Car idles rough...in gear and in park.
#1
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Car: 91 RS Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73
Car idles rough...in gear and in park.
My car runs rich especially on start up and it idles rough when the idle starts dropping down below 1500 or so. Doesn't matter if it is warmed up or not. It does this in drive or park. Seems to get worse the lower the idle. I have an adjustable fuel pressure regulator but my pressure is sitting still at 13 psi. I have an air/fuel gauge and it seems to be reading fine most of the time. (Loosing faith with that thing anyhow.) The TBI, and injectors are fairly new. I just put in new spark plugs, cap, and rotor. The IAT sensor looks fine. The timing is dead on and doesn't move a bit. Could this be a vacuum problem? Any suggestions as to what could be causing this idle problem? Thanks.
Last edited by iroczrockz; 08-04-2004 at 08:44 PM.
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Car: '86 Berlinetta
Engine: 350
Transmission: 700R4
QUOTE:
idles rough when the idle starts dropping down below 1500 or so
--------------------------------
Eh? 1500RPM idle is high... mine idles around 500-600ish
(EDIT) BTW, have you changed your O2 sensor? Engine Coolant Temperature Sensor (not to be confused with the one that sends the temperature to your gauges) can send the ECM messages saying it's too cold ( 0 degrees if it is not hooked up or just plain not working at all) and tells the engine to pour in gas so that it will heat it up faster.
I'm going to guess that you still have the stock Q-Jet Carb, so I'd say that you cant really adjust it very well manually, the computer does that pretty well for you.
So if your computer is not getting the correct information (from several different sources, such as oxygen sensor, and ECTS) then it will act accordingly.
idles rough when the idle starts dropping down below 1500 or so
--------------------------------
Eh? 1500RPM idle is high... mine idles around 500-600ish
(EDIT) BTW, have you changed your O2 sensor? Engine Coolant Temperature Sensor (not to be confused with the one that sends the temperature to your gauges) can send the ECM messages saying it's too cold ( 0 degrees if it is not hooked up or just plain not working at all) and tells the engine to pour in gas so that it will heat it up faster.
I'm going to guess that you still have the stock Q-Jet Carb, so I'd say that you cant really adjust it very well manually, the computer does that pretty well for you.
So if your computer is not getting the correct information (from several different sources, such as oxygen sensor, and ECTS) then it will act accordingly.
Last edited by sellmanb; 08-05-2004 at 01:14 AM.
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Car: 91 RS Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73
Well, the O2 sensor isn't too old. The coolant sensor sounds like a good candidate to check. I don't have a stock TBI I have one from TurboCity. It has been bored out some and polished.It has matched 61lb. injectors. Not a carb though. It is a 90RS but there isn't much left of the old 305 stuff.
I'll give that coolant sensor a try and see what happens. Thanks
I'll give that coolant sensor a try and see what happens. Thanks
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Car: 1988 Camaro IROC-Z
Engine: 350 Crate Motor Holley Stealth Ram
Transmission: WC T-5
Axle/Gears: 3.73
Originally posted by sellmanb
QUOTE:
idles rough when the idle starts dropping down below 1500 or so
--------------------------------
So if your computer is not getting the correct information (from several different sources, such as oxygen sensor, and ECTS) then it will act accordingly.
QUOTE:
idles rough when the idle starts dropping down below 1500 or so
--------------------------------
So if your computer is not getting the correct information (from several different sources, such as oxygen sensor, and ECTS) then it will act accordingly.
#5
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Car: 91 RS Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73
Originally posted by sellmanb
QUOTE: 1500RPM idle is high... mine idles around 500-600ish
QUOTE: 1500RPM idle is high... mine idles around 500-600ish
#6
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Car: 85 IROC
Engine: 406
Transmission: A4
Is that tbi larger than stock if so I would think you may need some reprogramming but if that is what comes stock on there you may have a map sensor problem.
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Car: '86 Berlinetta
Engine: 350
Transmission: 700R4
Originally posted by BadIroc
where's the ECTS located?
where's the ECTS located?
I'm not sure on TPI cars, but on TBI cars it's right where the thermostat housing is. you can do a search for "engine coolant temperature sensor" or just go to the tech articles
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Car: 91 RS Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73
Originally posted by MR. KIDD
Is that tbi larger than stock if so I would think you may need some reprogramming but if that is what comes stock on there you may have a map sensor problem.
Is that tbi larger than stock if so I would think you may need some reprogramming but if that is what comes stock on there you may have a map sensor problem.
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Car: 85 IROC
Engine: 406
Transmission: A4
Did you check the map sensor make sure it has vaccum going to it because if it doesnot it will make the computer think that you are accelerating and call for more fuel.
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Car: 87 Camaro LT
Engine: 305 4BBL
Transmission: TH700R4
wow, I think I just found out why it seems that my choke is always on... thanks guys.
when I installed the Nordskog instrument cluster and used the temperature sender that came with it, I must've disconnected the one that goes to the computer (I thought it went to the old instrument cluster... ) alright, that might solve all my problems... but I'm still gonna get a new carb anyways cause even when my computer is telling the engine to use up the right amount of gas it's still burning up more than I can afford.
before nordskog: 16mpg consistently
after: 12-14mpg
who knows, when my investments close I should have enough to replace the carb with the edelbrock 1403 500cfm carb.. if it runs too lean I'll just install water injection.
heh, I have a sticker on my car that says :built with my children'$ inheritance.... I'm truely living up to that... though I'm only pulling out my failing investments.
when I installed the Nordskog instrument cluster and used the temperature sender that came with it, I must've disconnected the one that goes to the computer (I thought it went to the old instrument cluster... ) alright, that might solve all my problems... but I'm still gonna get a new carb anyways cause even when my computer is telling the engine to use up the right amount of gas it's still burning up more than I can afford.
before nordskog: 16mpg consistently
after: 12-14mpg
who knows, when my investments close I should have enough to replace the carb with the edelbrock 1403 500cfm carb.. if it runs too lean I'll just install water injection.
heh, I have a sticker on my car that says :built with my children'$ inheritance.... I'm truely living up to that... though I'm only pulling out my failing investments.
#13
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Car: 91 RS Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73
Originally posted by MR. KIDD
Did you check the map sensor make sure it has vaccum going to it because if it doesnot it will make the computer think that you are accelerating and call for more fuel.
Did you check the map sensor make sure it has vaccum going to it because if it doesnot it will make the computer think that you are accelerating and call for more fuel.
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Car: 91 RS Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 2.73
Well, it took me a while but I finally found the problem. Vacuum! I found it by accident too. I was trying to install a new stainless fuel line when I seen a vacuum check valve broken in half. Replaced it for about $3 and now the car idles right, mixture is back and is no longer sluggish. What a day!
Anyhow here is a pic of the part sorry but it is a bit blurry:
Anyhow here is a pic of the part sorry but it is a bit blurry:
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