CIS-E Problem

[chris locke]

Ben,

If you're experiencing leak down, and you're not flooded when you start, then I'd save a whole lot of money and rather than just replacing the accumulator (sp?) and the injectors, and replace the check valve at the fuel pump.  Very easy to get to, cheap, and it doesn't take much for it to fail.  BTDT.  The next question is why should that matter?  When you first turn the key to the "on" position, if the residual pressure isn't high enough, the fuel pump should run for a second or two.  During cranking, the fuel pressure builds very quickly (with the fuel pump running) to 5 bar (or so, depends on system, could be 5.4-5.8 also) within .75 seconds.  When the engine is shut down, the residual fuel pressure drops back down to 2.3 bar to shut the injectors.  Bosch states that the
residual pressure should last at least an hour, my experience shows my CIS-E to go much longer than that.

HTH.

Chris Locke
'86 4KCSTQ
'91 2C20VTQ





>
> Date: Thu, 1 Jan 2004 13:37:32 -0500
> From: "Ben Swann" <benswann at comcast.net>
> Subject: Re: CIS-e problems
> To: "Brian Sims" <sims at miliserv.net>
> Cc: quattro at audifans.com
> Message-ID: <08ef01c3d096$516e22b0$6401a8c0 at SWANSONG>
> Content-Type: text/plain;       charset="iso-8859-1"
>
> What you say is relevant for the CIS and CIS-E systems, which have full pressure to CSV when fuel pump is running.  On the other hand, from what I understand, the CSV on the CIS-E3 systems operates at the same pressure as the other 5 injector lines.  They only get pressurized when the air plate is lifted, even if the pump is running.  Just cranking the engine over is not enough flow to lift the plate - there needs to be residual pressure.
>
> Someone correct me if I'm wrong.  My experience in getting this car started when cold and has been sitting for indefinate amount of time supports this.  For example, car has been sitting for a couple weeks now.  I jumpered the pump to run, lifted the plate(using 3mm allen) for about 1 sec to pressurize the lines.  Put FP relay back in place of jumper wire.  Get in car, turn key and engine starts - some fooling with accel pedal used as I don't have everything dialed in correctly yet, and I suspect ISV may not be working properly either.
>
> Car will restart just after shutdown  and up to about an hour without re-priming injector lines.  Over time there seems to be a leakdown - question is where?  I will start by replacing injectors and the accumulator.
>
> I should also probably perform pressure tests and run some other diagnostics, and may well do, but I feel I should have put in new injectors when I rebuilt the engine, and will do this now since I built this engine up and didn't really want to cut corners anyway.   Hindsight is 20/20 and I've learned a few things since I did the job, and have experienced similar hard start problems due to injectors - CIS in 5000 turbo quattro(s) and CIS-E in 4000Q.  Difference there was the CSV is fed directly off system pressure and the car would eventually start after cranking for about 7 sec.  New injectors briough the time down to 1 turnover of the crank in 5ktq or pretty much immediately, and all you need to do in the 4kq is bump the starter and VROOM.
>
> Ben