MPS testing/adjustment problem. Can't get anything higher than 0.9 H Options

[scottthephotog]

I've been following this explanation and walkthrough of testing the MPS; https://members.rennlist.com/pbanders/manif...sure_sensor.htm, and I've come across a problem.

My MPS holds vacuum, I've got correct resistance readings on each of the coils, confirmed that they were isolated properly, so I moved on to adjusting. At 15 in. Hg, reading were correct (.71H). I found that I couldn't get the MPS to reach any higher than 0.9 H with my inductance meter at either the 4 in Hg or 0 in. Hg. I pulled the MPS apart, and measured again with it open (nothing pushing back on the main armature shaft with the armature shaft stops in place). The armature stops don't appear to be bent. With the armature shaft pushed in all the way, I get a reading of 0.45 H.

Any thoughts? Is this MPS toast? I can't figure out why it won't register more than 0.9 H, which i way off from 1.44 H.

[tvdinnerbythepool]

I can tell you that the meter makes all the difference. My cheap meter #s were way low so I bought the LCR55A. Using the LCR55A I was able to calibrate to the PBanders numbers easily. And as I'm sure guys will point out, tuning to the PBanders #s won't necessarily tune the MPS to your specific engine.

This is quite literally where I am at with my car and had the same issue. #s way off with cheap meter, got the good meter, #s spot on, still runs like a turd.

I'm now in the process of installing a Fuel/Air Meter system this week to help get it dialed in.

Good luck!

For reference below, these were the #s I got with my cheap meter and wasn't able to adjust close to where I needed. The LCR55A solved that problem.

@PBanders Sea Level Numbers for 0"/4"/15" - 1.40/1.20/.74 @20H
My MPS ----------------------------- 0"/4"/15" - .95/.84/.63 @20H

[scottthephotog]

I can tell you that the meter makes all the difference. My cheap meter #s were way low so I bought the LCR55A. Using the LCR55A I was able to calibrate to the PBanders numbers easily. And as I'm sure guys will point out, tuning to the PBanders #s won't necessarily tune the MPS to your specific engine.

This is quite literally where I am at with my car and had the same issue. #s way off with cheap meter, got the good meter, #s spot on, still runs like a turd.

I'm now in the process of installing a Fuel/Air Meter system this week to help get it dialed in.

Good luck!

For reference below, these were the #s I got with my cheap meter and wasn't able to adjust close to where I needed. The LCR55A solved that problem.

@PBanders Sea Level Numbers for 0"/4"/15" - 1.40/1.20/.74 @20H
My MPS ----------------------------- 0"/4"/15" - .95/.84/.63 @20H

Thanks. I wonder why that would make such a big difference. I bought a $35 meter off Amazon because it could arrive the next day and was inexpensive. Guess that was a mistake. At least it is giving me numbers so I have some frame of reference. I set the MPS to your lower set of numbers, and we'll see what happens. I've got a second MPS that is unopened, but leaks. It's numbers at the various test points are about the same as the ones from your cheap meter.

The MPS in the car (73' 2.0) currently is the one with the leak. The motor runs with it, but runs very lean (15-15.5 AFR). The spare, which I'm trying to calibrate, holds air, but someone had messed with the calibration screws. When hooked up to the car, it barely idles, but revs fine. My goal is to calibrate the spare back to stock so the car will run with it, then calibrate it for my engine using an LC-1.

In addition, I've got an ECU tester on the way incase the ECU is the problem. Hopefully it between the MPS testing/adjustment, and the ECU testing, I can get this running lean problem sorted out!

[JeffBowlsby]

Which ECU tester did you get?