Hi Guys

I'm still trying to figure out my FI system. Car in question is a early 92 2 litre with 102 engine in Singapore. The FI system is slightly different from US models as I do not have an O2 sensor (pin 3 in X11 plug is blank). I do have the EHA on the distributor. I wonder if I can get someone to help explain to me:

1) What is the EHA controlling if there is no O2 sensor?
2) My idle control valve has an air bypass screw that can control the idle speed. How do I set the base setting for this?
3) My car has a problem that when warm/hot, it fires up and immediately dies on the first try. Subsequently starts are fine. Adjusting the idle mixture and swapping fuel pump relay did not help. I did managed to alleviate this up to 90% by increasing the idle speed as in 2) but I'm not sure if it is the right thing to do. Idle is now at about 8-900 in neutral and 750 in gear. I read in the archives and from other post this phenomenon is a normal thing for the K Jetronic but other 124s I've seen do not do this

Thanks all
Oreo

 

cookie,

the EHA is controlling the fuel injection pressure.

if your system pressure is 5.4 bar, the EHA will control the lower chamber to 5.0 bar (must be 0.4 lower) in order to get the right mixture.

the idle control valve is factory calibrated. normal is between 4 to 8 milliamperes during idle.

that idle adjusting screw actually adjust the carbon monoxide (CO). if you are trying to lean it out by adjusting the idle speed, then it is not right.

on the other side of the EHA is the air flow meter sensor. that controls the EHA! make sure it is 4.6 - 5.1 and 0.55 - 0.95 volts during idle (3 terminals 1 is common).

 

Sleepwalker

Thanks for the insight. Now I trying to take in what you just said and will break out the ohmmeter to get those readings. But now I am more confused....

1) How does the idle valve air bypass affect CO? Isn't this set by the idle air mixture screw?
2) If the air flow meter sensor does not conform to the voltage - what do I do to correct this?
3) Will any of these affect my crank and die warm start condition?

Thanks for helping a K Jetronic newbie!
Oreo

 

as what it's name implies, it only supplement the air to prevent the engine from stalling at idle. we also call it idle speed air valve. the screw is to adjust the idle speed.

it can be adjusted by loosening the two screws on the side and very slightly moving it on either direction.

you must adjust them while the engine is running.

the hard starting on warm engine is a different problem. for example...if you got air in the fuel system, faulty crankshaft position sensor, or leaky fuel injectors.

remember, whatever you move... make a mark on it with a permanent ink or paint. remember the previous position.

 

Sleepwalker

Thanks - got you. Will go poking around a bit first....

Regards
Oreo