cgtdenmark

funny stuff is going on with my CGT.

It has allways started at the first turn of the key, but now it starts and then want to die, after 20 sec. of applying a little throttle of about 1500 RPM it idles fine and runs great as allways.

My girlfriend (not so "car cleaver") has to start it 3-4 times to get it to run normal.

It's only after standing 24 hours or so it will occour.

Am i looking at loss of fuel pressure due to bad accumulator, or the CSV not working. Ambient temp is around 20-25 C so its pretty hot here.

- GT Style -

<center><img src="http://pictureposter.audiworld.com/53828/107_0717.jpg"></center><p>(or just use a jumper wire to run fuel pump if you have 1 handy) when cold in the morning.

If say after 15 tries (or 15 sec w/ jumper wire) it fires normally then it's most likely your fuel pressure regulator (little squarish grey item mounted on front side of fuel distributor held on w/ 2 screws, you can just barely make it out in 1 of your pic poster photos).

AudiCGTSB

I dont see the wires. I have a spare dizzy that came with my 4kq that doesn't have one either. Can anyone shed some light?

mt6127

the fact that it starts and runs for 20 seconds or so says your CSV is doing its job but you stall with the engine being cold and the fuel not having enough "enrichment". Does it run fine once warmed up? I'd look at a) temp sensor and FI ground wires b) air leaks in the FI (you could be running slightly lean) c) weak spark - Check those before blaming fuel pressure etc.

cgtdenmark

unless you give it some throttle for 20 secs, then it runs and pulls great.

RallyXAudi

When I start it up, it runs REALLY rough. the longer it's been sitting, the longer it takes to run smoothly. I drove it today after letting it sit for about a week, and it took a good 60 seconds of holding the throttle at ~2500rpm, plus a good mile or so of driving to get it to run without hesitating and sputtering. The fuel pump is brand new, as is the filter and a few of the lines back there, but I skipped the accumulator, so I'm thinking that may be my problem. Sometimes turning the key a few times helps, sometimes it doesn't.

Katman

As I understand it, the check valve in the pump, and the accumulator are to keep the fuel pressure up immidiatly after shutting down, to help prevent vapour lock when the motor and injector lines heat soak.

Symptoms of the check valve/accumulator/injectors going bad and allowing fuel pressure to go low is problems starting on HOT restarts.

Nothing to do with cold starts, as by then the residual pressure is expected to be low anyway. (Bently has a 'leakdown' spec for how long the fuel pressure should not leak down for)

I'd be thinking as to checking the ecu temp sender (at the head end of the upper rad hose. IT's the bottom sender, that has the metal clip on it.)

As a test, you can simulate a REALLY COLD sender, by just disconnecting the connector with the metal clip. If the car starts better when cold with that connector off, that the sender is probably bad. With the connector off, ecu sets mixture really rich.

Same as the choke on full, for the carburettor guys!

Suffolk

<center><img src="http://www.quattro123.com/4000/VacuumLEaks/MVC-383F.JPG"></center><p>Here's a photo. -Scott by BOSTON

P.S. Wow my photo sucks!
here the connector to it.

As GT style sayz:
The two screw thingy on the front end towards the hood latch of the fuel distributor.
The AMP connector going to it is a two pin.


If yours IS bad an Ohm meter across the two terminals will show an open circuit like infinity.........
480 ohms is a constant spec that should work from memory.

I've had two go bad on two different 4000Q's
HTH<ul><li><a href="http://www.quattro123.com/4000VacuumLeaksandWires.htm">http://www.quattro123.com/4000VacuumLeaksandWires.htm</a</li></ul>

cgtdenmark

thanks alot, will have a look :-)

Supercoupe

it has the 2 FI lines going to it. I can't find my CIS book right now but when I do I'll get back to you.