So I'm on my way home tonight.. get on the highway and run it up through the gears.. doing about 85mph in 3rd gear (about 5500rpm) and shift into "4th". unfortunately, that wound up being 2nd gear and approx 8700rpm!! :
I wasn't on it hard, so I was slowly letting out on the clutch, but I heard the engine take off and looked down just as I saw the tach banging on the internal stop at about 8300rpm.. after about 2-3 seconds of it (as quick as it mentally registered since I wasn't really shifting hard and looking for things like this), I shifted into 4th gear and coasted for a while...

The engine misfired and ran on 5 cyl for about 20 seconds after the mis-shift, but it cleaned up and the engine ran fine for the next 20 miles after that.

I've got a JWT ECU, and the engine revs to 7200 without a problem, but I'm wondering what the damage to the engine may be above 8000?

Keep in mind the bottom end of my engine is JE 10.5:1 forged pistons, shotpeened rods, GOOD rings, clevite bearings, etc etc etc,

the engine iteself is about 8000 miles old so the bearings are 'relatively' new compared to the 225,000 old stuff that was in it before the rebuild.


after a few seconds or so of choking on the high end limit (maybe an oil-fouled plug), the engine ran fine for 15-20 minutes until I parked it at home. no abnormal noises or engine behavior such as oil pressure drops, oil & coolant temp, etc... , which leads me to believe its going to be okay... but the skeptic in me says to check everything over before doing anything else. my concern is why the thing dropped a cylinder for that short while immediately afterwards and came back.. oil fouling I'm hoping..

Any thoughts?

 

Its always scary to mishift but I think you're gonna be okay, if anything was damage it would have shown itself immediately. Just before careful next time when shifting from 3rd to 4th, I did it when I first got my car 4 years ago. My friend did it earlier this year after I did my dek swap, shot up to 8k but didnt bounce as he caught it . My friend in his built SI did it and bent all of his valves and chipped one of his pistons. Since your bottom end is build, I would worry more about your valves/heads but it seems like your car ran fine for a good period of time so I wouldnt stress much more about it.

 

heh.. crap... edited to fix the drunken ramblings I got myself into after I got home. (no, I wasn't drinking and driving... I got drunk AFTER I got home. )

 

If nothing has manifest itself already then I'd say you're probably OK. Things I would have worried about at the time were oil/water pump overspinning, valve to piston contact.

I overrevved my 96 three times in the first year or so that I had it, all going from 3rd to 2nd under WOT (the shifter position always lended itself to that). Never had a problem with that motor. On the other hand i30tmiked did the same exact thing once, and ruined an engine. Just luck of the draw I guess.

 

That or spun bearings are my main concerns. As you've said, I don't think it did any major damage, as the car felt fine on my drive in to work this morning as well.


But when the thing drops a cylinder for the first minute after doing it, I'm going to be a bit paranoid about things.

 

You should be fine...I've experienced a cylinder misfire about 2 different times after running my car very hard. One of the times, my friend was following behind me and he said he saw a puff of black smoke (no blue tint to it) when it happened. Ths leads me to believe that one of the cylinders was temporarely flooded. I also have the JWT ECU and I fawking hate it because it doesn't pull the timing when it's knocking. My engine has about 80k on it and compression is 195-200 psi on all cylinders.

 

same here.. the **** pings on 93 octane if I set it to stock base timing. (new knock sensor and harness). I have to dial it back to 12-13 BTDC in order to keep it from pinging in the higher gears.

maybe I'll just start running AvGas in it for daily driving.

 

Unfortunately a main bearing might not manifest itself right away. I ran my stupid Ve low on oil once and filled it. A slight tick started to develop followed by massive failure about a week later.The tick got louder and louder until it turned into a knock etc......

Check your oil level and pull the plugs. See if you clipped the electrode or something. And KEEP checking the oil level. ie.. every day.

 

I also just replaced my KS and harness...I found out, later on, that the KS is useless with the JWT ECU. At sea level, it would ping like a **** on hot days so I had to pull the timing. At 4800rpm's the JWT advances the timing 7 degrees over the factory ECU.... Now I live in Albuquerque, NM (5500 ft) and I can advance my base timing almost all of the way up. I think that JWT got lazy when made the ecu. They probably didn't want to make another timing map for the extended rev-limiter.

 

I did some more thinking as to why the engine would misfire after reving it really high....Basically it means that your valves were floating which caused your lifters to completely fill up with oil. So your motor was misfiring because your valves were being kept open by the lifters for a short period of time at lower RPM's. Since the valves were staying open slightly at lower RPM's in that cylinder, you had very little or no compression in the cylinder that was misfiring. It took a little while to start firing again because it took a little while before the oil would escape the lifter(s). I had this exact same problem. The reason I had a puff of black smoke (you probably did too) is because the fuel wouldn't really burn in the cylinder that didn't have any compression. No need to worry....

 

Jeff, that's basically what I'm worried about... oil is fine. I'll be replacing the plugs tomorrow or Friday anyway, so I'll closely inspect when I do that. My main concern is just like you said- a spun bearing that I won't notice until I have to throw the thing away. it's got ARP rod bolts and such in it, so I'm not worried about it coming apart like my last engine (which I'm sure is what happened to it.. kept driving for a while with a bad bearing and it finally beat the rod apart and kablooey)

505Max, your theory is basically what I was thinking as well. the engine still has a tiny amount of blow-by or some valve seal leakage as it still burns a bit of oil and will leave a light puff of blue smoke when I leave from stoplights. (it's worse if I leave the A/C on for some reason). I'm not terribly happy about that (not after spending this kind of money to build this engine), but the thing runs okay and it's got good compression and near zero leakdown (under 1%) in all cylinders... so wherever the oil is coming from, it's not too serious.

anyway, when I put this engine together, I had some issues with the hydraulic lifters being overfilled and holding valves open when I first built it. I smashed the oil out and put them back in and the problem was gone... it's very possible what happened is as you described.

 

Matt- sounds like a perfect excuse for a VQ35 swap!

That sucks on the oil consumption though.

~Alex

 

Nice call Sean. I never would have thought of that.

 

Too bad he drives a 3rd gen. No 3.5 swaps for them ... at least not that I know of. Besides, Matt's engine is built to hell. Remember that "Dropped the VE off at the machine shop" thread. Man was that a long one.

 

oh and your oil consumption might have alot to do with how well you warm up those forged pistons

 

My broken DEK had spun bearings, broken camshaft, and a cracked oil pump.

 

Nah... it does it when it's warm and when it's cold.

the shop bored the block just a bit on the tight side so there's no piston slap on cold startups.

 

and yes, VQ swap is out. I thought about doing one while I had this engine out, but it's just too much work for a DD and too many hassles later.

Now, once I have a new DD and this car is relegated to "that shady spot behind the garage since I'll never be able to sell it", THEN I might consider a VQ swap... but if I do, it'll be getting more than just a VQ and keeping the crappy FWD handling characteristics.