Hi

looking to buy a imprezza and have test driven a few

however, I have a question, I am used to driving Golf VW 16V's which are incredibly smooth running engines, all the way up the rev range

but the imprezza's all MY99 turbo wagons seem a bit lumpy, is this normal due to the boxer configfuration? (they all went like **** of a shovel though)

James

 

they sound more "lumpy" than they really are.

 

I has a GTI before my 2003 Wagon. The Golf seemed very smooth compared to the Scube which was noisier - but a lot faster and has a turbo which gives a different driving character.

Just my 2 cents.

 

I'm not thinking straight - the GTI is a turbo engine but only 150 BHP - kinda long day

 

ok, so its not just me, they do seem a little "lumpy" then

 

Was the car warm when you drove it; they are lumpy when cold (lamda sensor keeping things emission friendly) but the boxer engine is very smooth when warm if all is well with it.

Ns04

 

I agree, very smooth, shouldnt be lumpy...

 

well -- both were started from cold and maybe I am being too sensitive

they both pulled well too, maybe not used to such loud exhausts, one had a twin tail pipe sebring backbox -- but then i am getting on a bit

 

The unequal length headers make them lumpy, ones with equal lenght headers like the latest JDM twin scroll cars are not

Tony

 

what are headers -- do you mean exhaust manifold

 

yes it a "TERM" we use on here

 

Mate, don't drive em on boost from cold! They need time to warm up before the oil becomes effective. Giving them some beans before them is cruel to the engine. Mine takes about 5 mins to warm and from then on is as smooth as you like. Smoothness is one of the perks of the flat four configuration!

Ns04

 

I Think 5 minutes aren´t enough.

Buy an Oiltemperature gage and and watch at it.

It should be at 75 to 80° before flooring it.

 

yes -- i,m pretty **** about this too, in the winter I wont let the misses use the heater until the engine is well up to temp

back to an earlier question - what in scooby speak are "headers"

Cheers
James

 

The manifold, the latest JDM cars have equal length manifolds, the older and uk/euro/us cars have uneven length (hence you get the burble but you also get a slightly lumpy feel to it too).

Tony

 

i have 2 16v golfs (one is a race car) i felt the same before i bought the wrx.........what went through my head when i started the impreza was.................last time i heard a noise like that was when my race car droped a cylinder!!.................,i would say it was more the worry of going from german to jap!

 

yes - thats the job, sounds like its misfiring, but like peopls have said maybe its just the exhaust noise/note

but the 16v golf engine was like driving a sewing machine -- soooo smooth

 

its more the engine matey...............pistons go from side to side instead of up and down! its like a v6 or a v8 they all sound lumpier as you said in the topic heading.........its just characteristics!...............my old man had a legacy years ago thats why i knew it was the norm.

 

cool -- topic closed

what am hearing/feeling is the difference between and DOHC 16V and a boxer engine

thanks for all the input

 

Quite right!

Apologies, my comments were a bit confusing!

I meant 5 mins before the lumpiness goes!

That does NOT mean the oil is up to temp!!

Mine gets 8-10 miles before boost is used!!

Ns04

 

They SOUND lumpy, like an old Beetle does, but shouldn't actually BE lumpy. A healthy Impreza does not have a lumpy or uneven idle or power delivery.

 

Stick your hand on the inlet manifold and give the engine a rev...should be VERY smooth, if you FEEL any shakes, vibrations or lumpyness it ain't running on all 4 properly.

Exhaust note of an ImpreZa without equal length headers (exhaust manifold) on the other hand...lumpier than SC 's cellulite


Don't ask why we use americanisms (re: headers) on here - blame the feejits

 

Agree when they've had a few minutes to run from idle, but a bit of lumpiness when stone cold is not uncommon and IIRC is more to do with the influence of the Lambda sensor trying to keep things emission friendly than any "fault" with the engine.

Running properly a flat 4 should be noticeably smoother than a VW in line 4 though!

Ns04

 

Its just cold start enrichment; Its a low compression engine which means it needs a fair amount of fuel dumped in there to get it going.

Remember how lumpy an old car with a manual choke runs if you pull the choke lever out too far? Similar thing - too rich.

If you have a decat, give it a good rev while its doing it within 10 seconds of starting it from cold and marvel at the smoke cloud that comes out the back. (then post a thread in technical about your car smoking whilst revving when cold, asking whats wrong ).


Also OS sensors need at least 30 seconds of running for the heater to preheat them, as it won't give any fueling info until it up to temperature. Hence the ECU will ignore sensor readings for preset period of time from cold start (about 30secs, but don't quote me on that). Problems do arise if the sensor's heater is a bit old and takes longer to reach operating temperature up than it should.

 

"If you have a decat, give it a good rev while its doing it within 10 seconds of starting it from cold and marvel at the smoke cloud that comes out the back. (then post a thread in technical about your car smoking whilst revving when cold, asking whats wrong ). "

you read my mind -- In one of the cars I tested -- i did blip the throttle straight from start up (nothing extreme i,m not a plonker) and did notice a bit of smoke from the exhaust

I couldn,t see any whilst diving -- but i didnt want to look too hard in case I "kissed the ****" of the car in front, it would all get a bit embarrassing then