Trouble getting hemi running right

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dartboy73

dartboy73

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so I have a 6.1 hemi its running a bbk 87mm throttle and a megasquirt gold box it has TTI Headers with no exhaust.
the car will run and idle but it backfires every once in awhile if I touch the throttle it just seems to die or backfire then die anybody had this problem? I called megasquirt and the guy said he figured it was a fuel problem I installed a pressure gauge and its 58psi please help lol
 
Might need some more info... does it smell like it's running rich/lean? Are all the O2 sensors hooked up right? Loose plug or coil wires? If you have good fuel pressure, all the injectors are firing right, and your ignition system is working right, I would look at whatever airflow/pressure sensor you have an the throttle position sensor. I would start by double-checking all the connections on the engine and making sure everything is talking to each other correctly. Then maybe look at the megasquirt settings/parameters to see if anything is wrong.
 
Chained_360 said:
Might need some more info... does it smell like it's running rich/lean? Are all the O2 sensors hooked up right? Loose plug or coil wires? If you have good fuel pressure, all the injectors are firing right, and your ignition system is working right, I would look at whatever airflow/pressure sensor you have an the throttle position sensor. I would start by double-checking all the connections on the engine and making sure everything is talking to each other correctly. Then maybe look at the megasquirt settings/parameters to see if anything is wrong.
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it does not smell like it is running rich I was thinking maybe a coil pack or maybe a plug but the engine was running smooth when it was pulled. all the sensors are new im not saying that means they are good. the air pressure sensor was reading 89 if I remember correctly I am at a high altitude if that does anything.
 
Your throttle position may not be learned I don’t know about the mega squirt but have seen this happen on a couple of swaps. Hold the accelerator pedal down and turn the key to on, not to start and wait 10 to 15 seconds and let off then start the motor. Disconnect and reconnect battery first to reset everything.
 
That did seem to help I can give it a bit of throttle now but still backfiring and then stalling out. one more thing I noticed is the fuel pressure is at 58 when pump is on but car not running but then jumps above 60 when running that's as high as my gage goes
 
I have the stock intake and I have the port on the back of the intake plugged as well as the small one on the front. I also have the port on the oil cap filler plugged as well. I did have the intake off so I though I might have a leak I sprayed brake clean along the outside edge to look for a leak but the idle stayed the same
 
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You may need a breather filter on the one by the oil cap. It may be that simple.
 
I tried the breather idea but then the car idles really high like 1200 rpm. see what I mean this car is driving me crazy
 
ok so after doing the throttle trick and putting the breather back on it seems to run a bit better it is idling a bit high 1100 rpm though and still back fires when you give it throttle could it be cause im running open headers with no exhaust? its not stalling anymore
 
I had an exhaust leak and it would backfire. I’m wandering if it needs the mufflers for some kinda backpressure.
 
loganscuda said:
I had an exhaust leak and it would backfire. I’m wandering if it needs the mufflers for some kinda backpressure.
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I just called the exhaust shop im going to try and get it booked in I feel like it might be a big part of my problem. the 02 sensor probably does not get a very good reading without it
 
loganscuda said:
I had an exhaust leak and it would backfire. I’m wandering if it needs the mufflers for some kinda backpressure.
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I don't know much about your particular app, but for a regular old engine, if you have backfiring, it could be exhaust leak, complicated by insufficient combustion, which could be from a rich condition or a vacuum leak
 
what are your guys though on it being the corvette fuel regulator? the fuel pressure does go over 60 when its running
 
dartboy73 said:
what are your guys though on it being the corvette fuel regulator? the fuel pressure does go over 60 when its running
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It all depends on what the injectors are supposed to be running. Are they stock? Aftermarket? Try to find the suggested PSI for your application/power range and go from there.
 
You can't get a good reading from the O2 sensors with out the exhaust being at least 18" after the O2's because in between pulses oxygen gets sucked back in and the O2's read it as lean

That also goes for header flange leaks oxygen gets sucked into the tubes
 
brian6pac said:
You can't get a good reading from the O2 sensors with out the exhaust being at least 18" after the O2's because in between pulses oxygen gets sucked back in and the O2's read it as lean
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so the exhaust could defiantly be my problem
 
The engine module reads that it's lean so it cranks up the fuel to try to compensate, it's not burning all the fuel and it ignites in the header tube causing the pop out the exhaust.
 
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