besty6543

iTrader: (1)

need a bit of help, tried to start the scooby this morning wouldnt start (flat battery) so i jumped it off. put a new battery on now the car is reving between 600 - 1000 rpm on tick over its a 99 uk with a decat center

any1 any ideas?

kalv

Mine revs around the same mark when idle.. ? Is it causing a problem?

besty6543

iTrader: (1)

its never done it before and feels as thou its going to cut out

been told it could be due to the bettery been flat that is cleared the ecu

havent got a clue

besty6543

iTrader: (1)

it doesnt stay the same its up and down

banny sti

iTrader: (68)

Maf sensor mate, disconnection of battery has cleared ecu so now fault is no longer masked. Had same problem on mine, changed the maf sensor £70 ish and all okay.

Maz

besty6543

iTrader: (1)

would that not cause tthe check engine light to come on?

banny sti

iTrader: (68)

Nope, didn't on mine. The 99 models have very fragile maf sensors which are susceptible to vibration and are a common fault. Just do a search on faulty mafs and you will get all the info you need.

Maz

besty6543

iTrader: (1)

is there anyway i can check it or does it need to be put on a computer?

scotty44

iTrader: (12)

Dito mate , same happend with MY00 a few months ago , changed the MAF *sorted*

besty6543

iTrader: (1)

are the maf sensors dealer parts only?

is it just a case of putting a new 1 in and problem solved?

thedeester1

This might help but i think you need a check engine fault for it to work.
http://www.saxonfields.freeserve.co....iag%20Page.htm

besty6543

iTrader: (1)

any chance it could be anything else

thedeester1

Poor idle can be a lot of things. MAF is the main i think. The oxygen sensor or sensors in the exhaust is another.
Im no expert but ive worked on a lot of cars as a hobby. ive been driving scoobs for 6 years i have 3 mates that also turned to subaru when they realised how good they were. I work on their cars too.
Look on the bright side they dont go wrong that often and when they do they are pretty easy to fix. Especialy with a site like this!

besty6543

iTrader: (1)

so is it just a straight replacement then, then thats it problem sorted?

thedeester1

if it is the mass air flow sensor (MAF). Its P**S to replace. Whoever is doing it should run the diagnostic test and narrow it down first.

Im looking back through the posts and i see the flat battery. The ecu should have a standard set of parrameters on an eprom. They will stay if everything else is lost. The Scoob brain programs itself with time. A number of people have told me about using standard unleaded petrol all the damage it does. Ive run the main run about scoob (a 95 inport wrx wagon) on mostly 95 ron (unleaded) for 6 years now. it has 82k Km on the clock. The ECU compensates. Ok its not as responsive as with 98 (optimax or whatever) ron but it aint killing my engine. I have had the run about since it had 12k Km on the clock. Ive found that if i use 98 ron petrol it does more to the gallon. The ECU equates the power expected for a "squirt" of petrol if it doesnt get that it adds to it.
Give the car a good run give it some motorway and some hard driving (avoiding speed cameras and other hazards...coppers other cars old women in micra's etc) and see how it works out for you. After a few good hours of driving the ECU should sort itself out. If it doesnt then your gonna have to replace stuff.

besty6543

iTrader: (1)

so if i take it to my main dealer they should be able to tell me what it is

thedeester1

main dealers cost a lot. But its up to you! Ill buy parts from them but if i can fix it i will!

besty6543

iTrader: (1)

i have had the car now for nearlyy 2 years and all i have ever ran it on is optimax. does my head in when my pride and joy isnt running right. i will give it a good run out at the weekend to see if that sorts it out, if not will get it booked in to the main dealers to see what comes up on there computer. then will probs buy the part from them and fit it myself

banny sti

iTrader: (68)

Wouldn't advise that mate. If there is something amiss with the maf sensor and the air to fuel ratio goes awry then in a worst case scenario you could blow the engine. Easy way to tell if its the maf sensor is to unplug the lead which is connected just after the airbox. If the car cuts out then it is not the maf sensor if it carries on idling then it is. Infact I would change the sensor anyway as a precautionary measure, especially if you have an induction kit.

Maz

besty6543

iTrader: (1)

hi maz i looked through some older threads and seen that you advised some1 else to do. i tried that earlier and it cut out straight away. it has standard filter and air box

thedeester1

it takes about half an hour to run a diagnostic that should be no more than 35 pounds tops. I dont trust dealers M8. I have had M8's that sent their astras to them. One guy sent it back 4 times.. they charged him for a tune and labour, plugs and labour, leads and labour then finaly a coil and labour. I told him it was a coil problem before it went. It cost him 400 quid but an astra coil at that time was 33 quid (30 minutes work). I had an audi too once the heater matrix was gone Audi quoted me 450 quid. I got one for 55 quid and it took me an hour to fit!
The dealers are taking the mickey i think!

besty6543

iTrader: (1)

i live in the north east of england any ideas where i could take it

Eprom

Take the advice of the people saying MAF.
The MY99 and MY00 are prone to this; the Ecu has been masking the problem, if you drive hard on boost, with the MAF faulty you will be looking at more than £70.00.
The new MAF's have a green dot on them, think these are a revised part, you will also need a security Torx tool to remove replace it.

10 minutes of a job though and that's with a cup of tea.

besty6543

iTrader: (1)

ok will do are the mafs dealer parts only?????

banny sti

iTrader: (68)

Yes they are mate.

Maz

thedeester1

Not sure but i doubt the engine would blow for a MAF fault the engine would run so rich that the air wouldnt be enough to ignite the fuel and the engine would just stall since the plugs would fail to ignite just petrol? I maybe wrong but carbon based fuels dont conduct a spark and therefore the plugs would "drown" and nothing would ignite!

DaveW

A failing MAF can cause the engine to run lean, so the engine runs hotter and worst case you melt a piston. Better to be safe than sorry if your not sure and get it checked at a dealer.

SCOOBY TOWERS

iTrader: (7)

...might also be the idle cointrol valve needs cleaning.

MAF wise, the only cheap way to test one, is to borrow a known good one from a mate and see if the problem goes away.

Have a read of this http://bbs.scoobynet.co.uk/showthread.php?t=501980 - not all 99/00 MAF's are faulty - people jump to conclusions without testing things first.

thedeester1

Never considered the engine lean option to be honest. Only had MAF problems a few times with different cars in the last 15 years or so and they have always gone rich. Supose it depends on which end of the air flow scale the sensor fails to.

I suppose there is a way to test the MAF. In the early days of fuel injection they were just a switch off at low speed and start up. and on when the air flowed faster through them so the fuel injector could regulate fuel. Well i guess things have come on a bit since then and theyre now like a potentiometer? Ill put some leads onto mine and run them inside the car and drive it with a multimeter attached. should then be able to say once and for all if the MAF is working or not. Doubt it be will today though!

kalv

have u tried cleaning the MAF first with some brake cleaner? I did and mines a treat now..