Engine Hesitation at 4000 rpm when not in gear - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 12-29-2002, 03:48 AM   #1
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Dec 2002
Location: New Jersey, USA
Posts: 147
Thanks: 0
Thanked 0 Times in 0 Posts
StoopidSavant is on a distinguished road
Default Engine Hesitation at 4000 rpm when not in gear

Hello,

I just noticed, when not in gear and I try to rev the engine, when the tach hits 4000 rpm, the engine hesitates and the needle falls again, almost as if it were shifting gears while driving (which of course is not possible since I'm just sitting in the driveway). While driving and stomping on the pedal, it'* a smooth delivery all the way up to 5000 rpm'* without any complaints. Does anybody know if this is a safety feature to not allow it to rev high while not in gear, or possibly there might be another problem that I need to figure out? Thanks for any help!
StoopidSavant is offline   Reply With Quote
Old 12-29-2002, 03:58 AM   #2
Senior Member
Posts like a Camaro
 
Join Date: Nov 2002
Posts: 1,109
Thanks: 0
Thanked 0 Times in 0 Posts
1995BvSSE is on a distinguished road
Default

Yep... in park, the 4000 RPM load that you are putting on the engine doesn't have any torque on it. When you are driving, the torque is transferred properly to the wheels, effectively putting a "load" on the engine. An engine without a load can blow up easily, since there is no place to transfer the power!! Essentially it'* Newton'* second(?) law. At least, this is an electrical engineer'* explanation
1995BvSSE is offline   Reply With Quote
Old 12-29-2002, 04:00 AM   #3
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

Revving your engine when not under load is a bad thing. The PCM knows this, and retards the timing to prevent it. Rev limit is done by timing retard, top speed limit is done by cutting off fuel delivery. That'* where some guys with NOS get into trouble. Straight NOS after the top end cutoff makes things go BOOM!

Your car is working as it should. Even revving in park or neutral to 4000 is bad. Don't do it.
willwren is offline   Reply With Quote
Old 12-29-2002, 04:18 AM   #4
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Dec 2002
Location: New Jersey, USA
Posts: 147
Thanks: 0
Thanked 0 Times in 0 Posts
StoopidSavant is on a distinguished road
Default

It never fails to astound me how fast you guys are. Thanks for the info.
StoopidSavant is offline   Reply With Quote
Old 12-29-2002, 05:36 PM   #5
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

Yup. Been there a couple times. Remember, the Jet raised my redline, too. I shift higher in both normal and performance mode. Can't remember what it changed to, maybe I'll have to run it again!
willwren is offline   Reply With Quote
Old 12-29-2002, 09:29 PM   #6
Senior Member
Posts like a 4 Banger
Thread Starter
 
Join Date: Dec 2002
Location: New Jersey, USA
Posts: 147
Thanks: 0
Thanked 0 Times in 0 Posts
StoopidSavant is on a distinguished road
Default

Yeah, from what I've always understood is that redline (or peak horsepower, or both) occurs around 5500 rpm, then the PCM will cut off fuel at 6000 rpm. I don't think I've ever hit the red while actually driving, but I was revving just to test if the engine would stutter, which it did, but at least it'* not a problem - in fact a good thing.

Will, for what purpose does the jet chip raise your redline? I thought that the redline was determined based on the measured tolerances of the parts of the engine, not on timing or a/f ratio (which I presume the chip modifies), so raising the redline could be destructive to the engine unless the innards have actually been modified.
StoopidSavant is offline   Reply With Quote
Old 12-29-2002, 10:29 PM   #7
Junior Member
Posts like a Ricer Type-R
 
Join Date: Aug 2002
Posts: 10
Thanks: 0
Thanked 0 Times in 0 Posts
willwren is on a distinguished road
Default

They raised the physical redline limit based on dyno data for the adjusted torque/hp curves. Didn't raise much, but they're making better use of the improved horsepower that way. I don't hit it often, and when I do, I don't stay in it for long.
willwren is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
SSEi wont rev over 4000 RPM HELP! chewy_mxer 2000-2005 21 10-02-2009 10:27 AM
While driving the car doesnt rev more than 4000 rpm Tama 1992-1999 17 03-23-2009 05:55 PM
why can't i rev my 95 more then 4000 rpm's in park.? 88bonnsse 1992-1999 21 07-12-2007 07:04 PM
P0300 Misfires past 4000 RPM impy 2000-2005 20 10-27-2006 10:00 PM
Help my tach stays between 4000 and 4500 rpm all the time! suctoes 1992-1999 3 11-12-2005 10:05 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 03:35 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.