Another crack at my rough idle.
12-09-2006, 10:21 PM
#1
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Another crack at my rough idle.
So I've recently noticed something that may help some of you geniuses diagnose my longstanding rough idle issue
. First, for those whom I haven't told 50 times, I've tried everything that you can recommend to cure this slight rough idle my car has. My newest observation is that my lights all flicker a bit--headlights, and all interior lights. At first I thought that they were only flickering at idle, and that it was because my idle was not steady, and thus neither was my charging. Tonight, however, I noticed that they flicker a bit even above 2k rpms...when I'm getting a full charge to the battery. I think the rough idle and flickering lights are linked somehow. What may be causing this?
. First, for those whom I haven't told 50 times, I've tried everything that you can recommend to cure this slight rough idle my car has. My newest observation is that my lights all flicker a bit--headlights, and all interior lights. At first I thought that they were only flickering at idle, and that it was because my idle was not steady, and thus neither was my charging. Tonight, however, I noticed that they flicker a bit even above 2k rpms...when I'm getting a full charge to the battery. I think the rough idle and flickering lights are linked somehow. What may be causing this?
12-09-2006, 10:31 PM
#3
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RE: Another crack at my rough idle.
ORIGINAL: will
Bad/loose ground?Corroded cables? Disco anyone?
Bad/loose ground?Corroded cables? Disco anyone?
12-09-2006, 10:35 PM
#4
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RE: Another crack at my rough idle.
hehe my cables are corroded to crap. with them fully tight ive had them come off.
the first day i bought the stang i had just brought it home. i go to show my brother and the thing wouldnt even turn over. so now hes laughing in my face and im thinking WTF!!!!
i pop the hood and my neighbor was watching. before i even got it open he noticed the terminals were corroded to crap and came off.
they looked good when i was testing the car. i guess u cant judge everything by the looks.
anyway i would say u have a serious charging issue. time to upgrade the alt
the first day i bought the stang i had just brought it home. i go to show my brother and the thing wouldnt even turn over. so now hes laughing in my face and im thinking WTF!!!!
i pop the hood and my neighbor was watching. before i even got it open he noticed the terminals were corroded to crap and came off.
they looked good when i was testing the car. i guess u cant judge everything by the looks.
anyway i would say u have a serious charging issue. time to upgrade the alt
12-09-2006, 10:39 PM
#5
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Join Date: Feb 2006
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RE: Another crack at my rough idle.
ORIGINAL: 93 LX FiveO
hehe my cables are corroded to crap. with them fully tight ive had them come off.
the first day i bought the stang i had just brought it home. i go to show my brother and the thing wouldnt even turn over. so now hes laughing in my face and im thinking WTF!!!!
i pop the hood and my neighbor was watching. before i even got it open he noticed the terminals were corroded to crap and came off.
they looked good when i was testing the car. i guess u cant judge everything by the looks.
anyway i would say u have a serious charging issue. time to upgrade the alt
hehe my cables are corroded to crap. with them fully tight ive had them come off.
the first day i bought the stang i had just brought it home. i go to show my brother and the thing wouldnt even turn over. so now hes laughing in my face and im thinking WTF!!!!
i pop the hood and my neighbor was watching. before i even got it open he noticed the terminals were corroded to crap and came off.
they looked good when i was testing the car. i guess u cant judge everything by the looks.
anyway i would say u have a serious charging issue. time to upgrade the alt
12-09-2006, 10:45 PM
#6
The Rogue Mod
Join Date: Feb 2006
Location: Maryland Sucka's!!
Posts: 21,918
RE: Another crack at my rough idle.
Do you have an extra ground strap from the engine to the frame? And for the grease, never been a fan. It can get hot and seep into the connection and cause problems. Def sounds like a ground issue.
12-09-2006, 10:52 PM
#7
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Join Date: Sep 2005
Location: Ohio
Posts: 387
RE: Another crack at my rough idle.
Batt acid tastes like sh-t take my word for it. I still have problems with my battery ground comming loose, even if your grounds are questionable replace them, make sure you have a good ground from block to chassis, block to batt, and batt to chassis. You can't have enough good grounds. Alt is poss bad so a 3g would be the way to go there. After all of that you shouldn't have any charging/lighting issues,as far as your idle goes I'm assuming you did all the normal tune up stuff(you don't post dumb shi- so I assume u actually do know what your doing) Have you run a leakdown test on each cyl? That would rule out weak valvesprings,sealing valves,dropped lifters. I have a valve that is not quite sealed perfectally, only effect it has is once in a while it will flutter the idle then straighten up, I have stock heads so I'm not doing anything about it till new heads come in.Try a carbon clean,maybe you have carbon deposits on the backside of the valves. Look at your ign system in the dark running, you might see sparks from dizzy, coil, or wires
) Have you run a leakdown test on each cyl? That would rule out weak valvesprings,sealing valves,dropped lifters. I have a valve that is not quite sealed perfectally, only effect it has is once in a while it will flutter the idle then straighten up, I have stock heads so I'm not doing anything about it till new heads come in.Try a carbon clean,maybe you have carbon deposits on the backside of the valves. Look at your ign system in the dark running, you might see sparks from dizzy, coil, or wires
12-09-2006, 10:54 PM
#8
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RE: Another crack at my rough idle.
Need to do a Voltage Drop test on the ground circuits, using the main ground (battery (-)) as the reference point for the rest of the grounds. Basically, you will be checking the grounds for "noise", anything with a voltage over .1vdc...= too much resistance (bad ground).
12-10-2006, 07:02 AM
#10
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RE: Another crack at my rough idle.
Thanks for the great info, fellas. Pro, I just have the one stock ground strap going from my motor to the firewall, I believe.
Will, let me revise my initial statement about having done everything to cure the problem. I have not run a leakdown test yet. Good idea though. I had ruled out a cylinder sealing issue once the car passed a KOER cylinder balance test (even though I've heard vastly differing opinions on what this test actually measures). One day, I'll get down to testing the cylinders. I once made a list of about 30 things that I did (that could affect a rough idle), none of which had any effect on the issue whatsoever. I did a full tuneup, and then replaced, adjusted and cleaned everything that can be replaced, adjusted or cleaned (o2s, timing, IAC, TPS, EGR, and on and on). I replaced my motor mounts and balancer, just incase. Before changing my plugs, wires, cap and rotor, I stared at my ignition system in the dark, misting it with water, and found nothing but replaced everything anyway. I made a bunch of other attempts at curing the issue, none of which have had even the least effect on the problem (which is not much of a problem really...just annoying sometimes.) My last thoughts are an electrical problem, a tiny vacuum leak, or possibly, as you said, a slightly burnt valve/seat. Oh, I've also tried various decarbonizing treatments, none of which have had any effect on the car's running. Whatever is causing the problem is slight, as the problem is hardly noticeable most of the time.
Joel, thanks for the great info...once again. I'll do that voltage drop test this weekend. I swear the idle issue sounds like an electrical problem, as there is this almost electrical sounding whine from the engine area, that's rough in direct proportion to the rough idle. I guess it might just seem that way though, regardless of whether it were actually the cause or the effect of the rough idle. At any rate, thanks again for the link.
Will, let me revise my initial statement about having done everything to cure the problem. I have not run a leakdown test yet. Good idea though. I had ruled out a cylinder sealing issue once the car passed a KOER cylinder balance test (even though I've heard vastly differing opinions on what this test actually measures). One day, I'll get down to testing the cylinders. I once made a list of about 30 things that I did (that could affect a rough idle), none of which had any effect on the issue whatsoever. I did a full tuneup, and then replaced, adjusted and cleaned everything that can be replaced, adjusted or cleaned (o2s, timing, IAC, TPS, EGR, and on and on). I replaced my motor mounts and balancer, just incase. Before changing my plugs, wires, cap and rotor, I stared at my ignition system in the dark, misting it with water, and found nothing but replaced everything anyway. I made a bunch of other attempts at curing the issue, none of which have had even the least effect on the problem (which is not much of a problem really...just annoying sometimes.) My last thoughts are an electrical problem, a tiny vacuum leak, or possibly, as you said, a slightly burnt valve/seat. Oh, I've also tried various decarbonizing treatments, none of which have had any effect on the car's running. Whatever is causing the problem is slight, as the problem is hardly noticeable most of the time.
Joel, thanks for the great info...once again. I'll do that voltage drop test this weekend. I swear the idle issue sounds like an electrical problem, as there is this almost electrical sounding whine from the engine area, that's rough in direct proportion to the rough idle. I guess it might just seem that way though, regardless of whether it were actually the cause or the effect of the rough idle. At any rate, thanks again for the link.
