Can't get smooth idle!
08-30-2007, 07:01 AM
#1
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Join Date: May 2007
Location: Ontario
Posts: 94
Can't get smooth idle!
I have an 87GT, stock,and I'vetried everything I can think of to smooth out my Idle (TPS .98, IAC, new cap, rotor plugs and wires, replaced fuel filter, set timing, EGR,cleaned TB) recently I checked for vaccum leaks with carb cleaner but could not find any. However I can hear a slight hiss near the top of the engine in front of the upper IM but cant pinpoint it, maybe thats normal.Im not getting any codes either. This is driving me crazy because the car runs great otherwise, just this annoying"lumpy" idle. Kind of a pulse you can feel but no pattern. It shakes the car a bit and it is primarily at idle but youcan still feel itif you increase RPM up to about 1500 or so.Im guessing its not a miss because it only does thisin neutral, not under load. I would appreciate any help or suggestions.
08-30-2007, 09:33 AM
#3
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Join Date: May 2007
Location: Ontario
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RE: Can't get smooth idle!
thanks, I had my injectors cleaned with that Teraclean system about a couple weeks ago it seemed to help a bit at first but now its back to the way it was before the cleaning. Maybe the injectors are just really bad and should be replaced?
Are you stock? and if you are, did you replace with 19's. Where did you buy your injectors from?
Are you stock? and if you are, did you replace with 19's. Where did you buy your injectors from?
08-30-2007, 10:05 AM
#4
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Join Date: Oct 2005
Location: Ohio USA
Posts: 4,616
RE: Can't get smooth idle!
ORIGINAL: tiburon
I have an 87GT, stock,and I'vetried everything I can think of to smooth out my Idle (TPS .98, IAC, new cap, rotor plugs and wires, replaced fuel filter, set timing, EGR,cleaned TB) recently I checked for vaccum leaks with carb cleaner but could not find any. However I can hear a slight hiss near the top of the engine in front of the upper IM but cant pinpoint it, maybe thats normal.Im not getting any codes either. This is driving me crazy because the car runs great otherwise, just this annoying"lumpy" idle. Kind of a pulse you can feel but no pattern. It shakes the car a bit and it is primarily at idle but youcan still feel itif you increase RPM up to about 1500 or so.Im guessing its not a miss because it only does thisin neutral, not under load. I would appreciate any help or suggestions.
I have an 87GT, stock,and I'vetried everything I can think of to smooth out my Idle (TPS .98, IAC, new cap, rotor plugs and wires, replaced fuel filter, set timing, EGR,cleaned TB) recently I checked for vaccum leaks with carb cleaner but could not find any. However I can hear a slight hiss near the top of the engine in front of the upper IM but cant pinpoint it, maybe thats normal.Im not getting any codes either. This is driving me crazy because the car runs great otherwise, just this annoying"lumpy" idle. Kind of a pulse you can feel but no pattern. It shakes the car a bit and it is primarily at idle but youcan still feel itif you increase RPM up to about 1500 or so.Im guessing its not a miss because it only does thisin neutral, not under load. I would appreciate any help or suggestions.
If the intake manifold(lower) has been removed, a special sequence is required to seal it flush along with some rtv/, unfortuanately there is no way around this
trust me
08-30-2007, 11:17 AM
#5
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Join Date: May 2007
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RE: Can't get smooth idle!
The lower IM has not been removed but I will check around the ports again for leaks. Which is the fuel pressure regulator hose, is it a vaccum line?
also, where do you find the egr vaccum motor, and for that matter what does it look like?
also, where do you find the egr vaccum motor, and for that matter what does it look like?
08-30-2007, 12:11 PM
#6
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Join Date: Oct 2005
Location: Ohio USA
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RE: Can't get smooth idle!
ORIGINAL: tiburon
The lower IM has not been removed but I will check around the ports again for leaks. Which is the fuel pressure regulator hose, is it a vaccum line?
also, where do you find the egr vaccum motor, and for that matter what does it look like?
The lower IM has not been removed but I will check around the ports again for leaks. Which is the fuel pressure regulator hose, is it a vaccum line?
also, where do you find the egr vaccum motor, and for that matter what does it look like?
fuel pressure regualtor line to intake manifold
08-30-2007, 02:46 PM
#7
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Join Date: Aug 2007
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Posts: 66
RE: Can't get smooth idle!
The wandering idle is pretty common on these Speed Density engines.
Fixes can include most of what you've mentioned
It's often hit or miss though, there's no one cure for everyone's wander
I also have "cured" it with an adjustable fuel pressure regulator
There's a TSB about it out now, I'll find the link
I have not used the part in the TSB (an idle bypass kit), but have heard from sources I trust it can work well
http://www.mn12performance.com/mn12-...-7.pdf#search=
Fixes can include most of what you've mentioned
It's often hit or miss though, there's no one cure for everyone's wander
I also have "cured" it with an adjustable fuel pressure regulator
There's a TSB about it out now, I'll find the link
I have not used the part in the TSB (an idle bypass kit), but have heard from sources I trust it can work well
http://www.mn12performance.com/mn12-...-7.pdf#search=
08-30-2007, 03:14 PM
#8
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Join Date: May 2007
Location: Ontario
Posts: 94
RE: Can't get smooth idle!
I cantsay that the idle wanders.It comes offchoke and sits at 800 andthen doesn't fluctuate at all, but it is just a bumpy idle more likean intermittent miss. Thanks for the link though, maybe the IAC bypass is something that would help, although when I cleaned the IAC it made no difference so I ruled it out as the culprit. Any other ideas?
08-30-2007, 03:52 PM
#10
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RE: Can't get smooth idle!
ORIGINAL: slickshift
What wires and plugs did you use?
What wires and plugs did you use?
Also,t he gap looked OK so I went with it, it was way better than what came out. Replacing them made very little difference in idle though.
The gap looked close to what it should be. How important is it to gap your plugs exactly to spec?