High Idle and Surging

[mgriff67]

93 FZJ80. I was working on reconnecting my IACV as the plastic 6 pin connector on the harness disintegrated. I had connected the two wires supplying power and was testing the possible order that the other 4 could go. 3 combinations and it made no difference vs having the IACV disconnected then, on the 4th try, it immediately revved to 2100 and sat there on start. At some point after restarting the motor it started surging and would go from 1200 to 2100 and has continued to surge. (In park and neutral) Did not continue to surge when revved.

Checked the throttle cable/cams, vacuum lines, MAF and after running codes got TPS and O2 sensor. I’ve replaced the O2 sensor/ and I still have O2 code. Can I resistance test TPS for functionality? Any other advice on things to check?

Link to video

 

[ceylonfj40nut]

Use the electric wiring manual to confirm you have the right wires pinned in.

 

[petegangies]

if this happened as you were messing with the IACV, this is exactly where I'd start. Replace the connector and terminals. The EWD should show the correct configuration. There FSM also has resistance tests for both the IACV and TPS. If you haven't touched the TPS, then don't mess with it, they're a pain to recalibrate.

 

[petegangies]

 

[TheBussman]

thats what they do when the IAC is in too open of a position. if you 100% sure on iac wiring, let it run for a min and it might calm down now that its hooked up right.

 

[jonheld]

Once it's hooked up correctly, the IAC should reset each time the engine shuts down.
It is a stepper motor and moves the plunger in VERY small increments.
Explanation and test procedures are all in the FSM.

Below are snips from the EWD.

 

[mgriff67]

Once it's hooked up correctly, the IAC should reset each time the engine shuts down.
It is a stepper motor and moves the plunger in VERY small increments.
Explanation and test procedures are all in the FSM.

Below are snips from the EWD.

View attachment 4220969 View attachment 4220973

I reconnected the iacv, immediately revved up to 2k and sat there. I’m a little hesitant to let it sit and warm up that high. In the past I could pull back on the pedal and the idle would drop a little but not anymore.

I’ve disconnect battery and 15a fuse trying to reset but still getting tps and o2 code.

 

[mgriff67]

thats what they do when the IAC is in too open of a position. if you 100% sure on iac wiring, let it run for a min and it might calm down now that its hooked up right.

I reconnected the iacv, immediately revved up to 2k and sat there. I’m a little hesitant to let it sit and warm up that high. In the past I could pull back on the pedal and the idle would drop a little but not anymore.

I’ve disconnect battery and 15a fuse trying to reset but still getting tps and o2 code.

 

[mgriff67]

if this happened as you were messing with the IACV, this is exactly where I'd start. Replace the connector and terminals. The EWD should show the correct configuration. There FSM also has resistance tests for both the IACV and TPS. If you haven't touched the TPS, then don't mess with it, they're a pain to recalibrate.

I reconnected the iacv, immediately revved up to 2k and sat there. I’m a little hesitant to let it sit and warm up that high. In the past I could pull back on the pedal and the idle would drop a little but not anymore.

I’ve disconnect battery and 15a fuse trying to reset but still getting tps and o2 code.

 

[petegangies]

same behaviour whether hot or cold?

 

[robnicko]

I reconnected the iacv, immediately revved up to 2k and sat there. I’m a little hesitant to let it sit and warm up that high. In the past I could pull back on the pedal and the idle would drop a little but not anymore.

I’ve disconnect battery and 15a fuse trying to reset but still getting tps and o2 code.

the bit i bolded above, sounds like a sticky throttle cable or too tightly adjusted. if you removed the throttle body can you post a pic of the cable arrangements as they may be routed incorrect?
maybe try disconnecting the throttle & kickdown / cruise(if equipped) cables from the throttle body and start it to see where the idle is at?

 

[lumbee1]

I had a similar problem and it was my TPS. Engine was revving to 1200 then 1600 then 2100 rpm. Stopping the Cruiser was difficult. I ordered a new TPS from RockAuto. Almost 16 months later, it started doing the same thing. I replaced the RockAuto TPS with a Toyota OEM and the Cruiser has been fine since.

 

[TheBussman]

test and repair what ever is causing the TPS code. perform the calibration and tests for the sensor. if they all pass then test wires to and from the ecu to the sensor.

 

[jonheld]

I’ve disconnect battery and 15a fuse trying to reset but still getting tps and o2 code.

TPS TPS TPS
If the TPS is faulty or misadjusted, the ECU doesn't know what position the throttle is in. It will never run correctly in this condition.

 

[mgriff67]

TPS TPS TPS
If the TPS is faulty or misadjusted, the ECU doesn't know what position the throttle is in. It will never run correctly in this condition.

I have replaced and calibrated tps. I don’t have feelers but I was able to rotate ever so slightly off closed circuit to get open loop. I wonder if IACV is stuck open?

 

[petegangies]

I have replaced and calibrated tps. I don’t have feelers but I was able to rotate ever so slightly off closed circuit to get open loop. I wonder if IACV is stuck open?

It's easy to test off the vehicle using the procedure in the FSM. It moves in very small increments as you apply power to the different pins. You can complete a full circuit and take note of how far out and in it was.

 

[jonheld]

I have replaced and calibrated tps. I don’t have feelers but I was able to rotate ever so slightly off closed circuit to get open loop.

What do you mean by "open loop"?
Are you still getting the TPS error after clearing codes?
Any consistent error code will cause the ECU to run in "open loop", meaning it is NOT reading sensors, but reverting back to base programming.
This is explained in detail in the FSM.
That is not what you want.

Follow the directions in the FSM.

 

[petegangies]

What do you mean by "open loop"?
Are you still getting the TPS error after clearing codes?
Any consistent error code will cause the ECU to run in "open loop", meaning it is NOT reading sensors, but reverting back to base programming.
This is explained in detail in the FSM.
That is not what you want.

Follow the directions in the FSM.

Might be referring to OL on multimeter?

 

[mgriff67]

What do you mean by "open loop"?
Are you still getting the TPS error after clearing codes?
Any consistent error code will cause the ECU to run in "open loop", meaning it is NOT reading sensors, but reverting back to base programming.
This is explained in detail in the FSM.
That is not what you want.

Follow the directions in the FSM.

Sorry, poor wording. Found the point where the tangs were not making contact and turns slightly so that the ohm meter deflected.

Removed the throttle body and found this:

 

[jonheld]

Sorry, poor wording. Found the point where the tangs were not making contact and turns slightly so that the ohm meter deflected.

Removed the throttle body and found this:

DASH POT SUB-ASSY 22202-66021
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