4 replies to this topic

[pakgorgor]

I've been experiencing a weird idle issue recently that I can't seem to solve.

 

From a cold start, the car starts fine and idles perfectly.

 

After it warms up from driving it for 5 minutes or so, the engine cuts and cannot maintain idle once I come to a stop. It will start up again without any problems, but will not idle and the engine dies. If I apply a bit of throttle, it stays running.

 

Here's the weird part: once it dies, if I immediately undo the fuel cap and then back on, it will start and idle without any problems! Afterwards, it will drive perfectly fine for consequent drives throughout the day (or I guess while the engine is still warm).

 

Things I have checked/replaced:

 

- When I undo the fuel cap, I can hear pressure releasing

- All vacuum lines are silicone and have no leaks

- Fuel trap is clean

- Water temp sensor replaced

- New lambda (Bosch)

- Stepper motor loss motion link is set with equal gaps

- IAC position set to between 30-35 steps with MemsFCR

- New coil and spark plugs

 

The car drives fine without hesitation. It is just the idle issue that I can't seem to solve. Any ideas?

 

 

[purple_fly06]

Sounds like your fuel cap isn't breathing and you're essentially creating a vacuum in the fuel tank.

Hence why you can hear air rushing in when you undo it.

 

May be worth trying another fuel cap to see if the issue still persists.

[Deeppockets]

The tanks on injection cars breath via a charcoal canister located in the LH front wing to catch the vapours. The fuel cap is operating correctly when it makes a good seal.

 

Between the fuel tank and the carbon cannister are two valves which may be causing you problems. The first is a roll-over fuel cut-off valve locate at the top of the tank (WLV10007/WLV10009/WFU100560) and the purge valve at or near the cannister, which switches the lines to suck the collected vapours into the engine.

 

I have had difficulty with the roll-over valve not flowing, causing fuel vapour pressure to build while standing and then leaking from the tank into the passenger space.

[pakgorgor]

Upon further inspection, it looks like my car doesn't have the 2 way valve (WLV10009). It had been running fine for some years prior to this idle problem though. 

 

Any other ideas?

Edited by pakgorgor, 06 August 2023 - 08:43 PM.

[mina08]

I also had an idle issue recently, turns out the FORBIDDEN idle screw had come loose, top back of the intake. We had another spi in smae garage and could see the proper set up, now it works fine.

Edited by mina08, 07 August 2023 - 12:35 PM.