AKlowriderZ71

iTrader: (22)

I'd like to know how an injector problem, or coil issue, will bend a connecting rod. Anybody?

slowfive0

I'm with you on what you're saying. That is why I mentioned the coolant. Something hydro locked that cylinder. Either coolant, fuel or water. A problem with that injector could have hurt the motor/gasket (lean condition/detonation) and caused it to start taking in coolant (if the gasket blew into a water jacket) in that cylinder. Obviously, speculation all the way around here.

I've seen motors hydro locked like that (bent rods) from coolant. Also, seen motors with bent rods from low mounted ram air intake systems that drove through standing water and sucked up water. Was handful of bent rods in that case. In his case, if it isn't coolant, then what is left besides the fuel. The only time I've seen an injector cause a bent connecting rod was when the injector signal wire got shorted to ground causing the injector to stay on 100%. That was on a much older fuel injection system. These systems will set an injector driver dtc for starters and will temporarily disable that injector driver if that situation occurs so I would probably rule that out.

Bottom line, getting his injectors flowed would show any issues (restricted flow, dribbling stream, mechanical issue with solenoid, i.e. stuck, whatever) going on with the injectors regardless. Since he is replacing/upgrading the injectors, it should be a non-issue, but personally I would rather he diagnose it so that the original problem is addressed. Otherwise, he may pass that problem on (sell injectors) or still have it present with his new combo. Forged motors can be broken too if something isn't right. They just take more abuse.

Good point though. Situations where I've seen an issue with that much coolant or fuel, the vehicle never ran worth a chit. Should have been pretty obvious that there was a dead hole (runs rough). Good point from the other post about the software potentially having a disabled misfire counter too. Good discussion. Take care.

shawnss

iTrader: (8)

heres what happened the day i bent the rod on that motor LQ4. i was on my way home from work and some new M3 pulled up next to me wanting to mess around. we went from a roll at about 40MPH or so. I went WOT and the truck kind of stumbled on its face and then took off. but as it stumbled on its face i looked at my exhaust from my passenger mirror and it let out a big *** backfire/pop and a big puff of black smoke/ rich fuel out the exhuast. after i got done messing around with the M3 i rolled up to the next stop light and i heard a very light tapping noise coming from the motor. i babied it home which was about 5 or 6 miles. the truck ran fine just had a slight tapping noise at idle. but as i would bring the RPMs up the noise would go away. after getting it home i checked it over very well and found the noise to be coming from the bottom end. i yanked the motor and there was nothing in that cylinder with the bent rod it was clean just like all the other cylinder. so im with you on this one i feel it was a fuel hydrolock or a misfire/backfire that bent the rod. i wasn't blowing smoke or anything just the tapping noise. this was a pretty fresh motor. heres the cylinder that the bent rod came out of. looks good to me.

cylinder the bent rod came from.

04BlackSilverado

iTrader: (6)

Were these both in the same engine?

Looks like the stronger (and HEAVIER) rod won....


Who is going to build your new engine?

slowfive0

Hard to say what happened. It would seem possible that the head gasket failed (can't really tell in the pics---but there is an area at the 9 o clock position of the picture that looks a lot cleaner at the fire ring to water jacket area. Do you have any other pics of that area and of the gasket or head?) I've blown lots of head gaskets and have never hydro locked anything. If the engine was to hydro lock, I'd expect it to happen on a restart after I hurt the gasket and had shut off the engine. Not saying it couldn't happen at the time of failure and that may have been what happened here. Makes sense with the higher compression, high boost situation.......

Have to love the speculation game Hope you smashed the M3

YodiBrodi

but he says momentary stumble, black smoke and a backfire. that's overfueling, not coolant going into the exhaust.

slowfive0

Black smoke = rich condition
Blue smoke = burning oil
White smoke = moisture or coolant

I agree with you to a point. If it puked the gasket, I would expect it to pour out white smoke. However, I never say never about anything. He noticed the tapping right after he got on it and had this episode. Something hydro-locked it. Probably coolant or fuel.

Personally, I've never seen a rod bent under power like this (not a lot of time to get a significant enough of an amount of anything in there to hydro lock the cylinder). Could it happen? Sure and I believe it did here. Could fuel do it---sure, but unlikely at WOT. Think about what happens here. My truck is a great example. Similar in performance and we both have 42's. My injectors are open 100% duty cycle at WOT/redline. So in other words, they are open 100%. Because the engine is turning extremely fast, there isn't enough time to get enough fuel to hydro lock the motor in this scenario. Now if it quit firing, maybe....I've never seen it, but that doesn't mean nothing and I wouldn't be surprised if it "could". Never say never is my motto.

Speculation speculation. He needs to inspect everything really closely (gasket and surfaces - both head and block) and check things out. Have the injectors flowed. Look everything over real close, my opinion. Figure out what broke so it can be prevented next time. Sorry for the rant, really do hope you can figure out what screwed up and get it back together stronger then ever. Take care.