Knock problems (boosted)
 

Problems solved.

:(

If you’re running cats you might have an exhaust restriction. Have you checked backpressure? When the knock happens, which cylinder(s) are making noise? What is the engine load at which the knock is occurring? What is the calculated timing vs the actual timing?

All good places to look for clues.

Did you check the passages of the turbo manifolds?

https://www.gtrlife.com/forums/topic...-the-findings/

LOL, that was hilarious..... What a junk manifold. This doesn't surprise me at all.

Here is the picture of the blockage.

https://www.gtrlife.com/forums/uploa...1538708678.jpg

WOW on that manifold. My set is pre-used though, i bought it on here from a forum owner which made over 600whp with it and ran it successfully. I will keep it in mind.

I can drive the car with just the downpipes to exclude a blocked exhaust. I do not run catalic converters. Knock mainly on cyl 3 and 4

Because i was achieving knock with boost, i disconnected the wastegate flappers and drove without boost.

Here is a low RPM example, no boost and timing pull:
https://i.ibb.co/Wfw5fNG/1-EM9-A-201...SUMM-KNOCK.jpg

Here is a run started at higher RPM, with about 10psi of boost and a bit more timing. There is no timing pull here. As long as I start my runs in higher RPM ranges like 4500rpm+ i get no timing pull)

https://i.ibb.co/TK22Gcm/No-knock.jpg

can You swap the knock sensors around and see if the knock changes cylinders? Maybe a bad sensor?

It's something I can do, but i think to have "validated" the knock with my Link Knockbox (audible).

For the audio file, check and listen for the typical tin can/shaking change sound: https://drive.google.com/open?id=1pm...smo-NJwlxDleUY

Im sorry what am i looking at ? is that a AAM manifold thats been cut open ???and why ? Im missing something im sure.

That is casting slag in the middle of the pipe closing off cylinder 3 by 80 to 90%. That's not supposed to be there. Follow the link above for more pictures.

Did you replace the injectors with new ones or used? It is showing you have issues on Cylinder 1 and 3 as you know. You may need to take those out and have them cleaned and tested.

Yes i replaced injectors by IDx1050s. Used set, not tested.

Heres pictures of my spark plugs, car is running a bit rich but didnt see anything out of the ordenary:

https://uploads.tapatalk-cdn.com/201...f80d93e325.jpghttps://uploads.tapatalk-cdn.com/201...ff1fd60d0c.jpg

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Pull all the injectors and have them cleaned and tested since you used used ones that were not tested.

Holy crap! :eek:

Weird question you have a catch can?

No i dont, i placed 2 filters (vent to air) on the tubes from the valve covers (which normally go into the intake pipes)

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Gotcha. I’m not boosted yet but I had a similar issue with my car pulling timing like your car, installed a catch can and poof no more timing issues, but what spooler linked in that would be a issue. I’m tuned by Seb

What was your original setup? Venting back into the intakes?

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That would be caused by a ring sealing issue causing excessive blow bye. You had a motor issue and didn't know you had it. Still do. Good thing you are going for a new motor soon. How do you like the SOHO catch can? Did you get the one with the drain back mounted to the dipstick tube?

Seb had me add two more filters. When I pulled off the hoses there was a quite a bit of oil in them.

https://z80lww.bn.files.1drv.com/y4m...&cropmode=none


https://181w5g.bn.files.1drv.com/y4m...&cropmode=none

Yes, when I swapped manifolds is was quite a bit of oil residue.

Mmmm interesting. No I didn’t want the blow by to go back into the oil. I like the set up. Seems to be helping to catch the blow by my
Motor was producing rather efficiently

So you plugged the 2 openings on the intake manifold, and put an air filter on the hoses?

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Yes but i put the filter on the driver side directly on the port. The passenger has a small piece of hose since the fuel line didnt allow the filter to fit.

Alright, little update:

- vented all hoses which come from the head and manifold to air
- took out the dilkar8a8 gtr spark plugs and put the stock ones back
- performed a compression test; 240-250psi across al cylinders
- moved ign coils and injectors around

No result, still knock.

Next up im thinking to drive the car back with the original software, open the wastegates and disconnect intercooler piping. Bring it back to the previous state (which had no issues) about as much as i can.

I inspected all pistons with a boroscope. Validated the knock, its visible on all 6 pistons. To me this means that whatever the cause is, its not tied to one single cylinder.



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Another suspicion could be carbon build up. Now the intake valves are really clean, but the pistons look a bit black to me.

Is this normal for an engine with 50k miles?https://uploads.tapatalk-cdn.com/201...c5061a28f1.jpghttps://uploads.tapatalk-cdn.com/201...b6bc6364ab.jpghttps://uploads.tapatalk-cdn.com/201...5f848a9610.jpg

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Your intake valve is really clean. Most times, there is a carbon build up on them. Same with your pistons. what you are looking for is small potholes in the top of the piston and cracks around the edge. When a engine has detonation bad enough. It will turn the tops of the pistons into silly putty and melt a hole through. Look at some of the pictures on google.

https://www.google.com/search?q=engi...ih=578#imgrc=_

Drove the car on stock map and injectors and without boost. I experienced no audible knock. Couldnt see if the ECU retarded timing as the stock rom doesnt support ecutek data logging.

Next up is cleaning the pistons with some sort of seafoam/combustion chamber cleaner. Put back the id1050 injectors and run again.

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Knock often times cannot be heard with the human ear, I would carefully plot the signals and check for spikes for each cylinder vs the threshold. In the rom settings you can disable racerom timing and this will let you run the stock calibration but with additional diagnostic parameters to fully understand the problem. Your tuner can set up the rom for you to do this. This will allow you to see if the ecu is pulling tuning, etc.

Thanks for your reply. I am using the Link Knock Box to listen to knock. Heres an audio file (when i had knock)
https://drive.google.com/file/d/1pmO...w?usp=drivesdk



I do want to datalog as well to analyze the knock sensor parameters and have requested a map with logging features

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Are you sure the car is knocking?

Yes

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Allright, little update here.

There seems to be an issue with Ecutek after flashing the car, registering abnormal amounts of knock.

At a certain point, I got the tip to unplug the two ECU connectors in the passenger footwell after flashing the ECU with a new file. This helped a lot and removed 80% of my knock.

Right now, the only moment that I have timing retard is when I go in boost in low RPM (say 3000 to 3500). The car doesnt seem to like 12 degrees of timing there (at 6-13 psi). I think it's "lugging" the engine and it pulls like 2-5 degrees of timing depending on various conditions.

I think its a combination between stock high CR + building boost + requested timing - in low RPM's.

I would be interested knowing what timing retard other people run in the 3000-3500 range on stock block and 93 pump.

That is definitely way too much timing. I usually run half of that at that RPM range as it's better to be safe than to throw a rod out of the side.

Sounds like a case of the tuner not knowing what the car needs.

https://www.ebay.com/itm/Knock-Guard...4AAOSwVYNeHxQ-

Any News?