Help for RPM problem during Radiator Fan on

[princelotus]

Hi! Friends,

I wish all a very happy new year.

I am using Fabia 2008 1.4 Manual version. I have also Fitted CNG sequential Kit.

My problem is that Car run fine on both Fuel i.e. Pertol and CNG both, but during the time Radiator Fan run, RPN down till 300 or sometime dead when I press clutch to shift gear.

Few time back my Radiator fan also burnt and I got it changed, but the problem is still there. So no fan fault I guess.

Pls. help me to know the possible reason and if I can check to diagnose this.

Thanks in advance.

Cheers.

[Guest]

Hello princelotus, and a Happy New Year to you to.

 

So if I have this right, your engine revs are dropping down to 300rpm when the engine coolant fan is on? And sometimes it stalls as you go to engage 1st gear when the engine fan is operating. Ok, so I think this is just an engine idle problem and it needs resetting to operate at the proper level. The engine fan will cause the engine revs to drop down slightly but these should then rise again to the proper level when the engine management system kicks in. If you have had some work done on the car recently then it's likely resetting the idle speed is all that is needed. I suspect you will have rightly disconnected the car battery to do the work and this means you may have to do a proper idle speed/ecu reset if you are having problems. However, it could be a faulty Lambda sensor on the engine exhaust front pipe, or it's disconnected. If you are burning CNG that does run very hot and it can burn out the lambda sensor early especially if it's already done a good few miles.  It can be other things but those are my best guess at the moment and are easy to check. Idle reset is google searchable under 'VAG engine idle reset'. There are differing methods for different cars, but if you are not sure contact your dealer. Good luck.

[princelotus]

Hello Estate Man,

Thanks for your quick reply and sorry for me to late...

I could notice that Car run very fine with Petrol and no drop in RPM in any case.

But its only in CNG, RPM drops during coolant fan on.

Also during morning time, ignition takes very longer time, start with missing voice and jerks, ECM light gets on. Goes off after few KM, is it related to this problem.

I have reset the VAG engine idle, but the same result.

Do you have any guess based on this.