Misfire at Idle & Boggs down when given throttle
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Misfire at Idle & Boggs down when given throttle
Hello, I am new here as I have taken on the task of getting an old 99 4wd 3.9L magnum running right.
Here is what's happening-
The truck starts up as soon as you touch the key. No check engine light. Misfire at idle. When accelerating almost all power is cut. ( when pressing gas it bogs down and stutters.) It hesitates when given throttle then RPMs suddenly jump up. If that makes sense.
Other known problems that may be contributing to it-
1. Pretty loud lifter tick( Any tips on this?)
2.Used to leak gas from the filler neck when filling up gas. Fixed with silicone and duct tape(Evap leak?)
3.An injector on the right side ticks(Stuck injector? Seafoam through them? Gas additive?)
4.Sometimes smells like gas or exhaust fumes in the cabin and outside it.
5.Smoke/vapor has come through the vents in the cabin a handful of times.
6.A/C is out.
7. There is a hole in the cat/resonator whichever one is before the muffler and has an O2 sensor on it.
Yes, I know it has a lot of problems.It was neglected most of its life and was given to me. The goal is not for it to be perfect. It will hopefully be my beater if I can get it running okay.
What I've done to try and fix it-
Firstly, I changed the valve cover gasket since oil was dumping from both sides fouling out the plugs. Next, I Took apart TB which had an excessive amount of carbon build-up, and cleaned it thoroughly. Including taking off the IAC and cleaning it as well.(IAC could just need replaced but would that throw a code?) Everything in there was so gummed up I was sure that was the issue. It did help with the idle, but still stutters and loses power, etc. Also, the smaller nipple off the Intake was not plugged and was the cause of a whistling noise that I since plugged also helping to clear up the idle a bit.
Any advice or suggestions would be greatly appreciated!!!!
Here is what's happening-
The truck starts up as soon as you touch the key. No check engine light. Misfire at idle. When accelerating almost all power is cut. ( when pressing gas it bogs down and stutters.) It hesitates when given throttle then RPMs suddenly jump up. If that makes sense.
Other known problems that may be contributing to it-
1. Pretty loud lifter tick( Any tips on this?)
2.Used to leak gas from the filler neck when filling up gas. Fixed with silicone and duct tape(Evap leak?)
3.An injector on the right side ticks(Stuck injector? Seafoam through them? Gas additive?)
4.Sometimes smells like gas or exhaust fumes in the cabin and outside it.
5.Smoke/vapor has come through the vents in the cabin a handful of times.
6.A/C is out.
7. There is a hole in the cat/resonator whichever one is before the muffler and has an O2 sensor on it.
Yes, I know it has a lot of problems.It was neglected most of its life and was given to me. The goal is not for it to be perfect. It will hopefully be my beater if I can get it running okay.
What I've done to try and fix it-
Firstly, I changed the valve cover gasket since oil was dumping from both sides fouling out the plugs. Next, I Took apart TB which had an excessive amount of carbon build-up, and cleaned it thoroughly. Including taking off the IAC and cleaning it as well.(IAC could just need replaced but would that throw a code?) Everything in there was so gummed up I was sure that was the issue. It did help with the idle, but still stutters and loses power, etc. Also, the smaller nipple off the Intake was not plugged and was the cause of a whistling noise that I since plugged also helping to clear up the idle a bit.
Any advice or suggestions would be greatly appreciated!!!!
Legend
Joined: Feb 2005
Posts: 8,058
Likes: 184
From: Fort Worth, TX
Cam could be jumped a tooth. In theory you'd have a cam sync error. O2's could be shot, giving a rich condition (and contributing to misfire). Vent smoke/vapor is heater core corrosion. Sticking injector could also be causing rich condition.