3.2 injection setup

There is an adjustment screw under the cover but please do not adjust without reading up and fully understanding the Bosch CIS fuel system. Adjustment here should form part of a range of checks and adjustments.

 

I assume you noticed a rich condition by the smell of sulphur. My '86 sometimes had that. I searched out some [catalytic converter] cleaner and other such decarbon compounds. Used bottle after bottle.

However, I am convinced the carbon build up is best addressed in two ways.

1) Never warm up the car at idle. Let it idle ten seconds to get the oil going then drive away keeping the revs above 2,000 rpm. I live on a long mountain hill and just keep it in second gear 2-3k the whole way.

2) Shift above 3,000 rmps.

3) These constant flow injector systems were notorious in BMWs at the time for carbon build up. Their solution? Introduce crushed walnuts into a runing car. I am not making that up.

Our cars are not that bad. However, my car now runs like I would expect it to run new. And LOTS faster then when purchased. I even undid the mixture cover and, with the engine stopped, used a small hex wrench to give 1/8 turn to richen it. I think that was clockwise. Can't remember. Touchy thing to mess with. Can't do it while running.

Anyway, have not had a sulphur smell in a year; starts and runs like a scalded dog. And of course I do a couple of other home remedy stuff. Every tank of gas gets about 6oz 2cycl oil. Its mechanical fuel injection, the oil might protect the metal parts from ethanol, and of course the mechnical parts of the injection system get some lube and you get some cylindar top lube.

I do not recommend these unorthodox things. However, I am now working on 10,000 miles and the entire vehicle might as well be new - except for the oil cooler leak. For the time being I just add a quart every couple of hundred miles.

 

Actually the whole jetronic system has a one time no change configuration from factory sort of speak. If the fuel mix is to lean or to rich it means usually that you have an issue in the setup. Vacuüm leak, WUR problem you name it and one needs to trace this down rather then adjusting this screw. Problem is that we do not know who got his hands on it already

IMHO old cars need to have a full check on the CIS setup and replace every single vacum hose, injector seals, plenum seals as rubber just has no eternal live. One will be amazed how fast the rich fuel smell will go away without turning this screw. however sometimes it is unavoidable.

having seen your earlier pics I guess it has been taken care of

 

I do not think our cars have "learning" ECUs, though I could be mistaken. However, you are correct about issues with elevation. Eight thousand ft. is quite a lot. I lived in the Denver area many years ago which is only 6,000 ft and at that time carbs were rejetted rich.

On the other hand our cars DO have O2 sensors. Theoretically this plus MAP [manifold absolute pressure] readings would seem to take that into account. I still come back to carbon build up. Carbon deposits on valves absorb raw fuel and subsequently expel it in non-linear manner. Our constant flow system sprays raw fuel right into an intake port that is CLOSED.

A few months ago one member showed a photo of a two valve 3.0 that dropped a valve. The valves had so much carbon on them I could not believe it at first. I don't just mean coated. I mean absolutely crudded up as one might expect from a worn out lawn mower engine. That, I suspect, was the problem with two valve BMWs of the era.

Just my two cents worth. I am confident, however, that my engine does not suffer this problem any longer.

 

This is how I adj fuel mixture on CIS mondials and 308/328. Warm car fully, Shut off. Unplug O2 sensor, remove O2 sensor. Install Wide Band O2 sensor with meter and restart car. You adj mixture screw behind plug (Drill out or remove before hand) with car running!!! It does not take much. I have taken good running cars and made them run perfect with just a very small tweak of the base mixture adj. Pay attention to what the car likes as well as the numbers. The base idle adj affects mixture for the entire rev range. This is after all other tests and inspections have been done. Don't forget Sensor plate adj. Often overlooked and they do move - these cars are old now.

Joe Frazar