Hello all,

I need to adjust my MPS as it is a TYPE4 unit. I have adjusted it before "Guess and Check" method but decided to do it the correct way. Last time I used the "Guess and Check" method I got lucky and it ran beautifully.

Just changed and adjusted points/dwell/timing. Valve job done 1000 miles ago.
74 2.0 original FI

I have read PBanders thread a bunch of times.

I have a multimeter that will do HFE tests.

I looked at the multimeter he suggests and I don't see any difference between mine.

I need to have it explained to me "like a small child" how to hook up the multimeter to the MPS. I see the HFE input terminal on my mulitmeter. It has EBCE inputs both PNP and NPN.

I know I need to hook to 8 and 10 on my MPS.

I have tested the unit to make sure it is within spec. 350 ohms between 7 and 15 and 90 ohms between 8 and 10. Holds vacuum and no continuity between case and connections.

Any and all help will be greatly appreciated.

I don't believe you can adjust the MPS with a multi-meter
you can test the continuity that you already have done


I don't know how to use a wave-tek
hopefully someone with real experience will chime in


The other way to adjust one is to use a wide band o2 sensor and adjust under load either on a dyno or in real time on the road.
(that is how I have done them in the past)

brant

Forgot to mention:

The full load stop screw has been drilled out (PO) just enough to access the inner screw without removing full load stop screw. Kida different. Can't adjust the outer screw this way obviously.

I will try to post a pic if this is unclear to folks.

You need an inductance meter. This is different from a multi meter.

Its important to remember that Brad A developed his tables based on the Wavetek LCR55 and because of the sensitivities of the values he cautions about using any other meter. Other inductance meters may give other values...perhaps other tables specific to the other meter would need to be developed.

Also, the Brads calibration table values need to be adjusted for elevations above sea level, per his notes.

The wavetek LCR55 has been discontinued. At least I could not source a new one. The Amprobe LCR55A is available new. I too have enriched mine by reading the plugs, but want to set it correctly. Going for it this weekend. I will post my results.

regarding a "free hand" adjustment the MPS is more sensative than my human eye can see....

I spent a day doing back to back runs with the 2 adjustment screws... a tiny change made a big difference. There was no way my seat of the pants could tell any difference. Only the wide band could tell the difference. I don't believe you can get close without the right tools...

Well, FWIW my car hasn't run this well since I've owned it.(11 years) But ya, I have the correct tools, and want to calibrate it correctly.......

Yup, I know...

I have a Wavetek LCR-55. At some point maybe some side by side comparisons might need to happen (a shootout) to see how different meters are calibrated...maybe the good meters are precise enough for any differnces to be negligible.

Jeff I just bought the Amprobe.
Maybe I can make arrangements to send my meter to you so you can compare the readings on both.

With Geoff's guidance I just put an 037 top on an 41 base to create a working unit. Took longer to figure out how to get the right clips on the terminals. Than it did to do the adjustments.
Double checked my work 3 times. Dead on.
I just went with Brad's numbers. I'm here in Portland, about 300 feet.

Sure, just email me to coordinate. I have a few MPS on hand I could characterize and compare the meters.

Update :

I bought both an Amprobe LCR and an Innovate LM-1.
So now I'm in this up to my neck.

The LCR made adjusting the MPS very simple.
All adjustments dead on with Brad's MPS chart.
But the LM-1 still shows me very lean at idle.
I'm like 25.5%
Probably too lean at partial throttle too.
14 & 15%.

So I'm thinking I'll do the 2500 rpm test and dial the AFR to 12.7 with the MPS inner screw. Then back out the full throttle stop the same amount of turns?
Am I on the right track? Suggestions?

The full throttle stop screw has an adjustment hole in it. Does that have an operational effect?

Sorry thompson-mfr for kind of hijacking the thread.

I need to add one thing.
This is a 73.
But it doesn't have a ballast resistor. Never has had one.
Might this be part of the problem?

You are one more step down the rabbit hole than I........I couldn't find a new LM-1 though?

also and apology for the hijack

Yes!
Put one on before you go any further with adjustments.

Dang it......... that's what I thought you were going to say. I was hoping to tweak the MPS and drive off into the sunset.

$1.19 for a five pack at Radio Shack.

Well I finally got the ballast resistor installed.
Looks like it dropped the AFR about 2%.
Drove a little smoother.

So I decided to adjust the inner screw.
I started with an AFR at idle of about 23%.
At 2500 RPM's its about 17.5%.

I decided to adjust the 2500 rpm first.
Boy, it doesn't take much.
I might have moved it 75 degrees CCW total.
Click to view attachment
Here's the 2500 reading

That left me at idle with a 15.4%
Click to view attachment

Set up for a road test.
Click to view attachment

It was really cool to hear the engine start to smooth out as I lowered the AFR past about 17%. Now that AFR is close TO being correct. Everything works. The idle speed and mixture both work like they're supposed to.

It was also really amazing watching the AFR as I adjusted the idle speed.

Now drive it like you stole it!

That is the plan ......................
Thanks for the help.

Wash and a wax and she's good to go. I'll put 500 miles on her and do a final adjustment.

other than idle...

I assume you are doing your 2500 test under load (driving down the road)

you need to
you can run the lm1 in the window and watch it while driving.

brant

Both static and road test.

dont forget fuel pressure , if it is way out of wack, it will effect AF readings.

I have had mine as high as 34 psi to hep enrichen it (wilder cam, big bore) now have played with MPS and AFM.

anyway check fuel pressure before adjusting MPS

Now thats a thought.
Pretty certain I'm dead on at 29#'s.
Might move it up to 32-34#'s.

I'm still a little lean.
I want to drive it 500 miles. Adjust the valves.
Then adjust AFR again.

Went for a spirited 35 mile drive. Other than the decel kind of hanging up. Everything went great.

Finished the 500 miles with a trip to Cascade Locks and Crown Point.

Couldn't drive it like I stole it. Too much Sunday traffic. But it was great driving with the sun and wind. Perfect 75 degree day.

Click to view attachment

Click to view attachment

Then yesterday I did the 500 mile oil change and valve adjustment.
And fixed my oil leak. I'd put a copper washed under the oil pressure gauge hose to block connection. The tapered threads didn't think that was funny.

Great thread thanks.

I haven't found the LM-1 though...from the Innovate site they have been discontinued?

They stopped selling LM-1 when they released LM-2.
I bought an LM-2 and, as a result of the experience, will never buy another product from Innovate.

What do you use Chris?...No hijack intended but I would assume wide band.

I'm using a narrow band in my own vehicle.
I insist that all my customers with modified engines get a wideband meter. I sell an AEM digital wideband unit.

After hijacking the post last summer.

I thought I'd bring everyone up to date. After charging the battery. She fired right up. Idle climbed to 1500 with AAR. Dropped to around 800 rpms as it warmed up.
Then sat there and idled at 950 rpms.

All that work and adjusting last fall was well worth it.

Hi Cary,
So after all is said and done, would you say that you needed the inductance measurements or did the wideband meter alone allow you to set the MPS? I love shopping for tools, but there is a limit. I doubt I will need to measure inductance very often, but I can probably get my hands on one if it is important.

I would say the LCR is good for the initial setting, but to fine tune to the engine you need a wideband.

Just get both, used waveteks are pretty cheap and I think all cars should have widebands.

inductance measurements

I felt the LCR made a huge change.
But the AFR makes sure you have enough fuel.

I'm a Tool Whore. I'm glad I bought both.

Yeah, me too. Another question comes from my physics classes in which a Henry was a Henry. In theory all instruments should measure the same plus or minus some tolerances. I understand that in some ranges a small instrument could not test a large inductance, but is there that much variation between appropriately matched testers? If so, why do they even show numbers?

Did you get the variable "pot" resister?

No just a standard one. With heat shrink over it.