HELP - supposed to do 5000rpm (only dose 3)

[Gunney]

So I was told today that other 4.7 V8 100's will rev up to 5000 rpm befre they change up, with the go peddle mashed into the carpet.

My one has only EVER reved up to 3000 before changing, irespective of power or O/D buttons being on or off.

This is INSANE! my truck should be redlining at 5000!

What could be worng with it?

 

[mister bean]

I don't know what the problem is. But I can verify that you should be able to hit 5k. You're missing a bunch of power there.

 

[Gunney]

I know! This is a HUGE PROBLEM

 

[2000UZJ]

Can you hold it in a gear and go above 3K?

 

[RobRed]

Can you hold it in a gear and go above 3K?

Agree on this test.... Put the trans in 1st or second and roll to red line.... does it still shift early?

Something that comes to mind is detonation - the ECU/TCU has detected an issue and is retarding the power.

I know you have done a ton of work on your truck so check to make sure you havent pulled a vacuum line or some other intake doodad. Also check your spark plugs to make sure you gapped right. Fuel Bad? There are a ton of possibilities making the 100 behave this way.

 

[2000UZJ]

Agree on this test.... Put the trans in 1st or second and roll to red line.... does it still shift early?

Something that comes to mind is detonation - the ECU/TCU has detected an issue and is retarding the power.

I know you have done a ton of work on your truck so check to make sure you havent pulled a vacuum line or some other intake doodad. Also check your spark plugs to make sure you gapped right. Fuel Bad? There are a ton of possibilities making the 100 behave this way.

Generally when the trans fluid is cold it will shift prematurely. I remember Gunney installing a non-Toyota trans cooler ( correct me of I'm wrong). Few things, could the tranny cooler be cooling the fluid to much? Doubtful but maybe. Like you said, a vacuum line of some sorts, a sticking shift solenoid due to not enough vacuum.
I would say hold it in first, the. Shift directly into "D" and see what it shifts into. Do you have the same probably in Low-Range?

 

[Gunney]

Thanks for the feedback guys. I got home last night and chatted to one of the 100 guys from South Africa. He reccomended we start at the beggining and check the rev guage.

we mapped out the rev vs speed in L and got the following.
I was at 1800rpm at 40 kph
Then at 3000rpm at 60 kph
Then at 3500rpm at 80 khp

So it turns out its my rev guage that is the problem



It was under reading by about 1.6 constantly. at least now I know it’s working (this is also why I was dumbfounded to hear there should be an additional 2000 rpm, can you image what that would feel like at 7000 rpm )

Again, thanks to Paul and Marius for the help, another reason why this forum is such a great place.


p.s. it is still a stable 35 to 40 degrees here, NOTHING is cool/cold (except the drinks in my cool box)

Thanks for the feedback