Engine stalls right after starting

[lukebenish]

Recently bought a 90 Coupe Quattro 20v and the problem is that it will start fine, but it will stall soon after if I don't give it some gas. It then idles really rough around 400 rpm. It even does this at operating temperature. It also stalls when driving if I put it in neutral. I have cleaned the ISV and the MAF sensor.

I'm thinking it could be a fuel system issue

[Error404]

Often starting and stalling right away it’s a sign of too much cold start fuel
You should also check the idle switch is working correctly, if it stalls coasting in neutral.

[lukebenish]

What do you think is causing there to be too much fuel?

Any tips to see if the ISV is working properly?

[steve briance]

Excess fuel is a possible cause of your problem, excess air is a other cause. When it is running badly, does it smell very rich and are the plugs black? That would point towards too much fuel. Easier to diagnose is too much air - take the big hose off from between the maf and throttle body, the quite often split underneath and let far too much air in and lead to stalling. Also check the hoses connecting the isv, they fail in the same way.

[Lago Blue]

How you making out here sir? Did you have a chance to go through the steps listed under "engine problems and diagnostics" at 20v.org?

[dr.strangelove]

Check your codes...http://20v.org/fault.htm

Bad wiring or dispatched sensor. Fault codes will indicate which system is malfunctioning.

[lukebenish]

My main air hose coming from the filter housing to the throttle manifold is very hard and starting to dry rot. I can tell where the previous owner has tried to repair it so i think this may be the problem. Does anyone know where I could buy a new one?

(side note: the main air hose almost feels like plastic it's so hard. This is bad aint it. )

[Lago Blue]

It's normal, it may or may not be bad. Others have called this the Michelin-man hose. The usual problem with used ones is they are as old. You ought to try the Audi dealer. You may have to scour E-bay.

It is only a problem if it is leaking. You may have to repair it for the time being. Think about how you might do that (shoe-goo & patience).

Even a new one is not real flexible, be very careful if you must take it off, better to do that where it is warm, and perhaps best leave it in place for the time being. They usually tear first underneath at the mid-point where the crankcase vent tube should be pushed up into it. Is that C/V tube in place in your M/M hose? The hose can also tear at edge of either ends opening also, are the end clamps present? Are all the smaller M/M hose connections actually connected to something? Are the ISV hoses intact?

I can walk you through some testing of the the hose if need be. Can you put the car inside? Tell me about the repair you see.

[steve briance]

A while ago I tried the v6 maf housing on my 7a to see how it was. Wasn't happy so returned to standard. The point of telling you this is that to get it to fit I had to come up with a solution to replacing the Michelin man hose with an alternative to accommodate the larger diameter of the v6 maf. A generic 90 degree silicone elbow pipe was almost spot on. I forget the sizes but there was only a couple of mm difference in internal circumference and that clamped down o.k. The difficulty will be fitting the isv and breather tube into the elbow. Silicone hose manufacturers can supply vacuum take off bosses which form a well sealed pipe outlet, this would need connecting with a short rubber hose to the isv and breather pipe.
If yours has been repaired previously, this tells me that you should start your problem solving there bit, be aware that previous owners may have altered other settings (idle speed and idle mixture) to try and compensate. Once you are airtight GET SOME ONE TO CHECK THESE FOR YOU. if its not right, you will continue to have problems leak or no leak.

[newsh]

They usually tear first underneath at the mid-point where the crankcase vent tube should be pushed up into it.

There was a chap on here called Stick Insect who had a similar problem to this.

The small hose had come disconnected underneath.

[Lago Blue]

lukebenish

Re M/M hose repair, If you think yours is not repairable, this fellow may have one more suitable, item 13:

https://www.audizine.com/forum/showt...ts-034-7a-more

[DEREKCO]

I had a similar issue with a coupe Quattro before I bought the s2 turned out it was cold start injector and MAF running on excess fiel

[lukebenish]

Can someone please point my towards a forum that has instructions on how to test the diagnostic codes because 20v.org is very vague and I have no idea what I’m doing.

[Lago Blue]

Re "pulling" codes:

Let's try to go through the 20v.org instructions step by step shall we, everyone has to learn this. Those instructions have to cover off different versions of the car (that's perhaps why they're confusing), which is yours?

1) What is the build date of your car?

2) Is it a California version or 49 state?

3) Have you located the diagnostic connectors?

4) Do you have the little owners manual that fits in the glove box?

5) Do you know if you have a functional Check Engine Light?

[lukebenish]

1) the build date on the inside of the door is April 1989
2) 49 state model
3) I have no idea where the diagnostic connectors are (main problem)
4) I do have the little owners manual
5) I’m pretty sure I do not have a check engine light