How wierd is this? and any ideas pls!

[a91_formula]

Developed a misfire on my 2000 3.8 V6 Camaro.  Changed the normal culprits: leads, plugs etc but still no luck.  Did a search on-line to see if there were any posts anywhere that could help - found a few that said to check different things like coils etc etc.  Did all this - still no good.

Anyway decided to bite the bullitt and buy an OBD2 code reader to see if this would bring up any codes to help - nothing!! not one code!!!

Have bought a fuel fiter (just in case!) which we'll get round to doing soon - but any ideas anyone?

TIA

[F Body]

Quoting: a91_formula

Have bought a fuel fiter (just in case!) which we'll get round to doing soon

Don't forget that with the electric fuel pump inside the fuel tank the fuel pipes are always pressurized


Having a look in my GM Manuals


Is the misfire at idle, at a certain rpm or all the time ?

[F Body]

Quoting: F Body

Having a look in my GM Manuals

According to the Official GM Service manuals ( all 1,187 pages of them ) Most electrical faults should throw a code and/or illuminate the Engine management light, therefore I think your on the right path thinking fuel related.

Check the intake system for a vacuum leak which may cause a misfire.

Damaged/worn vacuum hoses.
Loose or split connections around the MAP sensor.
MAP sensor sealing grommet.
Throttle body gasket.

After that it gets more difficult & expensive :

Warped intake manifold.
Warped of damaged cylinder head sealing surface *

* I'd be expecting some sort of coolant loss and/or oil contamination.
  Pull the oil filler cap and check it's not full of mayonnaise.

[a91_formula]

thx m8 - will do some more tests

[Gator]

temp sensor is another suspect that can cause all sorts of grief and not show any codes

[HardRockCamaro]

Coil?

[a91_formula]

Finally got round to changing the fuel filter. Started her up and she imeddiately sounded better - idled perfectly, I took her out for a test drive and wow so much improvement, until I turned round at a roundabout and put my foot down - there it was again  What I don't get is that if you haven't got your foot in it and are just cruising, she's fine but as soon as you put your foot in it you still get the "popping (not very technical word i know)" sound.

Having thoughts now that it could be a blocked injector?? Have given the car to our mate Kiwi who is gonna removed the injectors and check them to make sure there isn't a blockage.

What I am also stumped about is that there are no codes being stored - surely if she's missing it would store a code??

[F Body]

Quoting: a91_formula

What I am also stumped about is that there are no codes being stored - surely if she's missing it would store a code??

If only OB2 was that imformative

If the problem is not related to the electrical system ( i.e. spark etc ) or to the fuel delivery system it won't show a code

Quoting: Gator

temp sensor is another suspect that can cause all sorts of grief and not show any codes

or

Quoting: F Body

Check the intake system for a vacuum leak which may cause a misfire.

Damaged/worn vacuum hoses.
Loose or split connections around the MAP sensor.
MAP sensor sealing grommet.
Throttle body gasket.

Sorry I can't be more helpful

[a91_formula]

Thanks - will see what comes back about the injectors, if it doesn't solve it then we'll check those things too.

Thanks again

[a91_formula]

All I want to do is sell her to get me something else

[FUBAR]

Is it only at Wide-open-throttle that its now got a problem?

Could it possibly be a weak fuel pump? if its on its way out might it not be able to keep up with the fuel demands of WOT but in normal driving its fine...

Could it have been struggling against a partly blocked fuel filter for ages and worn out?

Anyone else think this is possible as its just a thought...

[Titsy]

Quoting: FUBAR

Anyone else think this is possible as its just a thought...

I had thought the same thing... Could you be hearing knock at WOT as the mixture leans out?

[a91_formula]

Quoting: Titsy

I had thought the same thing... Could you be hearing knock at WOT as the mixture leans out?

Can't say i have noticed it