1997 Rav4 stumbles

[6gunn]

My daughter's '97 Rav stumbles so bad that it is undriveable. The plugs, cap and rotor all are in good condition. The wires test out under 15K. The coil was replaced lately because the wire connector tab was broken off.

The engine light comes on when it stumbles, but goes right back off when it stops stumbling. There are no codes set.

It idles great, and sometimes it will drive fine for a couple of miles before it acts up. Other times it will stumble as soon as you start driving. The stumbling gets much worse as the engine warms up and is driven.

I appreciate any help you can give me.

[Pim]

First off: you will need to get the error code read out. That will give you a better idea what to look for.
From your story i guess the knock sensor might be passing out or is badly connected.
If that is true, the engine will automatically switch to safety mode disabling you from driving over 35 MPH.

Repair manual concerning the knock sensor can be found here
Location below.
Greetz

Pim

[Ken Allistone]

Did the problem exists before you replaced the coil?
Did you test the wires by measuring resistance? If so they could be breaking down under load - this is a common problem on our Rav's, that and poor insulation on the plug end of the wires.
You could try spraying WD40 on all the leads and ends and see if it improves but I would order a new set - Denso's, try Rockauto.com
Good luck.

[LugNut]

Could be a plugged-up catalytic converter, or many other things.

But some cheap things to do first:

Open the gas cap; if you get a big sucking sound and the car runs fine for a while, you need a new OEM cap.

Change the air filter and spark plugs. Could be a fuel filter too.