I think I may have spun a bearing on my 94 Z28 with 138k miles.

I got the laptop with Datamasters hooked up today and did a 0-100 run, and when I let off I started getting a funny sound. At idle the car goes from 0-69,000 counts of knock in about 5 seconds and I have spark retard all over the place. Kinda sounds like I spun a bearing ;[ On the other hand, it looks like something is up with the EGR valve...it seems to like to goto 100% duty and shows up at the same time as my spark retard. Is there any chance something could be up with the EGR that would screw this stuff up. I also had a loss of power down low from 1-2k rpm's. Any help or anything to look for in my logs would be MUCH appreciated. TIA.

 

BTW, with 10 miles or so since this occured with my trying to figure it out I still have normal oil pressure...dunno if that matters, and we don't see anything in the oil. If its a spun bearing ima cry...but no idea what else it could be really...it datamaster it says somethinga bout engine malf, eek.

 

If you spun a bearing you'll most likely get a very loud knocking consistent with engine speed, I.E. higher the rev the faster the knocking. It's going to be a very solid sounding knocking too.

 

it started off more like a squeeking sound...but it does go with the revs...is there a good way to diagnose a spun bearing other than tearing into the engine?....or throwing a rod through the side of the block, lol.

 

Someone must have some ideas. I went out and started it this morning after it sat all night and there wasn't the bad clacking sound like before, my drivers side sounded pretty loud under the valve cover, is it just those 4 bolts on top to take it off? Should I check and see if the rockers are tight and everything? Oil pressure on startup went up above 40psi with the mobile 1 10w30...it usualy goes a little higher though...but stayed high, car ran for like 3 minutes, stayed in open loop the whole time, and I didn't get any knock so I have no idea whats going on. Does our crank sit in oil when its all drained to the bottom after sitting for a while? Just curious if maybe since it was soaking in oil it didn't make a nasty sound. If I spun a bearing it should make the clunking sound all the time right? I didn't dare rev the engine much over 1500.

 

Your email to me said you were getting lots of knock counts. See if you get them just revving the engine a little. I don't think your EGR is having an influence on that.

 

I think I emailed you before I posted up that info this morning. I had the car, rev'd it to 3k and didn't have any knock counts....however a little before that at idle for like no reason it went from 5k counts of knock(starting it) to 20k counts of knock..but thats it...but no new knock counts when i rev'd to 3k.

Thats why I dunno if the crank sits in oil when its all in the pan or whatever. im new to LT1's

 

I have an LT4 knock module by the way...and a video upstairs that I took this morning, but that computer is being stupid.