Low idle, black smoke & blackfire problems!!!

[Anonymous]

Hi Guys,

Everytime I change gear, there will be puff of black smoke, backfiring and the car idle would drop to close to 0. It will remain low until either the car comes to a complete stop or if I put it in gear.

Sometimes the car idle would become unstable and drops to around 250 - 500 even when the car is stationary.

Diagnosis from my mechanic

- He thinks is my blow off valve (Turbosmart) that is most likely causing the leak or giving inaccurate reading causing the above problems.

It make sense to me but since I don't have a lot of spare cash for trial and error, I was hoping you guys would be able to give me your thoughts on what you think is the problem or whether you think its the BOV too?

Other causes I have experienced in the past that has lead similar problem of low idle, backfire and smokes include

- bad batch of fuel. Solution: Somehow changing the spark plug resolved this problem

- leak in the pipes. Solution: replace old clams with new and tighter ones

- o2 sensor had problem. Solution: replace old o2 sensor with a new one.

Please share your opinion, I am desperate for your advice :shock:

Thanks

 

[geetee]

When changin gear a BOV quite often causes backfiring, pops, bangs and even flames from the exhaust as the engine management get confused as you're dumping metered air to the atmosphere.

It may be that the BOV is not closing / sealing properly after dumping - try putting your standard one back on.

Bad idling (usually lumpy and low) can also be caused by a faulty MAF or connections to it. Check the FAQ for info on checking and regrounding the MAF.


Let us know whow u get on!

Cheers
GeeTee
8)

 

[Carl Hammond]

I prefv posted something similar to this under Tricky ONe Here Lads in the Problem solving Pages, look for it in the seach area and it may explain all, may be the same may not be but mines was just water in plug one and cars been fine ever since, Is ur story like mine form the orig post before mate:

I PUT

My R, Running Fine (Aprat from the normal tick over being between 1100 and 1200 RPM (which I have been told can be sorted by getting the idle control valve checked as this could be stuck or jamed or something), Firstly anyone know how to sort this?

OK here is the weird part on Sunday I cleaned the car and put it away again in the garage for Monday's trip to work, in the morning I took it out (as on lates) and it started to run really lumpy and it gradually got worse and got the to stage of trying to stall and cut out, I then parked up to have a look and check no pipes were off and nothing so I turned round to go home and on tick over it was cutting out nearly so I started having to use the hand brake to stop which keeping the revs up slightly to keep the car alive. I did NOT Floor it to get home I toodled at about 20mph and it started kicking out small puffs of black smoke (over fueling I thought) so as I got it home it started to run fine again as I was out opening the garage then when I got in it again to pull forward and park it got lumpy. Anyway after a few people adv this may be the Air Flow Meter I spoke to a mate who had this and he just cleaned his AFM connection and its run fine ever since so when he came to check mine we atrted it and it ran perfect again, we let it warm up and again nothing wrong (apart from no petrol), so we cleaned the connection anyway and went to get petrol and still fine, I have driven this today and nothing wrong apart from the high idle that I have always had...

Anyone know of this prob or has anyone experienced this as I htought maybe the stopping and starting of the car to go to and fro the garage and house to clean it may have flooded it or could it be bad petrol or what?

Any advice and opinions will be most appreciated, P.S I have a new Air Flow Meter Lined up and will buy this as a back up for future no matter what but just want to know what this could have been.

pe this helps mate

 

[Anonymous]

Thanks Carl, yes I have read your problem extensively before posting mine. I am not a very knowledgable person when it comes to cars but from experience there seems to be quite a few different reason this can happen. I also have experienced when I am low on fuel this seems to happen more frequent too as some other people on this forum have also experienced.

GeeTee: I am trying to get more information on BOV on why it is not closing properly to confirm since I didn't keep the standard BOV (stupid thing to do in hindsight)

 

[Jon]

I had exactly the same prob on my R last year, sounded really bad!ran really bad
spat out black 'carbon' deposits from the exhaust, smelt really rich
& sometimes sounded like my exhaust had fallen off?
which was great fun taking my producer & documents down the Local nick!

i posted up & had several feedbacks, most of them centred around the maf.
i called the AA out & the bloke had no idea
after taking the tmic off & cleaning, cleaning the maf up, pulling all the ht's off & cleaning the connections it sort of got better & better until finally, the prob totally went?
i didnt replace any part, just cleaned up a few things

not that this helps much but that's all i done & the prob went (slowly)
hope it sorts itself out
cheers
Jon

 

[Anonymous]

Guys problem solved.
After reading up on past forum post, one of the most common cause for the blacksmoke, poor idling and backfire seems to be caused by the MAF.

So I printed the instructions from the FAQ on how to reground the MAF, show it to my mechanic, also got the MAF connecter cleaned up.

Problem solved!

For now anyways, this problem seems to come back from time to time. So fingers crossed for now.

Thanks to all who have helped! :lol: