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#1
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Rough idle
Since my engine reseal I've had a bit of a rough idle.
But I didn't really notice how bad it was until getting stuck in stop and go traffic this afternoon. At a stop the idle goes up and down to the point that one mintue it feels like it is about to die, then it will almost lurch forward if I'm not on the brake very hard. The RPMs seem to stay about the same, it's not like the needle is dancing up and down during this. Also while coasting at very low speed in bad traffic the same thing was occuring. I've got a new battery in there and during the up and downs I don't notice the headlights dimming or anything so I don't "think" it's anything electrical related. I could be wrong though? The stop and go low speed traffic driving also made me realize I have a very wicked 2-3 flare.
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Troy 1992 SVX LSL "Serenity" 250,000 miles! I don't care, I'm still free, You can't take the sky from me... |
#2
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Re: Rough idle
Vacuum leak maybe? Just a thought.
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#3
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Re: Rough idle
vac leak would be my thoughts too. What all did the shop replace when they took the manifold back out??
Tom |
#4
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Re: Rough idle
could be a stuck open egr too. engines don't idle well on exhaust gas instead of air
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#5
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Re: Rough idle
Quote:
Although you'll remember it had an uneven idle as soon as we got it all back together, but at that point you figured it was due to the poor battery.
__________________
Troy 1992 SVX LSL "Serenity" 250,000 miles! I don't care, I'm still free, You can't take the sky from me... |
#6
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Re: Rough idle
uneven idle... poor battery????
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#7
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Re: Rough idle
Knowing random shop mechanics.... the guy probably forgot to hook up a vac line or connected them wrong. You can try going under the manifold with a mechanics mirror and a flashlight... you might get lucky and find a disconnected hose, but if it happened immediately after they reinstalled the manifold... you have a vac hose connected wrong or they didnt install a new manifold gasket (maybe couldnt find one?). The point is.... you have to go back over whatever they messed with.... the answer lies within. I have worked with techs who spend 2 hours trying to diagnose a battery light and overheating problem, relieved when I walk up and point out the broken drive belt . Good luck!
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#8
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Re: Rough idle
krwen - brand new battery has been in there for a couple weeks.
Yeah, as much as I am nervous about the job the shop guys had to do (what had happened was I went in for an alignment, and one of the coolant hoses burst when they drove it into the shop - I had noticed something wrong a couple days before that, so no, they didn't sabatoge it, just bad timing), to be fair the rough idle was happening the week before they did it, Tom even noticed it when he put my engine back together but at that point I had a bad battery so we couldn't be sure if that was the cause or not. I'm going to call Tom tonight and he's going to walk me through a few things and we'll see if we can get this figured out. I'll report back.
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Troy 1992 SVX LSL "Serenity" 250,000 miles! I don't care, I'm still free, You can't take the sky from me... |
#9
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Re: Rough idle
Poor voltage can have many effects on the ECU. Most notably on injector response time. When this happens, the injector will take longer to open (due to less voltage) and actually lean the car out. The ECU will see a lean condition and take action to richen it up... And this the cycle continues. Also it effects the sensors like throttle position and the like that all depend on a good +v to read properly.
Tom |
#10
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Re: Rough idle
Thanks for the explanation Tom.
I was thinking that the alternator determines the voltage instead of the battery when idling. Just trying to learn as much everyday as possible! Keith |
#11
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Re: Rough idle
Quote:
The voltage used for the vital sensors is a regulated 5 volt, so that they are immune to variations in supply voltage. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#12
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Re: Rough idle
Quote:
Tom |
#13
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Re: Rough idle
If the battery is suspect might be a good idea to switch a good battery to it and see if the battery was the idle problem.
would just take a few seconds! |
#14
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Re: Rough idle
Quote:
Tom |
#15
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Re: Rough idle
Yeah what Tom said.
We determined it wasn't the TPS or a vacuum leak anywhere I could get to at least. Tom - last night I was wondering if the alternator was on it's way out if this could be affecting things? But if so, the new battery surely would have been drained by now, or at least not read as it good when I tested the ground last night? This morning I was at a stop light and the idle didn't fluctuate, but it just seems really low, like it's about to die. It's worse when it's just been started, but even after it warmed up 20 miles down the road it still just seems like if it sat there in D long enough with no gas pedal, it would die. Reads about 500 rpms at idle, and like I said, no fluctuation, at least this morning. Eagerly awaiting the care package and more troubleshooting.
__________________
Troy 1992 SVX LSL "Serenity" 250,000 miles! I don't care, I'm still free, You can't take the sky from me... |
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