1992 Passat Diff. fuel press. regulator

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Sawbones

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1992 Passat, 2 liter 16 valve.
With the engine running, sitting in place and revving it, it dumps a lot of smoke and runs very rich. Idles OK and it's driveable. When you're driving and you go from off/light throttle to "some" throttle it starts jerking. When you get past about 1/4 throttle it smooths out. I have no evidence to suspect it, but someone on a different site told me the differential fuel pressure regulator. It's the plastic block looking device with an electrical connection that attaches to the side of the fuel distributor. Yesterday I removed this regulator, blew carb cleaner and Marvel oil, compressed air and I was smacking it with a plastic screwdriver handle thinking maybe it was locked at a full pressure position. I tested it for resistance per the Bentley and it comes to 19 ohms so that's at least in spec. I was thinking to give it straight 12V and look/listen if anything moves inside it but I don't know if that would smoke it so I didn't do that. I was thinking to unplug it and see if the vehicle still runs the same way and that might be an indication that it's messed up. I don't know how else to test this thing. I thought about adapting an older CIS from a Rabbit/MK1 Golf. I'm really thinking about that Boggs Brothers manifold and carb setup but four carbs... I don't like four carbs. Also it's $1200. I wouldn't mind bolting another DFPR to it to see if it does something different but I can't find one for less than $200 and I don't know if that will do any good for me. A few months back I had it hooked up and it gave me this code. I was thinking to remove my ECU and take it to my Friend who is really good with electronics and have him go over it for leaking caps or blown resistors or any kind of trauma. I don't know where it is and if it's filled with epoxy as some manufacturers like to do.

I've replaced the injectors, the cold start is giving three nice puffs and then stops, no dribbling. The idle speed is at least very close if not dead nuts. I didn't have the metric feeler gauges so I had to come as close as I could with SAE feelers. I made the test/patch harness (VW 1315A/1) to dial in that 3mm Allen screw in the air flow sensor assembly and had it bouncing from damn near zero to about 4.5ma. I did the fuel delivery and volume test where you remove the fuel pump relay and jumper it out to keep the fuel pump running.


Anyone have any thoughts on any of this mess? Have you done the Boggs carb swap? Do you have a DFPR that you won't miss? Are you perhaps in northeast PA and happen to have the Holy Apparatus to really go over this thing? I need to have this thing back somehow. Right now I'm fueling an 87 Bronco with the 5 liter engine and it's killing me... My next fallback is a 71 Chevy C-20 and that gets about 8MPG on a good day...

Serenity now... Serenity now... Serenity now...
 
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Uwe

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I tested it for resistance per the Bentley and it comes to 19 ohms so that's at least in spec. I was thinking to give it straight 12V and look/listen if anything moves inside it but I don't know if that would smoke it so I didn't do that.
I would NOT do that. It works on current. I've forgotten what the currents involved are, but IIRC, it's less than 100 mA, and if you put 12V across it 19 ohms, it will draw ~630 mA.

If you wanna test this, use a "lab" supply with an adjustable current limit, or some 1.5V batteries and measure the current with a meter. I'd start with a single 1.5V battery and see what happens, then perhaps put two in series for 3V and again see what happens.

-Uwe-
 
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I would NOT do that. It works on current. I've forgotten what the currents involved are, but IIRC, it's less than 100 mA, and if you put 12V across it 19 ohms, it will draw ~630 mA.

If you wanna test this, use a "lab" supply with an adjustable current limit, or some 1.5V batteries and measure the current with a meter. I'd start with a single 1.5V battery and see what happens, then perhaps put two in series for 3V and again see what happens.

-Uwe-
Understood. That sounds reasonable. Do you think a functional one will give any sort of audible cue if it's doing anything?
 
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You need a test harness to test mv. of differential fuel pressure regulator while watching fuel pressure react to the amount of currant.
As Uwe said IIRC. LOL These are old and most tech's that know CIS-E are dead or retired.
Believe it or not you maybe in luck. I have the tools for CIS-E and your real lucky that I live in Wilkes-Barre, PA. also. That is amazing! LOL
P.M. me a phone # and I will reach out to you. Actually have a lot of use parts also. Mostly Jetta GLI and Golf GTI

Good Luck
 
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Uwe

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As Uwe said IIRC. LOL
My wife and I had a number of CIS cars (1977 Rabbit, 1984 GTI, 1985 Jetta, 1985 MBZ 190E 2.3, 1989 GTI-16V), but never a CIS-E / Motronic like the 1992 Passat had.

-Uwe-
 
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My wife still drives a 1990 Jetta Carat.
She learned to drive late in life only car she ever drove.
Been trying for years to get her to take a newer car. Damn thing won't die! Best damn car V.W. ever made.
It's like her Cat she just won't let me get rid of it. Drives me nuts.

Good Luck
 
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Sawbones

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You need a test harness to test mv. of differential fuel pressure regulator while watching fuel pressure react to the amount of currant.
As Uwe said IIRC. LOL These are old and most tech's that know CIS-E are dead or retired.
Believe it or not you maybe in luck. I have the tools for CIS-E and your real lucky that I live in Wilkes-Barre, PA. also. That is amazing! LOL
P.M. me a phone # and I will reach out to you. Actually have a lot of use parts also. Mostly Jetta GLI and Golf GTI

Good Luck

I think I sent you a PM. I clicked on your name and started a conversation. I talked to someone in Wilkes Barre a while back, it may have been you. VW Stan? I have the test harness where I can jack in on the DFPR circuit but I don't have the gear to measure fuel pressure. One thing I noticed while doing the fuel delivery and volume test with the injectors out, as I lift that air flow sensor plate, the injectors don't start going all at once. IIRC it went #2 #1 #3 #4 as I lift the plate. I'd think as soon as I move that plate up, all the injectors would start at the same time. Nature of the beast? I don't know but it doesn't seem right. I also went over it with a home brew smoke machine and ether checking for vacuum leaks but found nothing there.
 
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Sawbones

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My wife and I had a number of CIS cars (1977 Rabbit, 1984 GTI, 1985 Jetta, 1985 MBZ 190E 2.3, 1989 GTI-16V), but never a CIS-E / Motronic like the 1992 Passat had.

-Uwe-

I'm used to those. I can work with those. If those CIS start giving me fits it's not hard at all to carburate them and I even have a breaker point distributor that works with them. The intake manifold from a VW powered 1981 Dodge Omni bolts right up. From there you can use the 2bbl Holley that comes with it or you can make adapters for whatever you like. Life was good back then.
 
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Sawbones

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My wife still drives a 1990 Jetta Carat.
She learned to drive late in life only car she ever drove.
Been trying for years to get her to take a newer car. Damn thing won't die! Best damn car V.W. ever made.
It's like her Cat she just won't let me get rid of it. Drives me nuts.

Good Luck

I'd love to have anything MK3 or earlier. I have this thing listed on FB Marketplace for $3500 or a swap, got a few hits but noone followed through. I figure I'm stuck with it. If not for this fueling issue it'd be a great car. Overengineered and kind of a pain in the rear to work on but the rest of it is in good shape and it's a good ride with decent mileage. Plus I love station wagons. I really miss Rabbits and Quantums.
 
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Uwe

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The intake manifold from a VW powered 1981 Dodge Omni bolts right up. From there you can use the 2bbl Holley that comes with it or you can make adapters for whatever you like. Life was good back then.
Ick! I would never consider converting an amazingly clean and efficient running (for its time) CIS engine to use a carburetor.

-Uwe-
 
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Ick! I would never consider converting an amazingly clean and efficient running (for its time) CIS engine to use a carburetor.

-Uwe-
I did it because I had a CIS that I was unable to get working right. This was on a 1984 Audi 4000. It sat for years with fuel in it and was pretty much junk. It was full of sludge from stem to stern. I figured if I was ripping it all out to replace it I'd make it simpler to work on. The mileage wasn't horrible and it ran alright. It was also something I wondered if I could do it or not. I ended up ditching the Holley and adapting a small Rochester(I think) that would have gone to something like a Studebaker inline 6 engine.
 
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VW Stan is the name the younger generation gave me in Wilkes-Barre area. So if you spoke to VW Stan it was me. Was I an asshole? Sometime that happens...
I do remember a conversation about an older Passat with CIS-E just not the details of the conversation.
Problem is I got this disorder called O.L.D. Only gets worse and there is no cure!

Usually if I speak to someone I don't know on the phone about a CIS system. I am very blunt!!! Someone that doesn't know me would take offense.
To actually get me to look at or fix CIS would not be cheap. But cheaper then driving a "87 Bronco with the 5 liter engine and it's killing me..." They are a PITA! No self diagnostics that really works well. Even if it uses the 2+2 connector.

First and foremost is fuel system pressure then control pressure. You said: "I don't have the gear to measure fuel pressure." That's not good!
Second would be ECU electrical tests. This is done by back probing all the ECU pins with a digital Volt meter. Because there isn't really much data using 2+2 and VCDS. Again PITA.
Third is vacuum leaks. Not only is vac. important but any leak takes vac. away from lifting the sensor plate. Lifting of plate controls how much fuel is delivered.
"home brew smoke machine" Again not good! Smoke machine isn't cheap and if you could make your own who would buy one?

With all this said if you still have my phone # give a call and we can start over. I will try not to be a dick. LOL. Key word is try.....
But I am very blunt and sometime truth hurts. A lot of people have trouble hearing the truth.
I wish Jack who is not longer with us on this forum was around. He was my hero on being a Dick, Asshole and Blunt. He made me look like a pussy cat.
If you don't have my # tell me I will call you. Your P.M. worked I just didn't call because I figured I offended you last time.

You are also correct all four injectors should spray fuel at same time when sensor plate is lifted.

Good Luck
 
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Uwe

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Was I an asshole? Sometime that happens...
tyFGzUy.gif


I wish Jack who is not longer with us on this forum was around. He was my hero on being a Dick, Asshole and Blunt. He made me look like a pussy cat.
Truth!

-Uwe-
 
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Sawbones

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VW Stan is the name the younger generation gave me in Wilkes-Barre area. So if you spoke to VW Stan it was me. Was I an asshole? Sometime that happens...
I do remember a conversation about an older Passat with CIS-E just not the details of the conversation.
Problem is I got this disorder called O.L.D. Only gets worse and there is no cure!

You were direct and I really appreciate that. I'm sick to death of candy coated bullshit because it's always hogwash. I still have your phone number. I'll have to figure out transporting this thing to you. I took it off the road as it's probably not great to drive it. I'll get a few hundo scraped together to get us started and get in touch. Long story short, runs rich, transition from off to on throttle makes it buck, runs pretty crappy when it's at operating temp. Not much for pecker tracks. Mostly stock.
 
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Sawbones

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I wish Jack who is not longer with us on this forum was around. He was my hero on being a Dick, Asshole and Blunt. He made me look like a pussy cat.
If you don't have my # tell me I will call you. Your P.M. worked I just didn't call because I figured I offended you last time.

You are also correct all four injectors should spray fuel at same time when sensor plate is lifted.

Good Luck
I knew a guy, Bob Hartmann. He was a Doctor on these things. He was VW trained and absolutely everything was by the book for him. He had all the gear and the know how to use it. Once he passed on, his Kids pretty much grabbed anything that looked like money. I got to clean out the rest. I can't complain as I'll never want for things like wheel bearing grease and other consumables but there were a couple of tools that I'd have been able to use as well as a hoard of parts for air and water cooled engines. I sent another message with some details as I kind of suck on the phone. I'll get with you when I have a little wad saved up.
 
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