Engine rpm variation

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I have 1987 toyota 4runner model and I keep servicing and when needed repair it on my own. worth it !!!

After the MIL is turned off or the battery was disconnected for some time, all monitors are set to incomplete. However with several short trips with engine getting at least to hot enough for thermostat to open, (I believe 8 is the magic number of trips) most monitors are set, you may be able to pass the test with only one incomplete only.

Shear coincidence. You have a transmission problem. Doing 60 MPH your RPM's should be around 2000, Usually a little less. One of you has a heavier foot than the other.

Go to Autozone, or any chain auto parts store. Have them read your engine trouble codes. It's called an OBD reader.
The trouble code is a 4 digit number that should tell you what component on your engine is faulty.

When you say "sputters at 2000 rpm" , are you referring to ANY time the engine is at 2000 rpm - meaning in Park, when you are just goosing the throttle, or in gear when you are accelerating, or at highway speed in high gear? If you are experiencing a "shuddering" in the engine at certain speeds/rpms - especially if these are speeds you regularly cruise at (long commutes at steady speeds), the problem could be in the Throttle Position Sensor (TPS). They have a tendency to wear unevenly if you drive a certain steady speeds. Eventually, the problem would progress to an engine code, but it may occur without setting the check engine light.

You may have a slipping torque converter clutch or worn bands. Contact a local transmission repair shop for further diagnoisis. The turbine speed sensors measure in and out speed of the main shaft, if a excess differance is seen then it will turn on the light and set the appropriate fault codes.

Here is the OBD2 emission system drive cycle test procedure.
Engine coolant temp must be below 70c (158f) before starting the engine for either the first or second trip
The fuel level should be less than 1/2 full
First trip:
Start engine, idle for at least 1.5 minutes
Drive 3 minutes, hold b/f schdl: 1.5-2.0 msec, selector lever "3rd" eng rpm 1,800-2,000 A/C switch:ON Hold the recommended b/f schdl range. Allow road speed to vary as necessary.
Drive at 55-65 mph for 1.5 min b/f schdl 2.0-3.2 msec, selector lever "5th" Engine rpm 2,200-3,000
IGN "off" for at least 10 seconds (not more than 5 min)
Dive at 50-60 mph for 3 minutes Selector lever "4th" keep engine speed above 3,000 rpm Allow speed to vary if necessary. Do not decelerate for more than 3 consecutive seconds. A/C switch ON.
Drive at a steady state cruise of 53-58mhp b/f schdl more than 1.8 msec selector lever "5th" eng rpm 2,400-2,600
Downshift to "4th" and decel more than 5 seconds without breaking, then idle for 1 minute.
Drive two minutes b/f schdl less than 2.0 msec Accelerate to 41 mph, decelerate to 34 mph, accelerate to 41mph. Do not completely release the accelerator. A/C switch off.
Idle 1 minute in park or neutral
Drive two minutes Steady state cruise at 31-44 mph. Selector lever "4th" A/C switch OFF. Hold the accelerator pedal as steady as possible. Allow speed to change if necessary.
End of first trip. Turn the key off the begin the second trip.
Second trip:
Start engine, idle for at least 1.5 minutes
Drive 3 minutes, hold b/f schdl: 1.5-2.0 msec, selector lever "3rd" eng rpm 1,800-2,000 A/C switch:ON Hold the recommended b/f schdl range. Allow road speed to vary as necessary.
Drive at 55-65 mph for 1.5 min b/f schdl 2.0-3.2 msec, selector lever "5th" Engine rpm 2,200-3,000
IGN "off" add four gallons of fuel
Dive at 50-60 mph for 3 minutes Selector lever "4th" keep engine speed above 3,000 rpm Allow speed to vary if necessary. Do not decelerate for more than 3 consecutive seconds. A/C switch ON.
Drive at a steady state cruise of 53-58mhp b/f schdl more than 1.8 msec selector lever "5th" eng rpm 2,400-2,600
Downshift to "4th" and decel more than 5 seconds without breaking, then idle for 1 minute.
Drive two minutes b/f schdl less than 2.0 msec Accelerate to 41 mph, decelerate to 34 mph, accelerate to 41mph. Do not completely release the accelerator. A/C switch off.
Idle 1 minute in park or neutral
Drive two minutes Steady state cruise at 31-44 mph. Selector lever "4th" A/C switch OFF. Hold the accelerator pedal as steady as possible. Allow speed to change if necessary. I especially like the part where they want you to add four gallons of fuel. Not three gallons, not five gallons, four gallons. Gotta love those Nissan engineers. ...and of course they state that if the trace is not followed exactly (i.e. you botch the acceleration/deceleration) you have to start all over again from scratch

you need to check your ignition system it seems like you have a coil or module or crank sensor breaking down you should see if you have any stored codes good luck

Hi
your problem seems very easy :) hope this one work with your envoy. Just buy AC DELCO carburetor tune-up conditioner.

How you use it: engine running , AC off please

1. detached the big black airflow hose which is attached in the mannifold of the engine block.

2. ask your friend to step on the gas pedal and set the rpm steady in 2000 rpm only.

3. then spray vigorously in 8 seconds the inside circle opening of mannifold while your friend steady step on gas pedal with steady 2000 RPM only.

4. after you spray, let your freind continue on gas pedal with 2000 rpm for 15 more seconds.

5. attached back the airflow big black hose to the manifold and you are ready to roll with your AC on.

if this one doesnt work, please scan your envoy by scanner called TECH II. and find out.

check the gas padel cable which runs to the engine, it might be strucking.