to do but you can count the number of clicks going CW on all screws and then return them to their starting position. I think the range of the white and black screws is 64 clicks. I can check on my spare pump if need be. My point was if you are at 32 CCW clicks from the CW stop you would be at the midpoint. It would be nice but not necessary to know where you are presently in the ranges for the white and black screws. In any event I would richen the white screws 2 clicks and see where you are with the part and full load specs.

[dicklague]

Jeff,

Thanks. I have never messed with the white or black screws and the pump has been reset and resealed about 5 years ago, so I can assume the adjustment is in the middle for both.

Another question, can I get to these by removing the idle adjuster cover, or do I have to take the back cover off the pump.....it looks like I have to take my fan shroud off to get to this.

[356RS]

Dick, you might want to read through the start of this thread your on that Jeff Higgins wrote. Jeff went through all the adjustments with the pump on the engine and explains the do's & dont's. Tons of information. To answer your question about the adjusting screws behind the small idle adj cover, the black & white screws are in their, along with all the oil in the pump!

[jeffc280sl]

Dick,

Be sure to read the entire thread. Jeff talks about adjustments he made and why and as he learned more he changed his thinking some.

[dicklague]

I will read the whole thread......I promise!! I have already started.

This is not the solution, but I just installed a great little lever on the former warm up regulator adjustment. Makes overall richening fast and easy. The lever actually "indexes". Pull it out and give it a half turn or so to put the lever in a good rest position and allow it to clear the air cleaner.

[dicklague]

sorry. here is the photo:

[Jeff Higgins]

Originally Posted by dicklague

Jeff,

Thanks. I have never messed with the white or black screws and the pump has been reset and resealed about 5 years ago, so I can assume the adjustment is in the middle for both.

Another question, can I get to these by removing the idle adjuster cover, or do I have to take the back cover off the pump.....it looks like I have to take my fan shroud off to get to this.

On page three of this thread, post #77, I posted some photos of how I have been accessing these screws. The trick little ratcheting screwdriver shown there is the key; if you don't have one, buy one. Nothing else will get that inboard cover screw. Make sure you suck the oil out of the pump first; again, that one post shows how.

There are three keys to success here. Good records, subtle adjustments, and only changing one thing at a time. Begin by establishing your baseline using an LM1, a dyno, or whatever method you have available for measuring A/F. Whatever it is, use the same instrument all the way through this.

The first thing to do when you have that cover off is to record how far out the screws are; screw them in until they lightly bottom, counting clicks the whole way. Turn the idle screw in first, then back it back out to where it was. The black and white screws need to be turned as a pair, otherwise the spring seat ring they bear against may bind. Kind of "rock" the ring down by turning, say, twelve clicks on one white screw, then twelve on the other, alternating until they both lightly bottom. Then back them back out to wherever they started. Repeat with the black screws. Now you have your "nominal" for all three springs.

The next step is to really study your first chart, the one made before you touched anything. A couple of guys have already chimed in here with their analysis of your data. You need to be that kind of a "sleuth", able to somewhat "read between the lines" and understand what the data is telling you, and what to do about it (if anything).

Using your current condition and the insightful analysis given for it, you see that the A/F is going lean too fast on top, after starting out plenty rich. As has been mentioned, the stylus is climbing back out of the trough that makes it go rich (for peak torque) sooner than it should at higher rpm. An adjustment to the white screws is indicated.

Remember, subtle adjustments. A couple, maybe three clicks rich (clockwise) to add a bit of high end spring pressure to keep the stylus in the trough a bit longer. Button it all up and go for another data collection run, recording the new data to compare with the "nominal". Repeat as necessary... This can be very, very time consuming.

You will reach a point in the adjustment of the white screws where their affect on the mid range becomes unacceptable; i.e., they will richen the mid range too much. The heavy spring they position has been pushed too far forward, either flush with, or just below flush with the lighter mid range spring. Trying to lean the mid range by backing out the black screws at this point only makes matters worse, maybe to the point of effectively disabling the black screws, and really only running on the idle and white screw adjustments.

In other words, the delta between adjustment positions between adjacent ranges is not all that great. At some point, you will simply reach the limit of what any particular space cam can accomplish. That's where I'm at with my 3.0 running the "T" space cam. I can't get a "perfect" A/F across the range, simply because the trough is not deep or wide enough, and the ridges are not high or steep enough. If I want the stylus to ride fully in the bottom of the trough for full rich at peak torque, I can't arrest the movement of the space cam enough with spring pressure to keep the stylus there far enough up into the rev range. So, expectations regarding the variation in A/F across the range need to be realistic. A point to point and a half variation is about as good as I can get mine right now.

[kenikh]

This thread needs a thread that summarizes the thread...

[dicklague]

Jeff,

Thanks for the long post, and thanks for the reference back to page 3 of this post. I read that through and it gives me a good idea how to get in to the screws and about getting oil out of the pump. I have one of those siphon pumps as well so I can pull some oil out of there.

I do have a good AFR instrument in the Daytona Sensors Wego IV. This is what I have been using and it is very accurate and easy to download data and chart data. I have a map sensor input, so I can also look at load.

I will have to make a few hours to get into this. Not sure when it will be , but will report back.

Thanks so much for your help.

Dick

[jeffc280sl]

Dick,

Jeff has provided a great summary. This part is going to be tedious and time consuming. Accurate data and repeatable tests are very important. You have seen pics of the space cam. As Jeff says to get more fuel you want the stylus in the trough. There are two ways to go in and come out of the trough, forwards or backwards. Please note that your rich adjustments can take you into the trough and if you were to keep going, through the trough to a lean point on the other side. It sounds crazy but this is why good data is so important and why tuning these pumps is challenging.

[dicklague]

Jeffc280,

Thanks for the insight on going too far, and going through the trough on the cam. I will proceed carefully and make good notes as well as be very organized in my data downloads from the Daytona Wego IV. I will post the progress and data.

My biggest problem is time in my work schedule at this point. My schedule is so busy these days, I have limited my recent adjustments to the former warm up regulator which is now a lever. I have moved this out 1.5 turns to get overall a bit more rich. this seems to have resulted in .5 richer in AFR.

thanks for your input. I will keep you posted.

[Flieger]

I saw you on the Snake this morning while riding my bicycle. (I said Hi but you were busy and did not notice.) Your car sounded to be running nice and smooth. I did not detect any unburnt fuel or oil. The engine note as you accelerated up the hill was clean and strong. I think you must be close to ideal, wherever you are.

[dicklague]

Sorry I missed you......would have stopped.

Yes I was smiling on that uphill....we are getting closer to the right AFR it seems. I cranked another 1/2 turn rich out of the now manual warm up lever.


That gave me another .3 AFR richer all over according to my Daytona Wego IV. It made a huge difference. I made a run out to 23 on Mulholland and down into Westlake for some appliance parts.

I am surprised what a big difference that made overall. WOT on the freeway pulling hard in 3rd was 13.4 or so which I like. I need to get into the white screws, but need to have some time to do that.

Have a great weekend.

[dicklague]

This the lever I have been using to get overall richness increases. It has been surprisingly effective.

The car also idles much better when cold. It does take a lot longer to warm up however.



A full turn to the left is worth about .5 AFR richer overall. It affects idle to WOT.

The most surprising thing I have found with this modification to the warm up system is that the starting point is so rich. Our climate here is So Cal is not too cold of course. But what I find is that the system started out very rich and it took quite a bit of running before the engine would idle decently. Now you have to work with it on first start with the manual solenoid valve, but it idles really will within 30 to 60 seconds.