When I am driving and I floor it, once the revs get to about 4500-5500rpm I hear a sound like the valves are bouncing or a metallic rattling sound, and also it splutters and coughs. After 5500rpm it is clear to redline. When the car is idling, it is fine (except for the occasional "popping" sound) and revving all the way to 4500rpm is fine. Once I reach the 4500-5500rpm range and back off after the problem occurs, it's like I'm running on 3 cylinders for about 30 seconds..then it clears up. My friend who was driving behind me said that smoke only came out of the Drivers side exhaust after the problem occured. I have a leaking water pump which I will be changing on the weekend, so could it be the timing belt, after water is leaking on it? It has only happened recently and seems to be getting worse. Naturally I don't go that high in the revs anymore incase I cause anymore damage. Any other suggestions? Thanks guys. Ben :thumbsup: P.S I have a Series 2 PTU and I have a 1MegOhm resistor in place of the detonation sensor. All connections are clean.
my thoughts on your current and explicable dilema. Sounds like Detonation. What fuel are you running, what boost are you running. Is it only under load or do you hear it when reving it out of gear. 'IF' it is detonation you may have damaged your piston and the smoke is oil passing the ring (theory only) Relocate the det sensor if you don't want to fork out for a replacement, you gonna f*&k your engine if you stay on this path.
I am running Optimax and 1Bar of boost. I will put the boost down and see if still does it. I believe it is only under load, and it doesn't occur in first gear (WOT). I haven't really tested it when it is out of gear. I believe (from memory) it doesn't occur out of gear.
No it doesn't occur whilst revving in neutral gear. Only under load. Just wentfor a hard run and lowered the boost to 0.8 Bar and it didn't do it. No noise or hesitation. It's also pretty cold outside. Well I've using 1Bar for a long time now and nothing happening. How come it has just started to detonate at high revs now? I haven't changed anything. I always use Optimax and I am running 13 degrees timing ATM so what could I do to stop this? Any suggestions. Thanks, Ben
possibly a bad batch of fuel??? run the tank till completely empty then fill up a 1/4 then run that till empty, then fill up and try going back to 1 bar and see if it detonates..
How many k's since timing belt etc serviced? Sudden onset of detonation may be bad fuel (as suggested) if you've filled up at a dodgy little servo recently, but may also indicate timing belt or auto-tensioner is on the way out and causing erratic timing. Hopefully the former. Have you done any recent mods?
Well, I haven't done any mods recently and only use Shell Optimax... I bought my car from a Ford dealer, but he got it from a guy who bought it from UAS. I acquired the service sheets from UAS and it says that the timing belt has been changed but hasn't got the km's on it. I am changing the water pump this weekend so will check the belt and will probably change it anyway. Thinking about the Gates one. So I'm hoping that changing the belt will eliminate the problem. Thanks :thumbsup:
Ok, check the belt condition & tension You can do this with top covers off. NB: Gates T180 is about $36 TRADE & Caz1 has auto-tensioners in stock @ good price.
Could the CAS stuff up at high RPM? I'm thinking that when high RPM is reached the CAS doesn't produce a signal for some reason and doesn't fire some cylinders? So the fuel is going into the cylinder and no spark is firing it, allowing the fuel to detonate itself at the wrong time? Just a thought. That's why I am asking if someone in Sydney has a working CAS for me to borrow to test if this is the case. If someone does please contact me as I would like to test it tonight if possible. Thanks guys. Ben :thumbsup:
some questions for you.... have you checked you fuel pressure?? have you checked for boost/vacuum leaks?? have you checked your TPS, O2 sensors and neutral switch? Cheers
I haven't checked the fuel pressure or boost leaks... as I don't have the right items to check them. I have checked the TPS and O2 sensors. TPS is set at 0.45V and the passenger side O2 is a little slow. How do you know if your Neutral switch is buggered? Does the neutral switch prevent the car from starting in 1st gear or reverse without the clutch engaged? Mine starts with it in reverse without the clutch engaged (well tries to hehe...forgot it was in gear). Haven't checked 1st gear yet. I'm hoping that is the problem as it seems easy and cheap to fix. I hate not being able to go fast in my car without worring about the engine blowing up hehe. Thanks, Ben
Ben, if/when you get to the point where u 'think' you've fixed the problem, take it straight down for a dyno to check the A/F mixtures at your 1bar boost setting. - you can still be having detonation without hearing it you know. Your profile says you have a JUN computer. Would i be correct in assuming you have a 300ZX ECU with a generic JUN chip in it???
to test neutral switch.... the easiest way is to hook the car up to ConZult or Datascan and see if the switch goes on and off when you select gears. Also, I highly recommend you check your fuel pressure. Its easy to do, just go buy a fuel guage from autobahn and put it in after the fuel filter. You should check it while at idle and also while driving... Cheers
Yeah I think so. It was in the car when I bought it. It is a remanufactured Nissan ECU by JUN as it says. I've been meaning to get around to getting it dynoed but don't know the costs and where to go exactly in Sydney.
Don't know why but... seems there were too many washers in the BOVs and now the problem is gone. Anyone know why?
