Re: Setting Fuelling - Why does the DMC PRV Hunt? [long]

["David Teitelbaum" <jtrealty@xxxx>]

Having seen many Deloreans and worked on some I can say that the PRV 
engine with the K-Jetronic with Lambda and idle motor system can be 
set up to run smooth with very little hunting. It takes a lot of work, 
knowledge, special tools, and time but it can be done. All of the 
cylinders of the engine must fire equally with very nearly the same 
compression, spark plug gap, and injector settings. If any cylinder is 
different from the other it causes the idle motor to try to compensate 
resulting in "overshoot". By the time the correction kicks in the 
engine is on another cylinder and now it is too fast so the idle motor 
tries to slow it down, hence the hunting. You also have the lambda 
cycling up and down so when these 2 functions overlap the hunting is 
even more noticeable. Vacuum leaks only add to the mix making the 
hunting worse by diluting the control of the idle system. On a 20 year 
old car there are many things that usually need to be attended to 
before you can even try to adjust things. Old wires and spark plugs 
must be changed. Disconnected or misadjusted parts need to be taken 
care of. Dirty, plugged up fuel injectors must be cleaned. On many 
cars less knowledgeable mechanics trying to "fix" things didn't do 
things correctly so you have to go over all of the work and fix all of 
the underlying problems. This is not to scare anyone but to get things 
right sometimes requires undoing someone else's work and setting 
things up right. This takes a lot of time but when you get it running 
correctly there is a large sense of accomplishment. The first thing I 
would suggest is a compression test, if the cylinders are not within 
10% (5% is better) then you will never get it smooth. Clean and regap 
the plugs to .028, replace the ignition wires, clean the fuel 
injectors, fix all of the vacuum leaks, and now you can begin to get 
it smooth.
David Teitelbaum
vin 10757 


--- In dmcnews@xxxx, "mgutkowski@xxxx" <webmaster@xxxx> wrote:
> Hi All
> 
> Bit of a lengthy one this. Let me set the scene.
> 
> I've bought a new project car, VIN#4426 from Germany. It needs a new
> engine. As you are aware, the PRV was used extensively over here by 
all
> three manufacturers and a couple more besides.
> 
> By an extraordinary stroke of luck, I was put in touch with a guy by 
the
> name of Darren Bowker who hails from Manchester. Not only is he a 
mad keen
.