Hi all.

 

Car has been missfiring for a while had the o2 sensor changed which helped. Ive noticed on start up there is heavy blue smoke with a strong petrol smell. when accelerating it gets worse and can see smoke through the rear view mirror. I suspect this is giving me the poor mpg im getting and lack of performance. Any ideas people?

 

Regards Andy

just a guess m8 but it sounds like could be piston rings

 

sniff the exhaust and see if it smells like oil

hi, smelt the exhaust and defo petrol. Thinking about an engine strip down and rebuilt, anyone have any ideas on how much this would cost?? Regards Andy

It could be bad connections on injectors or coil packs, the wiring gets quite brittle and the contacts fur up.

i bought some spray from the car shop the other day that cleans contacts

might be woth getting some and giving it a try

sounds like its just running rich to me. is it running on all 6 cylinders?

If the smell of petrol is coming from the engine bay it is the petrol pipework.

 

Blue smoke on startup are the pcv valves, particularly the front hoses and or the valve stem seals.

Blue smoke on startup are the pcv valves, particularly the front hoses and or the valve stem seals.

Or it's really rich and washing the bore of all oil

Or it's really rich and washing the bore of all oil

 

That's an unusual one, can you point us in the direction of where you got it from?

That's an unusual one, can you point us in the direction of where you got it from?

It's not too unusual. The mechanic at work first told me about it and is quite often the case when you have a strong petrol smell too. Do a search on this forum for "bore wash", it pops up from time to time.

In the 300ZX, overfuelling can be caused by the temp sender which is notorious for giving problems.

I know bore wash happens, but always thought it caused low compression due to ring/bore glazing and not anything to do blue smoke on startup, doing a google for it brings virtually nil results?

If your motor is run in already, glazing shouldn't occur. The fuel washes the oil off the bore and gets burnt giving the blue oil smoke with a heavy soot content from the fuel. Smells and looks terrible.

I did a google for "bore wash" and got .....

Results 1 - 10 of about 2,520,000 for bore wash. (0.18 seconds)

Which google are you using ;)

I think there may be a crossed line somewhere.

 

I did a search for "bore wash" "start up" and "blue smoke" and got naff all!

 

Bore wash can occur at any point of an engine's lifespan!

 

Bore wash does not cause blue smoke on starting, if it has damaged an engine's rings they will give low compression and possibly blue smoke all of the time!

 

There is so little oil on the bore walls once the rings have passed over them, that for petrol to wash it off and burn it on startup would be difficult!

 

Petrol dilutes the oil on the rings and causes them to wear prematurely, the petrol also thins the engine oil causing it cause wear in the rest of the engine as well!

Edited March 20, 200916 yr by TopLess

Ive already replaced the temp sensor with a brand new one, no faults stored either in the system. No smell coming from engine bay at all. Going to try connectors but i dont think that will work tho as i only did this a month ago. Thanks everyone for your help. Any more ideas keep them coming.

are you definatly running on all 6?

Has he tested the fuel pressure?

feels like all six nice and smooth engine just at 3000-3500rpm get a backfire sound in the exhaust. can i do a fuel pressure test myself? Thanks again

Here are some diagnostics that you should carry out and will help with your dilemna!

 

 

Boost leak test

Conzult

Fuel Pressure test

Ignition timng check

Compression check

 

If you do a search on the forum there are many threads with these procedures being detailed?

 

One small question have you replaced or had any work done on the injectors at all?

Edited March 20, 200916 yr by TopLess

Bore wash does not cause blue smoke on starting

When I had a temp sender fault I got plenty of blue smoke then and it cleared quite quickly. My rings / valve stem seals and compressions are fine. Never smoked any other time.

I really don't want to clog this gents problem thread discussing cause and effect of bore wash, if you wish to quiz me some more then please pm me?

I really don't want to clog this gents problem thread discussing cause and effect of bore wash

Agreed

Can't PM sorry

All I was saying is that it is possible that bore wash could be a factor in the problem. I can find many Google searches which back my statement.

You seem to disagree but I'm happy to leave it at that. Cheers for your input

Toplessz32@hotmail.com

 

email them to me?