Multiple codes stored - help

[rincewind]

I thought I'd re post my previous problem.  IS200 on a 2004 plate, 148k miles

I've now read the codes. 

P0300 Random/Multiple Cyliner misfire detected

P0301 Cylinder 1 misfire detected

P0303 Cylinder 3 misfire detected

P0304 Cylinder 4 misfire detected

P0305 Cylinder 5 misfire detected

As in the original post, starting from cold it runs fine right the up to running temperature, it only seems to be happening when I restart from when the engine is already pretty warm i.e. it's been run up to operating temperature, switched off and then restarted a few minutes later. 

 

Any ideas people?

[ROYT]

As nobody has replied,here is my guess,assuming it's a petrol engine not diesel

Bear in mind I know nothing about IS models'

Cold start injected engines have some sort of overfuelling device to provide a rich starting mixture.

As your runs right with this rich mixture, when the 'overfuelling' times out, the mixture is

adjusted for normal running I.e leaned off.

if you have an air leak weakening the mixture more than the ECU can compensate for

this may cause multiple misfires.

Assuming spark plugs, Ok.coils, OK

Just my 2cents worth..

cheers

 

'

[rincewind]

Thanks ROYT.  I'm going to have a good look around the various hoses and other points to check for air leaks.  I have msifires on 4 cylinders, so seriously doubt that 4 plugs or injectors would go faulty at the same time.

I have found that the pre cat O2 sensor heater is stuffed.  I checked it this morning with a test meter and the heater element is reading zero ohms (it should be mid teens).  So, ordered a new Denso O2 sensor and fingers crossed.

 

Cheers

 

Paul

 

[ROYT]

That certainly wont help, if the sensor is sending duff info. to the ECU, the fuel

trims will be all wrong,

Ecu struggling to figure it all out!

[rincewind]

Well, an update.  I changed the O2 pre cat sensor, fault still there.   However, a new error code has appeared - P0171 Fuel mixture too lean bank 1.  So, possibly the MAF sensor but could also be other things, so I've boked it in to a local garage for a proper scan.