Bit of a problem

TheInterceptor · 15-08-2010, 11:30 AM

hello all, im in need of some help.

Yesterday, the au has decided it doesnt want to rev anymore. Meaning, when foot to the floor, it will bumble along very very slowly. This happened after i revved it to around 3 , 4K rpm to get of an intersection...my thoughts were the catalitic converter has given up. but apon inspection this morning, i found no rattles or any bits coming out. Theres also a burning smell when hot, maybe due to the oil all over the underside under near where the radiator bottom is (according to the dipstick, its still full, and it doesnt drop any oil on the ground), the smell only came about after this problem started. The car also sounds a bit off, leaning towards a boat sound.
Also had a look round the engine bay, everything is connected where it should be but theres a whistling sound coming from somwhere around the throttle body/back of the engine. Couldent pinpoint where it comes from though.

Any thoughts as to what it might be? Has the engine given up?

I appreciate any help.
Cheers...

KR1STO · 15-08-2010, 11:34 AM

Can you rev it past 3k in neutral, but while driving not go past 3k..?
I had the same problem and it was the cat..
Although there was no rattles of bits coming out of it, it had all fused together into one big lump inside the catalytic convertor...
I was also getting a whistling which i coudn't pin point and it was due to the excessive back pressure the blocked cat was causing..
Thats all i can think of mate..

TheInterceptor · 15-08-2010, 11:41 AM

Revs over 3K in neutral and it will go past 3K when driving aswell, at 2.5K it starts to pull away fairly quickly, but still fairly labored...i didnt dare rev it past 3.5, didnt want to make matters worse.

KR1STO · 15-08-2010, 11:42 AM

is it dual fuel...?

TheInterceptor · 15-08-2010, 11:49 AM

nup just petrol

AUIIPURSUIT · 15-08-2010, 12:00 PM

fuel filter blocked, or fuel pump dying.

check fuel, check spark, check intake/outtake.

KR1STO · 15-08-2010, 12:03 PM

that was my next thought too...!

TheInterceptor · 15-08-2010, 12:13 PM

i thought about the fuel pump but it was replaced about a year or so ago...
AUIIPURSUIT what do you mean by intake outtake?

Il probobly do the checks later on in the day, but i will definatly be bringing the car into the mechanics first thing tomorrow morn.

thanks for the replies so far gents

AUIIPURSUIT · 15-08-2010, 03:00 PM

intake, meaning your air fow sensor, airbox etc...

outtake -exhaust, namely catalytic convertor being blocked. when they break, they roll around in the chamber and basically form a cork out of the honeycomb. you should notice your car is a fair bit quieter if this has happened though (if you have an a/m exhaust).

change the fuel filter, its probably due. ive had a walbro fuel pump die a year after install.. so it can happen.

RspecAU · 15-08-2010, 03:12 PM

It sounds like you have a spark issue there pull the plugs one at a time, check leads and coil pack.

TheInterceptor · 16-08-2010, 06:56 PM

Doesnt feel like a spark issue...? engine runs fine, apart from the back pressure whistling. If the spark plugs dont light up, wont the engine give me feedback? eg: Running rough?
Gave it a few good revs up to 5k and it goes a bit better so im thinking it really might actually be the cat, maybe its shifted giving the slightly better flow...?
Havent gotten the chance today to check the plugs, and conveniantly the mechanic opened shop really late today...
Also the exhaust system is fully stock, car sounds louder, but sounds sick. (read: not "cool" sick)

AUIIPURSUIT · 16-08-2010, 09:04 PM

if anything your car would be more quiet than stock when ur not getting the power... unless you are hearing the engine labour because of the excessive backpressure the blocked cat is causing.

and yes, whilst the honeycomb does tend to cork, it can bounce around eventually and give you pockets of power... i wouldnt be leaving this problem too long, and flooring it to get the power isnt really ideal.. dropping the cat will take you 30 minutes max by yourself. one the cat is out, give it a shake.. youll know if its buggered..

you might also want to check your exhaust tip. you *may* notice tiny shards of honeycomb.. will look like tiny spinters of grey wood i suppose.

dont touch anything from inside the cat either, its highly caustic.

if you find the cat is rattling like a spray can. *dont* bash it out with a hammer and long screw driver so you can drive down to the exhaust shop n purchase a metal cat or similar... yes.. *dont* do that ;)

mik · 16-08-2010, 09:40 PM

my mates car blocked its cat up it had a tendancy to run worse when it got hot, outwardly there were no signs of a cat problem, it took him 2 years of pain changeing all other service items, if the usual stuff fails i would try the cat, its not an overly expensive item anyway.

TheInterceptor · 20-08-2010, 04:33 PM

Ok, mechanics looked at it today, they've checked the cat, removed it, drove the car, still the same problem, they scanned for codes and only got a Knock sensor code come up. Fuel pressures and such are all fine also.

the search for the problem continues....

KR1STO · 20-08-2010, 07:44 PM

no good man...
Looks like its going to be a long search...
Do they have any ideas on what it may be..?

TheInterceptor · 20-08-2010, 08:08 PM

Not as yet, they will be keeping the car till next week, gives enough time to check absolutley everything.
It even stalled this morning when i was pulling out of the driveway to go drop it off.

TheInterceptor · 25-08-2010, 06:34 PM

ok, finally picked up the au today! the problem?
The Harmonic balancer! The teeth moved way way out of place, almost a full half turn from where it should be lined up to. Also they found 2 and a half injectors that were blocked. Anyways all is fixed, runs beautifully. The car is completley different, its got incredible accelaration, its actually fast now, not that you can go fast but thats not the point.