Weird misfire
Thread Starter
Staging Lane
Joined: Feb 2015
Posts: 58
Likes: 0
From: Oklahoma City, OK
Weird misfire Ok so I have a 383 I built like a year ago. LE trick flows. Big LE cam, forged bottom. I've been breaking in the engine every weekend taking it out for drives. Car has a ton of power when I hit it. It'll start right up. Idle at around 5-600. It'll drive fine going through town and on the highway. But as soon as I pull in my driveway after a drive only one side of the engine fires. Can't figure it out. Could it be an opti issue?
What does this mean? Do you know for a fact you have dead cylinders only on one bank or does it sound like it's just misfiring on more than one cylinder? Is this constant after pulling into the driveway or does it misfire for a few seconds and then recover? Is it firing on all 8 while on your drives?
Thread Starter
Staging Lane
Joined: Feb 2015
Posts: 58
Likes: 0
From: Oklahoma City, OK
Yes fires on all 8 during the drives. And when I in my drive way you can only hear the drivers hearder. And it'll putt and die when I take my foot off the pedal. And repeats about every time I take out. Fires just fine till I get home
So while you're out on your drives and you stop at a light it'll idle fine, yet when you pull into your driveway is when it starts acting up? How long has this been going on and what throttle body do you have? Have you checked fuel pressure when it starts acting up?
Thread Starter
Staging Lane
Joined: Feb 2015
Posts: 58
Likes: 0
From: Oklahoma City, OK
Yeah out on the drives it idles fine and everything at red lights. And at high rpms it's really smooth and crisp. Tons of power feels like it just wants to keep pulling. Just only when I get home. And it's been doing it this past month. It seems to be running a little rich. I have not check fuel pressure. And like I said when I first start it up it'll idle around 5-600
Get a fuel pressure gauge from a parts store and put it on the Schraeder valve and run the engine w/out the vacuum attached to the fuel pressure regulator. Pay attention to the pressure when it starts acting up. Who tuned it? How long are these drives you take? Is it enough to get to operating temp for the PCM to go into closed loop?
Thread Starter
Staging Lane
Joined: Feb 2015
Posts: 58
Likes: 0
From: Oklahoma City, OK
The drives vary. But definitely enough to get to operating temperature. Drove it to work yesterday. About 20 min drive all highway. But the temperature stays at 160-170 every drive. It has new fuel pump. And radiator. Everything is new really. I wanted to build it the right way. Was supposed to be a track car. Just breaking in the engine right now. And tuned by pcmforless for now. Oh and throttle body is from professional products
Last edited by noer; Jun 9, 2016 at 02:42 PM.
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Some aftermarket TB's do not have an idle air passage below the throttle blades which can cause the car to stumble and die. Basically the car is suffocating because the blades are closed at idle and the IAC is not supplying enough air into the plenum. Take the elbow off the throttle body and see if there is a passage:
If there's not, you need to drill one. Do a search on this forum. I think an 11/64" bit is what everyone uses.
If there's not, you need to drill one. Do a search on this forum. I think an 11/64" bit is what everyone uses.
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