Help with sluggish running and back fire.
04-03-2015, 12:02 PM
#1
Help with sluggish running and back fire. Hey guys,
I have been working on the car for about a month now. It started running pretty poor. Really sluggish when accelerating. And it back fires quite a bit, even at idle. I've replaced plugs, and fuel filter. I've also tested the plug wires. All is good there. Recently started tuning to 91 octane, as it was e85 before I bought it. Fuel pressure was high, so adjusted down to around 57. 80lb injectors.
Tuner said that the tune is close and there is no reason it should be running this way. Could a vacuum leak cause this? Bad fuel injector?
I have been working on the car for about a month now. It started running pretty poor. Really sluggish when accelerating. And it back fires quite a bit, even at idle. I've replaced plugs, and fuel filter. I've also tested the plug wires. All is good there. Recently started tuning to 91 octane, as it was e85 before I bought it. Fuel pressure was high, so adjusted down to around 57. 80lb injectors.
Tuner said that the tune is close and there is no reason it should be running this way. Could a vacuum leak cause this? Bad fuel injector?
04-03-2015, 07:51 PM
#6
If injector is stuck open, car will read that it is running rich. If an injector is not opening you could usually tell that by a certain primary not heating up, or checking out spark plugs. For coil packs, the easiest thing I have found to do is to sway out coils with someone else that is a known good. Fastest and easiest way to tell.
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04-03-2015, 10:03 PM
#8
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Read the spark plugs. If they are all very black then it's running rich. If one looks real wet and smells like gas then you may have a bad injector on that hole. To test the coil packs just hook up a spark tester to the end of the plug wire and set the gap at about an inch, the coil should be able to easily jump the gap. Can't jump it then the coil is bad.
04-03-2015, 11:21 PM
#10
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The motor must be running very rich for some reason. Lots of possible causes like tune, map sensor, maf sensor, coolant temp sensor, motor not warming up properly, ect.....
If you have access to a scan tool you really need to read live data and see what the computer is seeing.
If you have access to a scan tool you really need to read live data and see what the computer is seeing.
04-03-2015, 11:26 PM
#11
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Has it been retuned since you switched back to 91? If it is still putting in the same amount of fuel through the injectors as it was with e85 that could be why it's running so rich. E85 motors run much richer then 91 motors.
04-03-2015, 11:29 PM
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Sounds like a restricted exhaust to me..... Might want to try attaching a vacuum gauge to the intake manifold, should have 18 to 22 in.-Hg of vacuum or more at idle, then as it runs it will slowly drop if the exhaust is restricted. Disconnecting the exhaust and retesting can verify.
