I will be going alone at a steady speed then all of a sudden it will start missing and hesitating if I take my foot off the accelerator or press it down a bit it clears but then comes back after a while. My car is an MY00 impreza turbo anyone got any ideas what it could be?

 

What petrol are you using? Supermarket 95 RON fuel makes my MY00 run like a pig.
When were your plugs last changed?
Is your coilpack clean?
Try these as no cost/ cheap options

 

i noticed a similar problem on my 02 wrx. the dealer says it could be an airflow meter problem (mine's a dutch import and they have recently had similar problems at the same dealership with other cars from holland and cyprus apparently). i went in and asked the guy to drive it up the road, which he did, and he noticed the problem. he says they'll change it under the warranty. could be worth checking that out

 

I only use shell optimax or bp ultimate, oil is changed every 3k, put new plugs in about 1.5k ago. Was thinking it may be the coil pack but I have taken leads off sprayed it with WD40 and it's still the same. Suppose it could be the MAF sensor may take plugs out see what they look like.

Dad works for AA may try and get his laptop off him and plug it in see if there are any fault codes stored.

 

one word (well 3 actually) MAF

 

Could also be the injectors, my 99 type-r had the same problem. one of the injectors was messing about and over fuelling in one cyclinder. Changed the injectors (after i had tried changing plugs, leads, coil pack first) and problem solved.

 

How much is a MAF??

How much is an injector?

How much is a coil pack?

 

22794AA010 Maf replacement aprox £70 in the Uk me Thinks

 

Matt,

Same car, same problem here! I've had a new MAF, service and 02 sensor in the past few weeks, so I'd be tempted away from the MAF unless your idle seems a bit of a problem.

Interestingly, my hesitation was fine for about six months, lovely and smooth right through the rev range. Then I got a CEL (32) and replaced the 02 - BINGO, back comes the fault.

Mine's typically at around 3000rpm, on very light throttle, WOT has no issues at all. I can only conclude it's my new 02 sensor, which fits in nicely with all of the previous MY00 hesitation bug threads when the car came out. I've heard that the MY00 ECU is the culprit, with quite a few MY00 owners sticking a MY99 ECU to solve the problem.

Do a search (if they go back that far) and you'll be able to dig up loads on the subject. Try searching on 'they all do that sir!'

Dave

 

My '98 car did EXACTLY this after a plug change, and 3 visits to a dealer later, it turned out to be a dodgy plug lead.

Alcazar

 

Mine had EXACTLY the same symptoms also MY00. Turned out to be the O2 sensor on the EXHAUST.

Certainly worth a try.

 

I thought that the MAF either works or it doesn't and it won't give you problems one day then fine the next.

 

rob, are you saying that a replacement 02 cured your problem? hmmm, weird, a new 02 brought mine back!!!

Oh well, am I right in saying there's just one 02 sensor, on the downpipe area, left hand side?

 

Mic, i've heard that a good MAF test is to unplug the thing whilst idleing, apparently a stall is normal, continuous running is a problem. AFAIK the MAF degrades over time, hence no real CEL or error codes.

Just before I had mine changed the scoob would do this REALLY weird breathing thing at idle, like it was searching or out of breath, well strange. Occasionallt a blip of throttle would help, but not always.

 

Mr. DBM

Mine had to go to the dealer as it was an intermittent fault, they found that the signal going back to the ECU (O2 sensor) was constant and not variable like it should be. so that on a constant throttle it was confusing it ?!!?

Anyhoo it worked. (not very technically minded, just drive the bloody thing)