LM-1 data from 2.4T MFI

[orange911]

OK, let me first start off with a BIG thank you to all the contributors to the MFI resource page. Secondly, without Pelican and Early S, none of this could even be possible, so Thank You. And no real fun could be had without an LM-1, so I must thank Scott (Kaefer) who allowed me to borrow his LM-1 for the CO test.

STEP 1: Cleaning & Correlation

My project first started after reading how John Cramer cleaned and correlated his TBs with a vacuum cleaner, so away I went. Initial results from this step was an awfully rich case.
Items to note. Prior to me starting this, all the air by-pass screws were all the way open, so there was no adjustment left. The vacuum ports were completely plugged with carbon soot, which had to be drilled out. Throttle stops were all set to where the butterfly was just off the bore to prevent binding after warming up. This was accomplished by having the vacuum cleaner attached down-stream and the syncrometer on the upstream side. Stops were adjusted to where the air flow made a sudden change once the butterfly came off the bore.
Linkages were all set such that the throttles open at the same time as best as possible without a protractor set. After all of this was completed, the by-pass screws were set with a syncrometer.

Step 2: Timing
Here was a problem I was unaware of until I went through this process. Timing was jumping all around - points or pertronix made no difference. Found a good used dizzy and timing is much better.

Step 3: Replaced Injectors
New ones installed after having the old ones tested. Spray pattern was sometimes off to one side and a couple did not atomize very well. New ones had a nice conical pattern and I was convinced.

Step 4:Thermostat Cleaning
Cleaned the thermostat because it was easy, but I am not sure it made any difference.

Step 5: CO adjustment
This was the really fun part. I removed the aftermarket free flow exaust and put on an original Leistritz (sp). I put a bug on each inlet so that I could measure each cylinder bank independently. Right now, I can only measure 4,5,6 because the welder did not center the bung on the hole of 1,2,3 and the o2 sensor does not fit.. Initially the LM-1 confirmed what I already knew, which was the settings were way too rich. (~10:1). I started with the part load adjustment and then tinkered with the idle. I have read many things about the MFIs want to be rich, but I also want to avoid contaminating my oil. Klaus (innovate) indicated that the best HP for best fuel consumption was on the lean side of 15.2-15.4. This really stumped me because so many people say that they have reduced their AFR to regain the power. But then I reread and realized that it wasn't the best HP, only the max HP for max MPG. So I decided the range to be in was 12-14:1.

I am open to comments from the floor on my results posted below. This is my first time really tuning a motor this way, so I would appreciate explanations to correct where I might have steered incorrectly.


Here is a run through the gears on the interstate with a light hill.



Here is the car at a steady state of 3000 rpm




Steady State at 3500 RPM (I took my foot off the throttle at the end)




Steady State at 4000

RPM

[304065]

Olin,

Interesting data- you should expect a big rich spike (downward on the graph) when you close the throttle for a shift, particularly if your speed switch is not working.

Usually if you have things adjusted right the pump leans out as RPMs climb. This makes sense insofar as the pump has to be adjusted to keep up with higher airflow. Really exacerbated if you have megaphone exhaust or a sport muffler or anything that allows proportinately more air than the factory expects.

One thing that is strange is your 3500 rpm graph-- perhaps this is the transition from idle to part load control in the pump, causing the mixture to flip around. You can see this clearly in my graph below-- as the RPMS climb, the pump goes from idle to part load and my part-load is VERY rich-- see how the mixture line takes a nosedive at around the same point before each RPM peak?




Keep it up, more data is a lot better-- eventually you will be able to read the traces and correlate to what is going on in the car. A throttle position switch would be REALLY good but kind of expensive to set up.

[orange911]

One thing I have also noticed that I did not publish before is that my car is much harder to start now when cold. Could this be too lean on the idle setting? Thermostat is working because the AFR is around 10 - 10.5:1 when cold.

John, can you tell me what extra data I should take?
What is wrong with what I have now?
What is correct with what I have now?

[orange911]

I think I am done with the adjustments. I had some good results this weekend and the car is driving great. I realized a couple of things that may have skewed earlier tests.
1) my throttle linkages were in sync, but were not letting the linkage to the pump return all the way. All my adjustments were based on the pump being ahead of the throttle. Huge difference after getting this set, made it super lean. I DID NOT ADJUST THE PUMP LINKAGE, it is still 114mm.
2) the earlier tests were based on the throttle micro switch being inactive (due to the linkage issue), therefore it never properly leaned out when releasing the throttle.
3) the car was hard to start when cold because I had forgot that I unplugged the cold start pump to test for continuos running.
4) also I found in the archives that the part-load test should be performed at 9% throttle opening at 2400 rpm. All the tests I did were at steady state on the highway. I had no way to measure the throttle position, but later I found a good hill that I was able to gauge the pedal position and "assumed" about 10% travel and hold it at 2400.

To sumarize, I now have the AFR at 13.5 for idle (spec is 13.4-13.7) and AFR at part load is 13.8 (spec is 13.9 - 13.7). These spec numbers are based on a %CO to AFR conversion table. (Idle 2-3 %CO and Part Load 1.5 - 2% CO). As it is, the car will pop through the intake every once in a while as I am coming off idle, and I can live with that for now. It seems that it leans out quite a bit between 1000 and 1500 RPM. When I get more adventurous, I can take the cover off to adjust the 2 black screws as discussed in "MFI Open Heart Surgery"

One thing I learned that later made good sense (as most experiments do) was that the afr is really rich when coasting or going down a hill and foot is on throttle (microswitch not activated). But as soon as I went up the hill with throttle, the afr would rise to a reasonable level.

I have put about 200 miles on it in the last week and I have already seen an improvement in performance and fuel mileage. When the rain quits I would like to get some more data and post it here. So, stay tuned (pun intended)

Thanks again to Scott, as this would not be possible without his generosity and trust.

[PcarPhil]

Originally Posted by orange911

Thanks again to Scott, as this would not be possible without his generosity and trust.

You're welcome and I'm glad it's helping out!

When I get the LM-1 back I'm going to hook it up to my 3.2 for the first time and see how the AFR's are doing on my own engine...

[orange911]

Notes about the LM-1 and Sensor Timing 08 error codes.

I did get the error in the first week after many runs of being too rich, and I had many good runs before getting the code again at the end. As I understand from googling the error code (http://www.google.com/search?client=safari&rls=en-us&q=Sensor+Timing+Error+08+lm-1&ie=UTF-8&oe=UTF-8), this is quite a common problem and can be resolved with sensor replacement or try performing a heater calibration with sensor out of exhaust. The recalibration can only be done by resetting calibration in logworks (lm-1 connected to computer then plugging into the sensor while out of car). Remember that the unit must be off for 30 seconds minimum before turning back on after heater calibration. Also, never start the car with the unit on, turn it on immediately after starting.

I did recalibrate once after I got the error codes in the first week and it worked without fault until the last bit of use. If you read about the error codes on Innovates forum, you will find that many people had the same problems I had trying to get a good reading just before getting the error. It flashes between 8 and 20.9 AFR and then goes to error.