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Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 22440
Location: Kimball, Mi
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 Posted: Sun Feb 25, 2024 3:02 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| tjmartin317 wrote: |
| Alright Tram, Unplugging TS-1 on intake at dead cold made a world of difference. Every throttle blip was responsive. Upon plugging it back in? Back to choking and sputtering when I touched the gas. I take it that’s a sign that either 1.) I need a new TS-1 or 2.) something is wrong with my end to end connection if the TS and the ECU. |
I believe you've just proven that you were running lean, which means you might have to reset the MPS, or leave TS1 unplugged for now, so it's not running lean. Ray would probably suggest resetting the MPS, while Tram would just leave TS1 unplugged for now until you get everything else correctly set.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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rosevillain
Samba Member
Joined: December 28, 2005
Posts: 1290
Location: roseville, ca
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| Posted: Sun Feb 25, 2024 8:24 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| Everything needs to be checked to figure out why you are running lean. Once everything (ensure that there are no component mis-matches, temp sensors have good readings, fuel pressure is set, valves adjusted, timing correct, TPS adjusted, no vacuum leaks, no bad electrical connections) is good, then adjust the MPS. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21521
Location: Oklahoma City
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| Posted: Sun Feb 25, 2024 10:19 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| Bobnotch wrote: |
| tjmartin317 wrote: |
| Alright Tram, Unplugging TS-1 on intake at dead cold made a world of difference. Every throttle blip was responsive. Upon plugging it back in? Back to choking and sputtering when I touched the gas. I take it that’s a sign that either 1.) I need a new TS-1 or 2.) something is wrong with my end to end connection if the TS and the ECU. |
I believe you've just proven that you were running lean, which means you might have to reset the MPS, or leave TS1 unplugged for now, so it's not running lean. Ray would probably suggest resetting the MPS, while Tram would just leave TS1 unplugged for now until you get everything else correctly set. |
Nope.... not yet. His MPS from his pictures has not been opened up on the adjusting end. Depending on how good the engine internals are and how close to stock they are and how close to stock the vacuum signature is.....sure....it may eventually need an adjustment. But that kind of adjustment is just tweaking....refinements.
Right now from what he is telling us....no vacuum leaks and the induction coils read correctly.....it means the MPS is working. That is also backed up by the fact that it CHANGES the fuel mixture when you plug the hose onto it.....so it's WORKING.
So.....if unplugging the MPS hose.....and plugging that hose.....causes it to start....and run....and with an open to air MPS.....that could only mean very rich......IF .....the fuel pressure is correct and normal......the question is where is it getting the air to add to that excessive fuel?
Ray |
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Tram
Samba Socialist
Joined: May 02, 2003
Posts: 22729
Location: Still Feelin' the Bern- Once you've felt it you can't un- feel it.
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| Posted: Mon Feb 26, 2024 1:23 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| tjmartin317 wrote: |
| Alright Tram, Unplugging TS-1 on intake at dead cold made a world of difference. Every throttle blip was responsive. Upon plugging it back in? Back to choking and sputtering when I touched the gas. I take it that’s a sign that either 1.) I need a new TS-1 or 2.) something is wrong with my end to end connection if the TS and the ECU. |
OK, so you need a definitive test on both temp sensors. If they test good, then we need to trace down exactly why you are running lean. Only when everything checks out do we get to thinking about opening and adjusting the MPS.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21521
Location: Oklahoma City
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| Posted: Mon Feb 26, 2024 6:30 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| Tram wrote: |
| tjmartin317 wrote: |
| Alright Tram, Unplugging TS-1 on intake at dead cold made a world of difference. Every throttle blip was responsive. Upon plugging it back in? Back to choking and sputtering when I touched the gas. I take it that’s a sign that either 1.) I need a new TS-1 or 2.) something is wrong with my end to end connection if the TS and the ECU. |
OK, so you need a definitive test on both temp sensors. If they test good, then we need to trace down exactly why you are running lean. Only when everything checks out do we get to thinking about opening and adjusting the MPS. |
Yes...totally agree. A little lean is one thing. Need to know more about fuel pressure and volume at pump capability too.
Ray |
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tjmartin317
Samba Member
Joined: March 18, 2022
Posts: 246
Location: West Virginia
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| Posted: Mon Feb 26, 2024 7:40 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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Probably a useful bit of information if we’re going to talk fuel pressure, but I installed the Airtex E2000 pump off a Ford Ranger. One of the first things I did, in fact. So I no longer have the 3 port fuel system and I have that aftermarket pump. BUT when I did test fuel pressure at the rail on the left side of the engine, I got 28psi, so fuel pressure should be within spec.
I’ll be taking out TS-2 and doing water tests once I have time to watch a boiling pot and money to buy a thermometer. But what about TS-1 (on the intake?) Is there a specific test procedure for that one? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21521
Location: Oklahoma City
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| Posted: Mon Feb 26, 2024 3:00 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| tjmartin317 wrote: |
Probably a useful bit of information if we’re going to talk fuel pressure, but I installed the Airtex E2000 pump off a Ford Ranger. One of the first things I did, in fact. So I no longer have the 3 port fuel system and I have that aftermarket pump. BUT when I did test fuel pressure at the rail on the left side of the engine, I got 28psi, so fuel pressure should be within spec.
I’ll be taking out TS-2 and doing water tests once I have time to watch a boiling pot and money to buy a thermometer. But what about TS-1 (on the intake?) Is there a specific test procedure for that one? |
Same method, just a different temp range and resistance profile. I will see if I havea listing where I am.
But another thing that can cause a huge amount of lean running is maybe one pair of inje tors not injecting at all. Or intermittent.....or short cycling from odd lyrics adjusted or bent trigger points. Lots of things to ponder.
Test the sensors for now. Ray
Ray |
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tjmartin317
Samba Member
Joined: March 18, 2022
Posts: 246
Location: West Virginia
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| Posted: Sun Mar 10, 2024 3:53 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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Alright, after weeks of being sick/busy/both, I’ve done a test of “both” sensors. Here’s the results of the intake temp sensor:
At about 70 degrees Fahrenheit, I measured 295 to 300 ohms of resistance. Which seems about right for TS-1 (according to the table I found)
As for TS-2…
I swear I was gentle. I cut up a big hole in my 13mm socket to feed the wire through and made sure it didn’t bend… but it did not survive the extraction, so I’ll be getting a new one tomorrow from my local VW guy. Thankfully they’re in abundance, and fairly cheap, unlike the intake.
Perhaps I was getting poor resistance from the head temp sensor all along thanks to a semi-fraying wire… I doubt the solution is that simple but who knows. Either way, it’ll be nice knowing both my temp sensors are fresh (or, at the very least, functional). |
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Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 22440
Location: Kimball, Mi
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| Posted: Mon Mar 11, 2024 12:14 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| tjmartin317 wrote: |
As for TS-2…
I swear I was gentle. I cut up a big hole in my 13mm socket to feed the wire through and made sure it didn’t bend… but it did not survive the extraction, so I’ll be getting a new one tomorrow from my local VW guy. Thankfully they’re in abundance, and fairly cheap, unlike the intake.
Perhaps I was getting poor resistance from the head temp sensor all along thanks to a semi-fraying wire… I doubt the solution is that simple but who knows. Either way, it’ll be nice knowing both my temp sensors are fresh (or, at the very least, functional). |
Sorry, but that ones NFG. It's a goner. I'm surprised the engine even ran with it like that.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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tjmartin317
Samba Member
Joined: March 18, 2022
Posts: 246
Location: West Virginia
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| Posted: Tue Mar 12, 2024 2:49 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| Bob, that’s exactly what I wanted to hear! It means the new sensor I got for nothing at all is possibly going to fix the car! And that makes me incredibly happy! |
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rosevillain
Samba Member
Joined: December 28, 2005
Posts: 1290
Location: roseville, ca
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| Posted: Tue Mar 12, 2024 7:26 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| That sensor certainly was A problem. But was it THE problem? |
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 34023
Location: Conejo Valley, CA
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| Posted: Tue Mar 12, 2024 10:15 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| Careful grounding of the sensor (if you use any anti-seize paste, make sure it is conductive like for O2 sensors), and care in the push-on connector, both change the effective resistance the ECU sees, which is the driving signal from these, so be careful and make tight connections! |
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tjmartin317
Samba Member
Joined: March 18, 2022
Posts: 246
Location: West Virginia
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| Posted: Tue Mar 12, 2024 10:47 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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Well… it didn’t solve the problem. Nice having a shiny new temp sensor in place, but the choking and dying upon the touch of the throttle still lingered. So decidedly not temp sensor related, though the new one did make things a touch better…
For shits and giggle I went to reset timing and not it won’t start. I’m guessing because I ran the engine, warmed it up, and then tried to time it (vacuum advance and all that fun stuff). Will let it cool and retime it tomorrow.
Next best guess after that… fuel injectors? Didn’t want to rip those out again but I suppose if I outta.
I know there’s something about the yellow caps on the injectors causing issues, which I’m fairly certain mine still have on. Any confirmation on that? |
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rosevillain
Samba Member
Joined: December 28, 2005
Posts: 1290
Location: roseville, ca
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| Posted: Tue Mar 12, 2024 11:10 am Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| Have to verified that the trigger contacts for the fuel injection located in the distributor are making and breaking contact with distributor rotation? Oftentimes these don’t make and break as they should. The center pin is common, as the distributor turns, each outside pin should alternately become continuous with the center for about 180°. The two outside pins should never be continuous with each other. When those contacts make(or break I don’t remember), it signals the ECU to fire a bank of injectors. |
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tjmartin317
Samba Member
Joined: March 18, 2022
Posts: 246
Location: West Virginia
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| Posted: Tue Mar 12, 2024 12:31 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| I will say the thing has new points, but they haven’t been checked in a while so I can definitely do that. That said, enough wiggling with the distributor while the car was running and I got timing back in place. Will fiddle with it more another time, when the engine is cold, but that and the temp sensor don’t seem to be the issue, unfortunately… |
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rosevillain
Samba Member
Joined: December 28, 2005
Posts: 1290
Location: roseville, ca
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| Posted: Tue Mar 12, 2024 2:40 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| The ignition points are not the trigger contacts for the fuel injection. And, timing should be set warm. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21521
Location: Oklahoma City
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| Posted: Tue Mar 12, 2024 3:56 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| tjmartin317 wrote: |
| I will say the thing has new points, but they haven’t been checked in a while so I can definitely do that. That said, enough wiggling with the distributor while the car was running and I got timing back in place. Will fiddle with it more another time, when the engine is cold, but that and the temp sensor don’t seem to be the issue, unfortunately… |
Ok....right there. It is what rosevillain was pointing out....or partly attributed to this.
In the bottom of the distributor you have the fuel injection trigger points that connect to the 3 pin plug on the side of the distributor.
What needs to be done as rosevillain was pointing out is to remove the distributor....this is very easy without disturbing the timing. Just leave the clamp tight and remove the 13mm nut that holds the clamp to the case and the clamp stays locked to the distributor.
Once you get it out, pull out the trigger points plate. Clean them with circuit cleaner. No abrasives. If they need tarnish removal...take a piece of brown paper bag and drag it through both contact sets a few times.
Then, take your VOM set on continuity. Put black probe on center pin and red on the left pin of the plug. It should beep. Open the left contact and it should stop beeping. Repeat for the right side. Pin.
Now....just as a background check.....put the black probe on the left pin and the red on the right pin. There should be 0 beep or connectivity. This is what rosevillain was getting at. It's rare but sometimes happens. Corrosion can cause a connection between both trigger point circuits.
The way trigger points work is that the pair of injectors they control....trigger when the points open. And...I believe I am correct.....on some...maybe not all...D-jet...that in order for one trigger set to inject, the opposite one has to cycle first. It's a collapsing circuit. One circuit must fire to enable the second set. In turn the second set must fire to again enable the first set.
Then check the resistance on each side pin between the center ground pin. It should read 1.2 ohms maximum...lower is better....with no more than 0.2 ohms difference between the two sets (more on that later its not a huge deal).
The next thing is install the plate back in the distributor. Put the black probe on center pin and red probe on either left or right pin. Set it for continuity so it beeps whe. You make contact.
Turn the distributor shaft. The trigger set you have your probes on should beep for 180° of rotation. If it beeps longer something is bent or you are touching the probes together. If it beeps shorter than 180° of rotation then the trigger points rubbing block is worn down.
Repeat for other side and let us know what you find. It is possible to bend the fixed points to correct adjustment but let's wait on that until you test. Ray |
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KTPhil
Samba Member
Joined: April 06, 2006
Posts: 34023
Location: Conejo Valley, CA
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| Posted: Tue Mar 12, 2024 4:46 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| raygreenwood wrote: |
What needs to be done as rosevillain was pointing out is to remove the distributor....this is very easy without disturbing the timing. Just leave the clamp tight and remove the 13mm nut that holds the clamp to the case and the clamp stays locked to the distributor.
Ray |
Note that this only works if you have removed the thermostat, flaps, and crossbar from the shroud. Otherwise the crossbar prevents you from removing the distributor with the clamp attached. Otherwise, you have to loosen the clamp and work the distributor up and out without chewing up the O-ring. |
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Bobnotch
Samba Member
Joined: July 06, 2003
Posts: 22440
Location: Kimball, Mi
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| Posted: Wed Mar 13, 2024 1:05 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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| KTPhil wrote: |
| raygreenwood wrote: |
What needs to be done as rosevillain was pointing out is to remove the distributor....this is very easy without disturbing the timing. Just leave the clamp tight and remove the 13mm nut that holds the clamp to the case and the clamp stays locked to the distributor.
Ray |
Note that this only works if you have removed the thermostat, flaps, and crossbar from the shroud. Otherwise the crossbar prevents you from removing the distributor with the clamp attached. Otherwise, you have to loosen the clamp and work the distributor up and out without chewing up the O-ring. |
Yup, that's the way it's designed on a type 3 engine.
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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tjmartin317
Samba Member
Joined: March 18, 2022
Posts: 246
Location: West Virginia
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| Posted: Mon Mar 18, 2024 2:34 pm Post subject: Re: 72 Manifold Pressure Sensor Issues? |
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I’ve removed the distributor before, to replace the condenser. Am fine with having to redo timing, because I know it probably isn’t accurate. Did some fiddling with it, forcing it to be advanced or retarded at certain points… because…
Threw some tags on and went for a real drive!!! I know I shouldn’t have, as the car isn’t perfect yet, but it was time. I wanted to see how Fargo would do. And he did fairly well!
About an hour of nonconsecutive driving. We reached a top speed of 50 miles an hour on backroads (no highway yet, I’m not quite mentally ready for that). The first 30 minutes were very smooth, a little bit of trouble on hills but nothing dire. Stopped the car and then did a hot start about 10 minutes later. Fargo suddenly developed more noticeable shakes and misfires. And under load/uphill it was pretty keen on popping. Did 15 minutes, stopped for lunch, then another 10 minutes home.
Still not the most responsive pedal. And the odd thing is that when you rev the engine it doesn’t immediately go back to idle. In fact, when you stab the throttle, it thinks for all of a moment, goes up, then goes down but it idles high for at least 5 seconds. Then it returns to a normal idle speed.
Sounds like a timing thing. Could it be a deceleration valve thing? I’m not certain, but what I am certain of is that this car is surprisingly easy to drive, and I can’t wait to get it to a point where I’m confident taking it longer distances. Already very impressed.
Especially considering we started with a non-running non-driving floorless car exactly two years ago:
Photos taken on March 18th, 2022  |
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