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  View original topic: 1972 411 FI issues
Island411 Mon Sep 02, 2019 6:24 pm

Hey all,

New member here. Still newish to the air-cooled game but looking to dive in deep

My father has a '72 411 that looks great, is superb inside, but doesn't run well at all.

I suspect it's mainly fuel injection issues. There's been a couple of people look at it, and try to fix it to no avail.

Fuel pressure has been played with/adjusted a bit, compression tests done (all around 110 or 115 with one cyl down a touch, 90-95)

Fuel injector connectors aren't very tight in the injectors, I suspect maybe a fair connection there, or maybe broken wires in the FI harness?

It spits and spudders and isn't very fast or powerful, and it has a 3speed auto hooked up to it, and occasionally will leave you stranded on the side of the road when it dies while cruising. We also tend to pop it into neutral at a red light or stop sign because the load of sitting in gear while stopped can/will make it stall. Seems to run better while cold (first start up) vs when it's hot (driving for 10-15mins. I don't trust it to go much farther then 10 or 15 mins away from home.



I've very much thought about a dual carb setup for it, but would be cool to have an original FI setup in it. I have no idea on engine/FI system history in regards to what's been replaced for sensors or not etc

Any input would be greatly appreciated

Thanks

raygreenwood Mon Sep 02, 2019 7:29 pm

Island411 wrote: Hey all,

New member here. Still newish to the air-cooled game but looking to dive in deep

My father has a '72 411 that looks great, is superb inside, but doesn't run well at all.

I suspect it's mainly fuel injection issues. There's been a couple of people look at it, and try to fix it to no avail.

Fuel pressure has been played with/adjusted a bit, compression tests done (all around 110 or 115 with one cyl down a touch, 90-95)

Fuel injector connectors aren't very tight in the injectors, I suspect maybe a fair connection there, or maybe broken wires in the FI harness?

It spits and spudders and isn't very fast or powerful, and it has a 3speed auto hooked up to it, and occasionally will leave you stranded on the side of the road when it dies while cruising. We also tend to pop it into neutral at a red light or stop sign because the load of sitting in gear while stopped can/will make it stall. Seems to run better while cold (first start up) vs when it's hot (driving for 10-15mins. I don't trust it to go much farther then 10 or 15 mins away from home.



I've very much thought about a dual carb setup for it, but would be cool to have an original FI setup in it. I have no idea on engine/FI system history in regards to what's been replaced for sensors or not etc

Any input would be greatly appreciated

Thanks


Welcome! :D ....first...do not put twin carbs on. That is a downgrade.

I can guarantee you that all of your problems are vacuum leaks, EFI and power supply electrical connection related ....and ignition related.

Its not that hard to fix...but will not be done easily by just "US" suggesting things to try. We will be here for months.

If I were there I could sort it out in about 2-3 hours. But I'm not...so start by taking a few detailed pictures of the engine compartment.

Then...take a picture of the electrical connections at the battery. There is one particular connection that commonly will leave you on the side of the road....and mysteriously start right back up.

A few things to remember....exactly "0" vacuum leaks no matter how small...are allowed with this system. All of the parts have to be there. There are no extraneous "smog" parts you can run without like early 70's American cars.

The EfI has exactly 23 wires and four sensors. The female wire connectors are problematic. But if the harness is in good shape and not crispy and cracked....it can be made serviceable in an about an hour with a little work.

Start by showing us what you have and we can get a list together of things to sort out in order. Ray

Island411 Mon Sep 02, 2019 8:08 pm

raygreenwood wrote: Island411 wrote: Hey all,

New member here. Still newish to the air-cooled game but looking to dive in deep

My father has a '72 411 that looks great, is superb inside, but doesn't run well at all.

I suspect it's mainly fuel injection issues. There's been a couple of people look at it, and try to fix it to no avail.

Fuel pressure has been played with/adjusted a bit, compression tests done (all around 110 or 115 with one cyl down a touch, 90-95)

Fuel injector connectors aren't very tight in the injectors, I suspect maybe a fair connection there, or maybe broken wires in the FI harness?

It spits and spudders and isn't very fast or powerful, and it has a 3speed auto hooked up to it, and occasionally will leave you stranded on the side of the road when it dies while cruising. We also tend to pop it into neutral at a red light or stop sign because the load of sitting in gear while stopped can/will make it stall. Seems to run better while cold (first start up) vs when it's hot (driving for 10-15mins. I don't trust it to go much farther then 10 or 15 mins away from home.



I've very much thought about a dual carb setup for it, but would be cool to have an original FI setup in it. I have no idea on engine/FI system history in regards to what's been replaced for sensors or not etc

Any input would be greatly appreciated

Thanks


Welcome! :D ....first...do not put twin carbs on. That is a downgrade.

I can guarantee you that all of your problems are vacuum leaks, EFI and power supply electrical connection related ....and ignition related.

Its not that hard to fix...but will not be done easily by just "US" suggesting things to try. We will be here for months.

If I were there I could sort it out in about 2-3 hours. But I'm not...so start by taking a few detailed pictures of the engine compartment.

Then...take a picture of the electrical connections at the battery. There is one particular connection that commonly will leave you on the side of the road....and mysteriously start right back up.

A few things to remember....exactly "0" vacuum leaks no matter how small...are allowed with this system. All of the parts have to be there. There are no extraneous "smog" parts you can run without like early 70's American cars.

The EfI has exactly 23 wires and four sensors. The female wire connectors are problematic. But if the harness is in good shape and not crispy and cracked....it can be made serviceable in an about an hour with a little work.

Start by showing us what you have and we can get a list together of things to sort out in order. Ray

This is all I have at the moment. I can get more detailed ones later on. Its possible this may not be the original engine either. Is there some sort of engine code markings on the motor itself that I can confirm it's a 1700.

Also curious on if I can buy a new engine electrical harness, or if I'm on my own to make my own. Id love to replace the harness because i feel like it's sort of crusty and likely have broken wires

Someone also mentioned that there's 2 or 3 different ecu setups and sensors don't like being mixed between them, is this also a potential problem?

Just curious why you don't recommend the carb setups?



MarcVoss Mon Sep 02, 2019 10:07 pm

Island411 wrote:

.... Its possible this may not be the original engine either.



Yes, it looks like a Type 3 engine (Type 3 based on Beetle), but also a FI.

You can compare it there:https://www.thesamba.com/vw/forum/posting.php?mode=quote&p=6115783:

Orbison74 wrote:
p.s. 73 FI original engine.



Island411 wrote:
.... Is there some sort of engine code markings on the motor itself that I can confirm it's a 1700.

411 engines should have Code W and look like this:



So, before downgrading this engine to carbs you should change it completely. This has less power and maybe someone with a Type 3 FI in good condition likes this engine as spare part as it is.

Type 4 engines are still available and now it is a good time to fix the complete problem and getting a running 411 back on the street.

Island411 Mon Sep 02, 2019 10:27 pm

Thanks for the picture comparison. So issue number one is a type 3 engine, trying to be run with the type 4 FI setup.

raygreenwood Tue Sep 03, 2019 8:20 am

Island411 wrote: Thanks for the picture comparison. So issue number one is a type 3 engine, trying to be run with the type 4 FI setup.


Actually....thats a type 3 engine with a type 3 set up.

The type 3 and 4 D-jet EFI systems...are largely the same. Though the ECU and MPS and TVS calibration specs can be slightly different....some of the parts are dead on the same...fuel pump, relays, at least one of the MPS's, several of the TVS, the fuel pressure regulator, the injectors etc.

With very little effort...a complete EFI system from a type 3 can be slaved onto a type 4 and vica versa....with just some minor adjustments.

However...the type 3 engine is about 25-30 hp short of what the type 4 engine had with the same injection system. And...going to carbs on either engine...while a good running system...will also leave you short throttle response and hp wise.

The type 4 with twin carbs in European form was maybe 68hp. Not that it could not be tuned up to 72-75hp....but the type 4 with D-jet injection was 82hp.

I mean you have to give Kudo's to whomever swapped engines...at least it looks very complete....but it will have all of the same tuning issues as a type 4 with D-jet that I mentioned above....vacuum leaks...wire harness....ignition.

What you need to do is check the part numbers on a few items to make sure that the EFI is not a Frankenstein of type 3 and 4 parts.

Check the MPS part number, the distributor part number, the throttle valve switch part number and the ECU part number.

Check the fuel pressure and report what it is. It does not need to be "fiddled" with. It need to be checked for stability with a good gauge, check pump volume output...and set it to spec....and leave it. So whomever you took it to who diddled with it...find out what they did. If they did not do what I just described....and did not know what or why they were doing it...do not take the car back to them.

As for the wiring harness...there are at least two people who can make factory reproduction harnesses here and do. Or...for about half the cost you can make your own. Its not that hard....you will save about $150 making your own...but it will still cost you about $200-250. You will need to buy a crimping tool and dies....which will cost maybe $50 if you are not looking for world class longevity in the tool. The connectors will cost about $3.50 each x 25....and wire will be $75-100 depending on what you use.

Ray

Island411 Tue Sep 03, 2019 6:21 pm

I'll get my hands on a fuel pressure gauge and do some looking.


Also, is there an index or something I can use to reference which part numbers I should be looking for on these sensors?

Also curious on where to look on the block for a stamp to identify what exactly it is also.

Thanks so much for the info, I'm more then capable of doing the work, I just need a service manual and an experienced mind for some help.

raygreenwood Tue Sep 03, 2019 6:37 pm

Also....all of the above being said.....I am not bashing carbs. It depends o. What you want to change. If you actually had a type 4 engine and it was a stocl 1.7L from a 411....with twin carbs....and good compression, exhaust and a correct cam....you could do 80hp. But tje throttle response would still be less than the injected 1.7.

In 1974 VW put a 1.8L in the last 412's. It will bolt right into any of them. The issue it had was that it was detuned for smog and went to a more reliable but less adjustable injection system (L-jet). It put out only maybe 3-4hp more than the 1.7L, ran hotter and had worse throttle response. Mainly a compression and ignition thing.

But the same 1.8L in the European version with twin carbs...mainly in the UK.....put out about 90hp. High compression.

Yes....you could tweak up the type 3 engine....little more displacement, cam and ignition....keep the injection....and it can put out as much as the type 4 1.7L....but a little less cooling, torque and long term reliability. Ray

Island411 Tue Sep 03, 2019 8:50 pm

raygreenwood wrote: Also....all of the above being said.....I am not bashing carbs. It depends o. What you want to change. If you actually had a type 4 engine and it was a stocl 1.7L from a 411....with twin carbs....and good compression, exhaust and a correct cam....you could do 80hp. But tje throttle response would still be less than the injected 1.7.

In 1974 VW put a 1.8L in the last 412's. It will bolt right into any of them. The issue it had was that it was detuned for smog and went to a more reliable but less adjustable injection system (L-jet). It put out only maybe 3-4hp more than the 1.7L, ran hotter and had worse throttle response. Mainly a compression and ignition thing.

But the same 1.8L in the European version with twin carbs...mainly in the UK.....put out about 90hp. High compression.

Yes....you could tweak up the type 3 engine....little more displacement, cam and ignition....keep the injection....and it can put out as much as the type 4 1.7L....but a little less cooling, torque and long term reliability. Ray

A twin carb setup may very possible yet. I'm not concerned with power output so much right now, especially with the car being an automatic. I just want it to run smoothly. Hence why I'm tempted for carbs being that theyre simplier and removing 1970s electrical. If I had a type4 engine and all the proper sensors, I'd be more likely to keep and try to fix the FI.

Lars S Wed Sep 04, 2019 12:12 pm

Welcome!
I have never seen a Type3 engine in a Type4 but if you want to keep it I believe you should try to fix the FI....it wont be very fast or powerful but it will, compared to twin carbs have a good throttle response, nice cold start behavior and a good fuel economy.

The symptoms it has could have many reasons most of them usually not to hard or expensive to fix...running worse when warm than cold could be a lean condition.
Has it been running OK anytime or has the problems appeared recently?
Has the car been sitting for a longer period (one year or more)?


/Lars S



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