Hello everyone,

Problem started about month ago. On every cold start engine is keeping revs on about 1100rpm even when outside temperature is very high, talking about 30 Celsius. I checked, with obd11 scanner, live data and it's showing me intake temp, engine output  temp, oil temp and ambient temp all working properly (thought that maybe engine coolant temp sensor was faulty). Does anyone have any idea what to check next?

P.S. I discovered that membrane on PCV valve is thorn, and new one is on the way, could it be cause for problem 🤔

Most likely as not supposed to be torn.

You will know as soon as the replacement is fitted if it was the cause.

Update..

Nope, replaced PCV valve and regarding engine rpm it didn't helped. I'm wondering, ecu is comanding cold start rpm as it's outside temp below zero, as I mentioned before, coolant sensor is working properly and cluster gauge is showing temp as always. Is there any other sensor from which ecu is gathering information?

There is some kind of sensor on back of engine block just below intake manifold. What is it for?

My assumption is that it's for oil temp, can't see it on dashboard, but it's giving readings on obd11 scan tool.

Edited 23 June, 20223 yr by Ljuba

Lambda sensors not reading right?

Knock sensor is on rear of engine block under inlet manifold.

Oil level/temperature is close to lower end of dipstick tube I think.

 

 

If the engine ECU thinks the alternator is heavily loaded, it might increase idle rpm to help. How old is the car battery?

Can you inspect the signal wiring between alternator (terminal DF) and engine ECU? Unplug the two-way connector from the alternator and measure volts relative to battery negative on each contact of the loom plug, with ignition/contact switched on. This should prove neither wire is broken, if you see voltage on both.

Battery is few years old, didn't tested it but starter motor is cranking strong, so I think that battery is good. Pete, if I understand you correctly, I should get 12V on both of those wires you mentioned?

3 hours ago, AnnoyingPentium said:

Lambda sensors not reading right

Idk, no fault codes for those ones. Apart from that funky behavior on cold start, the engine is working like Swiss clock, no misfires or increased consumption etc.

Update, I didn't touch anything but whole last week everything is back to normal. Is it permanent i don't know but for now engine is acting as it should..