When I accelerate, even at 3000-3500 RPM, I can here a strong Sssssssshhhh under the bonnet (like you normally hear when you accelerate and then back off). Reckon it might be a loose or split pipe but don\'t know how to start to identify where it is - anybody got any suggestions as to what it might be and if its a hose how to identify which it is (I can\'t see anything obvious but then I don\'t really know what I\'m looking for anyway)... :3Confused
Are you twin tubby setup, or have you got a single?
Basically, you have a boost leak somewhere, and need to check over all your hoses for splits, and check all jubilee clips are tight as tight can be
Actually, I suspect your a twin setup, aren\'t you? Are you only getting this hissing noise at 3000-3500rpm? If so, it may have something to do with the second turbos pre-spooling and trying to bleed off the extra boost.
Yes, sorry I should have made this clear..It is a twin setup and I am used to the hissing when I accelerate and then back off, the car has always done that, as you say, I guess this is just any redundant boost being bled off. But this constant hiss under acceleration is very recent (it is not just at 3-3500 RPM but at higher revs as well if I accelerate) trouble is I can\'t duplicate the effect when the car is stationary with the bonnet up so is hard to pinpoint where its coming from....also wondered if there are any other possible (more serious) causes......!!!!!
You won\'t be able to replicate the problem when the car is stood still, as you won\'t be able to generate any boost. Boost is generated when moving due to the air being forced into the engine and being pressurized due to the engine begine a component that will let let the air through at the same rate - when the car is staionary, the engine is freely able to turn, as it is not turning the wheels: so they;re not acting as an opposing force.
Think of it like a bicycle pump: if you pump it without anything on the end, it\'s easy to do, but if you put your finger over the end it\'s much harder to do because you\'re pressurizing the air, which forces it\'s way out past your finger. It\'s like that, and that\'s why you cannot replicate the problem with your car stationary.
If the noise happens at any revs whilst accelerating, then i\'d put my money on a single boost leak. You\'d need to remove all pipes and check for splits, and check jubilee clips for tightness, and re-tighten where necassary.
Cheers for that. Yes, I kind of realised why I couldn\'t duplicate fault condition, I was just stating the obvious; Doh!
How difficult is it to access all the possible faulty boost pipes and how do I determine which ARE the boost pipes?????
Well, you want to check the most obvious pipes first (And by checking i mean remove, and thoroughly check for cracks and splits) - the Y-pip rubber coupler, plastic crossover pipe (The rubber coupler is very common to go - I will have an efini Y-pipe for sale soon if you\'re interested! :p) pipes leading to the intercooler and the pipes leading from the intercooler to the stock elbow.
A handy hint is that there\'s often a lot of oil re-circulated around the pipework, so also see if you can see signs of oil be blown out from any of these pipes - if there is, there\'s your leak. HTH
Cheers for the advise... :)
No worries - let us know how you get on.
I had a similar problem, turned out I split the pipe going to the IC (from top to bottom along the joint line!!)
If your running standard mazda pipeing, I\'d sujest investing in a hard pipe kit, this would iliminate the inferior standard issu piming!!
Jono
OK, just an update....The crossover pipe had popped off one end and was loose the other.....Problem solved you might think but, No.... even after this was fixed the car only boosts to 0.4 bar....Have spoken to Carl Hayward about it...he has taken a good look and even converted it to nonsequential (which removes most of the potential leaky pipe problems) but still no different....It is of course possible that we have overlooked a leak I guess, but Carl is going to Check the Cat to make sure it hasn\'t collapsed...After that its starting to look a bit like the Turbo\'s might be on the way out... :2eek
Haven\'t got a boost problem anymore :Thumbs-up split pipe identified and rectified. I can now surge past milkfloats with relative ease.. ;) I\'m actually very happy about this development.. :bandit (Thanks for all your suggestions and advise)
what was the split pipe, i have still got boost problems with mine,
Seem\'s that after 30mins of warming up the second turbo kick\'s in fine, but then sometime\'s it doesn\'t.
Quote from: BleakBoywhat was the split pipe, i have still got boost problems with mine,
Seem\'s that after 30mins of warming up the second turbo kick\'s in fine, but then sometime\'s it doesn\'t.
Sounds a bit like mine used to be although doesn\'t mean its the same problem. My crossover pipe had popped off (the jubilee clips had come loose to either end and was leaking badly, also one of the large bore hoses near the intercooler had a split several inches long. Even before these problems got so extreme I used to feel the second turbo didn\'t always come in properly - as part of the diagnostic process Carl Hayward put my car non-sequential as that eliminates much of the pipework and relay control system between the turbos, narrowing down the list of potential problems- he charges £150 to do this and it means both turbos work together and makes the car more predictable, although turbo\'s don\'t come in until about 3000rpm so the downside is you\'ve got a bit less power from 2000-3000rpm but from then on you get a smooth power delivery from both turbo\'s working together right up to the redline-overall it makes the car quicker once you\'ve sorted the boost problem. By the way if it is actually a turbo problem then I may have a good used turbopack for sale; PM me if interested.