5.8 Surging Idle?
Thread Starter
|
5th Wheeling
Joined: Oct 2019
Posts: 47
Likes: 1
From: st. louis, mo
5.8 Surging Idle?
Hi All,
Recently I replaced my exhaust manifolds and replaced them with some shorty headers I picked up from summit. I cut away the air tubes but left the breather up top by the coil and left the air pump connected. I am now seeing an issue with a sometimes rough idle and a loss of power in gears 3, 4, and 5. It will kind of chug along and run rich and it feels like I have a couple bad cylinders that sometime fire correctly or something. I do not have any codes despite letting it idle and driving around town a bit. Does anyone have any clues on what this could be? Am I arcing plug wires? could it be a bad plug? Clogged injector? does it have something to do with the EGR function or leaving the air pump? MAP and TPS have both been replaced in the last 5,000 miles.
Any help is greatly appreciated.
Recently I replaced my exhaust manifolds and replaced them with some shorty headers I picked up from summit. I cut away the air tubes but left the breather up top by the coil and left the air pump connected. I am now seeing an issue with a sometimes rough idle and a loss of power in gears 3, 4, and 5. It will kind of chug along and run rich and it feels like I have a couple bad cylinders that sometime fire correctly or something. I do not have any codes despite letting it idle and driving around town a bit. Does anyone have any clues on what this could be? Am I arcing plug wires? could it be a bad plug? Clogged injector? does it have something to do with the EGR function or leaving the air pump? MAP and TPS have both been replaced in the last 5,000 miles.
Any help is greatly appreciated.
Lead Driver
Joined: Jul 2017
Posts: 9,591
Likes: 1,169
From: San Jose, CA
Definitely test for codes if you haven't, like Sandy was saying.
But you could also be dealing with an exhaust leak, any of which, but especially ahead of the O2 sensor(s) can and will really mess with the tuning that the computer is trying to keep consistent.
Good luck. But all of your suggestions as to what it might be are legit, as making those changes could have added more than one issue.
Paul
But you could also be dealing with an exhaust leak, any of which, but especially ahead of the O2 sensor(s) can and will really mess with the tuning that the computer is trying to keep consistent.
Good luck. But all of your suggestions as to what it might be are legit, as making those changes could have added more than one issue.
Paul
Thread Starter
|
5th Wheeling
Joined: Oct 2019
Posts: 47
Likes: 1
From: st. louis, mo
Hi All,
No CEL only code thrown was for AC on during test. I have no muffler but Im also fairly certain I dont have an exhaust leak after checking with soap and water. A vacuum line wouldn't surprise me. Can I buy lines as a set and replace them? I figured electronic ignition issues would give me an issue throughout the power band not just closer to the top end. I'll run it today and see if I can get it to throw a code.
No CEL only code thrown was for AC on during test. I have no muffler but Im also fairly certain I dont have an exhaust leak after checking with soap and water. A vacuum line wouldn't surprise me. Can I buy lines as a set and replace them? I figured electronic ignition issues would give me an issue throughout the power band not just closer to the top end. I'll run it today and see if I can get it to throw a code.
Cargo Master
Joined: Oct 2016
Posts: 2,738
Likes: 217
From: Northern VA
You can also check for codes using KOER test. Vac lines need to be replaced individually with silicone hose preferably. Now a common cause for surging is a faulty or fouled Idle Air Controller. You can test it with a ohm meter or take it out and clean it.
Lead Driver
Joined: Jan 2019
Posts: 5,070
Likes: 863
From: N.W. Alabama
under hood sticker, shows vacuum line routing, if its there
93 F150 351w vacuum line replacement - Ford Truck Enthusiasts Forums
Silicone Boost/Vacuum Hose
93 F150 351w vacuum line replacement - Ford Truck Enthusiasts Forums
Silicone Boost/Vacuum Hose
Thread
Thread Starter
Forum
Replies
Last Post
Chris Chap
3.8 & 4.2L V6
0
Apr 15, 2016 08:54 AM
UGAPepin
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
1
Oct 7, 2013 08:59 PM
Red Raider 4x4
1987 - 1996 F150 & Larger F-Series Trucks
6
Apr 13, 2003 12:16 AM
