Guest jjohart Posted March 2, 2004 Share Posted March 2, 2004 Hi. Since I have had my NPR I/C and Greddy Profec B, I have noticed that revs above 4,000 sound increasingly raspy from under the engine, as if there were metal gnashing. If I keep going towards the redline, I hear escaping air woosh as well, being that I have a MDS blow off valve, but the funny thing is I'm hearing that air escaping even before I put the clutch in. It isn't the air releasing I'm so concerned about, it is that gnarly metal mash sound I hear, which makes me almost instinctively push in the clutch pedal. It seems to be worse in 2nd gear, for some reason, but maybe that's b/c 2nd is the shortest legged gear? For all I know, this could be the way my I/C'd car SHOULD sound, but it raises the question of whether I might be hearing an overspinning of the turbo? The other question I have, a bit off subject, but perhaps not...lately both my local mechanic and the fellow who put on my I/C tubes have asked me why I don't have a regulator, or something to increase the fuel. I guess their logic is I've got to increase fuel b/c the I/C and 3" exhaust have increased the air. SO, I told them Hybrid Z folks said I should be alright with stock fuel management. Now, I'm beginning to wonder if the sounds I described above could be the engine running without enough fuel at high revs. I've no way to tell...no dyno within many miles of MA, but I'm in a quandry since I thought I'd wait and do the Wolf chip/420injectors/rail/etc...all of which is said to be incompatible with add on fuel management, am I wrong? Hard to know what I need next, suggestions welcome! Thanks John Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 2, 2004 Share Posted March 2, 2004 john, the I/C is simply a device that air passes through and has no moving parts to make any sound and should not suddennly contribute to anything making metallic scraping sounds. The advice on the regulator is accurate. If you install an I/C and 3" exhaust AND you are still running the same boost pressure, the engine now should make more HP which will require more fuel. If you are running the same stock injs and FPR, you have no way to increase the fueling and an adjustable FPR will allow you to do that. As for the scraping sound, could be too much play in the turbo shaft and the wheel is touching the housing. Take off the hose from the compressor housing and see if there is any evidence of that. If you can hold the end of the shaft and move it around, then that is not good and likely the problem. As for the whooshing sound, most likely the BOV letting boost escape or hoses not on tight. Quote Link to comment Share on other sites More sharing options...
Moridin Posted March 2, 2004 Share Posted March 2, 2004 The whoosing sound comes when the throttle plate closes and the forced air has nowhere to go, but back. Do you let off the throttle before you push the clutch in? A good way to check how your A/F (air to fuel ratio) is doing, is to install a W/B O2 sensor setup. http://www.innovatemotorsports.com/lm1.php is supposed to be an excellent setup for the money. Talk to your installer about this. Definitely a good way to tell if you're running so lean that you may be pinging. Quote Link to comment Share on other sites More sharing options...
Guest jjohart Posted March 2, 2004 Share Posted March 2, 2004 What is the point of knowing whether you're running lean or rich when there's no stock way of adjusting it? I was planning on running JWT chip and injectors, but those units are pre-mapped according to factory spec, so it would be doubly frustrating to put on such a monitor and then have to pull out mods! John Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted March 2, 2004 Share Posted March 2, 2004 What is the point of knowing whether you're running lean or rich when there's no stock way of adjusting it? I was planning on running JWT chip and injectors' date=' but those units are pre-mapped according to factory spec, so it would be doubly frustrating to put on such a monitor and then have to pull out mods!John[/quote'] The "stock" way of adjusting it is to adjust fuel pressure. And the reason to check is to know for sure what the issue is. The factory EFI can handle fueling up to a certain level, so if you are running the same boost level measured at the manifold, but with an IC installed, you could indeed be exceeding the fueling capabilites of the stock computer. The injectors, and perhaps the pump are good for 250rwhp, or about 12-14 psi boost (more boost with stock turbo), but the factory EFI may not give good performance without some fuel pressure adjustments. Check that turbo compressor - it would suck to suck in a compressor blade! Quote Link to comment Share on other sites More sharing options...
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