Hi,
The last week, my engine blown when I was driving normally, it broke after a stop and the engine was at about 2k or 3k RPM.
I have this car for more than 3 years and I do all the required maintenance.
The car has 77 000 mi and I didn’t have any issue before that. I went to the drag only three times and the last one was last summer. The rest of the years I drive normally (it’s my daily drive).

The connecting rod # 4 bent and broke, and the engine block open.
I'm surprised by the size of the stock connecting rod, it's almost the same width of my little finger !!!



Before it happens, I had the engine code “misfire cylinder #4” but after few days the code became “random cylinder misfire”. I had this code for more than one year and half (since it’s tuned with ecuflash).

Do you have any idea of what could the reason of the bent connecting rod ?


My set-up is;
Complete 3 in exhaust (downpipe, cat, and muffler)
Camshaft gsc S1
Injectors FIC 1050 cc
Walbro 255 lph
Intake pipe with air filter injen
IC pipe injen
Water/meth injection kit snow performance (in the trunk) with 60% meth and 40% water
O2 housing in stainless
Grimspeed boost control 3 ports
Omni power map sensor 4 bar
Tuned with ecuflash (main map with a safe tune at 23-24 psi and the alternate map tuned for the drag with the water/meth at 26 psi)

By the way, I WTB a evo 8 or 9 block to rebuilt my engine so if there is someone who has one to sale, let me know.

Thanks,

 

Just thinking out loud... Is your ignition system still stock or did you upgrade to COP setup? My first thought was that and I would also check the gap on the spark plug (if it didn't get mangled ). And last thought... Have you checked the injectors to see if they are still good?

 

Yes, I had already check the gap of the sparkplugs (more than one time) and it was always OK.
I try different sparkplugs and coils on different cylinders but always the same result; misfire cylinder #4 or random cylinder misfire.


I didn't check the injector because they were new when I installed on the car.


Do you think that misfire can bend a connecting rod ?

 

Any others idea ?

It is normal to bend stock connecting rod with 24 psi of boost ?

 

Misfire could definitely bend the rod.
Got close up pic of the top of piston #4?

 

Yep looks to be an ignition or timing related issue.

 

Really ?
I was tinking that '' random cylinder misfire or misfire cylinder # 4'' were common codes with no major consequences.

I will show somes pictures of the piston later.

 

this is the picture of the top of the piston #4;

 

Looks like your mis-fire was causing the valves to hit the piston, and it looks like its been happening for a while. That makes me think it might be in the timing... have you checked the belt to make sure you didn't skip a tooth? Un-likely but worth checking. Also I still wasn't sure if you had a coil on plug set up or just the OEM set up. I have never run meth and I may be way off but any big jumps in horse power tend to put stress on other components, and in this case it may have been making the coil packs work too hard.

I never had a mis-fire but after I got tuned I had to re-gap my plugs cause it was hesitating at WOT. At that point my tuner recommended a COP set up but I never had the scratch to get one.

How long have you been running that current set up?

 

I run this set-up with the tune for more than one year an haft.
I use water/meth only when I go to the drag (only two times).


The problem is not the timing belt because the other pistons were OK and the timing was also OK.


The piston hit the valves when the connecting rod broke.


Before the engine blow, the compression was low ; about 100 psi (at cold) but I never had problem to start and I didn't had any hesitation at WOT over 3500 rpm.

 

send your injectors for analysis and see if they were all flowing properly. So you can rule out injectors. Make sure you label which injector was for which cylinder.

 

Before it happens, I planned to test injector by moving injector on different cylinder but I ran out time.


Now I will look to test the injectors before installing on the next engine or I will buy others.