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914World.com _ 914World Garage _ 2056 MPS Rebuild
Posted by: OGmikey914 May 28 2018, 01:33 PM
I have a Raby 2056 with a dead MPS. We pulled it off and tested it and it doesn't hold a vacuum, but the car seems to run fine other than idling a little high. It doesn't have a 73 MPS, it has an 043 which I understand calibration can be a bit tricky with. If I just rebuild the unit, will it need to be re calibrated?
I am trying to get it done before WCR, so a little short on time, but any ideas/help?
Posted by: 914Sixer May 28 2018, 02:01 PM
Send it to Jeff Bowlsby.
Posted by: Mblizzard May 28 2018, 05:14 PM
If you have an AFR you should be able to tune it pretty close. If you need instructions on adjusting pm me your email. Can be a time consuming process but doable.
If you really get stuck let me know I have a MPS set for a 2056 you can borrow.
Posted by: OGmikey914 May 29 2018, 01:52 PM
Unfortunately I work most days 7-7 or later so I won't have much time until this weekend to tinker with it so I may just have to run it as is. Put the current MPS that is not holding vacuum back for now, and I drove it on a couple 30 min quick trips this weekend and seemed to run fine once it warmed up. Was able to adjust the idle down to get it closer to normal as well
Posted by: Mblizzard May 29 2018, 02:24 PM
Unfortunately I work most days 7-7 or later so I won't have much time until this weekend to tinker with it so I may just have to run it as is. Put the current MPS that is not holding vacuum back for now, and I drove it on a couple 30 min quick trips this weekend and seemed to run fine once it warmed up. Was able to adjust the idle down to get it closer to normal as well
As long as you are running rich I think it will be OK. But I don't think that you can expect the leaking one to remain constant. Meaning that it will likely get worse and leave you stranded at some point.
Posted by: ConeDodger May 29 2018, 03:40 PM
Didn’t Chris Foley make a rebuild kit for these?
Posted by: BeatNavy May 29 2018, 03:46 PM
Didn’t Chris Foley make a rebuild kit for these?
Yes he does. It's a good product and pretty straightforward process.
If your MPS is not holding a vacuum it's not really going to run "fine" when warmed up. It's still going to be rich to very rich, depending how badly it leaks.
As mentioned, you can send it to Jeff Bowlsby. I also have one you could borrow while it's out for service, but Mike (mblizzard) has also offered one.
Posted by: 914_teener May 29 2018, 03:55 PM
Didn’t Chris Foley make a rebuild kit for these?
Yes he does. It's a good product and pretty straightforward process.
If your MPS is not holding a vacuum it's not really going to run "fine" when warmed up. It's still going to be rich to very rich, depending how badly it leaks.
As mentioned, you can send it to Jeff Bowlsby. I also have one you could borrow while it's out for service, but Mike (mblizzard) has also offered one.
They fail just like this by cracking partly and seem to run fine until they fail completly and will leave you stranded in a busy intersection.
Get Foleys kit and have Jeff calibrate it close.
Posted by: OGmikey914 May 29 2018, 07:18 PM
Sounds good!
I took it out again last night and it was running a little rich now that you mention it.
Thank you for all the help, I will order a rebuild kit, but if someone has one I could swap and borrow for the rally that would be awesome!
Hoping I can get the kit in time 
Posted by: BeatNavy May 29 2018, 07:39 PM
Sounds good!
I took it out again last night and it was running a little rich now that you mention it.
Thank you for all the help, I will order a rebuild kit, but if someone has one I could swap and borrow for the rally that would be awesome!
Hoping I can get the kit in time
Send me a PM with your address, and I'll try to get one mailed out to you this week. I have an 043 that's been tuned slightly richer than stock 2.0. My 2056 has the stock cam, so it doesn't need a big boost, but this should keep your running fine.
Posted by: Mblizzard May 30 2018, 06:47 AM
Sounds good!
I took it out again last night and it was running a little rich now that you mention it.
Thank you for all the help, I will order a rebuild kit, but if someone has one I could swap and borrow for the rally that would be awesome!
Hoping I can get the kit in time
Send me a PM with your address, and I'll try to get one mailed out to you this week. I have an 043 that's been tuned slightly richer than stock 2.0. My 2056 has the stock cam, so it doesn't need a big boost, but this should keep your running fine.
It is really awesome to have an issue and find so much support here.
Posted by: OGmikey914 May 30 2018, 08:04 AM
Sounds good!
I took it out again last night and it was running a little rich now that you mention it.
Thank you for all the help, I will order a rebuild kit, but if someone has one I could swap and borrow for the rally that would be awesome!
Hoping I can get the kit in time
Send me a PM with your address, and I'll try to get one mailed out to you this week. I have an 043 that's been tuned slightly richer than stock 2.0. My 2056 has the stock cam, so it doesn't need a big boost, but this should keep your running fine.
It is really awesome to have an issue and find so much support here.
Agreed! You guys are awesome and thanks a ton for the help!
Posted by: OGmikey914 Jun 4 2018, 11:31 PM
So I had a few minutes after work today to swap out the MPs. It seemed to normalize the idle but was running really rich. How do I adjust this bad boy?
Posted by: BeatNavy Jun 5 2018, 04:08 AM
So I had a few minutes after work today to swap out the MPs. It seemed to normalize the idle but was running really rich. How do I adjust this bad boy?
Hmmm....it shouldn't be running excessively rich with an MPS that holds a vacuum and is generally tuned to 2.0/2056 specs. Why do you think it's rich, and is that at idle or through the whole range.
Here's the MPS adjustment theory / process: https://members.rennlist.com/pbanders/manifold_pressure_sensor.htm
But it could be other things, like fuel pressure or leaking injector(s).
Posted by: Mblizzard Jun 5 2018, 06:19 AM
FI_Troubleshooting_Guide.pdf ( 3.22mb )
Number of downloads: 156
Might start with the checks starting on Page 48 and 62 before adjusting the MPS.
You have to have a special tool to adjust the MPS. Do you have it?
Posted by: Racer Chris Jun 5 2018, 10:42 AM
You have to have a special tool to adjust the MPS. Do you have it?
And the MPS has to be modified to accept the special tool.
Posted by: Mblizzard Jun 5 2018, 01:43 PM
You have to have a special tool to adjust the MPS. Do you have it?
And the MPS has to be modified to accept the special tool.
Chris's special tool! Don't lose it.
And don't try to adjust without it. It just does not work!
Posted by: Mblizzard Jun 5 2018, 01:45 PM
Almost forgot! Check your intake box for cracks. Mine was cracked and lowered the pressure which made it run rich.
Posted by: BeatNavy Jun 5 2018, 01:48 PM
He's actually got a spare 043 that I sent him to get him running until he can repair his or source another. Mine was repaired with your kit, Chris. He doesn't have the tools (at least I didn't send him those). It was tuned to slightly richer than 2.0 for an 043 using my inductance meter, but who knows the accuracy of it as it's a pretty cheap Chinese knockoff? I did set it very closely to the readings for another 043 I have that was rebuilt professionally.
The MPS could be tuned slightly too rich, but I'd be surprised if that was the sole cause of it being significantly rich. Also, I don't think he has an 02 sensor, so need to know the actual symptoms that would suggest that.
Posted by: Jeff Bowlsby Jun 5 2018, 01:59 PM
All this guessing for a 2056 MPS...on a Raby engine no less...too much risk. Even the several, same PN NOS MPS's I have or have documented are different from each other and the factory never made the 2056 obviously. The only way to responsibly know for sure what is correct for any engine, is to get it on a dyno or an exhaust gas analyzer to verify it is correct for that engines' needs.
Posted by: Racer Chris Jun 5 2018, 02:03 PM
So I had a few minutes after work today to swap out the MPs. It seemed to normalize the idle but was running really rich. How do I adjust this bad boy?
What's your fuel pressure?
Posted by: cary Jun 6 2018, 07:47 AM
One more thing to look at. Leaking cold start valve.
I've been laying low. I've too may commitments too say anything. Making sure your Uncle is driving his car has been job #1.
I have a complete MPS tuning kit. Inductance meter, Innovate LM2 Air Fuel Meter and Chris's tool kit. Plus I have one stop screw and cap left. I've yet to rebuild an MPS yet, just tuned working ones. From lean to singing a beautiful song. It's been a while since I've used it but I could bring to Newberg if we have time for a tech session.
I also have a Gunison Gas Tester I could bring Thursday night to find out how rich it's running. Just need a 110 outlet.
Posted by: rhodyguy Jun 6 2018, 07:49 AM
And a extension cord.
Posted by: cary Jun 6 2018, 05:08 PM
And a extension cord.
Forgot, 12 volt alligator clips. Easy deal ..........
Wes Andrews my go to engine guru is coming by tomorrow night and I asked that he'd take a look at it. The Gunson Gas Analyzer will give us a ball number on how rich it's running. ( 40 year retired air cooled Porsche tech )
Posted by: OGmikey914 Jun 6 2018, 10:20 PM
Dumb question here, but I live about a 30 min drive from Newberg and I won't do any damage by driving it over to Newberg will I? I was planning on heading over early Friday morning, but I can prob arrange to tow it if I need to with my dads truck/tow bar but would just make for late night since I usually work 7-7ish
Posted by: cary Jun 6 2018, 10:47 PM
Primary thing I want to measure is how rich it is. If its super excessive it will wash the oil out the cylinders and destroy the engine. I can't imagine its that bad.
But my motto, plan the worst. Hope for the best. I'll see your dad in the morning. We'll figure something
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