I need HELP

OK im new here but really need help I have a 1994 Camry V6 and when it gets hot it almost seems like it is hitting the rev limiter at about 3900 RPM and we can not figure out what is causing it

 Is it manual or automatic transmission ?  

Its a auto. and it will do it in gear or out of gear.

Engine has max RPM range when cold, but when hot tops out at 3900?

Has the same RPM limit both in and out of gear?

How does the car accelerate up to this RPM, normal, slow, hesitation?  Power and MPG OK?

When the RPM tops out does the engine buck, or just stop increasing in RPM?

 

Tops out at 3900 when it is hot and it hits the same thing in gear or out of gear,and it has a little hesitation, then the engine starts to buck.

I find it difficult to even guess what may be a reason for this.
You have this problem and no codes?
hopefully i dont get bashed for saying my oppinion but it sounds like ur lacking sufficient fuel or air.
from your description it almost sounds like the fuel system can''t supply fuel for anything more demanding than 3900 rpm.  is the car running lean? think about ur fuel system, maybe ur fuel filter? pull a spark plug see if there are any signs of teh car running rich or lean.
how old are ur plugs/wires/coil? although i dont think spark is a problem here
aside from that maybe somethign with the computer?  anyone know if the car has a lower rev limiter in park vs in gear?   (i ask because my chevy had a much lower rev limiter when in park)

The only code that is has is a 02 sensor. And its getting fuel, just put a new fuel pump anss fuel filter just to narrow it dow but it didnt help at all.

I am no mechanic but my sisters car had a similar problem. We took it to the mechanic and had the bearings changed in the transmission. It turned out that some of the bearings were broken. Idk if that''s what''s wrong with it but I hope you get it fixed soon it seems serious

Anyone else have any ideas. This stupid car is driving me crazy.

Don''t know.

The engine being RPM limited with and without a load when the engine is hot suggests an ignition problem.  Might be a faulty coil.  Try spraying a mist of water from a water bottle onto the coil and plug wires checking for arcing (do this in the dark).

A fuel starvation issue could cause this but the engine would typically rev OK out of gear but bogg when in gear.  A defective fuel pressure regulator can cause fuel starvation.  Engine start OK when hot? 

Might be the MAF sensor, try disconnecting the electrical plug and determining what happens. The computer would reset to a default setting.

Need to think about what changes in the engine operation when hot that does not generate a trouble code.

A plugged CAT will cause poor engine performance.  Check exhaust flow engine cold and hot.

Check the trans fluid for color and condition.  Not sure a bad convertor could cause this but doesn''t hurt to look for burned fluid.

Check coil resistance:
Primary 0.36-0.55 ohm cold, 0.45-0.65 ohm hot. 
Secondary 9.0-15.4K ohm cold,  11.4 -18.1K ohm hot.

Plug wires no more then 25K ohms.

Ok ill try a few of these things tonight, if you have anymore ideas just let me know. Thanks

Could be fuel or spark issue, but really I leaning toward it being air related. Either the MAF sensor or a faulty catalytic converter . Hopefully when you get this resolved you can share what the issue was, to help others in the future.

I''''ve had the same issue of limited rpm and bucking but it only occurred when in gear under load. In one case it was a bad coil and in another fuel starvation. If you have a vacuum gauge then it could help find an exhaust restriction.

Normal idle vacuum is 17-20hg and it should fluctuate to about 2hg to 25hg as you depress the gas pedel and release. For an exhaust restriction start with idle and slowly increase speed to 3000rpm, engine vacuum should be equal to or higher than idle at 3k rpm. If vacuum decreases at higher rpms there is excessive back pressure.

If you have access to a chassis dyno reproducing the condition with an engine computer hooked up makes it easier.

Vacuum leak is a good possibility too (again air)

yea i agree with the guy above it has to be air related especially if u just got parts of ur fuel system repaired, check ur vacuum hoses to see if they r dirty seafoam can always clean them out if u want a quick cheap possibility