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Engine cuts out at full throttle after long sweeping turns
Title says it all. My 996 is having a very unique issue where if I take a long sweeper (on ramp) at 50-60MPH when I floor it at the end of the ramp the engine with start to cut out and buck violently. Almost like a fuel starvation but it does it on all tank levels (full tank, less than a 1/4).
Once I get on the highway for a 1/4 mile to so it will run at full throttle without any problems.
Any thoughts before I let the indy troubleshoot it next oil change?
All maintenance up to date including plugs? How's your MAF sensor? Maybe fuel pump on the way out?? Are you running an aftermarket air intake or non OE air filters?
I assume you are not hitting the rev-limiter and experiencing fuel cut off. Nor are you engaging PSM.
All maintenance up to date including plugs? How's your MAF sensor? Maybe fuel pump on the way out?? Are you running an aftermarket air intake or non OE air filters?
I assume you are not hitting the rev-limiter and experiencing fuel cut off. Nor are you engaging PSM.
Bought the car earlier this year and is passed a full PPI plus another inspection by my local indy.
It had new plugs 3k miles ago as part of the 60k service. Running the evoms intake and so far no MAF issues.
The fuel filter is not explicitly stated on the 60k service invoice and I have no reason to believe the coils are not the originals so those two items are on the docket for the next oil change.
The fuel pump seems like a likely culprit but I wonder why it only hates long sweeping corners, full throttle on a straight has never been an issue.
I used to have the same problems with my car when at the track in long high power sweepers when the car was heat soaked. Thinking it was fuel starvation, I changed out pump, fuel lines, etc. Nothing helped. It wasn't until I got rid of the OEM check valve that I had retained and also got rid of the stock quick disconnect fitting that plug into the top hat of the fuel tank that the problem was resolved. Both the OEM check valve and the hat fittings are very restrictive due to their small I.D. thus limiting fuel flow at high demand, irrespective of the size of the fuel pump. I was already running a 450L/hr pump with -6 supply lines. Once I removed the OEM check valve and the hat fitting swapping for -6 connections, the problem totally went away. Long story short, if you are running 550hp+ and upgrade your fuel system, make sure to address these items.
I used to have the same problems with my car when at the track in long high power sweepers when the car was heat soaked. Thinking it was fuel starvation, I changed out pump, fuel lines, etc. Nothing helped. It wasn't until I got rid of the OEM check valve that I had retained and also got rid of the stock quick disconnect fitting that plug into the top hat of the fuel tank that the problem was resolved. Both the OEM check valve and the hat fittings are very restrictive due to their small I.D. thus limiting fuel flow at high demand, irrespective of the size of the fuel pump. I was already running a 450L/hr pump with -6 supply lines. Once I removed the OEM check valve and the hat fitting swapping for -6 connections, the problem totally went away. Long story short, if you are running 550hp+ and upgrade your fuel system, make sure to address these items.
Interesting. Is the check valve located at the tank end of the fuel line?
I'm tempted to get a durametric or cobb unit so I can read the af ratio to see if it leaning out.
I used to have the same problems with my car when at the track in long high power sweepers when the car was heat soaked. Thinking it was fuel starvation, I changed out pump, fuel lines, etc. Nothing helped. It wasn't until I got rid of the OEM check valve that I had retained and also got rid of the stock quick disconnect fitting that plug into the top hat of the fuel tank that the problem was resolved. Both the OEM check valve and the hat fittings are very restrictive due to their small I.D. thus limiting fuel flow at high demand, irrespective of the size of the fuel pump. I was already running a 450L/hr pump with -6 supply lines. Once I removed the OEM check valve and the hat fitting swapping for -6 connections, the problem totally went away. Long story short, if you are running 550hp+ and upgrade your fuel system, make sure to address these items.
PSM can shut down the throttle under these circumstances as well, true?
He can easily eliminate the PSM variable by unplugging the PSM pump. Takes 2 minutes to do. I doubt it's PSM as he would have to be loosing traction or having a yaw component. Doesn't sound like that's happening.
He can easily eliminate the PSM variable by unplugging the PSM pump. Takes 2 minutes to do. I doubt it's PSM as he would have to be loosing traction or having a yaw component. Doesn't sound like that's happening.
John can you toss out a diy? The t/c interferes with my proefi t/c
This is sounding more and more like a fuel issue. Took the car for a little canyon carving this weekend and when I got done the fuel pump was whining. I didn't think much of it since it always whines at low fuel which I was. Only this time after filling up and driving home it was still whining, odd. Then I tried to go WOT in a high gear and as soon as the car hit 1.1 (my tune is for 1.2) I started to hear what I would call violent backfires or miss-fires / detonation (no CEL). I stopped off for a coffee and once the car cooled down the whine was gone and so were the miss-fires though I didn't get deep into the pedal to avoid engine damage.
I plan on pulling the pump today to check for a split line, will probably order a new unit and check the venturi tubes for cracking. Sadly I just filled up so I got to find a way to empty the tank, I don't feel OK driving the car knowing I could be dangerously lean.
Well isn't this interesting. Looks like on of the previous owners installed a larger braided fuel line with a compression fitting.. So far the pump looks stock (still draining tank).
Here is a site that sold my car 1 owner ago. Wonder if the fuel line was done as part of a kit.
This is the compression sleeve on the sending unit. Debating if its worth the trouble to put in a AN bulkhead to clean things up. This looks to have leaked a little given the discoloration.
08-09-2016, 04:30 PM
Engine cuts out at full throttle after long sweeping turns
