Zola-the-master

Hi guys, I was wondering if any of you have come across this problem before..
Basically my year 2000 uk turbo is surgeing under light acceleration between 2-3k rpm but when it hits boost it's fine and pulls like a train. The problem is worse when cold but still there when warm.
I'm thinking MAF although this was replaced back in feb (For another problem, which it cured).
Could this be the lambda sensor or yet another MAF...??

silent running

Has it always been there or has it just started without any changes being made that you know of?

Zola-the-master

It has been doing it before any mods.
Mods done since i noticed it are: Green panel filter, P1 top mount, walbro fuel pump and i've also changed the plugs..?

I dont remember it doing it when i first picked the car up at xmas but i was quite right footed then. It was already de-catted when i brought it.

silent running

The mods you've done wouldn't have caused it to surge any more than before, unless the TMIC has something seriously wrong (either with its plumbing or the core itself).

Was the decat the ONLY mod that was on there when you bought it?

helium3

iTrader: (1)

mine does this when its cold,nothing to worry about.

burt2000

iTrader: (1)

mine to when cold, goes away when warmed up a bit, apparantly quite common on 99-00 cars

Zola-the-master

Cheers guys, But mine doesn't go away when its warmed up so it is something to worry about...!

The only other mod was a cheap VTA dump valve which i replaced with a forge one only for the fault to remain the same, I have since replaced this with a standard re-circ valve but obviously still got the same problem.

Also it was doing the same before i changed the I/C.

3barboost

I think your lambdas borked
not enough to throw a code
but on cruise / part throttle the ecu uses this to maintain afr and if its borked - the ecu adds more fuel - less fuel - more fuel and so on and you get that surge as you drive

MarkFitz

might be gummed-up solenoid, - try removing and cleaning out with WD40, etc. Lower loss filter might be causing breather crap to get to your sensor.

Zola-the-master

Mark do you meann boost solenoid...? If so, i've already tried that.
Thanks for your suggestion though.

MarkFitz

Yep, boost control solenoid...but you've already covered that. My 97UK surged a bit during spool when I freed up the intake and exhaust, - mostly noticeable during the winter months.
If you're still concerned about your maf then you could check if fueling is ok by sticking a wideband up the tailpipe to see what the AFR's are doing at full-load.

Rustle73

I've had a similar experience recently in a MY98. I had my MOT, then had it serviced before a long road trip and the garage diagniosed it running rich, the o2 sensor playing up, but recommending giving it a few months before re diagnosing it. I only noticed the (light) surgeing that same week, especially when trying to maintian a low constant speed in 2nd / 3rd, say in traffic etc, and as you say at 2-3,000rpm. I have thus assumed it to be the o2 sensor. I don't have enough technical knowledge to say whether this is definately the cause, but it seems linked in my situation. Perhaps worth investigating, along with the other suggestions.

gavs scooby

i chap i have a v plate my00 and it does it. feels like it misses a beat then back to normal then misses a beat and so on. i put it down to needing new plugs possibly.

Zola-the-master

Yeah, Think i'm gonna go down the o2 sensor route, Have any of you tried or got any info on these universal one's that can be brought for a tenth of the price of a genuine one from a main stealer....?

Zola-the-master

A big thumbs up to 3barboost. I fitted a new lambda today and all my troubles have gone away.

I have only brought a cheap (£15 inc delivery) sensor from ebay but it has done the job, I dont really mind how long it lasts as it has pin pointed the problem and when it does fail i will buy a genuine part.

Thanks again for all your help guys

exvaux

iTrader: (1)

zola which one did you buy the 3 or 4 wire as my 99 sti is doin the same been diagnosed as o2 sensor but dont really fancy the 150 quid subaru effort if its not cheers.

Zola-the-master

Mine is the 3 wire (2white 1black). Just pop your bonnet and have a look at the wires coming out of yours, and there's your answer.