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Model specific boards => Golf mk2 => Topic started by: cняis on 02 March 2007, 23:18

Title: Timing adjusted... odd results
Post by: cняis on 02 March 2007, 23:18

I recently had my pinking 8v digi GTI's timing adjusted, and the results are quite odd i think...?  :laugh:

Basically the engine is running smoother through the gears, no pinking at all, performance seems the same... BUT...

• the exhaust is now louder (especially at tickover) - its a powerflow stainless exhaust with 4 branch manifold. it isnt blowing, its almost as if someone has turned the volume up!
• the MPG has dropped from an average of 38-40 down to 34-36 on a run

Is this because the car now has the chance to ignite more fuel per spark resulting in more fuel used (low mpg) and therefore higher volume of gases emitted (louder exhuast)??

Some1 put my mind at rest!

Title: Re: Timing adjusted... odd results
Post by: Neaty on 03 March 2007, 01:06

perhaps before it was running a bit too lean, now its running properly - as in burning the right amount of fuel  :undecided:

Title: Re: Timing adjusted... odd results
Post by: cняis on 04 March 2007, 17:07

funnily enough, i thought it was overfueling before the timing was adjusted (as it was pinking and there was also fuel coming out of spark plug holes, which has now pretty much stopped)

maybe its now cleaner burning?  :huh:

just when i think i'm starting to understand cars! wierd.

Title: Re: Timing adjusted... odd results
Post by: jase555 on 04 March 2007, 21:41

pinking or piston slap is caused by a lean fuel to air mix. so everythink you describe sounds ledgible.

Title: Re: Timing adjusted... odd results
Post by: sacvwgolf on 04 March 2007, 21:56

what is pinking and piston slap?

Title: Re: Timing adjusted... odd results
Post by: jase555 on 04 March 2007, 22:15

Detonation (also called "spark knock , pinking, piston slap") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.


Mild or occasional detonation can occur in almost any engine and usually causes no harm. But prolonged or heavy detonation can be very damaging. So if you hear knocking or pinging when accelerating or lugging your engine, you probably have a detonation problem.

Title: Re: Timing adjusted... odd results
Post by: sacvwgolf on 04 March 2007, 22:16

oh thanks for clearing that up  :smiley:

Title: Re: Timing adjusted... odd results
Post by: jase555 on 04 March 2007, 23:00

no problem what so ever  :grin:

Title: Re: Timing adjusted... odd results
Post by: cняis on 04 March 2007, 23:40

wow ok so my car is running as its supposed to now then  :cool: thanks!!