(now that I am writing this, the answer may be somewhere on the forum already.. if so don't worry about responding. when I leave work I will search myself)
F.I. engine idle goes up and down.. up and down.. up and..
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
I am still a little unsure of the best way to search for vacuum leaks, I replaced the vacuum lines (except the intake runner boots, I am planning to do those soon) and put clamps or zip-ties on all of them, and it didn't affect the idle at all. I have been searching around forums for pictures of engine compartments and I have more clamps than any I have seen! I have sprayed carb cleaner around the engine compartment with no affect, is there another method? I put the lines under vacuum pressure and it held steady. What else should I do?
(now that I am writing this, the answer may be somewhere on the forum already.. if so don't worry about responding. when I leave work I will search myself)
(now that I am writing this, the answer may be somewhere on the forum already.. if so don't worry about responding. when I leave work I will search myself)
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Piledriver
- Moderator
- Posts: 22520
- Joined: Sat Feb 16, 2002 12:01 am
Vac leaks are only one possibilty... The MAP sensor must hold vacuum ~ perfectly itself (cracked diaphram) etc.
I use brake CLEANER, the chlorinated kind.
(I never knew there was non-chlorinated until someone mentioned it here)
Set the idle speed //do a good tune up and see what happens..
I use brake CLEANER, the chlorinated kind.
(I never knew there was non-chlorinated until someone mentioned it here)
Set the idle speed //do a good tune up and see what happens..
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
I sound like a broken record. I seem to bewriting a dissertation on this over in the Samba.....but my bet is that you have harness issues as well as a few vacuum leaks you have not yet found. If cleaning the grounds changed ANYTHING (which it usually does)....chances are you have issues all over the harness. The ground connectors actually are less sensitive to vibration that the injector, MPS and sensor plugs. Ray
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
Situation so far
OK, hoses are new and clamped, injectors and seals have been replaced, (still working on intake runner boots), I opened up the MPS and cleaned it out, more greasey than oily- and it does hold vacuum, ground wires are all cleaned and "greased". Here is where I am:
When the car is started cold it starts and idles well, after about 2 minutes the idle begins surging, after about 5 more minutes the idle settles down and sounds great!
The jumping at slow constant speed comes and goes, (I think it has something to do with the TPS but I could be wrong).
It seems that the more it warms up the worse it runs- I seem to remember reading that the valves must be adjusted both cold AND warm, but I am not exactly sure how to adjust them hot.
Speaking of which, when I am adjusting the valves how tight is the tolerance? ie, the book says to use a 0.06 feeler and tighten until "it drags slightly" does that mean a 0.07 should not fit? It seems to me that when I do this the car runs poorly when hot.
I honestly am spending A LOT of time searching forums for tips, (thesamba- fi problems and MPS discussion for example) but so much of the adjustments appear to be more of an art than technicality.
Tomorrow I am building a fuel gauge, replacing the runner boots, and adjusting the valves again. Besides the rolling idle at warm-up the car also shudders at higher speeds, like I am slightly tapping the brake. It sounds like a misfire so I am going to look at the timing as soon as I can get someone to figure out why my tach reads between 250 and 400 rp, at idle.
I know this sounds like a mess, and the most frustrating part is that my uncle who had the car for the last few years assures me that after his mechanic rebuilt the engine it ran great for the few months before I got it. The rolling idle only began about a week or so before I picked up the car.
I am doing my best, and I really appreciate the advice. I know there are a few things you have told me to do that I have not checked yet, but I am limited by time and tools (11 month old baby, and a pregnant wife). Hopefully I can get it running smoothly by spring.
When the car is started cold it starts and idles well, after about 2 minutes the idle begins surging, after about 5 more minutes the idle settles down and sounds great!
The jumping at slow constant speed comes and goes, (I think it has something to do with the TPS but I could be wrong).
It seems that the more it warms up the worse it runs- I seem to remember reading that the valves must be adjusted both cold AND warm, but I am not exactly sure how to adjust them hot.
Speaking of which, when I am adjusting the valves how tight is the tolerance? ie, the book says to use a 0.06 feeler and tighten until "it drags slightly" does that mean a 0.07 should not fit? It seems to me that when I do this the car runs poorly when hot.
I honestly am spending A LOT of time searching forums for tips, (thesamba- fi problems and MPS discussion for example) but so much of the adjustments appear to be more of an art than technicality.
Tomorrow I am building a fuel gauge, replacing the runner boots, and adjusting the valves again. Besides the rolling idle at warm-up the car also shudders at higher speeds, like I am slightly tapping the brake. It sounds like a misfire so I am going to look at the timing as soon as I can get someone to figure out why my tach reads between 250 and 400 rp, at idle.
I know this sounds like a mess, and the most frustrating part is that my uncle who had the car for the last few years assures me that after his mechanic rebuilt the engine it ran great for the few months before I got it. The rolling idle only began about a week or so before I picked up the car.
I am doing my best, and I really appreciate the advice. I know there are a few things you have told me to do that I have not checked yet, but I am limited by time and tools (11 month old baby, and a pregnant wife). Hopefully I can get it running smoothly by spring.
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
Ok....there are a couple of things to get into.
(1) Valve adjustment. As you have noticed, D-jet is very sensitove to valve adjustment. In general valve adjusting I use a go/no-go system. I use a .006" blade (checked with a micrometer to make sure its .006"). It should fit with decent drag. tight enough that a .007 gauge will not fit at all without enough force to crease the blade. In many peoples boo that is a .0055" or .00575" blade. But if a blade is .007"...it should not fit into a .006" gap at all.
I adjust them cold like factory...and drive for about 20-30 minutes and then pull over. With intake and valve points marked on the pulley....I quickly turn the engine over with a wrench to get exactly on one valve sets adjusting point. Then....pop that valve cover and with a glove a rag and a pair of feeler gauges...check tthe valve lash on one cylinder only.
In general...you will find that most .006" lash settings close to about .003" or .0025".
Check one set at a time with 10 minutes driving in between. Record tehm all. Do this several times to check consistency and getand idea of how each valve expands differently than the others.
If I find valves consistently closing to .002 or less...I adjust them that extra .001". If they are staying open to .004" or .005" adjust them .001" tighter at a time. You are looking for consistency between them all. It makes a diference.
Its remotely possible that vibration and a tight throttle cable might be causing an occasional miss from a TPS adjusted just on the egde of where it should be...but in general...with your foot far away from teh gas pedal...your TPS has nothing to do with idle.
The most probable cause is slop in teh distributor weights and springs or slop in the drive dog and breaker plates. You can see this at specified idle with a timing light connected. If teh idle is moving around more than 2-3 degrees each side of teh idle timing mark...you have slop....and we can tell you how to get rid of it.
The other common problem that causes exactly what you are seeing is teh CHT banking heat. As it gets too warm...itdrops resistance and leans your mixture excesively. Measure ohms cold...then warm while wraming up...then again when it starts acting up. Tell us what you see.
You can do this without turning the car off by poking the positive lead into the T-1 connector of the CHT and keeping the black lead grounded to the case or head. Usually when you get down to about 125 ohms or less it can be a problems if your fuel mixture is not spot on in the first place.
Have you checked you MPS for leaks? It must hold vacuum indefinately. If you have a pressure switch under the intake runners of your model...check that for vacuum leaks. leaks in either can cause this. Let us know how things go. Ray
(1) Valve adjustment. As you have noticed, D-jet is very sensitove to valve adjustment. In general valve adjusting I use a go/no-go system. I use a .006" blade (checked with a micrometer to make sure its .006"). It should fit with decent drag. tight enough that a .007 gauge will not fit at all without enough force to crease the blade. In many peoples boo that is a .0055" or .00575" blade. But if a blade is .007"...it should not fit into a .006" gap at all.
I adjust them cold like factory...and drive for about 20-30 minutes and then pull over. With intake and valve points marked on the pulley....I quickly turn the engine over with a wrench to get exactly on one valve sets adjusting point. Then....pop that valve cover and with a glove a rag and a pair of feeler gauges...check tthe valve lash on one cylinder only.
In general...you will find that most .006" lash settings close to about .003" or .0025".
Check one set at a time with 10 minutes driving in between. Record tehm all. Do this several times to check consistency and getand idea of how each valve expands differently than the others.
If I find valves consistently closing to .002 or less...I adjust them that extra .001". If they are staying open to .004" or .005" adjust them .001" tighter at a time. You are looking for consistency between them all. It makes a diference.
Its remotely possible that vibration and a tight throttle cable might be causing an occasional miss from a TPS adjusted just on the egde of where it should be...but in general...with your foot far away from teh gas pedal...your TPS has nothing to do with idle.
The most probable cause is slop in teh distributor weights and springs or slop in the drive dog and breaker plates. You can see this at specified idle with a timing light connected. If teh idle is moving around more than 2-3 degrees each side of teh idle timing mark...you have slop....and we can tell you how to get rid of it.
The other common problem that causes exactly what you are seeing is teh CHT banking heat. As it gets too warm...itdrops resistance and leans your mixture excesively. Measure ohms cold...then warm while wraming up...then again when it starts acting up. Tell us what you see.
You can do this without turning the car off by poking the positive lead into the T-1 connector of the CHT and keeping the black lead grounded to the case or head. Usually when you get down to about 125 ohms or less it can be a problems if your fuel mixture is not spot on in the first place.
Have you checked you MPS for leaks? It must hold vacuum indefinately. If you have a pressure switch under the intake runners of your model...check that for vacuum leaks. leaks in either can cause this. Let us know how things go. Ray
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Piledriver
- Moderator
- Posts: 22520
- Joined: Sat Feb 16, 2002 12:01 am
Ray makes a very good point (as always)
If the idle speed is above where the mechanical advance starts, the motor is ~guaranteed to "hunt" at idle, esp if the mixture isn't perfect.
I have never recurved a DJET distributor, but I know it can make a huge difference on performance/drivabilty off idle.
If the idle speed is above where the mechanical advance starts, the motor is ~guaranteed to "hunt" at idle, esp if the mixture isn't perfect.
I have never recurved a DJET distributor, but I know it can make a huge difference on performance/drivabilty off idle.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
Thank you for the info about valve adjusting, it is EXACTLY what I was after. I am going to work on it tomorrow. As for the TPS, I have seen on a few of your threads where you say no one has written the correct method of adjusting the TPS since all the pictures accompanying the literature are for the wrong model. What is the correct way to adjust the TPS on a '70 squareback? Just between you and me (and anyone else reading this) the way I adjusted mine was to loosen the adjustment screw and shift it one direction and rev the idle to see what happens, then shift it slightly back the other way and rev it again to see if its improved. I continued shifting the TPS until the throttle seemed responsive at accel, and cut fuel at decel within a reasonable time. After I tighten the screw, I can slowly rev the engine throttle with the engine off and clearly hear all 20 clicks; but I don't think that is a very accurate way to make the adjustments, especially since the more I read about the TPS's the more exact they seem to have to be.Its remotely possible that vibration and a tight throttle cable might be causing an occasional miss from a TPS adjusted just on the egde of where it should be...but in general...with your foot far away from teh gas pedal...your TPS has nothing to do with idle.
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
Having the valves adjusted really quiets the cabin noise! I worked on it this morning and got the valves just right at least for the Reno winter 
I did find however that the MPS is in fact not holding a vacuum at all. I opened it up and cleaned it out (per another one of Ray's threads) and reassembled it, but it still does not hold vacuum. It looks like it has been tampered with. Is it possible to rebuild, or do I need to find another one?
The car runs well, still hunts for idle for the first few minutes warming up; but once warm it sounds good. It does shudder, or bounce- I am not really sure how to describe the slight bouncing hesitation while running, nothing like the whiplash effect it had before at slow speeds, but much more gentle tug here and there- I imagine it might have something to do with the MPS.
In the mean time I will search for another MPS (and look over the MPS discussion on the Samba). I would prefer to rebuild this one though if it is not impossible.
I did find however that the MPS is in fact not holding a vacuum at all. I opened it up and cleaned it out (per another one of Ray's threads) and reassembled it, but it still does not hold vacuum. It looks like it has been tampered with. Is it possible to rebuild, or do I need to find another one?
The car runs well, still hunts for idle for the first few minutes warming up; but once warm it sounds good. It does shudder, or bounce- I am not really sure how to describe the slight bouncing hesitation while running, nothing like the whiplash effect it had before at slow speeds, but much more gentle tug here and there- I imagine it might have something to do with the MPS.
In the mean time I will search for another MPS (and look over the MPS discussion on the Samba). I would prefer to rebuild this one though if it is not impossible.
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
What year is your car? Do you have the late MPS with the copper diaphram in the back?....and what is your TPS part #?
If I know the TPS part # I can look at one I have of the same part # and put together an instructionsheet for how toadjust.
The key to accurate adjusting is...as you note but many people miss.....revving or moving the TPS after adjusting to insure that it does in fact end up at the properly adjusted starting point. Because of a certain leve lof built in slop to the floating throttle shaft coupler of certain TPS models...its quite common to do the adjustment just like the book says...and in fact still not have the wiper arm sitting in the exact correct throttle closed position. Ray
If I know the TPS part # I can look at one I have of the same part # and put together an instructionsheet for how toadjust.
The key to accurate adjusting is...as you note but many people miss.....revving or moving the TPS after adjusting to insure that it does in fact end up at the properly adjusted starting point. Because of a certain leve lof built in slop to the floating throttle shaft coupler of certain TPS models...its quite common to do the adjustment just like the book says...and in fact still not have the wiper arm sitting in the exact correct throttle closed position. Ray
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
I have a 1970 squareback. The MPS does have the copper diaphragm. I opened it and removed the stopblock (sp?), diaphragm, metal washer-like ring, and copper washer-like ring, leaving the cap with the air holes, and hole where the epoxy plug would have been. I tested it before I opened it and it would hold about 5lbs of vacuum. If I applied 20lbs it would drop to 5 and hold for a bit. After I opened it, cleaned the oil and grease out, and reassembled it- no vacuum at all. Like sucking air through a straw. (strange that the car runs well...)
I can't find where I wrote down the part #, but the MPS is just like the pics here:
http://members.rennlist.com/pbanders/ma ... isassembly
with two exceptions, the two halves are screwed together, no rivets; and the adjustment screw under the epoxy (in the pic, mine has no epoxy) is really small on mine rather than the large on on the website.
I am still not sure of the part # of my TPS, I will get that when it is light out and let you know.
One more thing... I thought it was of no consequence but it may be something, my generator light is on almost all the time. It lights up brightly at ignition then settles to a dull glow the rest of the time. I thought it was light leaking from another indicator; but the more I inspect it, no other indicators are lit. I only mention it because on the ...members.rennlist.com/pbanders... site there is an Idle Stability page somehow linking a lit generator light with idle instability.
ps. I just added MPS pics to thesamba gallery under
http://images.thesamba.com/vw/gallery/pix/513626.jpg
and pics of my engine:
http://images.thesamba.com/vw/gallery/pix/513642.jpg
I can't find where I wrote down the part #, but the MPS is just like the pics here:
http://members.rennlist.com/pbanders/ma ... isassembly
with two exceptions, the two halves are screwed together, no rivets; and the adjustment screw under the epoxy (in the pic, mine has no epoxy) is really small on mine rather than the large on on the website.
I am still not sure of the part # of my TPS, I will get that when it is light out and let you know.
One more thing... I thought it was of no consequence but it may be something, my generator light is on almost all the time. It lights up brightly at ignition then settles to a dull glow the rest of the time. I thought it was light leaking from another indicator; but the more I inspect it, no other indicators are lit. I only mention it because on the ...members.rennlist.com/pbanders... site there is an Idle Stability page somehow linking a lit generator light with idle instability.
ps. I just added MPS pics to thesamba gallery under
http://images.thesamba.com/vw/gallery/pix/513626.jpg
and pics of my engine:
http://images.thesamba.com/vw/gallery/pix/513642.jpg
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
STOOOOOP!
REMOVE NOTHING FROM THE MPS EVER!
Sorry for shouting....but (1) the aluminum plug in the back is not a plug. It is the outer full load enrichment stop and has a very specific adjustment. (2) Removing any of the washers inside changes the adjustment of the inner full lean stop.
Without all of its parts in all of the right places the MPS will never operate properly.
Ok..this is an edit....
...sorry...it seemed from reading ypur post that you had "removed" things and not put them back...sorry...carry on!
The most likely culprit of leakage is either the main o-ring or the seal between the copper plate and the body of the MPS.
The difficulty of replacing teh o-ring of the body is that it is a "fitted" or shaped o-ring and is not round in cross section. If you find an o-ring fat enough in cross section to seal....it changes the fit of the body enough that significant adjustment will be required.
Clean the body o-ring well and all of the mating surfaces of all parts...with electronics cleaner. Get some permatex ultra copper or ultra black. What you want to do is "treat" o-ring and the mating surfaces with only the THINNEST smear of RTV that you can possibly imagine. It must be virtually transpartent. Handling parts with tweezerss so as not to mar andy film of RTV...reassemble and lt dry for about 6 hours. This will solve most leakage issues with no appreciable change to dimensions.Ray
REMOVE NOTHING FROM THE MPS EVER!
Sorry for shouting....but (1) the aluminum plug in the back is not a plug. It is the outer full load enrichment stop and has a very specific adjustment. (2) Removing any of the washers inside changes the adjustment of the inner full lean stop.
Without all of its parts in all of the right places the MPS will never operate properly.
Ok..this is an edit....
...sorry...it seemed from reading ypur post that you had "removed" things and not put them back...sorry...carry on!The most likely culprit of leakage is either the main o-ring or the seal between the copper plate and the body of the MPS.
The difficulty of replacing teh o-ring of the body is that it is a "fitted" or shaped o-ring and is not round in cross section. If you find an o-ring fat enough in cross section to seal....it changes the fit of the body enough that significant adjustment will be required.
Clean the body o-ring well and all of the mating surfaces of all parts...with electronics cleaner. Get some permatex ultra copper or ultra black. What you want to do is "treat" o-ring and the mating surfaces with only the THINNEST smear of RTV that you can possibly imagine. It must be virtually transpartent. Handling parts with tweezerss so as not to mar andy film of RTV...reassemble and lt dry for about 6 hours. This will solve most leakage issues with no appreciable change to dimensions.Ray
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
I got the RTV and I want to make sure I am reassembling this correctly. Based on the pics in my last post:
First the "cap" (#1 in pic)
Place the copper washer-like ring inside the cap (#5)
Then place the metal washer-like ring (#4)
Then the copper diaphragm (#3)
Then the stop-block indent outward away from diapragm (#2)
Seal it all up once the RTV has dried. Correct? All items in proper order? I only ask because as I said, it held vacuum BEFORE I opened it, and doesn't now. I worry I put it together wrong.
p.s. The main o-ring looks good, but I am using RTV anyway.
First the "cap" (#1 in pic)
Place the copper washer-like ring inside the cap (#5)
Then place the metal washer-like ring (#4)
Then the copper diaphragm (#3)
Then the stop-block indent outward away from diapragm (#2)
Seal it all up once the RTV has dried. Correct? All items in proper order? I only ask because as I said, it held vacuum BEFORE I opened it, and doesn't now. I worry I put it together wrong.
p.s. The main o-ring looks good, but I am using RTV anyway.
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
Uh..I think I know the problem. There is no copper washer inside of the back cap. In most cases there is a very thin and stiff gasket....that may look a little like bakelight and is usually oily? It goes between cap and copper diaphram. That is a gasket that can use just a thin smear of sealant after cleaning off all of the oil. Now,...if you have a ring of copper with four screw holes in it....that is about 10mm wide and surrounds the diphram....that is actually theedge of the diaphram that has broken off....and that would be your problem. Ray
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squarebackagain
- Posts: 25
- Joined: Wed Oct 01, 2008 9:25 pm
Then I am not sure what I am dealing with. Maybe you can look at this picture and tell me what is what...
http://images.thesamba.com/vw/gallery/pix/513626.jpg
Thanks
Shawn
http://images.thesamba.com/vw/gallery/pix/513626.jpg
Thanks
Shawn
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raygreenwood
- Posts: 11895
- Joined: Wed Jan 22, 2003 12:01 am
Ok...cool. The brown ring #5 ...I think...is not copper. Its actually a vegetable parchment gasket. It will feel very stiff because its baked and aged. That should go into the cover first. Its the seal between the copper diaphram....which yours appears to be intact.....but look for fine cracks around the edge.....and the outer housing.
The silver metal ring...if memory serves.....goes on top of teh copper diaphram...then the dished stop plate on top of that...then the screws and washers.
Let me look at one of mine tonight and make sure of the order of that silver metal ring.
The problem with that gasket is that once its disturbed its no longer flexible enough to seal. But...you will hard pressed finding a gasket paper that is that exact thcikness. So....cutting a new gasket will change the adjustment of the MPS.
I carefully clean.....soak it and blot it until no more color comes off....the original gasket in something like b-12 chemtool. Dry it well overnight.....and like I noted...smear it with an almost transparent layer of RTV. You may pick up about 1/2 to 1 thousandth of an inch. Ray
The silver metal ring...if memory serves.....goes on top of teh copper diaphram...then the dished stop plate on top of that...then the screws and washers.
Let me look at one of mine tonight and make sure of the order of that silver metal ring.
The problem with that gasket is that once its disturbed its no longer flexible enough to seal. But...you will hard pressed finding a gasket paper that is that exact thcikness. So....cutting a new gasket will change the adjustment of the MPS.
I carefully clean.....soak it and blot it until no more color comes off....the original gasket in something like b-12 chemtool. Dry it well overnight.....and like I noted...smear it with an almost transparent layer of RTV. You may pick up about 1/2 to 1 thousandth of an inch. Ray