shawnk

While out tuning this afternoon I was doing a 3rd gear pull. I didnt time the pull right and ended up on a curve in the middle of the pull. I just held even throttle around the turn and went WOT after the curve and BOOM!! I let off immediately and look in my rear view mirror to see a giant cloud very similar to the first time I blew my engine. The engine still idled and it wasnt low on power so I headed home with a pain in my stomach I seem to get too frequently when in my FD.


I looked at the log trying to figure out what happened...




I called a FD buddy and relayed the events to him and his first question was "how much gas do you have?" - around 1/4 tank...

"What direction turn was it?" - left hand turn - long sweeping one...

Uggg. What an idiot I am.

I am sure the engine is now not what it once was - I am hoping the fact I was only at 10psi and I have RA super seals means I didnt hurt it too badly...

darkphantom

iTrader: (2)

maybe its just a seal problem, but good luck and i hope its not too bad.

How does it start! if its hard to start then its the motor!

DaveW

If the engine idles smoothly, has good vacuum, power, etc., you probably just had a backfire from unburned fuel in the exhaust. You may not have hurt the engine.

Don't panic yet.

dgeesaman

iTrader: (7)

Hyperion surge cover GB!!!

scotty305

iTrader: (2)

Do you have a datalog of the knock sensor?

DaveW

I didn't mention this in my previous post - these engines almost never go "BOOM."

They usually break an apex seal in relative silence, due to detonation. It's when you slow down that you notice that it no longer idles properly, and has noticeably less power when you get on it next time. That's why I said you probably just had a BIG backfire (improper mixture didn't burn in the engine, and was ignited in the hot exhaust). Of course, this may have damaged your exhaust system, but it's not likely to have ruined your engine.

shawnk

Here is a graph of the knock on the run:



And here is the log if you would like to look at the rest of the stuff and let me know what you think:

http://www.3rdgenrx7.com/maps/log.txt

shawnk

I was trying to figure out something other than "BOOM" to say when I first posted....there was no actual boom. I cant really even say if there was any noise at all. It was more of a terrible feeling and possibly the "throwing nails into a coffee can" sound I have heard during detonation (but I cant even remember that for sure).

It does still idle fine, starts fine, has good vacuum, and has power. And the knock log is encouraging.

Jason

iTrader: (5)

You will not break an RA super seal from detonation. If you blow anything it would be a corner seal. Thank the rotary gods you are running aviation seals as they probably saved your motor. This is another reason to run aviation as any other seal would be gone and you would be looking at a rebuild.

G's 3rd Gen

iTrader: (11)

Damn Shawn be careful! Are you still running the TO4S?

shawnk

Yep. Same turbo. I havent damaged the turbo once in 3 blown engines.

I am only running 10psi until December. Then I will kick it up to 12psi and increase 1psi per month for a while.

I am hoping I wont blow it for at least siz months with that technique.

You still on stock twins? Same set or new?

G's 3rd Gen

iTrader: (11)

Still on the twins. Slowly picking up tidbits to go single. Probably 500r after Deal's Gap. G

FD3S2005

iTrader: (11)

+1 on the gb.. we only need 4 more ppl

shawnk

I was skeptical about this device when I first saw it but the positive reports just keep coming in. While my skeptisim has been dissolved I have dual pumps so it would take some modification for me to use.

And this is the first time I have seen starvation. I am going to try to manage it with fuel level first - no way I should have been tuning on that little fuel.

shawnk

UPDATE:

I figured out what this problem was this past weekend. The initial symptom was listed above:

1. Lean on hard left hand turn.

I dealt with it by making sure my tank was 1/2 to 3/4 when tuning or driving hard but my car was acting very weird the whole time. I couldnt get it tuned as it seemed different everyday. Then I saw symptom 2..

2. Ran out of injector at 12psi.

When I decided to tune to 12psi I got to 100% duty and it still was a little lean. With 720/1680 injectors that I had taken to 18psi it didnt make much sense. So instead of watching my AFR religously I did some pulls watching fuel pressure and I saw the problem. My fuel pressure was building as it should but it eventually fell off all the way to below idle pressure. I started making a list of all the stuff it could be but before I started the troubleshooting process I discovered the 3rd symptom.

3. When tank got below 1/4 the pressure would fluctuate wildly when turning left.

This symptom did not happen when the tank was full. I figured the rest of the fuel system would have no idea the tank was full or empty so I started by pulling the assembly.

About 30 sec after pulling the assembly I found the problem - the hose on one of the pumps had been blown up the assembly. It wasnt enough to not work at all but it was enough to let fuel spray out of the bottom of the hose. So when there was fuel covering that gap it was restricted somewhat and I would only get falling pressure problem. But when there was no fuel covering that gap the pressure loss would be much more dramatic.

I made 2 changes to keep this from happening again.

1. I made new hoses that went all the way to the top of the assembly instead of just to the metal pipes. That way it is impossible for either hose to "slip" upward - they are butted against the top of the assembly.

2. I put a single bigger clamp at the pump instead of the smaller double clamps I had. Since the fuel pump nipple is kind of tapered the second clamp might have been forcing the hose to seperate from the pump.

Bad news was I was so worried about the clamp at the fuel pump I tightened it too much and broke the nipple off of my cosmo pump. I did have a stock pump to put in its place but I am a bit worried what kind of flow I will get at high boost on the supra/stock combo.

It is running great now.