5.3/243 heads milled - Knock Sensor P0332

[JNJchev77]

I posed this in LS1tech, but figured why not try here as well... You guys always seem to come through with the answers.

I recently swapped 243 heads that were milled .030 and cometic gaskets .040, and an ls6 manifold onto my 5.3.

I'm having a knock sensor code P0332 come up now. I've already replaced the knock sensors and harness and it did clear the code for a week or so. But I've only driven the truck on some test runs, maybe a total 10 miles, no tune, and it popped up again last night.

Could this be timing curve/fuel delivery issue and it just needs to be tuned? Could an upper exhaust leak near the collector cause knock sensor code?

Prior to the heads/intake swap the truck was tuned and ran perfect for about 2200 miles, so I had to go and mess with it.

I should also mention that I swapped in an LS6 cam when engine was first rebuilt, before heads and intake swap and I replaced the knock sensors with aftermarket ones...


Justin

[dec010974]

Do you have access to tuning software? Have you had this set up tuned after the changes? I Think, but im no expert, when such changes are made to an engine such as milled heads, intake manifold, etc. the engine will respond differently, to these changes i.e. trouble codes. Every LSx engine and pcm combo needs to be happy to run smoothly and efficiently. You may need the services of a tuning expert, to get your issues worked out. I think they are minor issues. I hate trouble codes too. I am interested in this set up you have especially those 243 milled heads. I think you have a good, low buck, recipe for what its worth. I would have gotten a bigger cam compared to the ls6 cam. JNJchev77, you are on the path to success. get it tuned and you may be on the path to 400HP, maybe more. Good luck. Clark.

[JNJchev77]

Thanks for the reply!

I do not have access to tuning software and it hasn't been tuned since I made these changes. I just want to be sure before heading out to get a tune ($650), that I only fork it over once lol. What you're saying makes sense to me.

I have a GM mechanic who said the tune would fix the issue, but I like to get as many opinions as possible when i'm just not sure.

I'm hoping to be in the 400hp range which should put me around 330-340hp to the wheels.

[Cobalt964ruf]

L33 5.3HO engine, has flat top pistons and comes with 243 heads stock. i installed a ls2 cam and springs, ported ls6 intake, ported tb, e85 injectors, longtubes, cai, and a tune. it made 463fwhp and only had around 1800. in it.

[BR3W CITY]

If you did head work, and haven't had it tuned since, that needs to be addressed regardless of whether or not its the issue. The truth is, everytime you change components like that (cams, intake manifolds, heads, headers, anything internal), the tune needs to be changed.

Also might be worth checking that your motor mounts aren't broken (if you used/reused an old sbc mount), and that your headers/mounts aren't physically touching anything they're not supposed to be. Rev the engine a touch and keep an eye on the clearances. I've gotten false knock counts from the engine torquing in the mounts and tapping the exh against a tight frame spot (fixed now).

If you get the tuning suites, or some of the nicer scanners, you can monitor the knock and it'll give you an idea of actual Kr versus false knock.

[JNJchev77]

Originally Posted by BR3W CITY

If you did head work, and haven't had it tuned since, that needs to be addressed regardless of whether or not its the issue. The truth is, everytime you change components like that (cams, intake manifolds, heads, headers, anything internal), the tune needs to be changed.

Also might be worth checking that your motor mounts aren't broken (if you used/reused an old sbc mount), and that your headers/mounts aren't physically touching anything they're not supposed to be. Rev the engine a touch and keep an eye on the clearances. I've gotten false knock counts from the engine torquing in the mounts and tapping the exh against a tight frame spot (fixed now).

If you get the tuning suites, or some of the nicer scanners, you can monitor the knock and it'll give you an idea of actual Kr versus false knock.

Thanks for chiming in BR3W! I guess my point was that I don't want to chase a KS code if the tune or lack of one, is the cause. It's not a daily so I'm not driving it at all other than testing. My next trip is to the dyno. I understand after any internal changes its time for a tune .

Motor mounts are good, I'm running a dropmember with poly bushings and exhaust is clear.

[BR3W CITY]

The thing it would help to know is if your actually getting Kr (knock retard, in number of *'s of timing being pulled), and watching where the counts hit (MAP vs Fuel vs spark).

The knock sensor code only tells us that; there is a problem with the sensor itself OR its wiring OR a physical interference OR soooo much knock that its tripping the sensor out.

If we know your not getting Kr counts, then we know that its a sensor error and can be dealt with. If you ARE getting Kr, then we have an actual problem with the tune or an internal component which needs to be addressed before damage is done.

[JNJchev77]

Originally Posted by BR3W CITY

The thing it would help to know is if your actually getting Kr (knock retard, in number of *'s of timing being pulled), and watching where the counts hit (MAP vs Fuel vs spark).

The knock sensor code only tells us that; there is a problem with the sensor itself OR its wiring OR a physical interference OR soooo much knock that its tripping the sensor out.

If we know your not getting Kr counts, then we know that its a sensor error and can be dealt with. If you ARE getting Kr, then we have an actual problem with the tune or an internal component which needs to be addressed before damage is done.

I have access to a scanner that gives live readings. Hopefully I can determine what's going on from there. Also going to check the sensors and wiring to make sure nothing is crimped, cut or broken.

I don't think there is an internal issue as the engine ran flawlessly for 2200 miles before the head swap. I don't hear any noticeable knock noise but obviously that doesn't mean it's not there. Thanks BR3W.

[JNJchev77]

Could fuel pressure cause a knock sensor fault?

[BR3W CITY]

Potentially if FP drops off and causes the engine to diesel at ultra low idle...so possible, but not likely to be the cause.

Are you getting repeated FP problems?

[JNJchev77]

Originally Posted by BR3W CITY

Potentially if FP drops off and causes the engine to diesel at ultra low idle...so possible, but not likely to be the cause.

Are you getting repeated FP problems?

No, pressure is good but I didn't test injectors. Wondered if that could affect the KS.

[JNJchev77]

Just wanted to come back to this one an finish it off...

I replaced both KS's with AC Delco's and also correctly torqued them to 15ft lbs. I may have over torqued both. Everything seems to check out now, going in for a tune... after I change out my brake booster (it decided to take a crap for whatever reason lol).

Thanks for all the help gentleman!
Justin