Engine went ka-boom... I think.

[Turbo 420a]

Uh oh, something bad happened to my motor the other day. While I was driving on the freeway in 5th gear, going 70mph, my motor hesitated for a second like it was seizing. No more than a second later it started repeatedly hesitating and backfiring when given gas. The whole car shook back and forth whenever I tried getting on the throttle.

The engine just turned off while I started making my way over to the side of the road. Once I pulled over I tried starting my car up. It started up, however, would just die once the rpms fell because it didn't idle. So I started her up again, and before the rpms could fall I gave a little throttle to manually keep it at an idle. Right after giving the throttle is when the rpm needle just started flying all over the place (would jump from 4k to 2k to 3k really quickly). After the car died this time it wouldn't start up again.

The tow truck driver said it sounds like it might be my timing belt snapping. This is doubtful to me as I installed a new one just 20,000 miles ago. I completely believed my bottom end had failed for the first hour after happening, however, I don't believe I was even feeding the slightest amount of boost to my motor when this happened. Also, isn't it supposed to be a really loud bang when your motor blows? The only noise I heard was the backfiring. My only other idea is that the crankshaft angle sensor, still unfamiliar to me, had failed.

Any ideas you may have to uncover the cause of this failure would be much appreciated!

 

[GSX90]

Boosting on stock internals?

 

[Initial DSM]

Yep. Running in the low 13's in the 1/4 on stock internals. doesnt sound like 7psi boost to me. Time to call gottude.com, rpmextreme, black dogmotorsports, Howell, or VTengines!

 

[Turbo 420a]

My 13.335 pass was made on 10psi of boost, not 7psi.

Does Howell automotive have the best prices on the internet? I have heard some negative things about them. Just so long as they send their products I guess.

 

[Initial DSM]

check the other names I mentioned above before going to Howell. And when you do the rebuild, replace and upgrade all your gaskets and bolts (ARP head studs, 4G63 exhaust manifold bolts etc). 10psi was pushing it on stock bottom end so its no wonder it went. Our engines are good for going 100hp over stock, so its always safe and smart to rebuild if your going turbo. Much more fun too cause of course you can turn up the boost more.

 

[talon94es]

I don't know but for some reason it sounds timing related. Do you have a logger or anything to pull some codes with? That sure would help. Good luck.

 

[dudasd]

Actually I think RPMExtreme has about the best prices, and they offer some sweet upgrades to the package(ie Pauter rods, ARP head studs already installed etc) and for the price of those add-ons you will still come out cheaper than Howell...
RPM Extreme

 

[thehyena]

check the little gasket connecting the MAS to the intake

 

[Turbo 420a]

Thanks for all the links. I was pushing it a little bit feeding 10psi to my stock block. It still didn't worry me much. A reason to pull the motor and build the bottom end sounded just fine to me

Of course this happened right when my mechanic closed for the holiday weekend. I find out the damage to my engine and wallet today when he opens up shop.

 

[Kirby]

Originally posted by Turbo 420a
Uh oh, something bad happened to my motor the other day. While I was driving on the freeway in 5th gear, going 70mph, my motor hesitated for a second like it was seizing. No more than a second later it started repeatedly hesitating and backfiring when given gas. The whole car shook back and forth whenever I tried getting on the throttle.

The engine just turned off while I started making my way over to the side of the road. Once I pulled over I tried starting my car up. It started up, however, would just die once the rpms fell because it didn't idle. So I started her up again, and before the rpms could fall I gave a little throttle to manually keep it at an idle. Right after giving the throttle is when the rpm needle just started flying all over the place (would jump from 4k to 2k to 3k really quickly). After the car died this time it wouldn't start up again.

The tow truck driver said it sounds like it might be my timing belt snapping. This is doubtful to me as I installed a new one just 20,000 miles ago. I completely believed my bottom end had failed for the first hour after happening, however, I don't believe I was even feeding the slightest amount of boost to my motor when this happened. Also, isn't it supposed to be a really loud bang when your motor blows? The only noise I heard was the backfiring. My only other idea is that the crankshaft angle sensor, still unfamiliar to me, had failed.

Any ideas you may have to uncover the cause of this failure would be much appreciated!

"check the little gasket connecting the MAS to the intake"


This car has no MAS. This is a 420a not a 4g63.
I don't think it's your bottom end. Nothing in your bottom end would cause the revs to jump like that. My guess is you have a sensor or t-belt related issue there. Did you inspect your car before it was towed? All you have to do is pull 1 bolt to see if it's the t-belt. I put a brand new t-belt on my car with the rebuild, and 400 miles later the tensioner pulley bracket broke and caused me to shred the t-belt. I bet yours started shredding and eventually pulled itself a few teeth off before snapping completely. Never never give a car that you know is having a problem more throttle. It is entirely possible that your engine could go while not in boost. If you abuse the motor to much and put it to the verge of breaking it might break a little after that you know what I mean. I still don't think that is your issue here though. The lack of idle tells me that it is not the bottom end, if you had thrown a rod or seezed the motor it would not have run at all. I just want to know if you bent valves. Did it make any noises at all? That backfireing you heard was prolly from the timing not being right, and the valves not being timed correctly. Check your timing belt and cam and crank angle sensors and I bet you find your problem. Please post back with the results.

 

[dsmrunnah95]

You ran a 13.335 @ 99.71mph?? you must have uber-traction! Most FWDs that trap 99 run about a 14flat... what kind 60' foot did you run?

 

[Turbo 420a]

Thanks a lot for the helpful response Kirby. My mechanic said there was an error code for my cam position sensor. Replacing it will be our first attempt to fix the problem. More confusing is that he said no power was reaching the ignition pack. His shop will be receiving some kind of new diagnostic equipment that goes beyond OBD-II that should help further locate the problem.

Dsmrunnah95. I really don't have that bad of a traction problem seeing as my turbo spools it's real power beyond where I would launch at. Breaking just below 2 seconds in the 60' time is a rare thing for me requiring a perfectly executed launch at the correct rpm - otherwise I bog out and always get 2.2 or worse.

 

[green95hrcgs]

Kinda sounds like you have the same symptoms I was suffering from just a week and a half ago. If your car still shows a check engine light, then you dont have to get a new PCM like me.

If the cam sensor is not functioning replace that, then the ASD ( Auto shutdown relay ) also called the ignition relay. I replaced my cam sensor, but still get a check engine light for it. Car seems to run fine tho.

I was not getting any spark, but my plugs and wires were new and my new MSD coil tested fine also. Kinda weird.

Let us know what you find.

 

[Kirby]

Well if the engine is not getting a cam signal then it prolly won't light the coil, cause it does not know if the car is timed properly. Fix the cam sensor first then worry about the ignition.

 

[tdoshi9]

thats what it is. i have a cam sensor that i pulled out of my car that is fine. i had this same problem and i replaced every sensor. if u can't find one let me know. they are about 50 from dealer and u have to get a new connector with it. they stop makeing the one that is in our cars. let me know i will let it go cheap and i will garrentee it works. with it being electronic i would be werry about buying a used one from someone i didn't know, with out that

 

[Turbo 420a]

Thanks for the all the feedback. Should have the new cam sensor in a couple of days.

 

[dsmrunnah95]

Originally posted by Turbo 420a
Dsmrunnah95. I really don't have that bad of a traction problem seeing as my turbo spools it's real power beyond where I would launch at. Breaking just below 2 seconds in the 60' time is a rare thing for me requiring a perfectly executed launch at the correct rpm - otherwise I bog out and always get 2.2 or worse.

Even with a 1.9 60' you still wouldnt run that low of an ET with that mph. You'd have to pull around a 1.5 60' (maybe lower) to hit that ET.

 

[Turbo 420a]

Originally posted by dsmrunnah95


Even with a 1.9 60' you still wouldnt run that low of an ET with that mph. You'd have to pull around a 1.5 60' (maybe lower) to hit that ET.

Well dsmrunnah95, you must think there was something positive to be gained from your post. Nothing I haven't already posted about my track time will change what you believe so just keep it to yourself and don't waste my time. Posts like your last one drain time away from the other friendly and constructive members here. Do you have a car modified exactly like mine? No. Believe what you will. But for the sake of others please keep it to yourself so nobody will have to waste their time on a pointless argument.

[update] The new cam angle sensor had to be shipped from a dealership in CA (obviously rare). If this isn't the problem the next suggestion by Mitsubishi themselves was possible failure of the crankshaft angle sensor due to crankwalk, rarely happening to 420a motors when compared to the 4g63.

 

[dsmrunnah95]

Originally posted by Turbo 420a


Well dsmrunnah95, you must think there was something positive to be gained from your post. Nothing I haven't already posted about my track time will change what you believe so just keep it to yourself and don't waste my time. Posts like your last one drain time away from the other friendly and constructive members here. Do you have a car modified exactly like mine? No. Believe what you will. But for the sake of others please keep it to yourself so nobody will have to waste their time on a pointless argument.

I'm just trying to find out your suspension setup so I can run a pass like that.

I still think that time is bs and i think that you're attacking me because you see that someone has seen past your bs

 

[Initial DSM]

post the time slip.

 

[Turbo 420a]

Originally posted by Initial DSM
post the time slip.

The time slip has been up for a long time now.

http://www.dsmtuners.com/gallery/showphoto.php?photo=20144&password=&sort=7&thecat=500

My time for being made in a 10psi RS with a great launch is not unordinary. My setup easily walks from my friends Camaro Z28 which is a high 13 second car. I will make some videos of my passes once I get my car fixed.

 

[dsmrunnah95]

I'm not arguing with you time, it can be done... I'm not believing your trap speed unless like you slammed on brakes before your crossed the line. What was your 1/8th in that run? It seems to have disappeared.

btw that dude beside you racing sucked ass 7.2 60' ?

 

[Turbo 420a]

Originally posted by dsmrunnah95
I'm not arguing with you time, it can be done... I'm not believing your trap speed unless like you slammed on brakes before your crossed the line. What was your 1/8th in that run? It seems to have disappeared.

btw that dude beside you racing sucked ass 7.2 60' ?

Something happened during that race that I still haven't figured out. The guy next to me didn't stage properly and was just finishing the end of his pass after I had already made my turn-around. Also there is no 1/8 mile result on the timeslip.. Does that mean I didn't stage correct or something? I have already said, twice now, in the forums that I let off the aceelerator a little too early as just a stupid ass mistake, probably otherwise running 103mph or so.