Hey everyone, I think my car has a boost leak. At high rpm the car stutters and it's like it hits a boost cut. Not exactly sure what PSI of boost this is at, but it's at the same rpm all the time. When this happens the car runs rich and blows black smoke. Now, I want to do a BLT but I'm thinking that the boost leak is only becoming apparent at a certain PSI of boost and if I can't pressurise the system to that amount, I won't be able to tell where the leak is. Everything I've read has indicated not to put anything more than 7psi through the system with an air compressor. Suggestions?
You won't be able to build much pressure with a BLT, it all goes out the exhaust Doesn't sound like a boost leak to me, more of a tune/ignition problem.
[q]more of a tune/ignition problem[/q] ^This, I've seen it a couple of times on other cars when their spark plugs are burnt/fouled or incorrectly gapped so that would be my first check. What boost are you running and mods do you have?
I had these symptoms with a faulty coil pack. Was difficult to diagnose as it as fine at low rpm, didn't start to fail until it hit high rpm. Only on close inspection did I notice a bit of a crack in one and once replaced problem was gone. Note: the voltage test over the terminals was still reading within acceptable margins.
5k ish. Strange though, I took it for a run last night and even taking it easy it coughed a tiny bit at awkward moments. I'm tending to agree its an electrical issue, as sometimes it will rev right out and go well, other times it won't. Happy birthday man.
I know what the issue is, I've seen it on a car before. I think you're running one of those super duper spark gizmos?
so to start with what checks have you done? what spec is the car and any mods? did you do anything (work) before it started happing? do the boost check, if you can get it up to 7 psi that won't be the problem..
Forged engine, GT28RS turbo's running 21 PSI, NISTUNE ECU, Nismo 555cc injectors, Spitfire coil packs, BCPR6ES plugs (.8mm gap). Checked for obvious loose clamps, replaced plugs (other ones were fouled and then I fouled the second lot when an intake pipe blew off and the car ran rich). Haven't done anything to test for leaks or ignition breaking down yet, I don't have a multimeter or an air compressor in QLD.
once you've made (or bought) a plug with tyre valve all you need to do is rock up to a petrol station pop the bonnet wip off the front cover and swap out the MAF for the plug... if you leave the front panel undone it will take about 5 mins... pump and listen/look... if it's holding pressure you're good to go if not the chase begins... but at least you know you have or don't have that issue.
I made these out of an old bit of plastic (for soffits/fascias) and a motor bike screw on valve... cost me about $5...
That's a cool setup... Curious as to how the boost doesn't escape out of the hole that the smoke is going in through, though?
the hole with the match in it is only a few mil deep.... however not really of much help anyway as I found out... unless you have a massive gaping hole!! lol... i.e. you don't see any smoke coming out of small leaks... best way was to listen for them and then go for that area...
