81 FI won't idle cold

Sounds like you need to check the fuel pressure. Probably a 'residual' fuel pressure problem which could be caused by many things such as injectors, fuel distributor, fuel pump check valve, fuel leak, etc.

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Can't see or smell any fuel leak. I'll have to find a mechanic to check the other (no pressure gauge). I was hoping to find an inexpensive fix. The mechanic who occasionally works on the car referred me to someone with smog check equipment who estimated "not less than $140 plus parts" based on the 'gross polluter' status. T'was a great car but maybe time to retire it.

Thanks for the suggestion.

nf

Sometimes the cheap way is to use the proper equipment and FIND the problem. :-) You could buy the tool, use it again and again, and then sell it! Harbor Freight may have one for around $100.

I don't like guessing...........too expensive! sooooo many components to try and some of them aren't cheap either! later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

It can certainly be the most satisfying way when it works!

Question: if the problem with not idling is caused by low residual fuel system pressure, how can the engine run smooth at 3000 rpm where it must certainly require more fuel flow?

Thanks, nf

It was my understanding that your engine would start and die out until a few minutes/moments of running. Then it would run well. I looked at the Subject title again and would assume that it idles warm but not cold.

Tell us exactly what it does?

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Engine not started since yesterday. Current ambient: 100F. It fires up immediately but won't idle. It will not stall, however, if I give it enough gas to run at 1500rpm or higher. After about 1 minute it will idle, very rough, at about 800rpm. I continue to give it enough gas to run at 1500. After about 3 minutes the idle goes up to about 900rpm with temp gauge about

1/2-way to normal--but still a bit rough. Idle is reasonably smooth fully warmed at just below 1K. (Isn't smooth much lower than that, and I had to time the thing between 0-3 ATC because the mark jumps around a bit.)

If I shut down and restart then it still idles, but when restarted after 10 minutes or so it'll take about 30 seconds giving it gas until it'll idle again.

Not many miles on Bosch silicone high-temp plug wires, I checked one and it was only about 7Kohms per foot. Plugs are Bosch platinum, also low miles. Cap and rotor nearly new. Anyway, I don't sense any misfire at high revs. No lack of power.

I said the problem was worse before I replaced the oxy sensor, but now I don't think so. Previously it would start, idle for few seconds, then refuse to idle for a few minutes. The difference may have been too-advanced timing, which I reset when I installed the sensor. All told, it's running smoother now.

Thanks, nf

OK so it does idle when the engine is warm. :-)

Your FI system adjusts fuel delivery according to the psi in the fuel lines. Warm up regulator (control pressure regulator) adjusts that pressure. Usually when this is bad the engine pops and spits and doesn't have a lot of power when cold. And yes it may not idle when the engine is cold.

There is also an Aux. Air Regulator that opens up and allows more air inside of engine when cold. As it heats up the opening closes up. Might be this

Also you have a temperature switch that kicks on the 02 sensor. That switch may be malfunctioning also. You could try disconnecting the 02 sensor to see what the engine will do.

I am not too fond of Bosch Plats in your engine, but it shouldn't be causing the problem.

Those are the things off the top of my head, but a fuel pressure reading will help you out. :-) Or start changing parts! 8^)

Do you have a manual on this vehicle? I might have a spare Bentley laying around here.

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

I would install my pressure guage, remove the injectors, install fused jumper wire and look for leaking injectors. I would get 4 coke bottels and look at spray pattern by lifting up air plate. Even without a pressure guage you can check for leaks and pattern. Replace orings, make sure injector buckets are in head tight enough and not broken. Sounds like leaky injectors to me.

I have run platinum plugs for years in my 80 and 84. I sort of wondered about the idle skipping but always got better than EPA mileage. I don't recall running the regular plugs as I had used the platinums for years.

I have had cruddy cold idle because the water temp switch turned on the Lamda system too early. This is not an issue for warm starts.

snipped-for-privacy@aol.comANTISPAM (dave) wrote:

Jim B.

Dave, according to the Clymer manual, the Aux. Air Reg. gate valve is supposed to be open when cold. It's fully closed. Is the manual correct?

thanks, nf

Thanks for the suggestion, but it looks like it might be the aux. air reg. Do plat plugs contribute to a skipping idle?

nf

Jim B.

Thanks again for the suggestion, but I believe you are at least partially misinformed about the aux air regulator. I replaced it this afternoon and the engine started right up and idled and ran very nicely. Before installing I could very clearly see a partial opening in the new one, while the old was fully closed.

nf

dave:

The aux air regulator was the fix. Many thanks for the suggestions and encouragement.

Do you have a VW repair shop? Where?

nf

Glad you got it up and running the way you want! It helps when you tell us all of the symptoms and when they occur. ;-)

Yes in Chicago. I just don't see any A1s, except Cabriolets, nor too many air cooled VWs anymore. So my mind forgets some things! :-(

Paypal contributions will not be refused! later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris