gsjimmy

Finally got the O2 thing sorted out and now runs on closed loop. So next on the list is the knock sensors tripping. [P0327 & P0332 codes]

When this happens the truck runs rough, usually when the engine fully warms up (195*) and after a short stop. Reading up on this stated that this could be the Crank position sensor failing, although I don't get that code. When I swapped out computers, I get a relearn code that I can't clear.

Could it be possible to tune out a relearn code trigger? Wondering if the computer was tuned that way when the rear O2's and EGR were taken out.

So, if I swap out the sensor and this is still going on, is it possible to lower the sensitivity on the knock sensors on a GEN III 5.3?

I may or may not have a slight contact with the exhaust on the pass side frame rail. Cam is a stock LS1 (2002 Corvette) unit, Engine mounts are polyurethane, trans is a stock mount.

gsjimmy

Found a loose/blown connection after the cat. Getting a new gasket today, will also rerun the rest of the pipe to find any contact points. Have a small vibration I can feel in the steering wheel (moving or stopped, kinda rules out a drive shaft). Small steps at this point.

tfi racing

iTrader: (2)

Have you actually looked at the knock sensors? They are usually a rusty mess with corroded connections if they haven't been changed.

gsjimmy

Knock sensors and harness were done in October and again in June. No change either time.

Last night I changed the gasket and also tightened up a loose motor mount. Still have the vibration and trips the P0327 & P0332 knock codes.

The vibration is present at idle and while driving, in park or in gear. Frequency does change with RPM. I would lean to say it is not a driveline issue. Could be exhaust related, but nothing is touching the frame or x member.

When I did the engine clean up, I replaced the oil pump and timing set, new LH8 oil pan & pick-up, LS1 cam. All stock parts. Oil was clean when I changed it in June. No metal (sparklie flakes not present, ran the oil thru a paint strainer)

Ideas as to the source of the "vibration"? I am running the CPP poly motor mounts. Would it be advisable to put a rubber pad under the frame side mount to absorb some vibration? Can the knock sensors be adjusted in the tune to make them less sensitive?

jmd

iTrader: (4)

I think I would try to temporarily turnbuckle the DS of the engine to the frame and wire tie the PS exhaust inboard and watch live data. If that reduces knock., fix the PS exhaust issue.

Edit, It sounded like things were close?

Suncc49

Is the code P0327 causing serious timing retard as you rev the engine under load?

gsjimmy

JMD - I'll give that a try, couldn't hurt

SUN - When cold, no issues (like first thing in the am going to work). After about 10-15 miles, if it is shut down and restarted (think getting coffee on the way to work) then I can feel the retard (not me, doh) in the timing advance/limp home mode. Feels like random cylinders shutting down. Hesitation while accelerating to hwy speed.

Like I said though, can definitely feel a rotational vibration in the RPM range. When I put the timing set on, seemed like an awful lot of free play in the chain. Saw that Gen IV have a slider to take up the slack, but not for my GEN III 5.3.

gsjimmy

Ok, since the last post I have had the engine out to cure an oil leak that started. Got that fixed and added in hard rubber under the Poly engine mounts. That cut down the vibrations I was getting in the driveline.

I also got the engine centered correctly by modding the pass side exhaust to clear the frame. Last night I was able to get the driver side contact point (upper control arm) clearanced. At this point, there is no exhaust contacts, no oil pan contact point, yet I'm still getting the P0327 Knock sensor code. I got rid of the P0332 code.

This is still putting me into a random misfire (retarded ignition). Above 2000 rpm it is better, but normal 55 mph driving is not good.

Oil pressure is at 45 lbs, 50 at first start up. Timing set is new, cam is a LS1 Corvette unit. Valvetrain is correct and torqued correctly.

I have put around 2500 miles on the truck since my swap. Still chasing this issue and running out of ideas.

Should I install a flex pipe into the exhaust system? Would need to be after the converter (test pipe). Not sure on this one, the truck is currently hard piped.

Can I tune the engine to reduce the sensitivity of the knock sensors? Both sensors are new, and I did replace them since the build (second set).

I am currently looking at either dyno tuning the truck or picking up a tuner software package (Diablo Sport).

Thoughts?????

cookseyb

I had a SLP underdrive balancer that was defective and would trigger the knock sensors at about 4000 rpm. Drove me nuts till I figured it started when I installed the pulley. Something to check...

gsjimmy

The vibration is definitely rotational. I'm running all stock truck set up. I will see if swapping out components does anything.