As stated in the title...

I have a 1992 4Runner 3.0 V6 Automatic that dramatically decelerates on long uphill pulls at interstate speeds.

It runs and drives great around town and I haven't had an issue with short steep hills around town at 30-50mph.

Not towing anything.
Cat gutted.
All fluids clean and at correct levels.
Downshifts correctly.
No check engine light.

I have searched the forum and this problem has been mentioned a few time but I have not seen a fix posted.

Thanks in advance for any help.

I plan to test the TPS and check ignition timing asap.

I may also need to check timing on the belt because it had a timing service done not long before I purchased it.

Torque converter? no shutter or typical symptoms of a bad torque convert.

 

Whats your timing set at? My 3 runs a lot better at 15 and Ive heard some folks running more advance than that. I know nothing of 3s and autos in 4 runners but I had a friend that had an 89 3 auto in a pickup and sometimes I went past him so fast, he thought his pickup had died. Good thing he didn't get out and check. I would think that in a heavier rig like yours it would be worse.

 

Have you cleaned or ever cleaned the MAF sensor? If not it should be done as part of regular 30k maintenance at the least, and if it solves the problem, which it very well could, then bonus.

 

Define long uphill grade?? Interstate Speed??

Does that mean posted speed limit or the 25mph over that seems to be normal here.

How many miles on engine ??

What is the every day curb weight of the vehicle??

You don`t mention tire size or what gears you have??

On a good day I can walk uphill faster then my 92 4Runner.

 

Cleaning the older flappy door AFMs will not help this problem as there is nothing to really get dirty inside it.

 

Interstate speeds = 70mph which is 5 over here. I almost immediately drop down to 50

124k miles

Trucks is stock on stock tire size and I am the only additional weight.

I think I have it boiled down to a bad lockup solenoid... I planned to do the solenoid kit asap anyway.

I will report back once installed.

 

What about when the flap does not open or close properly given the load on the engine and the ECM receives the incorrect data, thus incorrectly adjusts the A/F ratio causing the engine to act irradictly? I am asking this for my own knowledge. Thanks.

 

As far as I know that's normal for these trucks,they're slow and hate hills.

 

I have never once seen or heard of one getting dirty enough for the door to get stuck and stop working. You would have to be running without a filter and sucking up lots of dirt,sand, or mud if it is getting that dirty, and then then AFM will probably be the least of your problems.

 

Guys, I hate to say it, but I'm afraid this is just perfectly normal for a 3.0 3VZE with the a340H or similar automatic transmission. That tranny adds a ton of drag to your driveline and between the old and gutless 145hp motor, the draggy and lazy auto tranny, and the super heavy 4Runner, it just isn't capable of doing 70 uphill without either a 3.4 swap or a manual tranny swap (or maybe both!). I have the same truck, and drive it on freeways all the time. Same issue. It's so bad I feel like there must be something wrong with my transmission, but I'm afraid there might not be. Mine has the stock 4.88 towing package gears and 32x11.5s, but was just the same with 31x10.5s. I can't imagine having 4.10 or worse in this thing. Would love to swap up to 5.29s, hopefully that would help.

Already replaced and adjusted the TPS, replaced speed sensor, cleaned out throttle body, advanced timing, etc. Still about 50 is the fastest it'll go uphill, but if I click the OD Off button it will go faster at like 3500-4000 RPM as long as the hill ain't too steep. In steep mountains, even that won't get me past 40! If anyone has anything that'll help short of replacing the motor or tranny, I'm all ears!