hunting idle when cold - Page 7

Gouldy · 16-02-11, 09:00 PM

no mate its an injection so its all done my sensors mate, might try checking the 2 sensors in the stat housing this weekend,

rich.r · 16-02-11, 09:15 PM

would phil p have any ideas on this one

why did i think it had a carb

wonder if you have a small air leak somewhere and the sensor thinks it needs more fuel than it actually does

Gouldy · 16-02-11, 10:39 PM

well ive had the inlet manifold gasket done , and the injector colours/o rings , the dizzy vacuum pipe is new, will check all the breathers at the weekend, especially the crankcase breather

Gouldy · 17-02-11, 09:19 PM

right then guys, ive changed a few hoses on the car and its still idling lumpy,

my question is.... where is the crankcase breather i see people going on about? i cleaned all the pipes i could see but i cant see one coming from the bottom of the engine,

also the ISV is working, and the plunger is smooth,

probably going to get a dizzy cap/arm, and a set of leads next

does anyone know what the sensors in the thermostat housing, and the thermo time switch should read on a circuit tester?

might check these tomorrow .

20vcqdriver · 17-02-11, 09:50 PM

Just occured to me regards the temp sensor under the top heater hose on head. Sensor is used to set idle ISV control rate when cold as per the thread by Biggyin ( http://www.classic-audi.co.uk/forum/...ad.php?t=16214 ). If the connector is badly corroded remove, clean up and try again as a start, if still no good test with a meter between centre pin and earth on ohms. Resistance should change as engine warms up.

Gouldy · 18-02-11, 04:22 PM

and this is the same on the KV as his engine??

i will check the resistance when cold later tonight, then watch it as it warms, any ideas what the readings should be?

also i had a thought today, when the engine is cold, its idling at 800 (the same as when hot) surely this isnt right?

normally when cold it should try to idle at 12-1300 shouldnt it?

pimpdriver · 18-02-11, 04:52 PM

injection engines idle at the same speed, hot or cold give or take 50rpm..

Carb engines idle higher.

Gouldy · 18-02-11, 05:37 PM

not on any of the engines ive had, honda, nissan, saab etc maybe its a mechanical injection thing?

BIGGYIN · 18-02-11, 06:50 PM

Quote:

Originally Posted by Gouldy

and this is the same on the KV as his engine??

i will check the resistance when cold later tonight, then watch it as it warms, any ideas what the readings should be?

also i had a thought today, when the engine is cold, its idling at 800 (the same as when hot) surely this isnt right?

normally when cold it should try to idle at 12-1300 shouldnt it?

For-1986-90 5000/200TQ

With the single wire removed, the resistance should be tested between the sensor terminal and the cylinder head (engine ground). The resistance should be approximately 80 ohms with the coolant temp around 212F, (100C), approximately 130 ohms with the coolant temp at 176 degrees F (80C), approximately 1000 ohms at 68F (20C), and approximately 6000 ohms at -4F (-20C).

Don't know if it's the same,for your car?

Gouldy · 18-02-11, 07:17 PM

pretty sure mine have two wires .. not one

17-02-11, 09:50 PM	#65
20vcqdriver 4 ring whore! Classic Audi Club Member Join Date: Dec 2007 Location: Wirral Posts: 3,910	Just occured to me regards the temp sensor under the top heater hose on head. Sensor is used to set idle ISV control rate when cold as per the thread by Biggyin ( http://www.classic-audi.co.uk/forum/...ad.php?t=16214 ). If the connector is badly corroded remove, clean up and try again as a start, if still no good test with a meter between centre pin and earth on ohms. Resistance should change as engine warms up. __________________ Coupe quattro 1986:-~450bhp + loooong list of mods! Audi A7 Bi-TDI SLine Black edition 2015 mapped to produce 600lb/ft torque! Audi S4 4.2 V8 cabriolet 2004:-

18-02-11, 04:52 PM	#67
pimpdriver Devon Pastie Muncher Classic Audi Club Member Join Date: Jul 2007 Location: Calne Wiltshire Posts: 7,530	injection engines idle at the same speed, hot or cold give or take 50rpm.. Carb engines idle higher. __________________ Winter tyres now! Driving the B2 80CL as a daily and LOVING it!!!!

16-02-11, 09:00 PM	#61
Gouldy Senior Member Join Date: Feb 2010 Location: W.Somerset Posts: 1,083	no mate its an injection so its all done my sensors mate, might try checking the 2 sensors in the stat housing this weekend,

16-02-11, 09:15 PM	#62
rich.r Senior Member Join Date: Jul 2010 Posts: 1,832	would phil p have any ideas on this one why did i think it had a carb wonder if you have a small air leak somewhere and the sensor thinks it needs more fuel than it actually does

16-02-11, 10:39 PM	#63
Gouldy Senior Member Join Date: Feb 2010 Location: W.Somerset Posts: 1,083	well ive had the inlet manifold gasket done , and the injector colours/o rings , the dizzy vacuum pipe is new, will check all the breathers at the weekend, especially the crankcase breather

17-02-11, 09:19 PM	#64
Gouldy Senior Member Join Date: Feb 2010 Location: W.Somerset Posts: 1,083	right then guys, ive changed a few hoses on the car and its still idling lumpy, my question is.... where is the crankcase breather i see people going on about? i cleaned all the pipes i could see but i cant see one coming from the bottom of the engine, also the ISV is working, and the plunger is smooth, probably going to get a dizzy cap/arm, and a set of leads next does anyone know what the sensors in the thermostat housing, and the thermo time switch should read on a circuit tester? might check these tomorrow .

18-02-11, 04:22 PM	#66
Gouldy Senior Member Join Date: Feb 2010 Location: W.Somerset Posts: 1,083	and this is the same on the KV as his engine?? i will check the resistance when cold later tonight, then watch it as it warms, any ideas what the readings should be? also i had a thought today, when the engine is cold, its idling at 800 (the same as when hot) surely this isnt right? normally when cold it should try to idle at 12-1300 shouldnt it?

18-02-11, 05:37 PM	#68
Gouldy Senior Member Join Date: Feb 2010 Location: W.Somerset Posts: 1,083	not on any of the engines ive had, honda, nissan, saab etc maybe its a mechanical injection thing?

18-02-11, 07:17 PM	#70
Gouldy Senior Member Join Date: Feb 2010 Location: W.Somerset Posts: 1,083	pretty sure mine have two wires .. not one