Knock count issues?

[Engine07]

First off hello everyone...I am new here and wanted to say hello to all and I am glad to be here!! I have followed the forum doing some reading for a while now and there is tons of great information on here. I do have a question also as I have done some searching and not found anything matching my exact situation. I am new to datalogging and tuning but have figured out a ton by reading posts here and am trying hard to learn. I have gotten all the equipment I needed from moates to burn chips as well as aldl cable and am using tunerpro rt. Now here is the issue. My truck is a 95 Z71 K1500 with a 7427 ECM running BJYK. I am using $0D adx and xdf and have downloaded the BJYK bin. The previous owner had put true duals, manifold back on the truck which I am going to change in the next couple weeks as I am rebuilding the entire truck and don't like the sound but the o2 sensor is only in the passenger pipe. My first datalogs revealed the truck running lean all around the board to my 55 mph cruise being 145 to 150 blm. Now I have adjusted fuel and have the majority of the board staying 127-129 even under heavy acceleration with the exception of in drive idle at stand still is 135. The issue is I have stock spark table still as I am scared to touch it. My knock count on $OD is showing like 255 at idle and driving down the road it reads like 7000. Any ideas what can cause this? It has been like this since I owned the truck and the timing is at 0 degrees with the wire unplugged. Maybe faulty knock sensor? But I have no codes and hear no audible knock. Engine sounds smooth also. 185k miles but sounds like new. Maybe bad definition file? I am at a loss. Thanks in advance guys.

[JeepsAndGuns]

Does the data log show knock retard?

[Engine07]

Yes in a few spots mainly under medium to heavy acceleration up to 2 degrees

[Engine07]

It doesn't keep knock retard engaged though it is more like just a second or two then it's gone

[Woods]

Possibly an over torqued knock sensor? Seems that the 7427 ECM is very prone to knock count issues like that from what I had read. For me it turned out I had overtightened the knock sensor. Had read not to over tighten, but specs are only 15 ft lbs. Cured my excessive knock counts.

HTH

[Engine07]

Thanks for that. I read that somewhere on here earlier and was curious. The knock sensor is one of the few things that haven't been replaced on the engine this far so I am thinking about picking up a new one and making sure I don't get it to tight putting it in. I will give that a try tomorrow and post back. Thanks

[Engine07]

Ok guys, put in a new knock sensor this morning and was sure not to over tighten. Problem still exists. Seems as though the only noticeable amount of knock being picked up is at cruise. My cruise is roughly 55-60 mph and 1500-1600 rpm. It is steady picking up at this spot when the tcc is locked up. Steady spark retard of about .7-3.5 depending how much load the engine is under while tcc lockup. Any ideas?? I was first scared of timing chain slack or rocker noise as many miles as it has but only being mainly in that range makes me think otherwise. I'm stumped.

[1BadAction]

Is the engine stock internally?

[brian617]

During a steady cruise when you are seeing knock counts rise and spark retarded, try very lightly putting your left foot on the brake pedal just enough to unlock the TCC and see what happens?

[Engine07]

The engine is entirely stock at this time other than the dual pipes. And it just have it a shot. On acceleration it starts getting some knock counts around 2000 rpm but didn't notice any retard maybe flashed on so fast you could barely see it at like .7 once. During steady cruise with converter engaged knock count rose steadily and retard is constant .7-3. Holding brake just enough to unlock converter count definitely slows and most of the time retard goes to zero a few times it still bounced back to .7 . This was about a 4 mile drive and knock count was 3558.

[Engine07]

Oh and that second line is supposed to say I just gave it a shot, lol. Guess the spellcheck got me. Confused myself when I reread it.

[1BadAction]

by true duals, you must mean no H or X pipe?

I can see where around 2000 rpm that may cause a bit of resonance and knock, especially if it has flowdisasters on it. Loose Tq converter bolt can cause knock also, as can excess carbon buildup in the combustion chamber. Have you ever seafoamed it?

[Engine07]

Yes it has true duals manifold back with some kind of loud muffler. I think that's possibly part of it but that was on there when I bought the truck bout 6 months ago. I hate the exhaust issue, lol. I just ordered a new y piece and am going to run it right next week as soon as that comes in with a new o2 sensor. I did have the intake manifold off the weekend I bought it as it had an intake manifold leak so I got that sealed up and I did notice the heads seemed to have a fair amount of build up so I imagine the combustion chambers do as well. I have never sea foamed it but that might be a good idea. I did clean all of the carbon out of the intake and plugged egr and deleted in computer.

[Engine07]

I also did tune up a while back and while changing spark plugs I only managed to change 7 out of 8. The number 7 plug would only turn about 1/4 turn and could not get it to come on out. I was guessing excess carbon buildup on inside of spark plug at threads but I turned it enough I was getting scared of breaking it off in cylinder so until I get around to rebuilding the engine hopefully this summer it is stuck there I guess. It is my daily driver so I figured it better that way for now.

[1BadAction]

ahhhhhh, now we're getting somewhere. I'd seafoam that bitch a couple times, suck the whole can up into the manifold with one of the vacuum ports on the front of the TB, let it sit 15-30 minutes, then take it for a spin and hope no one calls the fire department on you. LOL. If it's bad (sounds like it is) might be a good idea to do it again. You MUST change the oil after you finish the seafoam process though, so I always have the oil change stuff on hand when I do it.

[Engine07]

Sounds like a plan!! I'll get to it this weekend while I'm off work for once, lol. I should know if someone calls 911 though lol I'm the volunteer fire chief in the town where I live so it should be interesting :laugh:. Hopefully between that and the new exhaust next week this thing will be back in order till I get a new trans built for her

[1BadAction]

This is after 80 thousand in my 4.8 powered GMC. (look in the rearview) https://www.facebook.com/video.php?v=286675084681356&l=7582524329774467090

I did my old TBI 350 silverado with 250k on it and had the fire department called on me. It was hilarious.

[Engine07]

Alright I think I'm getting there slowly. I seafoamed the crap out of it and I also went to dealership and bought top engine cleaner from them and soaked the combustion chambers. Also wound up getting that stuck spark plug out after deep creep and the cleaning. It was carbon on the threads after all. New exhaust is on now, so much better and no retard at around the 2k mark anymore. Still shows knock counts growing under load with converter locked up and retard but they have gone down quite a bit. I'm thinking the rest of it has to be the converter. I might fill up on premium next time just for giggles just to make sure but does the converter sound like a fair assumption?

[bybyc5]

Just for grins and an easy check. Pull your "set timing" connector that takes all PCM controlled spark timing away, then drive it while checking your knock counts. And while your there, put a timing light to it and be sure your mechanical base timing is set.
I'm guessing stock base timing is 0 degrees? Mine is anyway on my 93 K1500.

This should eliminate any spark related knock counts. If there are any.

Keith
NE Tennessee

[Engine07]

Thanks Keith, I'll give it a try. And yes it is set at 0 degrees with wire unhooked. Any ideas on egr being responsible? Mine is blocked off as old valve was bad and I bought 4 different valves for this truck and all of them caused it to hesitate badly every time I touch the gas to pick up speed at low speeds so after verifying I had no vacuum leaks and replacing solenoid I put plugs on the vacuum lines so there was no leak or egr and it runs great now. Maybe timing needs retarded just a hair because of no egr?

[JeepsAndGuns]

Has egr been disabled in the tune?

[Engine07]

As best as I know how. I increased the temps and stuff for egr on to the max and added fuel to get close to 128 is all I have done on tuning so far. No more check engine lights lol. Was getting code 32.

[bybyc5]

Yes, I did the exact same thing in my tune for no egr intervention, pushed temps up, etc.
My egr valve has been removed and replaced with a plate and gasket to cover the opening. I think that with egr enabled there is fuel removed during an egr event. It would then seem that fuel would then not be removed when we set the parameters in such a way that no egr takes place? Which is what we have done in our tune.

Your $0D and 16197427 must have some feed back that the valve was opening or not. My 16168625 and $E6 does not, save for the PCM maybe looking at a corresponding change in O2 readings while the egr valve is open, little or fully applied. I did turn off the 32 set flag because I removed the egr solenoid from my harness.

I remember to many years ago, when I used to work on the first GM CCC systems (and before) the headaches egr events caused in driveability, hesitations much like you described above. We had a few "band-aid" fixes for those issues. But nothing worked 100%.

This is so much better today what we have to work with!

Keith

[Engine07]

I think I'm going to try putting some higher octane in next fill up and try that out. It's under more of a load than I would like and 4.10 gears are on my list of things to do but could it possibly be pinging lightly enough I just can't hear it from the load it's having to pull at cruise? At 1600 my average map is 65+. Usually 75 is where it spends most of its time. And I actually got quite a few counts on a wot pull last night as well but I think it had to do with an over rev seeing what it would do. I'm thinking of pulling timing on upper map range and see what happens or just giving higher octane a try. If this is truly what it is I didn't think the factory spark table would be enough to cause knock counts and retard under load.

[Engine07]

Well, I retarded the timing a few degrees in the tables in the areas I was having trouble with under load at cruise. Drive to work this morning no knock counts in these areas anymore. Just gotta figure out a good timing table now so I can get rid of the roller coaster I created, lol. Guess they were legit after all.