I shall now attempt...

[audi5e]

to clean the air inlet paths around the injector shrouds. Got hold of a Bosch manual on how the KE-Jetronic system operates. Interesting stuff. I did not know that the injectors are mounted in those shrouds for two reasons, 1. to keep heat soak away from the injectors to avoid bubbling in the fuel and the accompanying hot start problems, and 2. to allow meatered air to pass directly past the tip of the injector (mainly at idle). This allows MUCH better mixing of the atomized fuel to take place. Instead of large globules of fuel, you instead will see a very fine mist. Obviously this mixture is a lot better for the combustion process.

For a while now, I have been trying to figure out why there would be an extra air inlet leading from the ISV inlet pipe to the injectors, now I know! The last time I pulled the injectors out I noticed just how gunked up those air passage ways had become. Maybe now I can finally solve the rough idle?

Will post again and let you folk know if it works.

 

[Rev-head]

Sounds like a good job to take on ......see if you take some pics

/ubbthreads/images/graemlins/beerchug.gif

 

[audi5e]

ok, job done. The passages were most certainly blocked. A good spray with carb cleaner into each of them... Interesting that the airway is a narrow passageway that opens out right near the tip of the injector. I was expecting a much bigger opening. When I sprayed the cleaner through, the cleaner formed a mist directly in front of where the fuel would come out... I also cleaned out the airways in the inlet manifold at the same time as they also seemed to have a lot of gunk in them.

Sorry about the lack of photo's, but it was dark, late, and this author was in a foul temper, having banged my hand...

If you want to know if this has solved the slightly rough idle, the answer is yes and no, the idle is smoother but not yet up to standard... next job, replace the ISV. I will post again if that completely solves the issue.

 

[atc]

Have you cleaned the ISV? I have always found the best way is to spray a load of carb cleaner in cover the holes and give it a good shake, then spray a very fine mist of WD-40 in. Always worked on my Golf GTi's. Assuming you can hear and feel it working when you turn the ingition key it should be fine. I only say all of this as they are not a cheap part. The other thing to check first is that there are no air leaks in the system. I used some black automotive silicone on all of the pipes and replaced all the cloth coverd pipes on one of my old Golfs and it helped a lot and is a fraction of the cost of an ISV.

 

[audi5e]

Thanks atc. yes, I have replaced all the pipes and done plenty of cleaning of the isv, i suspect it has now simply reached a stage where it needs to be replaced.

I will try and find some wd-40 (not sure if it is available in SA? will have to search)

 

[audi5e]

atc, sprayed another product called MOs2 into the isv and it seems to smooth it out quite a bit. not perfect, but you can notice quite an improvement. I suspect the ISV still needs changing though. I guess they are not meant to be pushed beyond 250000km's...