quicksilvr

My buddy has a 1996 4runner, 3.4L auto. It has close to 200K miles on it. He is pretty non-mechanical himself, and I have not experienced this problem first hand yet, because he's bringing the 4runner up to my place tomorrow for me to work on it. What I know is just what he has described over the phone.

It hesitates/lurches when he is cruising at constant higher speeds. He said it really never does it below 40mph. But the kicker is this: if it starts to act up while he's cruising at constant speed/constant throttle position, he can completely eliminate the problem by accelerating. Which based on all the reading and searching I've done on hesitation problems with the 3.4L....seems backwards.

I'm planning to clean the MAF, the intake, TB, replace the TPS, change the spark plugs, and test the coils. I'll probably do a compression test as well. Obviously once I drive it myself I might get a better idea what the heck is going on.


Any suggestions? Has anyone else experienced this "backwards" hesitation issue? Thanks!



EDIT: Oh yeah, no codes have been thrown. I'll check them anyway to see if there is something stored, but the CEL is not on currently.

VT4R

Try replacing both the plugs and wires. I had basically the same problem you described, and after cleaning the MAF changing the plugs and resetting the ECU, it persisted. After I changed the wires, the car ran fine. This was at about 170k with my 3.4l auto 4Runner.

brian2sun

All the stuff on your list is good. I agree that you should replace the wires too. Check the tranny fluid also, that could cause symptoms similar to lurching especially if the torque converter is messed up. Don't forget to reset the ECM after you're done so it can get used to all the new stuff. I personally would test the TPS before just replacing it. When they go bad they usually cause idle surges like after you stop and put it in "P" rather than the hesitation or lurching that he's experiencing while driving at higher speeds, but it's still possible.

quicksilvr

What is the ECM reset procedure? Can I just disconnect the neg battery cable for 5 minutes? Or is there more to it?

brian2sun

Yeah, just pull off the - battery cable. 5 min. may be enough, but I've heard up it takes up to 45 min. to be sure.

quicksilvr

Fixed. I replaced the plugs (they needed it BAD), wires and the #1 coil. On the drive to my place, he did get a CEL, which was Cyl #4 misfire. I also cleaned the MAF, the PCV valve, and installed a new airfilter.


There was also a "tornado" brand intake turbulance thingy stuck SIDEWAYS in his intake. No wonder he didn't have any power.

It's got 198K on it, and it runs like a new truck again. Mission accomplished.

brian2sun

Sweet!