Car misfires and hesitates after a run??
08 October 2006, 06:27 PM
#1
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Car misfires and hesitates after a run??
Can anyone please help with possible suggestions on how i can fix my problem??
After a good run-approx 30 or so miles my car begins to miss a bit and hesitates when i try and accelerate,almost as if it is running out of fuel.
I have only had the car a week,and first noticed it the day after i bought it.It had about a quarter of a tank of fuel left in it,and i assumed the guage may be wrong,or it is just one of those cars that like to have a decent amount of fuel in the tank,so i filled it up with Tesco 99 octane and all seemed fine..............so i thought the problem was solved.
However,it has now done it a couple more times,one with a full tank(near as dammit),and once again today,with half a tank(all Tesco 99).All showing the same signs,and only after a good run(albeit quite a quick run).
The car is a 2000 W reg Classic Turbo UK Car with 63k and FSH.It is all standard except a K+N Panel Filter(fitted for some time when i bought it),and a Stainless Exhaust and Decat Middle Section which i had fitted on Monday(but the car first done it on the way to collect the exhaust,and before it was fitted).
Please all help,as it is ruining an otherwise fantastic car
After a good run-approx 30 or so miles my car begins to miss a bit and hesitates when i try and accelerate,almost as if it is running out of fuel.
I have only had the car a week,and first noticed it the day after i bought it.It had about a quarter of a tank of fuel left in it,and i assumed the guage may be wrong,or it is just one of those cars that like to have a decent amount of fuel in the tank,so i filled it up with Tesco 99 octane and all seemed fine..............so i thought the problem was solved.
However,it has now done it a couple more times,one with a full tank(near as dammit),and once again today,with half a tank(all Tesco 99).All showing the same signs,and only after a good run(albeit quite a quick run).
The car is a 2000 W reg Classic Turbo UK Car with 63k and FSH.It is all standard except a K+N Panel Filter(fitted for some time when i bought it),and a Stainless Exhaust and Decat Middle Section which i had fitted on Monday(but the car first done it on the way to collect the exhaust,and before it was fitted).
Please all help,as it is ruining an otherwise fantastic car
10 October 2006, 05:13 PM
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1997 - 2000 model cars don't have coil packs like the earlier or newage cars, they have a single coilpack on the top of the engine connected to the spark plugs with ht leads. I'm not sure how prone to failure these are, do a search maybe for more info. I only know of the 2 previous cars the one with the single coilpack lasted a lot longer than 63k whereas the older wrx had to have new coilpacks before 60k.
I would suggest getting a diagnostic check done on the car first to eliminate any faulty sensors etc.
If it has fsh then it should have had new plugs at the 60k service. If it did then they should be ok after 3000 miles, although I'm not saying it is impossible for them to be faulty. Check the service history to see if they have been changed. If they haven't been done then get them changed asap. The fuel filter should have also been changed at 60k, again get it changed if it hasn't been changed already.
If the car has never had a maf sensor since new then it is probably prudent to just get a new one and replace it. They are prone to failure on 99/00 cars causing the car to run lean with potentially disastrous consequences, and cost around £80 to replace. A 2 minute job to fit.
Without the car being looked at properly it is impossible to say what's wrong with it, but you may be able to rule out your plugs, fuel filter and maf sensor easily and without spending a fortune.
It may be that the car just had a bad tank full of petrol, it can take a while for it to clear. You could try running the fuel level right down to speed things up, maybe have a can of petrol in the boot and let it run out to make sure it's all gone. Just take it easy when the gauge gets low.
One thing to consider, if you think it is a lack of fuel causing your problem, is that if it's not getting enough fuel at low revs or throttle openings then it certainly won't be getting enough on full boost and higer rpm so you probably want to take it easy until you get the problem sorted out.
I would suggest getting a diagnostic check done on the car first to eliminate any faulty sensors etc.
If it has fsh then it should have had new plugs at the 60k service. If it did then they should be ok after 3000 miles, although I'm not saying it is impossible for them to be faulty. Check the service history to see if they have been changed. If they haven't been done then get them changed asap. The fuel filter should have also been changed at 60k, again get it changed if it hasn't been changed already.
If the car has never had a maf sensor since new then it is probably prudent to just get a new one and replace it. They are prone to failure on 99/00 cars causing the car to run lean with potentially disastrous consequences, and cost around £80 to replace. A 2 minute job to fit.
Without the car being looked at properly it is impossible to say what's wrong with it, but you may be able to rule out your plugs, fuel filter and maf sensor easily and without spending a fortune.
It may be that the car just had a bad tank full of petrol, it can take a while for it to clear. You could try running the fuel level right down to speed things up, maybe have a can of petrol in the boot and let it run out to make sure it's all gone. Just take it easy when the gauge gets low.
One thing to consider, if you think it is a lack of fuel causing your problem, is that if it's not getting enough fuel at low revs or throttle openings then it certainly won't be getting enough on full boost and higer rpm so you probably want to take it easy until you get the problem sorted out.
10 October 2006, 10:47 PM
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Cheers guys,the car definately had new plugs at the 60k service as it says so in the history.
I don't know for sure about the fuel filter though,and the guy at Wincanton Motor Services suggested that today,so for the sake of £25 i will get this done asap.
He also suggested that it could be the MAF,which again,for £80 is probably money well spent anyway if you think it only has a 60k lifespan.
Two people have also suggested that it could be the Lambda.................is this very likely?? This can be checked by anyone with an emissions tester though can't it???
I don't know for sure about the fuel filter though,and the guy at Wincanton Motor Services suggested that today,so for the sake of £25 i will get this done asap.
He also suggested that it could be the MAF,which again,for £80 is probably money well spent anyway if you think it only has a 60k lifespan.
Two people have also suggested that it could be the Lambda.................is this very likely?? This can be checked by anyone with an emissions tester though can't it???
11 October 2006, 02:33 PM
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Faulty lambda sensor will usually cause the car to run rich in closed loop, ie low revs / off boost and can caus a hesitation or misfire when you go to put your foot down.
Best way to check it is with a select monitor or diagnostics tester that can actually test the sensor, sometimes they aren't completely knackered but switch slowly and this can be picked up. Just checking the emissions in this case may not confirm it for sure.
This test is usually done as part of a diagnostic check so probably worth getting it checked out anyway rather than going along the route of replacing parts to eliminate them.
Best way to check it is with a select monitor or diagnostics tester that can actually test the sensor, sometimes they aren't completely knackered but switch slowly and this can be picked up. Just checking the emissions in this case may not confirm it for sure.
This test is usually done as part of a diagnostic check so probably worth getting it checked out anyway rather than going along the route of replacing parts to eliminate them.
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11 October 2006, 03:35 PM
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I used to have a 94 wrx, it had 50k on the clock when I got it. I had to clean the boost solenoid out because the engine had been overfilled with oil and it got bunged up, as well as draining some oil. It needed coil packs at around 55k and the lambda (or oxygen) sensor needed replacing not long after that.
The lambda sensor is about £200 from subaru, or it cost me that about 4 years ago, so you want to be sure it needs replacing before you shell out your cash. They are located in the header on the early cars and the heat helps to shorten their lifespan. You may be able to get a cheaper generic type one but I have never tried one of these so can't comment if they are any good or not.
On later cars, 97 onwards I think, they are in the downpipe. I also had a 98 sti and it needed a lambda sensor at 40k, so I don't think they have a particular lifespan as such.
Get a diagnostic check done, find out what part is at fault, replace the part, the car has a good chance of being sorted and it limits your spending. It may cost some money to have it done, but may also save you more than it costs.
The lambda sensor is about £200 from subaru, or it cost me that about 4 years ago, so you want to be sure it needs replacing before you shell out your cash. They are located in the header on the early cars and the heat helps to shorten their lifespan. You may be able to get a cheaper generic type one but I have never tried one of these so can't comment if they are any good or not.
On later cars, 97 onwards I think, they are in the downpipe. I also had a 98 sti and it needed a lambda sensor at 40k, so I don't think they have a particular lifespan as such.
Get a diagnostic check done, find out what part is at fault, replace the part, the car has a good chance of being sorted and it limits your spending. It may cost some money to have it done, but may also save you more than it costs.
11 October 2006, 08:48 PM
#9
The pulsing you mention is "normal" on MY 99/00 cars. It is nothing to worry about. If it puts your mind at rest get a diagnostic check done ( My dealer did it free). Don't waste money on MAF until its confirmed as knackered, same with Lambda sensor.
11 October 2006, 09:25 PM
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Cheers people,some good advice(which is what i hoped ) .
The car is booked in with Wincanton Motor Services on Tuesday for a diagnostic check,so hopefully the problem will be solved.
I think it pays to be really fussy if you like cars as much as i do.................i just hope my instincts were right about the car in the first place and it is not anything too serious..............i think for the first time ever,i managed to buy the first car i looked at this time around,it was that good
,and virtually on my doorstep....................another first 
) .The car is booked in with Wincanton Motor Services on Tuesday for a diagnostic check,so hopefully the problem will be solved.
I think it pays to be really fussy if you like cars as much as i do.................i just hope my instincts were right about the car in the first place and it is not anything too serious..............i think for the first time ever,i managed to buy the first car i looked at this time around,it was that good
,and virtually on my doorstep....................another first
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