RPM/oil pressure.. weird problem
RPM/oil pressure.. weird problem i have a 97 WS6, auto, modded. a few weeks ago i was driving and went to slow down, when i pressed on my brake i glanced at my gauges and for a secong my rpm's dropped to 800 and my oil pressure dropped 20 psi and then they both bounced right back to normal. ive had time to play with it and this only happens when im driving at a higher speed, 45 mph +. it doesnt do it when im driving at slower speeds or when i put in in neutral and im rolling down a hill, at any speed. nothing happens to the motor, it doesnt sound like its gonna die or anything.
any thoughts? anything i could do to further diagnose the problem?
2 mechanics have seen it and neither one have a clue whats goin on. 1 was at a speed shop and 1 at SoCal Vettes.
any thoughts? anything i could do to further diagnose the problem?
2 mechanics have seen it and neither one have a clue whats goin on. 1 was at a speed shop and 1 at SoCal Vettes.
Well I know when I hit the brake and my tranny is in lockup the rpms fall down to idle after I hit the brake and the oil pressure drops when the rpms drop. Then when I accelerate it goes up with the rpms. I just assumed it was normal operation.
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What do you expect the pressure to be at when at 800rpm? The engine slows down, so does the pump and so does the pressure.
Doesn't sound like a pressure problem at all. What do you mean by "modded"?
Have you disconnected your PCM lately? Have you changed anything just before this started happening?
Doesn't sound like a pressure problem at all. What do you mean by "modded"?
Have you disconnected your PCM lately? Have you changed anything just before this started happening?
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Verdad Gallardo no i havent changed anything, nothings been disconnected. by modded i mean heads, headers, RR's, intake, tranny and oil coolers, fans, air foil, exhaust, gears, zexal carrier, etc.
i live down a 3 mile dirt road, so by the time i reach the highway shes warmed up. she does this regardless of the temp.
"Well I know when I hit the brake and my tranny is in lockup the rpms fall down to idle after I hit the brake and the oil pressure drops when the rpms drop. Then when I accelerate it goes up with the rpms. I just assumed it was normal operation."
i just BARELY tap my brake and it does this, itll jump back up w/o accelerating. last year i pulled the gauge cluster and the needles, everything works fine now but my oil pressure gauge is off. it did read 40 then go up to 60 when i drove, now its off 20. it reads 20 then goes to 40 when i drive. when i brake or tap my brake itll drop to 20 and the rpms to about 800. im usually around 2500 rpm when it falls.
i have a digital camera that takes video, i can get a video of it, you wont be able to see when im braking but you will see the rpms and oil gauge fall.
i live down a 3 mile dirt road, so by the time i reach the highway shes warmed up. she does this regardless of the temp.
"Well I know when I hit the brake and my tranny is in lockup the rpms fall down to idle after I hit the brake and the oil pressure drops when the rpms drop. Then when I accelerate it goes up with the rpms. I just assumed it was normal operation."
i just BARELY tap my brake and it does this, itll jump back up w/o accelerating. last year i pulled the gauge cluster and the needles, everything works fine now but my oil pressure gauge is off. it did read 40 then go up to 60 when i drove, now its off 20. it reads 20 then goes to 40 when i drive. when i brake or tap my brake itll drop to 20 and the rpms to about 800. im usually around 2500 rpm when it falls.
i have a digital camera that takes video, i can get a video of it, you wont be able to see when im braking but you will see the rpms and oil gauge fall.
Throw an extra quart of oil in it and see if it still jumps around while you are on the brakes. If it does then it's probably not a pick up problem since 6 qts should cover the pump unless you run a 2 qt filter. Either that or change your oil and when you drain the pan hit the bottom of it with your hand see if you can hear the pick up bounce around. I've had this happen to me twice on my previous motor first time pick up was pressed in, second it was tack welded, third time it was fully welded and hasn't fallen off since.
Its normal for 20psi at 800rpm's but you should not have that big of a dip in rpm's when ever you touch your brakes. It might be a problem with the t/c lockup. But in any respect I doubt very seriously that your pickup fell off.
On The Tree
Joined: Feb 2008
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Oil PSI will drop with RPM drop. Perhaps you have a vac. problem to the brake booster, maybe it is loose, cracked or not installed all the way. Maybe the check valve is missing/bad. With all of them upgrades you have had done its possible. Some large camshafts can not take the vac load of the booster at low RPMs. Did you have a cam installed with the heads and such?
