Weasy2k

grounds/power...that is really looking like a faulty electrical connection....

so now your not getting anymore cels?
What happens wehn this studder happens does anything else fail? liek on your gauge cluster...

TexJJ

no other failures we are really scratching out heads. No failures on the CEL. No obvious guage changes. Tach drops but only as engine speed does. Battery to radio and accessories goes on without missing a beat.

Can anyone explain to me how the MAF works?

JJ

Weasy2k

well you got a 3.0L
so you got a AFM (air flow meter).
As air gets sucked into the engine it pulls.pushes on a little plate that sits inside the afm housing....the more air that goes in the greater the opening becomes inside the afm. This sliding "door" is connected to pot sensor which sends a voltage in relation to how open the afm is (how much air is being drawn in). This voltage along with the intake air temp sensor adn tps sensor tells the ecu the amount of air and how dense it is, at which point the ecu fires the appropriate amount of fuel in the mix.

MTL_4runner

I am not sure if this is actually your problem but you might want to at least read this thread:
https://www.yotatech.com/forums/f2/very-interesting-95-4runner-ltd-w-3-0l-30134/

TexJJ

So update.

75 miles on a the current tank after about 10 minutes of starting holding 60 on highway and JERK/STUMBLE. It is so quick I can hardly react to look at the guages. My digital voltmeter 13.4 before and after. Speed stayed around 60 other than jerk. It immediately kept running like normal and no check engine light.

My only notice was the tach dropped to about 700 rpms and then back up to 2700 rpms which is about 60 mph. I have a 5spd and it was in 5th gear. A new clutch/pressure plate lead me to believe I did not have that much slippage so there is NO WAY the engine truly dropped to 700 rpms. I then ran it about an hour with no problems.

On the way home after about another hour of running I was sitting at a light with clutch engaged and foot on brake. I was idling around 600 rpms. Then all of the sudden I note the tach varying between about <100 rpms and 600rpms, but the engine stayed notibly smooth. No notice of it lowering rpms from inside the cabin.

I have a new igniter and coil. New spark plugs and wires. I am at a total loss on my 3.0. Any other ideas. I am about ready to get an o2 sensor to hopefully increase my 15 mpg for a stock rig with warn hubs (which I thought should bump up my mileage.) I could replace the MAF, but I don't know. $$$

Lastly I have noted that at certain "crusing" speed, say between 30-35 or 40-45 there is a bounce similar to a tire balane problem, but it is also like a richening/leaning of the motor. I could have knocked a wheel out of blance but they only have about 1000 miles. Not likely. I am going to get them checked, but maybe this is a very imperceivable (via tach) engine surge.

Any ideas? Other than this it runs fine. Could use some more low end power, but seems to be a common problem on 3.0.

JJ

Radyota

Maybe the pick-up coil is starting to go? It's inside the distributor. It takes a pulse reading from the sun-shaped gear on the shaft to tell the ECU the crank position. It is also the low-voltage input for the ignitor/coil (primary circuit). Does kinda the same thing as the old points-style ignition in older cars. Could be one of the wires going to the pick-up coil has a bad connection. I just figured that's the only part of the ignition system you haven't looked at yet. Also, maybe the distributor bushings are worn and cause the pick-up coil to "ground out" intermittently. The old 20R's would do this (my dad had a 1980 4x4 truck). Replaced the dizzy, and it was fine! Hope this gives you some insight. Good luck!

ts200r

my '91 3.0 5M is having the EXACT same symptoms. I've also been scratching my head over this for months. Let me know if you have any luck.

Squiddy

My mom's camry was doing this almost exactly, and turned out to be the O2 sensor...

pineapple

Have you checked your signal generator (magnetic pickup coil)? My truck sat through an ice/snow storm for the first time since I drove it off of the dealer lot NEW in '89. I changed coil and igniter but the problem remained. The magnetic pickup coil tested within specs ALMOST always except the last time I checked it. Proved to be an intermittent problem. Now my problem is the $3.18 /gal gas. Good luck.