Cold start issues continue (84 4000 quattro)

[John Cody Forbes]

The device bolted to the fuel metering head with a couple of wires to it is the differential pressure regulator (DPR), akin to the older warm up regulator from the earlier CIS cars. I have seen a number of them fail. Sometimes they just need to be cleaned out. I would think that the symptoms would last longer if it was a DPR problem, like until the temp gauge moved off the stop. It's worth checking.

Really the way to diagnose this problem (as opposed to randomly guessing and tossing parts at it) is with a CIS fuel pressure gauge set. I think on CIS-e there is a port for checking control pressure and system pressure, but I've only worked on a few and it's been a while.

-Cody (mobile)

On Aug 11, 2010, at 9:06 AM, Johnny B <pre95 at live.com> wrote:

> 
> Well thus far no luck. I have scoured the engine compartment for vac leaks, fixed one which corrected my high idle, but still have my cold start issue. The coolant temperature switch came in yesterday (that mounts between cylinders #1 and #2 on the bottom of the coolant neck leading in to the head), I installed it and this morning, still a bad cold start. 
> 
> Once the car is started, my idle is rock solid, does not wonder, and I have good power up to ~5k which seems fine for a JT. No running condition issues once started. I did notice this morning when it first started, I touched the gas pedal to bring the R's up and it simply died. I restarted and let it idle for ~30 seconds and all apparent running conditions went away. 
> 
> Someone had mentioned the fuel pressure regulator could be at fault, specifically the "warm up regulator on the fuel head" which I am uncertain as to what he means. There are 2 "fuel regulator" pieces near the fuel distributor, the vacuum regulated piece mounted towards the front of the car in front of the fuel distributor, and the FPR mounted directly to the fuel distributor that has 2 wires leading to it. 
> 
> Any insight greatly appreciated, I know I have said it but it's very annoying having a car that is otherwise well sorted and good running with a bad cold start. 
> 
> Johnny
> 
>                         
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