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 .