What are tiny holes in the exhaust manifold for?
Discussion
I think you must be talking about the threaded holes for the lambda sensors.
You say they are open?
Where have the lambda sensors gone.who has removed them?
I know that when an exhaust system is decatted, the ECU modified and tune resistor changed, there is no need for the lambda sensors, but obviously when they are removed something needs to be put in their place.
>> Edited by ian8542 on Monday 30th August 11:08
You say they are open?
Where have the lambda sensors gone.who has removed them? I know that when an exhaust system is decatted, the ECU modified and tune resistor changed, there is no need for the lambda sensors, but obviously when they are removed something needs to be put in their place.
>> Edited by ian8542 on Monday 30th August 11:08
That doesn't sound right at all. Does your car have cats? If so, these air leaks will throw the lambda readings out and make it run rich at part throttle. In any case, the air leak will cause lots of lovely popping noises on overrun, but also release exhaust fumes into the engine bay which probably isn't good for your health. Do they look as if they have been made deliberately? If do, perhaps somebody has bodged a hole for EGT sensors some time in the past, although this isn't a normal thing to do. Is it possible the manifold has simply corroded through at this point? If so you are probably looking at new manifolds rather than blocking up the holes. 
Chris,
I've just had my manifolds welded up and it was where the pipes join that they had to be welded. What you describe doesn't sound like anything I can think of that's there by design. Does your car make a ticking noise with the freqeuency varying with engine speed? If it does, then you've already identified the candidate. If your manifolds are holed/cracked, you need to get it fixed sooner rather than later to avoid the need for a new set of manifolds. Get the gaskets checked at the same time.
Cheers,
Steve.
I've just had my manifolds welded up and it was where the pipes join that they had to be welded. What you describe doesn't sound like anything I can think of that's there by design. Does your car make a ticking noise with the freqeuency varying with engine speed? If it does, then you've already identified the candidate. If your manifolds are holed/cracked, you need to get it fixed sooner rather than later to avoid the need for a new set of manifolds. Get the gaskets checked at the same time.
Cheers,
Steve.
These holes are in exactly the same place on either side and are 1 to 2 mm in diam. They are not for the cats as they are say 10mm diam.
Its been done on purpose.
They are not rusted through they are drilled. Are they standard or has come one drilled them. They have a tiny trail from the gases so they do weep but because they are so small don't leak much.
Suggestions on how to seal them please?
Green V8S, interesting about fooling the sensors. There are 5 sensors reporting faults, coolant sensor, lamda sensor, throttle pot sensor, throttle high low and road speed sensor. How it manages to idle at 800rpm is a miracle although the low speed running is rough and you have to keep clutching to compensate.
Mark at Tower View thought the cats may have been noisy and someone drilled and secured them. All very odd.
Going to cost me an arm and a leg but I am determined to get her going smoothly.
I have posted a question about the tyres rbbing through the wheel arch and am about to post one about missing and sheared engine mount bolts. Any advice gratefully received as the cost of all this lot is huge.
Chris
Its been done on purpose.
They are not rusted through they are drilled. Are they standard or has come one drilled them. They have a tiny trail from the gases so they do weep but because they are so small don't leak much.
Suggestions on how to seal them please?
Green V8S, interesting about fooling the sensors. There are 5 sensors reporting faults, coolant sensor, lamda sensor, throttle pot sensor, throttle high low and road speed sensor. How it manages to idle at 800rpm is a miracle although the low speed running is rough and you have to keep clutching to compensate.
Mark at Tower View thought the cats may have been noisy and someone drilled and secured them. All very odd.
Going to cost me an arm and a leg but I am determined to get her going smoothly.
I have posted a question about the tyres rbbing through the wheel arch and am about to post one about missing and sheared engine mount bolts. Any advice gratefully received as the cost of all this lot is huge.
Chris
ntel said:
Get the holes TIG welded over. They have been put there to allow oxygen into the exhaust gasses and therefore kid the L sensors into asking for more fuel. Job done!
Do you think it has been done deliberately to cause that? Why on earth would anyone? It would make it run rich at part load and lean at idle, the opposite of what you want.
Some garages drill holes through the exhaust pipes to aid them in tuning the car - once complete they normally put in self-tapping screws.
My Grandfather also use to do this to his cars (he was a precision engineer), apparently its an old fashion way of tuning high performance engines!
My Grandfather also use to do this to his cars (he was a precision engineer), apparently its an old fashion way of tuning high performance engines!
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