1976 2.0L D-jet, distributor vacuum Options

[Ron914]

@emerygt350
I was asked my a member helping me with my high idle /vacuum leak problem how I currently have it hooked up .This is the diagram I am using .

[emerygt350]

How high is the idle currently?

[Ron914]

How high is the idle currently?

still around 1400 but I need to work out positive verification of my timing . I now have a better idea on doing that by using the TDC (confirmed mark) on the flywheel , plus after running the new 2056 motor now for approximately 3-500 miles I probably need to adjust the valves .This may be the noise I'm thinking could be coming from the exhaust , so another reason to be spot on with TDC. If I move my distributor a little advanced or retarded I can get close to 1000 rpm but after putting away in the garage for the night I found it doesn't want to start unless I undo the distributor adjustment I did the night before . More things to work out still but life is always busy for me so I don't always get right back to it that soon.

[Ron914]

I think I might have a bad decel valve but others told me that probably is not the cause as it's mainly an emissions device.

[IronHillRestorations]

You might want to make sure the advance mechanism is working properly, it might be sticking.

[emerygt350]

That was my first thought. But you don't have your advance hooked up right?

Best thing to do is cap everything now and slowly readd. Get it warm, then plug it all. Aar, retard, decel, etc. you can even check the mps by pulling the vacuum off the plenum while it is running and plug it with your finger. It will be rich but it shouldn't rev once you plugged it. If you have a vacuum pump you can just put 20inhg in the hose going to the mps and plug the plenum.

If everything is plugged and it's still at 1400, grab a can of carb cleaner and start spraying around the plenum, the runner boots, and the injectors. If you don't get any change it has to be your timing (or possibly that combined with a lean idle mix).

[emerygt350]

Also ... 1400 just happens to be where the aar puts the motor during warm up...

Here is a cold start this morning 34F showing idle as the car warms. Today it would take quite a bit of driving (maybe 15 minutes) before I would be warm enough for idle to hit 'normal' hot idle. Even after the AAR is closed the richening from the charge temp sensor and the CHT seems to keep it up around 1100 untill everything is all happy.

https://www.youtube.com/shorts/fQ3FCZQWKKM

[Ron914]

That was my first thought. But you don't have your advance hooked up right?

Best thing to do is cap everything now and slowly readd. Get it warm, then plug it all. Aar, retard, decel, etc. you can even check the mps by pulling the vacuum off the plenum while it is running and plug it with your finger. It will be rich but it shouldn't rev once you plugged it. If you have a vacuum pump you can just put 20inhg in the hose going to the mps and plug the plenum.

If everything is plugged and it's still at 1400, grab a can of carb cleaner and start spraying around the plenum, the runner boots, and the injectors. If you don't get any change it has to be your timing (or possibly that combined with a lean idle mix).

After we installed the motor my brother in law used his vacuum pump and verified the advance plate movement in the distributor but he does not live by me so I will go and invest in one . The vacuum off the distributor is no longer hooked up ,it is open to to air now. Once I got that part correct things got much better .You were correct in your previous comments about that and I had it connected wrong. I think I could be close but something is still not quite right.
So let me make sure I understand .
1) get car warmed up with everything hooked up
2) then unplug all lines connected to the plenum and plug them.
3) Now re add those unplugged lines one at a time to the plenum looking for a change
4) while not running unplug the line going to the MPS from the plenum and put 20inhg on the unplugged line that goes to the the MPS and plug the plenum then start engine and check again?

[emerygt350]

That was my first thought. But you don't have your advance hooked up right?

Best thing to do is cap everything now and slowly readd. Get it warm, then plug it all. Aar, retard, decel, etc. you can even check the mps by pulling the vacuum off the plenum while it is running and plug it with your finger. It will be rich but it shouldn't rev once you plugged it. If you have a vacuum pump you can just put 20inhg in the hose going to the mps and plug the plenum.

If everything is plugged and it's still at 1400, grab a can of carb cleaner and start spraying around the plenum, the runner boots, and the injectors. If you don't get any change it has to be your timing (or possibly that combined with a lean idle mix).

After we installed the motor my brother in law used his vacuum pump and verified the advance plate movement in the distributor but he does not live by me so I will go and invest in one . The vacuum off the distributor is no longer hooked up ,it is open to to air now. Once I got that part correct things got much better .You were correct in your previous comments about that and I had it connected wrong. I think I could be close but something is still not quite right.
So let me make sure I understand .
1) get car warmed up with everything hooked up
2) then unplug all lines connected to the plenum and plug them.
3) Now re add those unplugged lines one at a time to the plenum looking for a change
4) while not running unplug the line going to the MPS from the plenum and put 20inhg on the unplugged line that goes to the the MPS and plug the plenum then start engine and check again?

Is your retard hooked up currently? That would nearly bring it down to 900 from 1400. I assume it is hooked up and doing its thing. You may want to play with that vacuum pump and the distributor. When you give it vacuum on the retard does it drop down to 900? Does the idle rise when you remove and plug the vacuum to the retard side of the can?


I believe your list above covers all the bases. Hopefully it isn't a combination of things so keep an eye on any smaller changes.

[Ron914]

Good morning Emery ,
I purchased these last night so I can continue trouble shooting my idle issues .
I want you to to know how much I appreciate yours and others help and patience with me as I try to figure this problem out ,my only regret is I didn't figure out how to post photos on this site 3 years ago . Too bad you are on the east coast and I am on the west coast, would really enjoy to meet you one day and buy you what ever your favors of drink is and chat or do a bike ride with you .

New question a bit out of order until I resolve my current problem .
I am not a mechanic but definitely a do it yourself guy , I hate to play and would rather learn.
When I had my motor rebuilt I upgraded to a 2055 cc .
I see a lot of comments here on the MPS .
You seem to be one of the members that understands the MPS well .
My question is a bit out of order but it seems I might have a future issue because of my upgrade to 2055 or 2056 the shop that put the lower end together for me wrote 2055 on mine .
I will not be able to get to my car today but plan on working on it tomorrow if its not raining .my garage is very tight as you can see so only way I can work on my car is to move something out side .

[emerygt350]

Oh the trouble we go through (IMG:style_emoticons/default/wink.gif).

Someday I hope to take a long road trip in the 914, who knows how far I will get. I have cousins in Huntington Beach, great uncle worked for Howard Hughes.

Tuning the MPS is a bit of a beast. After a couple of years poking at it I think I have determined why it is so hard to get perfect on my 2056. The vacuum profile of the motor is different at cruise. This will also play havoc with your EGR and retard. When it comes time the first thing you will want to do is get a good baseline of what vacuum you are pulling at idle and cruise. My engine pulls so much more than stock that it was activating the retard circuit when it shouldn't have been and same with the advance. Once you start reaching into the throttle it doesn't matter so much but it's the part throttle bits that really get screwy. Don't forget you can use that pump to monitor vacuum in the plenum. Will be interesting to know how much yours is pulling.

[Ron914]

Great to hear you have family in Huntington Beach , maybe it's possible to meet up one day . I have always wanted to ride my bicycle up the up the north east coast during fall sometime . That is not in the cards for a while as I retired 5 years ago and I take care of my 90 year old mother so getting much of a chance for any type of vacation /adventure is just impossible for me right now . I am thankful I can at least get out of the house a few hours a day while she is sleeping and get a shortbike ride in . Seems like we share similar interests road bikes and 914's . I have ridden down the coast of California a few times and can't tell you what a great ride it is an d the comrade of my cyclist friends . This 914 project was sort of a bucket list thing for me since I was no homebound after I retired ,had to find ways that helped my mental state . Again as I said I have skills but I never considered auto mechanics one that I was good at .I have a back up Trek Kamtail carbon bike if you ever get a chance to come visit you family I could let you ride it and I have some great hills and trails to ride on here .I ride a 56cm bike if that would be a fit for you bring your own saddle a pedals and your more than welcome .Hers a photo of some of the crazy (as I am told type of riding )I do ,or used to do .

[emerygt350]

Very cool. Nothing bike related going on for another month here. That and I am fighting pneumonia at the moment. Yuck.

Felt very Bavarian this morning on the way to work. Supposed to be thunderstorms and rain in another couple hours.

[Ron914]

Very cool. Nothing bike related going on for another month here. That and I am fighting pneumonia at the moment. Yuck.

Felt very Bavarian this morning on the way to work. Supposed to be thunderstorms and rain in another couple hours.

Love it , your car is not a garage queen ,although I don't think I would drive my in the snow ,shows how much you love that car .I get it .
Nice looking car

[emerygt350]

If there is salt she hides in the garage. Otherwise I drive it as much as I can. I wouldn't drive it on real snow though.

[Ron914]

Good morning Emery @emerygt350 ,
I finally had a chance to get time to work on my car yesterday .
As before when attempted to start it ,it just cranked over but did not want to start until
I slightly turned the dizzy CW to retard a bit then a quick 2 cranks and it fired up .
As always I never seem to get the same results . I let it warm up .



then I plugged the 10mm that went to the decel & the 5mm then plugged the 10mm that goes to the MPS
connected a 10mm to the MPS and connected my vacuum device ,added 22mmHG to it
when I started the car

Now the car seemed to be idling a where I would expect it to but the motor seemed to hunt a bit 950-1100rpmand if I revered it up say 1800 it seemed to take a second or two to come back down.
I checked with my infrared thermometer to see if gauge was reading correctly

something came up so I had to stop my testing and have not got back to the car so maybe I can get to it today .
I did not remove this from my in line connection for the CHT to the ECU

once when I turned off the car it made a shutter type noise rater than just turn off .
Car still hunts a bit 1-250rpm
My neighbor thought it smelled funny but I just think it was an exhaust smell not hot .
Maybe I can try and figutre out how to post a video but I would have to get a YouTube account I believe.
I did notice the vacuum 22mmHG added to my MPS bleed off
I had tested previously the MPS by pulling app 10-11mmHG

[Ron914]

Good morning Emery @emerygt350 ,
I finally had a chance to get time to work on my car yesterday .
As before when attempted to start it ,it just cranked over but did not want to start until
I slightly turned the dizzy CW to retard a bit then a quick 2 cranks and it fired up .
As always I never seem to get the same results . I let it warm up .



then I plugged the 10mm that went to the decel & the 5mm then plugged the 10mm that goes to the MPS
connected a 10mm to the MPS and connected my vacuum device ,added 22inHG to it
when I started the car

Now the car seemed to be idling a where I would expect it to but the motor seemed to hunt a bit 950-1100rpmand if I revered it up say 1800 it seemed to take a second or two to come back down.
I checked with my infrared thermometer to see if gauge was reading correctly

something came up so I had to stop my testing and have not got back to the car so maybe I can get to it today .
I did not remove this from my in line connection for the CHT to the ECU

once when I turned off the car it made a shutter type noise rather than just turn off .
Car still hunts a bit 1-250rpm
My neighbor thought it smelled funny but I just think it was an exhaust smell not hot .
Maybe I can try and figutre out how to post a video but I would have to get a YouTube account I believe.
I did notice the vacuum 22mmHG added to my MPS bleed off
I had tested previously the MPS by pulling app 10-11mmHG

I think I will hook everything back up and see what happens later and add to this post . We also know my timing has not yet been verified to be spot on and I think after reading BlueLighting's post I should probably check my valve adjustment

[Ron914]

Good morning Emery @emerygt350 ,
I finally had a chance to get time to work on my car yesterday .
As before when attempted to start it ,it just cranked over but did not want to start until
I slightly turned the dizzy CW to retard a bit then a quick 2 cranks and it fired up .
As always I never seem to get the same results . I let it warm up .



then I plugged the 10mm that went to the decel & the 5mm then plugged the 10mm that goes to the MPS
connected a 10mm to the MPS and connected my vacuum device ,added 22mmHG to it
when I started the car

Now the car seemed to be idling a where I would expect it to but the motor seemed to hunt a bit 950-1100rpmand if I revered it up say 1800 it seemed to take a second or two to come back down.
I checked with my infrared thermometer to see if gauge was reading correctly

something came up so I had to stop my testing and have not got back to the car so maybe I can get to it today .
I did not remove this from my in line connection for the CHT to the ECU

once when I turned off the car it made a shutter type noise rater than just turn off .
Car still hunts a bit 1-250rpm
My neighbor thought it smelled funny but I just think it was an exhaust smell not hot .
Maybe I can try and figutre out how to post a video but I would have to get a YouTube account I believe.
I did notice the vacuum 22mmHG added to my MPS bleed off
I had tested previously the MPS by pulling app 10-11mmHG

I think I will hook everything back up and see what happens later and add to this post . We also know my timing has not yet been verified to be spot on and I think after reading BlueLighting's post I should probably check my valve adjustment

If I get a chance today ,I believe I already checked this but I will do it again .

[emerygt350]

Let me see if I understand what you posted. When you plugged the MPS vacuum at the plenum and gave the MPS 22inhg with a warm engine the idle dropped to where it is supposed to be, and the MPS is leaking down as well?

I would double check your valves because it is relatively easy, but check your vacuum at the plenum first, it would be nice to know where it is at currently. Use the MPS port on the plenum. Just hook your mityvac to it and read the vacuum off of that. Be sure the engine is warmish when you do check or at least that the aar is closed or blocked and the leaking MPS is unplugged. If the vacuum is up around 18-20 inhg I might not bother with the valves just yet.

I would also time your engine for the moment using the vacuum method. This is the way people used to time their engines in the old days. Disconnect the retard. Get the engine warm and idling at that 900 again (disconnect the mps or whatever was necessary). Check the vacuum, turn the distributor either way and watch the vacuum. You want to find the highest vacuum with the engine still running well. Then back it down 1-2inhg. If the vacuum is quite high (over 21inhg) I would just bring it down to 19inhg. If 19 or 20 is as high as it goes, I would maybe bring it back 1 inhg so it's between 18 and 19 just to be safe.

If you don't have much faith in your timing marks or the light this should work fine. You could now check the timing with the light and see where you are at idle and all in at 3.5k rpm.

Since you have a 2056 I don't know what to think about the 'euro spec' MPS. Sounds like the daiphragm is busted anyway so you will probably need one of Chris Foley's rebuild kits and at that point you will be tuning your own MPS anyway. I am not sure if the 2056 sucks enough gas over the stock to require that inline resistor though. Your ECU is already richer than the 73 that required that resistor. Better rich than lean and if you have a hunting idle, I would keep it for the time being. You might try richening the ECU pot to see if that hunting idle goes away.

While you are working on this you may just want to keep that retard disconnected until everything is where it should be, then deal with the retard afterward. The nice thing about the retard is that you can put some extra timing into your engine and still have it start up nice and easy but we are not there yet.

[Ron914]

Let me see if I understand what you posted. When you plugged the MPS vacuum at the plenum and gave the MPS 22inhg with a warm engine the idle dropped to where it is supposed to be, and the MPS is leaking down as well?

I would double check your valves because it is relatively easy, but check your vacuum at the plenum first, it would be nice to know where it is at currently. Use the MPS port on the plenum. Just hook your mityvac to it and read the vacuum off of that. Be sure the engine is warmish when you do check or at least that the aar is closed or blocked and the leaking MPS is unplugged. If the vacuum is up around 18-20 inhg I might not bother with the valves just yet.

I would also time your engine for the moment using the vacuum method. This is the way people used to time their engines in the old days. Disconnect the retard. Get the engine warm and idling at that 900 again (disconnect the mps or whatever was necessary). Check the vacuum, turn the distributor either way and watch the vacuum. You want to find the highest vacuum with the engine still running well. Then back it down 1-2inhg. If the vacuum is quite high (over 21inhg) I would just bring it down to 19inhg. If 19 or 20 is as high as it goes, I would maybe bring it back 1 inhg so it's between 18 and 19 just to be safe.

If you don't have much faith in your timing marks or the light this should work fine. You could now check the timing with the light and see where you are at idle and all in at 3.5k rpm.

Since you have a 2056 I don't know what to think about the 'euro spec' MPS. Sounds like the daiphragm is busted anyway so you will probably need one of Chris Foley's rebuild kits and at that point you will be tuning your own MPS anyway. I am not sure if the 2056 sucks enough gas over the stock to require that inline resistor though. Your ECU is already richer than the 73 that required that resistor. Better rich than lean and if you have a hunting idle, I would keep it for the time being. You might try richening the ECU pot to see if that hunting idle goes away.

While you are working on this you may just want to keep that retard disconnected until everything is where it should be, then deal with the retard afterward. The nice thing about the retard is that you can put some extra timing into your engine and still have it start up nice and easy but we are not there yet.

Thanks Emery,
all good suggestions . My day is growing short as we have a dinner party to go to @5:00 so I might not be able to do all this today .Lots of great suggestions . That would great if I didn't have to worry about adjusting the valves today . I am going to have to look up and do some studying it's been almost 50 years since I last did this on my VW's and I read somewhere that I will need to remove my HE's for access this might take a while and I still need to have a TDC mark I can trust . I do have this to help There is a mark on my flywheel and I can see it . Maybe tomorrow when girlfriend is here I can get her to look for the mark when it is aligned where the cases meet and hold my accelerator to 3500 for me . I believe Blue Lighting used this mark in one of his posts . I will jack the car up and put in 5th and turn the rear wheel while she looks for it . Not sure how once aligned I could use that to add a paint pen mark to my cooling fan as I cannot see any marks in the V cutout on my fan.

I only ordered that hot set up resistor because the box of stuff that came with the car had a homemade thingy that looked like an inline resistor ( it feel apart on me ) I had no idea what it was for so I searched and found this on AA site.However the motor was the stock 2.0L although Im not sure why it was in box with the other parts of the motor or if was even connected inline with the CHT. I have the ECU adjustment knob set at 9:00 position as I read somewhere
I am pretty sure I warmed up the car with everything connected then I removed the 10mm & 5mm hoses that went to the decel and plugged them, I removed the 10mm that went to my MPS and clamped it close and added another hose to my MPS and added 20inHG to it and then started the car again.
Now to testing the vacuum on the plenum .
Im a bit confused about how to use the mityvac to test the amount of vacuum in the Plenum so let me think about that one for a bit and Ill get back to you .I like that method
let write a list outlining the steps for you to confirm my understanding in a bit