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Car dies only at WOT. Any ideas?


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I have the L28E with Megasquirt and everything runs fine except for when I go WOT.  I can accelerate quickly fine but if I give it quick throttle, the engine stops for a split second and then fires back on.  Does this sound like a fuel delivery issue or a Megasquirt issue?  Just wanted to check before messing with my tune

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I have the L28E with Megasquirt and everything runs fine except for when I go WOT.  I can accelerate quickly fine but if I give it quick throttle, the engine stops for a split second and then fires back on.  Does this sound like a fuel delivery issue or a Megasquirt issue?  Just wanted to check before messing with my tune

What does MS do for acceleration enrichments?  TPS-based? Sounds like either too much or too little extra fuel being injected when you snap the throttle open.

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I read the title, and my first thought was I wonder if he's running megasquirt.

 

It sounds like an acceleration enrichment problem. Do you have your msq or since I don't have tuner studio on this computer can you take a picture of your acceleration settings?

 

For me this was caused by a poor graph and a dot threshold that was too high

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I do have one and I messed with it last night but nothing seemed to be a fix.  Let me see if I can load my msq when I get home.  Thanks, guys.

 

Also, it seems whenever I floor it even after slowly building up speed, it will pretty much die unless I lift off the gas pedal.  Still Accel Enrichment?

Edited by dpuma8
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That is a good point. 

 

The symptom you describe in your second post indicates lack of fuel. 

 

Anecdote: I setup a base tune for a car and it would bog no matter how much fuel I threw at it. Turned out the fuel pressure would dive drastically with any throttle input. Inadequate fuel pressure meant no matter how much I played with the electronics, it wouldn't run correctly.

 

Without more facts cannot determine if that is caused by your map, your accel enrichment, your setup.

 

Have a build thread to reference?

 

And the values are pretty easy to write down if it is too difficult to get a screen shot or put up your msq. Hard to help if you won't give the numbers to help.

Edited by seattlejester
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The L28 stock fuel injection system operated off 35-40 psi.  That's what you'll need for the injectors to do their job reliably.  The OE system had a bypass pressure regulator. I see nothing about the particular vehicle you have the engine in so I'm not certain if it's an original fuel injected car with all the appropriate plumbing or not. Install a pressure gauge just before your fuel rail and see what it says.  With the hood off you could even watch it while you're driving.

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  • 3 weeks later...
  • 2 weeks later...

Car runs nearly perfect now but I have a new question.  I drove around and then parked my car to grab something to eat.  Temperature was 180 degrees when I turned the car of  After 20 minutes of sitting, I turned on the car and I had idle surge.  Temperature went to about 205.  When I checked under the hood, the MAP hose was pretty warm.  I put a few gallons of gas in the car and drove off and everything was fine and the temps dropped to 180 again.

 

Is this possibly because I could have had low fuel?  Or is this a tuning issue?

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Not sure what the MAP hose being hot would do for addressing your problem. 

 

Seems like you romped on it before parking? Give it some time to cool down before you shut it off, the water only circulates with the engine running unless you have an electric water pump and no thermostat. 

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