Rough idle and a intermittent noise along with lower than normal oil pressure.
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This engine has been together and running for 5 years. Now all of the sudden the oil pressure drops below 30 and struggles to get to 40 when hot. It used to stay a constant 40 and jump to 60 even when hot. Also, it is idling rough. I have it hooked up to HP tuner, scanning, and see the TPS at idle go from .04% to 1.8%, (this is even after changing out the TPS for a new one) which I am not sure that isn't normal. Once it sounds as if it is going to die I hear a "tink" noise coming from the engine, and it will bump back up to idle. I have changed the TPS, checked the valve springs and rockers. I'm assuming if it were the valve-train it would make that noise all the time. It is so intermittent, sometimes it will idle fine, and then after awhile it will idle horribly. The "tink noise I hear on occasion is somehow related to the idle, cause as I said, once it does that noise, the idle jumps back up. The car is tuned to idle at 800 RPM's and will fall as low as 400 RPM's according to HP tuners.
Has anyone ran into something like this before? I tried to do a search but came up empty.
Thanks for any help.
Has anyone ran into something like this before? I tried to do a search but came up empty.
Thanks for any help.
Last edited by Captain InsaneO; 07-08-2017 at 06:14 PM.
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Have you checked the oil pressure with a mechanical gauge? Otherwise it might be a ground issue with the gauge. I wonder if the "tink" is the IAC sticking, then suddenly returning to its proper position.
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I have not, and I have also wondered if it was the IAC as well. What I need is someone to put it in drive and I'll have to listen from under the hood. I was just hoping to get some direction. I really appreciate the response.
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After trying a new TPS and IAC, nothing worked. It is idling worst then before. One thing I forgot to mention was that it started doing this after it hit the rev limter hard on a nitrous run (nitrous shuts off at 6200, rev limter set at 7k). I looked over the valve springs, and they look good. There is no ticking noise, or new noises at all. I am very familiar with broken valve springs, replaced 12 of the, one at a time when they broke, on an old engine years ago. This is a speed density tuned car, and the computer is commanding it to idle at 900 RPM's. Could a bent pushrod cause this issue? I keep thinking it's electrical because it normally idles perrfectly in park. It is not thowing any codes either.
Vidoe below.
Vidoe below.