OK I have a MY95UK, done a lot of miles but still seems to be going strong.(100K)

My problem at the moment is lots of black smoke and hesitation after 6000 RPM, so much so that 6K is now my rev limiter I had this problem before and a new MAF seemed to fix it, but it has reared its head again and I only fitted the MAF a month ago. I have a Dave Wallis ECU, HKS filter, blitz dump valve, dawes device, scoobysport full decat system and thats about it on the mod front. I don't know if its related but the car cannot idle either, its constantly revving between 500RPM and 2000RPM.

Fuel economy is awful averaging about 100-150 miles to a tank, with "spirited" driving. when idling erratically the car will continue to emmit black smoke, but once it stabilises the black smoke no longer appears.

any ideas? its certainly stumpted me

 

Lambda sensor?

 

oh forgot to mention I had a couple of check engine lights, but they went out very quickly. I'll happily change the lambda sensor, I'm just a bit worried my car is developing a stable diet of MAF sensors!!

 

Is that an HKS induction kit or panel filter?

 

Firstly you need to check what the Check light illuminated for, this may give you an idea of your problem, it is most likely not your lambda as you are suffering the problem at 6k+ which is more than likely at positive pressure, ie. no lambda control.
It definately sounds like your MAF may be faulty, this would explain the idle prob and the black smoke.
If your MAF is reding higher airflow values than actual it will overfuel, even more so at high RPM as the mixture is so rich that it cannot be combusted causing power loss and black smoke.
Are you aware of the fault code check??

If not post back and me or someone else will let you know what to do, another thing to check is that your plug onto the MAF sensor is connected correctly, when the car is idling badly lift the bonnet and check that it does not correct the prob when you move the connector.

Rob

 

Just another possibility as well, if it is not the MAF it could well be the Fuel pressure Regulator.

Rob

I'd start with the MAF though.

 

Lambda sensor...

Go to Halfords and ask for an O2 Sensor L300......

will have to change plug to fit but all of £26..

It is drinking fuel so Lambda... if running lean the MAF..

MAF on older cars seem fine anyway and rarely go.

HKS induction seem a pretty good filter, partical wise.. have one on mine now.

JGM

 

Simon, Lambda has no control over fuelling on boost..
You can unplug the Lambda all together and you wont get black smoke
Do not forget that a MAF can read either way when it fails.

Rob

 

Cool thanks for the replies, its getting worse now so I will buy both a lambda and MAF sensor, the filter is a mushroom type HKS affair, I've heard certain filters are bad for MAFs, is this one of them?

thanks very much for the advice

 

Krade's HKS induction is good on his car mate so dont think its that.

Dont think its the MAF either cause we already changed that once (it was good for a wekk you said but then started again?) MAF wouldnt go again in a week would it?

 

I would say that it was the connector on the loom or a broken wire perhaps??

Rob

have you tried moving the wire/connector whilst idling badly? if the prob went away when you changed the MAF then you may have moved a wire or pushed the connector on better. Is the plug corroded at all?? I doubt very much that it is the MAF itself as they are a different design to the later ones and dont seem to suffer when used with a Induction kit.

Rob

 

One thing that is bad for MAF sensors is not being mounted firmly, high levels of turbulence will also cause issues and these are caused by some filters but I wouldn't imagine that the HKS would fit in to this category.