4Runner1988

I just rolled over 204,000 miles. Have owned it since 1993 and 32,000 miles. The truck acts like its on 5cyl when started and onced warmed up...it gets better, but not completely gone. There is a small leak above the #6cyl...but I think its just the valve cover gasket. Knock on wood, I dont think its a head gasket...yet!

My question is this...what else could cause this type of problem. I have checked all the vacum hoses...and while old...they still are doing the job. It seems to be more noticable at lower RPM's as well...but once you get up in RPM's(2800) it get much better?

COIL? MAF?

thanks in advance...

UncleBob

With that many miles, Start with a compression test, for sure. First dry, then wet.

You know, Harbor Freight has a compression tester that's $5.

http://www.harborfreight.com/cpi/cta...emnumber=92697

They also have a kit (which I couldn't find online) that has a lot of very useful tools for cheap. It has a timing light, vacuum tester, compression tester, and remote starter, etc. It was under $30.

I've used the $5 one, and it works fine. I have a nicer one now, though.

Even if loss of compression isn't your problem, it's a good idea to KNOW what your compression is across the cylinders. Keep track of that, and next time you have problems, you can refer back to your old readings to see if one cylinder is going down..

thook

Could be a number of things..... a sensor, an injector.
Have you looked at the plugs? Done a compression test?

()

TNRabbit

and here's a link to the FSM for explicit directions on how to do a compression test if you've never done one: http://personal.utulsa.edu/~nathan-b...fsm/index.html

snap-on

plugs, wires, cap, rotor, compression test, injector

4Runner1988

The plugs and wires are fine. Could check the rotor and cap.

UNCLEBOBand TNRabbit.......Thanks for the tip on the compression test and tools. I'll try that.

first4runner

Even though your vacuum hoses are good it could be the intake. If the main intake hose has a leak anywhere around the line going into the valve cover, it could affect that hose, your idle will be bad (around 500 RPM's or anything below a thousand) good idle should be around 1k. If the intake has never been replaced the hose could have dry rotted and start to crack around the hose clamps. So check for leaks along your intake. I have also found that where the hose connecting to the valve cover has come loose on my truck, it could leak there too. It might just be my truck, but its worth a look.