Yes clearing codes re sets the ECU and with that all fuel trim data.
But you said clearing codes helped the car run better?
When I shut the car off and clear the codes the knocking goes away and the car runs very well for a short time.
I think I may have a partially plugged oil passage in my electronic adjusters or head. I did find some tiny chunks of chain guide inside my mechanical adjuster when I pulled it apart.
So my plan of attack this weekend is to pull the cams to inspect the lifters and pull the mechanical and electronic adjusters to see if anything is in there.
Something is up. If you clear the codes and the car runs better there sounds like it might be more vac related. or something maybe not directly connected to the timing as I don’t think the timing parts are going to be effected by clearing the codes.
Next time you get the car running and it starts to act up pull the MAF wire off and see if that helps stop the noise.
So maybe I have more than one issue at play here. Additional problems worth noting are a groaning fuel filter that I’ll swap out this weekend and an exhaust leak on the opposite bank as the knocking.
I warmed up the car this morning to induce the knock and pulled the MAF connector. I observed little change and the knocking remained. I plugged it back in and the car died. I cleared the codes from the sensor and started it back up and the knocking was gone. Below are links to videos I took before and after the code clearing.
https://www.youtube.com/watch?v=CQiI_0PfvkY Before clearing - knock present
https://www.youtube.com/watch?v=hPFnUZSn2as After clearing - no knock
Is it normal for the cam phase position to change? Mine has moved around from -1 to -3.
Any other measuring blocks I can check before I pull it apart?
So I pulled my engine back out. Cams and rockers are out. Lifters all look good except a few that have gone soft from sitting for a few days I’m assuming. None are crushed or sloppy loose.
One thing of note is the main timing chain is very loose on top. To the point where it has marked the block above the top center guide. I have linked a video of it below. The tensioner for that chain seems much weaker than the others but looks new. The chains also have little to no wear so I don’t suspect it has stretched.
https://www.youtube.com/watch?v=BIDU5ch_aT8
From here I think my problem may be the main chain tensioner or oil supply to it. I’m considering pulling the oil pan while it’s out to see how things look in there.
Nobody has any input on this?
I watched the video and then had to take a few days to pull off the back side of a stock mid mileage motor I had here at the house. My 70k mile motor has the chain much tighter than that. I would have to imagine that would certianally be part of your issue if not the possible bulk of it.
Thanks for pulling that apart and taking a look for me Justin.
I looked everything over timing related and the only thing i could find was a missing o-ring on the main chain tensioner. I guess this could explain loss of pressure if the oil was bypassing when hot. So I put everything back together, primed the oil system and started it up yesterday. The racket was terrible and I attributed that to the lash adjusters taking some time to come up. After a few minutes ALL of the noise stopped and it sounded smoother and quieter than ever. Gave it some small revs and it sounded perfect. This only lasted about 30 seconds and the racket started again. At this point the only conclusion I can draw is that I’m losing oil pressure somehow. I have no oil pressure light on. So either the switch is faulty and I have a pump issue or I have a blockage after the switch.
Today I’m going to test the oil pressure then pull the oil pan off to inspect the pickup and possibly the pressure relief valve if I can find it.
Ran the oil pressure test. Results were normal. Below is a link to a video of how it currently sounds. It did not go quiet at all in the few minutes I ran it.
At this point, I think I just need to find a low mileage engine. If anyone has or knows of one let me know.
If anyone is still following this It’s the end of the road for this engine. For now at least. I scoped the cylinders and the valves contacted the pistons in cylinders 7 and 8. After pulling it out and tearing it apart I found the chain tensioner flat and the cam adjuster not locked so it appears I lost all oil pressure to that side. There must be a blockage somewhere. I will continue to tear it down and try to find a culprit but for now a new engine is on it’s way.
Justin, thanks for all your help. Your input on the forum is much appreciated.
chuck there are several people readying this still. I’m one of them. Keep us posted on this buddy… so sorry to hear about all of this. Good attitude and great updates. The more you know the more you are in control and taking the mystery out of the car.
Bought an engine that was supposed to have been professionally rebuilt. Turns out a toddler did it and not the shop that was claimed. I’m at fault for not getting all the documentation up from but I was rushing what I thought was a good deal. I highly doubt I’ll get my money back especially since the coward won’t respond to any communication. So I think I need to take the two engines and make one as the new one has rebuilt heads and supposed to have new rings and bearings. That’s yet to be confirmed. The cylinder walls on the new one are trashed from when he blew it up and tons of parts are missing.
So I’m looking for anyone with experience installing internals to give me some pointers and what to look for if I decide to merge these two to make a good engine.
A few motors under my belt here.
The biggest thing your going to be fighting is going to be the bearings. The crank bearings are very specific to each block and there are 4 or 5 different colors that they can be. So you can’t just drop out the crank and rotational assembly from one motor and put it into the other. Obviously you have to be careful of the rod bearings as well but its not as hard to work with.
I laugh when I hear pro built 4.2 Audi motor. For some reason there just isn’t such a thing. but lots of people say they are. Its a difficult motor to deal with and you get shops that think its an easy job only to find out… ITs crazy. So I would shy off the “pro” built motor unless you take it apart and then inspect things from the ground up.
Justin, how many time have you seen bad crank bearings? I’m thinking I might just leave the old ones in and swap out the rod bearings and rings only. It’s like $240 for new bolts just to install the crank itself. My cylinder walls aren’t terrible so I’ll hit them with some AN30.
The new heads have new cams and almost all new valves. I’m going to pull them apart, have them tested, and probably use them.
Its ultra rare. When I have seen or heard of bad bearings they have been super bad. Perhaps it would be a good idea to take an oil sample if you have it from the motor where you want to keep the crank bearings and send the oil sample out to get tested. That would give you an idea on how much material from the bearings is in the oil. At that point you can kinda see if its normal ware or not and then decide the best path.
Based on how the rod bearings look, I’ve decided to roll the dice and let the crank bearings live on. I inspected every oil passage in the block and head and I have not found a blockage. I’m puzzled as to why the tensioner was flat and the cam adjuster was unlocked when I tore it down. I understand the tensioner may have leaked down but both tested good anyways.
I did use my calibrated palm to test the valve spring pressure on the valves that hit and their neighbors. I found that the center intake valves on cylinders 5 and 6 are noticeably weaker than the others. Is it reasonable to say this has been my noise all along? The progression makes sense in that it started only when warm then onto hearing it all the time. If that’s the case and they were contacting at idle, I don’t know how it didnt do more damage when I drove the car and seen 4k rpm’s.
Anything else I should be looking at or is it safe to say that weak valve springs caused all that racket and made that banks timing values wander from the beginning?
The valve springs could have played a part obviously its so hard to tell.Having the tensioner and the adjuster out of sorts like that could have played a roll and seem to be something that isn’t adding up.
Perhaps inspect the oil pump unit and see if there is anything hideing there that might be a cause for concern.
With the heads. If your able to I would obviously do what you can do run the better set of heads with no issues. Just check to make sure those springs are in good shape as well.
So I’ve rebuilt my original block with new rod bearings, piston rings, and fresh heads. Got everything installed and to my surprise I still have a knock. Swapped the injectors around and it went away for a bit. Ordered rebuilt injectors and that put me back to where it all started. No knock when the engine is cold but comes on when warm. So it is safe to say it’s not mechanical but more a spark knock or pre detonation.
Things of note,
Got a bank 1 lean code after a bit of driving.
Also got a SAI insufficient flow code another time.
Knock sensor voltage is above 3v on cyl. 6 during knock
In troubleshooting the SAI, I discovered that if I run the SAI output tests and start the car the knock is gone for a few minutes. I did this half a dozen times and it worked every time. It appears the car is running lean when SAI is not on and causing the pre detonation. I don’t understand the link.
I’ve chased most of the vacuum lines and only found a leak in the intake actuator. Sealant is curing on that now.
Plugs are in great shape and I’ve moved the coils around but knock remained in cyl. 6.
I’m coming to quite the loss but currently pulling the SAI valves and giving them an ops check and cleaning.
I have no idea where to go from here or how to find out what’s causing the detonation. A/F ratios are a little off but not terrible in my opinion.
Pull the fuse for the SAI and see if that helps. There could be a big leak but maybe one of the valves is broken off the back of the head. The SAI vavles were cracked or broken that would cause issues for sure.
After extensive brain racking and troubleshooting I decided to crack open the timing covers again. At this point the only solid lead I have is bank 2’s cam values wandering and increasing when the knock is present. Bank 1 is running a little lean but not too far off. With the engine installed I pulled the timing cover for bank 2 to check the tensioner I suspected was the culprit. I found that chain and tensioner to both be tight. I did find the main chain loose again. I was a hard decision as all my timing components are less than 20k miles old but I pulled the engine again to have a look at them. I have a new main chain tensioner as well as one off a junk engine. I compared the three in several different ways to try to find differences. I couldn’t find any info on the spring tension and length specs of the tensioner but my results were interesting.
The spring in my tensioner was shorter than the used one and much shorter than the new one.
I used a scale to measure the compression force required to release the lock rod on the piston and found my tensioner at 15lbs, used one at 17lbs, and the new one at 18lbs.
I also filled and submerged each in oil and compressed with my hands to asses the bleed down rate. The findings were right in line with everything else as mine bled down faster than the used one and the new one held almost solid with a lot of force.
I don’t know that anyone has ever tested these to this extent but if this proves to be my issue and this tensioner has failed in under 20k miles then it might be some good info to get out to anyone else in a similar situation. I called JHM and the only new tensioner failure they heard of off hand was new out of the box.
I will post an update with any new info I have and kudos to you Justin for doing as many in-car timing jobs as you have. I’d almost rather pull it. It’s doable for sure but brutal.