BOSCH JETRONIC INJECTION

tim leech · Post by **tim leech** » Fri Oct 05, 2007 5:21 pm

My newly aquird Gti 8v has the above system fitted, and its running very rich it seems, ive fitted a new air filter, changed the oil and filter and given it a good thrashing but im still worried about the MOT on monday.

Any ideas how to adjust it?

Thanks

Jaba · Post by **Jaba** » Fri Oct 05, 2007 6:06 pm

Mixture adjustment is done by turning the mixture screw out - anti clockwise. If this is wrongly set then 3 to 5 turns should make a noticable difference. The screw is in the top cover of the flowmeter at the RH end.

If the coolant temperature sensor is faulty then this would keep the mixture too rich for a hot engine. Testing this involves measuring its resistance when hot at the flow meter ECU plug.

Leaking injectors can give funny too rich symptoms too.

tim leech · Post by **tim leech** » Sat Oct 06, 2007 10:03 am

Thanks matey, all the dials work (unlike the 16v) and the temperature seems to behave ok, plus I just flushed the cooling system and now she stays nice and cool.

Way2go · Post by **Way2go** » Sat Oct 06, 2007 2:42 pm

tim leech wrote:Thanks matey, all the dials work (unlike the 16v) and the temperature seems to behave ok, plus I just flushed the cooling system and now she stays nice and cool.

What's this got to do with the price of tomatoes?

tim leech · Post by **tim leech** » Sat Oct 06, 2007 8:19 pm

Meaning if the temp sensors up the duff surely the temp gauge would be affected?, even a man of my limited skills know that.

The car warms up nicely to 90 degrees and stays that way unless it sits in traffic then it fan cuts in.

AndersDK · Post by **AndersDK** » Sat Oct 06, 2007 9:21 pm

Errrr - not quite Tim

We are talking a VERY different temp sensor here - STRICTLY for the ECU. This sensor tells the ECU which temperature the engine is working at. If this sensor is duff - the ECU gets a wrong message on the engine temp - and accordingly enrichens the mixture. Its the electronic way doing an automatic choke.

The temp gauge on your instrument panel is a completely different beast - with its own separate sender. Nothing to do with the engine control.

Mike E (uk) · Post by **Mike E (uk)** » Sat Oct 06, 2007 9:46 pm

The temperature sensor for the ECU is a different one from that on the dashboard gauge.

The sensor for the ECU is near the thermostat and has a proper connector, not a push on crimp one that the dash gauge has.

At 20'C it should be: 2280 to 2720 Ohms

At 80'C is should be: 290 to 370 Ohms

tim leech · Post by **tim leech** » Sat Oct 06, 2007 10:17 pm

Fair enousky, will see what happens monday for the MOT. It may just need winding in on the air flow meter, if it still runs badly will try a new sensor.

Thanks

Jaba · Post by **Jaba** » Sun Oct 07, 2007 1:06 pm

Tim - if it fails on a too high CO reading this indicates a too rich mixture.

Assuming the ECU temp sender is ok the CO can be lowered by turning the screw ccw. 1.5 turns will lower the CO by approx 1%.

The tester may be happy to do this for you as it only takes a couple of minutes.