Passing Gear/Rev limiter

4096 Views 10 Replies 9 Participants Last post by Don Wigglesworth, Jan 26, 2015

Don Wigglesworth

Discussion Starter · Jan 18, 2015

In a previous thread I was asking about my '07 not upshifting when in passing gear. (Throttle to the floor - my favorite place). I have tried this a few times again, while close to home, and realized it is not a shifting problem.

What is really happening is the rev limiter is kicking in at 5200 RPM instead of redline - about 6200 RPM. So it never upshifts.
So before I blast the rod bearings....

Any ideas as to what "sensor" this might be? Any potential relationship to the recent (2nd) timing belt replacement process?
This truck is well maintained w/ 206k mi. Thanks, D

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eurban

· #2 · Jan 18, 2015 (Edited)

Probably not the rev limiter but rather the VTEC system is not functioning. The engine simply can't give anymore without the magic of VTEC. You may have some codes stored, even if your check engine light is not on.

I recently discovered that my VTEC oil pressure sensor was sheered off. It's located on the oil filter manifold and has a green plastic body. It could well have been "in harms way" during the timing belt procedure. There are any number of reasons why the VTEC system may not be functioning so see if there are any codes stored and perhaps someone could post the diagnostics from manual?

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Ridgekid

· #3 · Jan 18, 2015

Don Wigglesworth said:
In a previous thread I was asking about my '07 not upshifting when in passing gear. (Throttle to the floor - my favorite place). I have tried this a few times again, while close to home, and realized it is not a shifting problem.

What is really happening is the rev limiter is kicking in at 5200 RPM instead of redline - about 6200 RPM. So it never upshifts.
So before I blast the rod bearings....

Any ideas as to what "sensor" this might be? Any potential relationship to the recent (2nd) timing belt replacement process?
This truck is well maintained w/ 206k mi. Thanks, D

I don't understand what you are describing. What is passing gear??
Also, if in an overdrive gear, asking for more throttle at speed will usually result in a downshift not an upshift.

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csimo

· #4 · Jan 18, 2015

At highway speeds if more acceleration is required the first thing the transmission will do is unlock the torque converter, if the load is still high it will then downshift to 4th gear.

If your engine will not exceed 5200 RPM then you have an engine related problem... not the transmission. It could be the VTEC system as described, vacuum leak, throttle position sensor problem or a host of many other issues. You need a mechanic to do a good diagnostic before you just start replacing parts.

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beatle

· #5 · Jan 19, 2015

Will it rev past 5200 in neutral?

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zroger73

· #6 · Jan 19, 2015

beatle said:
Will it rev past 5200 in neutral?

It can't since the fuel cutoff is 5,000 RPM (or less if the engine is cold) if the vehicle isn't moving.

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speedlever

· #7 · Jan 19, 2015

csimo said:
At highway speeds if more acceleration is required the first thing the transmission will do is unlock the torque converter, if the load is still high it will then downshift to 4th gear.

If your engine will not exceed 5200 RPM then you have an engine related problem... not the transmission. It could be the VTEC system as described, vacuum leak, throttle position sensor problem or a host of many other issues. You need a mechanic to do a good diagnostic before you just start replacing parts.

When does the tranny ever see 5th gear? Or is it in 5th gear when the TC unlocks? When accelerating, does the tranny every shift to 5th or does it slide from 4th to TC lock? (that 5th gear seems a bit elusive to detect when accelerating normally).

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rollinhonda

· #8 · Jan 20, 2015

zroger73 said:
It can't since the fuel cutoff is 5,000 RPM (or less if the engine is cold) if the vehicle isn't moving.

Yup, and those are two adverse conditions when revving an engine:

A cold engine and one not under load.

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zroger73

· #9 · Jan 20, 2015

rollinhonda said:
Yup, and those are two adverse conditions when revving an engine:

A cold engine and one not under load.

This reminds me of a neighbor I used to have who always drove clunkers. For years, he had a metallic beige, early-80s Oldsmobile Ninety Eight Regency Brougham. Every morning he'd grind on the starter for a couple of minutes with his foot to the floor until two or three cylinders would start firing. Every few seconds, another cylinder would come to life and the engine speed would increase a few hundred more RPM. He kept his foot firmly planted on the gas pedal until all eight cylinders were finally firing at which time the engine revved until the valves floated and copious amounts of black soot shot several feet out of the curved tailpipe down onto the driveway. After he sprayed about a gallon of unburned gasoline on the ground, he'd let off the accelerator, back out of his driveway, and calmly head off to work. He kept up this routine for years until the car finally died. My brother and I always called him Uncle Buck from the movie with the same name.

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rmhpmi

· #10 · Jan 20, 2015

zroger73 said:
This reminds me of a neighbor I used to have who always drove clunkers. For years, he had a metallic beige, early-80s Oldsmobile Ninety Eight Regency Brougham. Every morning he'd grind on the starter for a couple of minutes with his foot to the floor until two or three cylinders would start firing. Every few seconds, another cylinder would come to life and the engine speed would increase a few hundred more RPM. He kept his foot firmly planted on the gas pedal until all eight cylinders were finally firing at which time the engine revved until the valves floated and copious amounts of black soot shot several feet out of the curved tailpipe down onto the driveway. After he sprayed about a gallon of unburned gasoline on the ground, he'd let off the accelerator, back out of his driveway, and calmly head off to work. He kept up this routine for years until the car finally died. My brother and I always called him Uncle Buck from the movie with the same name.

Wait, you mean that's NOT proper starting procedure for a early-80s Oldsmobile?

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Don Wigglesworth

Discussion Starter · #11 · Jan 26, 2015

While I may like to Burp & Fart like Uncle Buck but I only floor it while moving forward......Let the air out of the tires & an 88 makes a good dune buggy. When it blows you just leave it. Rusted away in 9 months.

Back to the issue. The tranny is fine. The term passing gear dates us back to the Olds 88 days - when auto trannies had 3 gears.

Will look at the VTEC issue, & especially for sensor damage down around the filter as the CV joint boots were recently replaced.
Hmmmm
By the way, was on the freeway this morning. It was about 40 & damp foggy. Nailed the pedal and she kicked down to 4th - climbing to 6100 rpm. Seems to be an intermittent condition.
Thanks Kids

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