Postman Pat

Hi all been a while since I've been on.

MY99 UK Imprezza Turbo 2000

Above has given me the runaround with a little misfire and hesitation over maybe the last year or so. Its most noticeable when just pottering about but she doesn't have the same go on WOT either.

Things I've changed so far; MAF, Lambda Sensor, Plug Leads, Coil Pack. A few months back I took it to a respectable rally outfit and they checked things like compression, injectors etc but couldn't find anything wrong (they did say before they started it could take 5 mins or 5 weeks to find)

Anyways over the last period it has been very dry over here (NI) and I had noticed the car has lost its miss and hesitation. Day before yesterday was first wet day in a long time and hey presto she's at it again. Its used by herself around town as I have a diesel for work so I'm assuming the moisture has something to do with the problem. (As long as it starts the Mrs wouldn't notice if it was only firing on three which is the main reason I'm a little unsure of the meteoroligical effects ie I don't get fitness reports from her good self)

Has anyone got any suggestions on what I should be looking at?

Thanks Pat

ReggieMY99

did you also change spark plugs?

joz8968

iTrader: (13)

Are your bonnet vent covers in place... esp. the driver's side one?!

beezor

iTrader: (1)

i used 2 get something quite similar when i had my induction kit on-im sure it used 2 mess with the maf when it was damp-ive put my factory airbox with panel filter back on and its been fine

Postman Pat

Thanks for the replies. Yes I have changed the plugs and the cambelt. Vent covers are still in place and the induction is std. It has me flumoxed.

Pat

Splitpin

Annoying. If this was mine, first thing I'd do would be to look at all the sensor inputs via the diagnostic while it's misbehaving. Hopefully that'll show something up.

If that didn't show something up (or the weather was dry and the car was running alright) I'd check all of the underbonnet engine cabling and connections either for damage or for signs of dampness or corrosion in the connectors.

If that doesn't show up anything obvious, I'd wait until the weather's good and the car's running 100%, and then use a water pistol (or similar) to shoot liquid at various parts of the loom and see if you can provoke it to act up.

If you're still none the wiser, I'd suggest taking the inlet manifold off, removing the main loom and giving it a thorough visual and electrical continuity test.

Postman Pat

Yeah I've been putting that on the long finger for a while Splitpin. Its going to be an awful job unless I get lucky.

r1c

iTrader: (9)

I had a similar issue with mine, turned out it was the maf sensor plug. Terminals were all green since I cleaned it up it's been spot on.

Postman Pat

Thanks I'll have a look at mine

joz8968

iTrader: (13)

If the wet weather running is really peeing you off, try liberally coating all the electrical looms that you can see (esp. the coilpack/HT leads) with WD40 - fantastic at dispersing moisture, etc.

andyxros

might be off the mark hear a bit, but can bad earth points and wires cause miss fires not much of a job to clean n cheak
plus id cheak next time its raining after a run to lift carpets and footplate back from ecu and cheak if theres and dampness as there is some bungs from air con drain off near by ad even after that open it up and see if any moiture inside it?

joz8968

iTrader: (13)

Sensible, simple to check/fix, advice from andy ^^^

Postman Pat

Thanks for all the replies guys. I've looked at all the connector plugs I can easily access and they are really clean. Doesn't have air con though I will still check mats. I was intending on maybe coating the loom with waxoyl.

joz8968

iTrader: (13)

I wouldn't use Waxoyl.

There is special green gunk in an aerosol that you spray onto electrical wiring - it then semi-sets keeping out subsequent moisture ingress.

[-(o)-]

iTrader: (1)

Check the main loom connector under the near side blanked bonnet vent. I had some wierd intermittent problems and eventually traced it to water coming through the blanking plate drain and getting into the connector. 1 homemade drip guard later and no more problems.

Postman Pat

It looks like I might have found the problem. Whilst checking around for where the vent blanking plate might be dripping water I noticed the earth terminal on the battery was loose. Bolt was tight but as there is a plastic housing in the terminal this was stopping a tight fit. Removed said plastic and tightened up (how the battery didn't discharge beats me as it was very loose). Anyway car has behaved since so hopefully that's it (and it was tipping down since). Can't believe this has bugged me for so long.

joz8968

iTrader: (13)

I'm sure that was the problem.

Let us know how it goes,,,