6.0L won't rev past 1400 rpm?

Sherk · 05-01-2008, 01:15 AM

It's an '03 out of a van, tune is an '02 Silverado 6.0 tune so it would work with the 411 PCM already in place. (Using EFILive for flashing). Truck is a 2000 S10 that had a 4.3/5 spd.

Either I've got a tuning issue somewhere (I wouldn't think so, the engine is totally stock), or something else is wrong...

I can't rev the engine past 1400 rpm! This is killing me. I can stab the throttle and get it up to maybe 2k very temporarily but it bounces back down extremely quickly. I can give it light throttle under 1400 rpm and am able to hold rpms, but if I get up to that level, it knocks me down.

Same issue in gear (manual transmission), I've got it up on jackstands but I've tried running it and it won't go over the same 1400 or so. Rev up, stumble down...

I've tried running with and without the MAF, unplugging the TPS and IAC (still cable driven throttle), can't get anything to change. Everything is up to operating temp (100C or so), no DTCs except the CKP relearn (can't do because I can't get to 5k) and 4 other ghost ones for the U0000 stuff.

I checked all over for vacuum leaks and can't find anything (the idle is very good too, leading me to believe that's not the issue). Fuel pressure is 4 bar without the vacuum line on, about 50 PSI with it in place... goes up slightly when I bump the throttle and goes down to 48 or so when I leave the throttle steady about 1k rpm...

All cyls are getting spark, I did a cylinder balance test and everything looks good, I think. I don't know what else to do...

sparkinak · 05-01-2008, 02:19 AM

who did the harness cause I wonder if something isnt hooked up correctly, Like the engine is looking for a particular parameter and isn't seeing it so its stayin a safe mode?? not sure but just a thought.

97 SS 350 · 05-01-2008, 07:16 AM

Is the '02 6.0 tune set for electronic throttle instead of cable throttle? That will cause what you are seeing without a doubt.

jhankinson · 05-01-2008, 09:35 AM

my P/N switch got grounded out and it did the exact same thing. Cuase it sensed it was ALWAYS in park or nuetral. Just another option

Sherk · 05-01-2008, 02:10 PM

I switched over to another tune from an '00 Silverado just to be sure that ETC was off. That apparently isn't the problem...

As for the P/N switch, I don't know how that would be wired up. It's a manual transmission (T56)... so it should only have the VSS output and backup lamp indicator wiring, right? The only other plugs that I can think of back there are the CAGS plug and a reverse lockout solenoid...

The clutch pedal position switch is wired up correctly, as you have to press the clutch to the floor to get the truck to start...

The tune has Camaro manual trans segments copied over, so it should not be asking for auto tranny stuff, right?

jhankinson · 05-01-2008, 04:31 PM

OO ok yes...then you shouldnt have any of that active. Hmm dunno man sorry

camaro1 · 05-01-2008, 05:50 PM

what are you using to tune it,, post up your tune

jnoehl · 05-01-2008, 08:51 PM

hmmm... i've heard of something similar to this. try this.
i know it wont rev past 1400 when the car is in neutral, try seeing if you can push the clutch in and see if it will rev. if that is the case then its the sensor on your clutch pedal.

s10-den · 05-02-2008, 07:41 AM

about like the rental cars have the rev limiter on them...Not very good at 5000rpm's neutral drops,just kills it.

Sherk · 05-02-2008, 10:34 AM

It was the cam position sensor. I got to thinking of why it was having rev limiter issues and unlugged that... as soon as I did and started it up, she was able to rev to the true limiter. What a beautiful sound.

Now I gotta go get a CMP sensor.

91sonomast · 05-03-2008, 10:41 AM

awesome dude, glad u got it figured out

05-01-2008, 01:15 AM	#1
Sherk Registered User Join Date: Jul 2006 Posts: 37 Location: User is: OffLine	6.0L won't rev past 1400 rpm? It's an '03 out of a van, tune is an '02 Silverado 6.0 tune so it would work with the 411 PCM already in place. (Using EFILive for flashing). Truck is a 2000 S10 that had a 4.3/5 spd. Either I've got a tuning issue somewhere (I wouldn't think so, the engine is totally stock), or something else is wrong... I can't rev the engine past 1400 rpm! This is killing me. I can stab the throttle and get it up to maybe 2k very temporarily but it bounces back down extremely quickly. I can give it light throttle under 1400 rpm and am able to hold rpms, but if I get up to that level, it knocks me down. Same issue in gear (manual transmission), I've got it up on jackstands but I've tried running it and it won't go over the same 1400 or so. Rev up, stumble down... I've tried running with and without the MAF, unplugging the TPS and IAC (still cable driven throttle), can't get anything to change. Everything is up to operating temp (100C or so), no DTCs except the CKP relearn (can't do because I can't get to 5k) and 4 other ghost ones for the U0000 stuff. I checked all over for vacuum leaks and can't find anything (the idle is very good too, leading me to believe that's not the issue). Fuel pressure is 4 bar without the vacuum line on, about 50 PSI with it in place... goes up slightly when I bump the throttle and goes down to 48 or so when I leave the throttle steady about 1k rpm... All cyls are getting spark, I did a cylinder balance test and everything looks good, I think. I don't know what else to do...
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05-01-2008, 02:19 AM	#2
sparkinak LSX Swapper Age: 28 Join Date: Jan 2006 Posts: 446 Location: User is: OffLine	Re: 6.0L won't rev past 1400 rpm? who did the harness cause I wonder if something isnt hooked up correctly, Like the engine is looking for a particular parameter and isn't seeing it so its stayin a safe mode?? not sure but just a thought.
	[Reply w/Quote]

05-01-2008, 07:16 AM	#3
97 SS 350 Makin Sparks Age: 30 Join Date: Jun 2002 Posts: 955 Location: Hudson, Florida User is: OffLine	Re: 6.0L won't rev past 1400 rpm? Is the '02 6.0 tune set for electronic throttle instead of cable throttle? That will cause what you are seeing without a doubt.
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05-01-2008, 09:35 AM	#4
jhankinson Registered User Age: 28 Join Date: Feb 2006 Posts: 329 Location: User is: OffLine	Re: 6.0L won't rev past 1400 rpm? my P/N switch got grounded out and it did the exact same thing. Cuase it sensed it was ALWAYS in park or nuetral. Just another option
	[Reply w/Quote]

05-01-2008, 02:10 PM	#5
Sherk Registered User Join Date: Jul 2006 Posts: 37 Location: User is: OffLine	Re: 6.0L won't rev past 1400 rpm? I switched over to another tune from an '00 Silverado just to be sure that ETC was off. That apparently isn't the problem... As for the P/N switch, I don't know how that would be wired up. It's a manual transmission (T56)... so it should only have the VSS output and backup lamp indicator wiring, right? The only other plugs that I can think of back there are the CAGS plug and a reverse lockout solenoid... The clutch pedal position switch is wired up correctly, as you have to press the clutch to the floor to get the truck to start... The tune has Camaro manual trans segments copied over, so it should not be asking for auto tranny stuff, right? Last edited by Sherk : 05-01-2008 at 02:14 PM.
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05-01-2008, 04:31 PM	#6
jhankinson Registered User Age: 28 Join Date: Feb 2006 Posts: 329 Location: User is: OffLine	Re: 6.0L won't rev past 1400 rpm? OO ok yes...then you shouldnt have any of that active. Hmm dunno man sorry
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05-01-2008, 05:50 PM	#7
camaro1 Registered User Age: 35 Join Date: Feb 2006 Posts: 300 Location: User is: OffLine	Re: 6.0L won't rev past 1400 rpm? what are you using to tune it,, post up your tune
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05-01-2008, 08:51 PM	#8
jnoehl Registered User Age: 21 Join Date: Mar 2007 Posts: 257 Location: New Orleans, La User is: OffLine	Re: 6.0L won't rev past 1400 rpm? hmmm... i've heard of something similar to this. try this. i know it wont rev past 1400 when the car is in neutral, try seeing if you can push the clutch in and see if it will rev. if that is the case then its the sensor on your clutch pedal.
	[Reply w/Quote]

05-02-2008, 07:41 AM	#9
s10-den takes 2 balls in our game Age: 36 Join Date: Nov 2005 Posts: 3,341 Location: florida User is: OffLine	Re: 6.0L won't rev past 1400 rpm? about like the rental cars have the rev limiter on them...Not very good at 5000rpm's neutral drops,just kills it.
	[Reply w/Quote]

05-02-2008, 10:34 AM	#10
Sherk Registered User Join Date: Jul 2006 Posts: 37 Location: User is: OffLine	Found the issue... It was the cam position sensor. I got to thinking of why it was having rev limiter issues and unlugged that... as soon as I did and started it up, she was able to rev to the true limiter. What a beautiful sound. Now I gotta go get a CMP sensor.
	[Reply w/Quote]

05-03-2008, 10:41 AM	#11
91sonomast Good Bye SonomaST Age: 24 Join Date: Sep 2005 Posts: 5,635 Location: Jacksonville, FL User is: OffLine	Re: 6.0L won't rev past 1400 rpm? awesome dude, glad u got it figured out
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