Back-firing.....?

[toysrus]

Ok, so whilst revving the Engine in neutral up to 6000rpm then letting the accelerator go, it will make about 3-4 pops /noise out the exhaust. Is this from unburnt fuel getting into the Turbine ?

It has new NGK Leads and Plugs but running the old coil......could it be a sign the coil is getting old and tired ? or something else such as the 2 1/2 > 4" Cat > 2 1/2" exhaust system design ?

Cheers

[chunkhead]

I have a 3" setup on mine, she makes the same noises! Like a crackle? Bit like a V8? :?

[tmz_99]

Sounds like it's running rich.. this may happen for a number of reasons if you're running the stock computer, it's basically trying to compensate for your mods by running in "safe" mode.

[Starion VR4]

mmm.. just have a look at yr exhaust manifold, me thinks U have a cracked 1 or a leak in the gasket area, they usually crack in the middle where the pipes joint in the centre, between #2-3 clyinder underneath. Another way is to place yr hand over the exhaust pipe to block all air escaping( have some1 else do it 4 U) it car stalls soon after all is well, if not U should be able 2 pim point where the leak is with the amount of air rushing out. :beer :beer

[honest_jim]

Mine does the same thing since i got a 2 1/2 inch turbo back exhaust fitted the car seems happy enough though and is running better than ever so im not too fussed about it. My old nissan s-12 turbo did the same thing when i got a big exhaust on that too. Im pritty sure my staz doesent spit fire in anger its only when it revs down it just pop's abit, sounds good though.

[toysrus]

Had the exhaust manifold crack welded up :beer

It does try to almost stall though after making the pop noises etc but composes itself and sets back to idling nicely. The only mods is the exhuast system, apart from that the Starion is stock as a rock.

[chunkhead]

Hey yeah, mine pretends to stall when I slow down through gears to a complete stop! Bastard! :x

[grumbly]

sounds like a mixture problem. mine does it, but wil tune it out later...I love programmable ecu's.

basically, when you release the throttle the injectors still squirt some fuel...

[toysrus]

Hmm, had the Injectors cleaned and flow tested and are perfect at the moment, so maybe AFM related or something along the fuel system such as the return line........

[plasticdash]

My starion backfires on over run - right on 2K rpm and 22" Vac (which happens to be what it holds coasting down hills at 50-60 kph) . pretty violently too !

[merlin]

the popping/backfireing on throttle overun is caused by too much ignition advance under vacume, and possibly too lean a mixture under these conditions.

Maybe you have the vac hose from dizzy to TB on the wrong port.

It wont do it if its running rich, but an excessive lean mixture will exaserbate the problem.

[toysrus]

Hmm, I've drop the static Timing down to 5 degrees BTDC for 14psi of

[merlin]

unfortunately dropping static timing kills off boost performance, as well as some of theon boost power. you realy need to go aftermarket ecu

[grumbly]

mine does it when rich, not lean, due to unburnt fuel (according to my dyno guy)

[Barney]

Ok, so whilst revving the Engine in neutral up to 6000rpm then letting the accelerator go, it will make about 3-4 pops /noise out the exhaust. Is this from unburnt fuel getting into the Turbine ?

It has new NGK Leads and Plugs but running the old coil......could it be a sign the coil is getting old and tired ? or something else such as the 2 1/2 > 4" Cat > 2 1/2" exhaust system design ?

Cheers

Reving to 6000rpm in neutral is the single worst thing you can do to an engine. There is no load on the piston this can cause major damage to the bearings especialy the little end. In racing terms it's known as "buzzing the engine" as it the same thing as missing a gear.

Think about it, at 6000rpm your piston is going up and down 100 times per second!

DONT DO IT ANYMORE. BEARINGS ARE YOUR FRIENDS

Ash