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What RPM does your 5.7 vortec idle at?


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#1 kylebigbucks

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Posted 09 December 2003 - 08:33 PM

I have a 98 GMC sierra 5.7 vortec. I am curious as to what other mechanically sound 5.7s idle at becuase I think mine idles to high for some reason. It idles at about 700 when warm. My dads truck idles at about 500 and seems to run a lot better. I would think that all mechanically sound 5.7 vortecs would have the same idle speeds if everything is stock on them...right?

Kyle

#2 99-2door

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Posted 10 December 2003 - 06:50 AM

Are both trucks automatics?
Idle speed depends on many things. Among them: AC on/off, air temp, engine temp, etc.....
If you consistantly see higher Idle RPMS with your truck under "identical" conditions (this will never really happen, but you know something close), check the IAC (Idle Air Control) valve.
Other things to check for incorrect idle RPM:
Faulty Park/neutral safety switch
Leaky injectors
sticking TPS or throttle blade
faulty battery cables leading to erratic computer compensation
compressor load through AC signal
Malfunctioning MAF sensor

Some things to check out there. :jester:

95 Chevy K3500 SRW converted to 5.7L Vortec 4L80e, 4.10 w/G80
2003 Tahoe w/ Silverado front clip
2001 GMC C3, 6.0L AWD, lowered 3/5, Volant intake, pulleys, tuned with HPtuners by me.

#3 Lou'sZ

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Posted 10 December 2003 - 08:04 AM

I'm at work now. :jester: I'll check my 98 5.7 tonight-will get back with you.

#4 HDChuck01

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Posted 10 December 2003 - 01:44 PM

Mine idles at 700 RPM when warm too! Nothing else running except the motor. 500RPM seems a little low?? :jester:
2000 Jeep Wrangler 4.0L
2007 Chevrolet Silverado 5.3L
2009 Scion tc 2.4L
2010 Toyota Rav4 V6

#5 HDChuck01

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Posted 10 December 2003 - 01:45 PM

OOPS! I have a '96 5.7 Liter. :jester:
2000 Jeep Wrangler 4.0L
2007 Chevrolet Silverado 5.3L
2009 Scion tc 2.4L
2010 Toyota Rav4 V6

#6 XR Man

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Posted 10 December 2003 - 02:56 PM

I think care needs to be taken here. I always thought the first mark on the tach was zero but I was actually reading the owner's manual (either of a 94 or a 99, can't remember) and it said the first mark on the tachs is 500, not 0. Using this mine idles at about 750 RPM when warm in gear (auto). If the first tach mark is assumed to be zero then it looks more like 500...Bryce
1999 Silverado 1500
Ex Cab 5.3 Z71

#7 Lou'sZ

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Posted 10 December 2003 - 07:17 PM

Fully warmed up, in park, no accessories on= 650 rpm at idle. Truck is 98 Z71 5.7 4L60E all stock. No mention in owners manual that 0 on tach is not 0.

#8 XR Man

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Posted 10 December 2003 - 08:01 PM

I just looked at some 95+ dashes and they clearly have a zero as the lowest position on the tach. The 94 and earlier of that body style have 500 as the lowest number.

Edited by XR Man, 10 December 2003 - 08:02 PM.

1999 Silverado 1500
Ex Cab 5.3 Z71

#9 99-2door

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Posted 10 December 2003 - 10:38 PM

I just looked at some 95+ dashes and they clearly have a zero as the lowest position on the tach. The 94 and earlier of that body style have 500 as the lowest number.

:rolleyes: when you turn the key on before you start the engine the needle moves to zero

95 Chevy K3500 SRW converted to 5.7L Vortec 4L80e, 4.10 w/G80
2003 Tahoe w/ Silverado front clip
2001 GMC C3, 6.0L AWD, lowered 3/5, Volant intake, pulleys, tuned with HPtuners by me.

#10 XR Man

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Posted 11 December 2003 - 02:11 AM

when you turn the key on before you start the engine the needle moves to zero

No, mine stays put all the way down when turning to run.

94 K1500
1999 Silverado 1500
Ex Cab 5.3 Z71

#11 MoJo

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Posted 11 December 2003 - 10:13 AM

Doesn't the "Emissions" Sticker in the engine bay give specs for that exact engine? Otherwise, the owner's manual will say. :rolleyes:

#12 99-2door

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Posted 11 December 2003 - 03:06 PM

when you turn the key on before you start the engine the needle moves to zero

No, mine stays put all the way down when turning to run.

94 K1500

Yeah....but yours is a 94, I am talking about 95-98 (00)

95 Chevy K3500 SRW converted to 5.7L Vortec 4L80e, 4.10 w/G80
2003 Tahoe w/ Silverado front clip
2001 GMC C3, 6.0L AWD, lowered 3/5, Volant intake, pulleys, tuned with HPtuners by me.

#13 k1500chevy97

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Posted 11 December 2003 - 04:27 PM

4.3 (3/4 of a 350) idles about 6 here

And 992door is right about the tach going to 0 when the key is turned
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#14 cyclejerk

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Posted 11 December 2003 - 07:21 PM

500 RPM here. actualy more like 490? Cleaned the throtle body about 3500 miles ago. the gas pedal was sticking. :D :rolleyes: :lol:
Michael V
Golden colorado
1999 Silverado Ext. cab, Sportside
5.3 Z71




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