tranny issues 4l60e repeat problem

Ok experts here it is

I have a 97 chevy 1500 2wd 4.3L 4l60e with 219k on it. I am having tranny problems that I thought I had fixed. Prblm is when I am going down hill at speeds abv 65mph in crz or out it will act like it is coming in and out of lock up. Then it will and downshift back into 4th and stay there even when gas is put back into eng when it should go back into lock up. I have had several opinions on this.

However the first time this happened all I did was chg the plugs,wires, cap and rotor. the problem went away. This was only after shop had it for 4 days and could find nothing wrong with trans. Even isolated tranny from eng and shifted using a tool he had. I have since recently chged the ign coil and to no avail it has not gone away.

I have some questions

  1. Can you take a 99 eng and swap it to my tranny for bolt patterns and wiring harnesses? I know the intake has to be swapped as well due to 99 had Fuel injection and mine has TBI. Also will the computer I have in my truck react differently to this eng?

  1. Does anyone have ant ideas of what may be causing the tranny to act like it is? I have been told that the eng is leaning out and the computer says you don't have enough power so it down shifts. I did a compression test the other day and found about 3 cyl not making the recommended pressure, some at 90 some at 120 psi book say should be

150psi with +/- 20psi.

  1. Also is it possible for the computer to learn this behavior of bringing the transmission down to to 4th? Also can you test the computer to see if it is giving bad info? I would rather replace computer than the whole eng.

  2. Could a loss of power in eng make the computer think it needs to downshift?

  1. Is there any sensor I could check? I have SES light on and already had it checked code read for the catalytic conv. TPS sensor is ok. Could bad camshaft sensor cause this problem or maybe bad distributer?

The transmission has had regular filter and fluid chges and was rebuilt at 116k and when in cruise controll when i hit the brake the rpms do rise like they are supposed too. I am about ready to chg this eng out for one with more power since mine is losing its. The rings need to be replaced in those cylinders losing power and after reading the proc in book its a little more than I am willing to tackle since I don't have all the tools or a garage to work in. I can massage tranny to make it stay in lock up by keeping more gas pedal in it , but what is point of crz ctrl if u can't use it?

Reply to
shadetree mx
Loading thread data ...

This was normal in the first 700R4's. Drove me nuts.

Al

Reply to
Big Al

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.