MPS vacuum readings - are these ok? Options

[Cevan]

I have picked up an 043 MPS to replace the one that holds no vacuum. I put a vacuum gauge on it and brought it up to 15 hg. Here's how it went as it leaked down:

Vacuum Time
15 0:00
14 2:20
13 4:45
12 7:20
11 10:15
10 13:15

So it took over 13 minutes to leak down from 15 to 10. Will this work?

[SLITS]

Read for yourself .....

MPS Diagnostics

[GaroldShaffer]

(IMG:style_emoticons/default/beer.gif) What great timing. I have some MPS that I wasn't 100% sure how to test. Thanks for the link Ron (IMG:style_emoticons/default/beerchug.gif)

[r_towle]

I have picked up an 043 MPS to replace the one that holds no vacuum. I put a vacuum gauge on it and brought it up to 15 hg. Here's how it went as it leaked down:

Vacuum Time
15 0:00
14 2:20
13 4:45
12 7:20
11 10:15
10 13:15

So it took over 13 minutes to leak down from 15 to 10. Will this work?

Show a pic of how you set up the test.
Reason....miti vac hand pumps leak, hoses leak etc etc.

I seems to be ok if all the leaks were in the hoses.
Do it the way I said,,,tongue on the mps (clean it first) to see if it stick and holds your tongue...like when we were kids.

For a real test you would need infalible connections to the mps and a way to shut off the vacuum...none of that can be said for a hand pump...they all leak.

Rich

[Cevan]

I used a hand-vacuum pump w/gauge and used new vacuum hose with FI clamps on either end. I know leakage in the hose conncections will effect my readings, but in reality, all the vacuum hoses in the car will leak in the same way.

I suppose I could pull a vacuum on a blocked line and record the leakage.

According to the above link, if you pull a vacuum of 20 in Hg and it doesn't leak down to below 5 in Hg in a minute, you're good. I will also check the coil resistances.

I think I'm good to go. I will install it in the 2.0 yellow beater and see if I can get it to idle nice.

[r_towle]

LOL you didnt say you wanted a Djet to idle nicely...did you???

Rich

[Cevan]

LOL you didnt say you wanted a Djet to idle nicely...did you???

Rich

Ha! Well, I don't spend too much time at idle. I couldn't get it to idle at 900 rpms. See video here. It was pretty high. I thought it might be the bad MPS or a stuck AAR. I want to get it some what sorted out before I pull it out this winter. I'm going to put the new MPS in it this weekend and rip around the pastures. I've just got to watch out for the cows. I've got plenty of clearance with those KYB Gas-adjust shocks. How much air can you get in a 914? (IMG:style_emoticons/default/w00t.gif)

[r_towle]

remove the AAR, the Decel valve, and leave only the MPS connected to the plenum...cap all the other holes in the plenum.

Leave just the advance line going to the distributor.
If your throttle body has two fittings (this seems to be optional) cap off the one for the retard on the distributor...you can leave the distributor retard alone and uncapped.

At this point you have only two lines going into the plenum/throttle body.
Car will run fine.
If you still cant set idle lower look at the injector seals (get new) and the intake runner large rubber tubes (clamps, cant get new ones) and most important is the intake gaskets...it goes like this...intake ---gasket---phenolic spacer---gasket---head (this part leaks alot.)

These are the critical Djet leakers...
Also, if you have time, pressure test the plenum...they do crack and leak (a really tough one to track down on the car)

I have duplicates of lots of the parts if you need anything.
I also have the Bosch Djet FI tester if you want to play...look at the PP web site and see if you want to play with it...

You are more than welcome to borrow it, and if you like I will sell it to you.
Rich

[Cevan]

remove the AAR, the Decel valve, and leave only the MPS connected to the plenum...cap all the other holes in the plenum.

Leave just the advance line going to the distributor.
If your throttle body has two fittings (this seems to be optional) cap off the one for the retard on the distributor...you can leave the distributor retard alone and uncapped.

At this point you have only two lines going into the plenum/throttle body.
Car will run fine.
If you still cant set idle lower look at the injector seals (get new) and the intake runner large rubber tubes (clamps, cant get new ones) and most important is the intake gaskets...it goes like this...intake ---gasket---phenolic spacer---gasket---head (this part leaks alot.)

These are the critical Djet leakers...
Also, if you have time, pressure test the plenum...they do crack and leak (a really tough one to track down on the car)

I have duplicates of lots of the parts if you need anything.
I also have the Bosch Djet FI tester if you want to play...look at the PP web site and see if you want to play with it...

You are more than welcome to borrow it, and if you like I will sell it to you.
Rich

Intake gaskets?? I don't have these on my 1.8 motor. Is this a D-Jet only thing or am I missing something?

The injector seals are pretty good. I'll do as you suggest above and take the AAR and decel valve out of the loop.

Once the motor comes out this winter, I'm going to go thru everything anyways.