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VERY LOUD knocking noise started in motor? Please help

VPer

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Hi Everybody. I apologize if I am going over the same ground as other posts, however, after reading dozens of very interesting posts I just haven't quite found the exact same scenario that my VP has started to do. So, here we go.... I purchased the vehicle a few months ago. Have replaced the lifters,injectors,oil/filter,plugs,dam rocker bolts (thanks Gregory manual for wrong torque setting),radiator flush and fluid. Am still doing maintenance on the vehicle so I know where it's up to with future maintenance. It did have lifter tick, hence replacing the lifters. It has been running rather well during this time. Yesterday was when I changed the plugs. The old ones were quite clean, nice grey on the tongue of the plug. After doing this, I started the vehicle,let warm up for 10 and then gave it a decent rev......once only.... When it returned to idle, it missed and farted,backfired and stalled. I tried to start it again and it wound over several times before firing. During wind over, it backfired twice through the intake. Once started it coughed and spluttered trying to maintain idle but then an aweful knock started. I mean like a diesel knock that has done a million klms! I shut it down. I built the courage up to start again and the knock had stopped but was misfiring and blue some nice blue flames out the exhaust tip. I gave it a gentle rev and the knocking started again. I noticed at holding the revs (1500) and lightly backing off,then lifting the revs,the knocking noise would come and go. I noticed it sounded more prominent at the rear lower rhs of the motor, however also at the top. I left it at idle,missing and spluttering and removed number 2 and 3 rhs injector plugs. This made absolutely no difference to the sound of the motor. I replaced them and removed the remainder 1 by 1 which all caused the motor to worsen and also stall. I have checked all spark and every cylinder is sparking. I removed the rocker covers and checked all components,they are all intact. I ran the motor with covers off and everything is moving the same. I replaced the injectors on 2 and 3 cylinder (with the old ones) and it made no difference. I have moved the injector plugs to different cylinders on that side (rhs) to see if the issue changed to another cylinder. No difference.....Know, I am leaning towards a timing issue,maybe? Backfiring,blowing flames,running rough is my reason. However, the aweful loud knock and why cylinder 2 and 3 are not firing has got me really fretting. I can only think that the knock might be piston slap or pre/post destination soynds due to those 2 cylinders not firing correctly due to timing? I have read on your very helpful Forums that the timing chain and Harmonic Balancer are issues with this model. Does anyone know of the timing chain having slipped a tooth or 2 causing the issues I am getting?
I am so sorry for the long winded post,just trying to give as much detail as possible.
I also appreciate the time,help and advice from anyone who could give me anything to start with trying to fix this issue. Thanking you slot.
 

MikeC

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Have to state the obvious, this started after you changed the plugs-are you sure you got the firing order correct?
 

VPer

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Hi Mike. Appreciate your question. Yeah, Ive checked,rechecked and double checked that they are correct.
 

MikeC

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I don't have a 3.8 but your issues certainly sound like their caused by incorrect timing- of either the ignition or valves.
 

VPer

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Hey Mike. Well, it appears I have an outcome. I'm still a little baffled tbh, but the motor is back to normal after many of hours re-going over absolutely everything.
First thing, I went over the injectors again and stumbled across the very rear injector , rhs bank, making the engine change its tune when I wriggled it. I removed the plug (again) and checked it and I found one of the female pins had bent and was pushed up inside the plug. Not making a decent connection I would guess. This could be why that cylinder was knocking and why I had a misfire?? Also, the engine light finally come on. So I done the old school flash code short (I only have OBD2 scan tool) and it come up code 45 (Rich fuel). Sort of adds up to the injector plug issue. With this, I done a computer reset, still in much doubt, only to find when I got the key again the motor purred back to normal. In so much disbelief still, I have started,stopped,revved, idled the motor so many rimes, it has not missed a beat......so far.
I'm still a little confused on something's that don't quite add up with how this all started,but,so far so good.
Thank you, Mike, for your replies and time. I do sincerely appreciate this,hey.
Guess we will see how it goes over the week or so.......
 
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