Rough Idle when Warm / Carbon Build up on 3 of 4 plugs

[changedsoul]

Ok, So recently, almost over night, my 2000 4Runner started to idle rather rough at a stop, in gear or out of gear. I pulled the plugs to see if they looks bad, and found 3 out of 4 plugs had carbon build up on it, the 4th looked good.

Anyone know what might cause this rough idle / carbon build up? Are these two issues linked?

Thanks for any help.
My trucks got 160k miles on it. Ran great all these years with virtually no issues at all.

 

[Baja Runner]

Id probably go with a full tune up first.

- Spark plugs and wires (NGK or Denso only)
- Clean your Mass Air Flow sensor (easy)
- Clean your Throttle body and Idle Air Control Valve
- Install a new fuel filter

See where that gets you. You're only spending about $30 on the filter and $30 for the plugs/wires.

Something tells me its something else, but I would do the easy stuff first just in case.

 

[matthinnant]

I would go with some sea foam first and if that doesnt help anythng then do wat the above post says.

 

[LittleCaesar]

Can you post some pics?

I take it you have the 2.7; changing the fuel filter would be tasking. But I think Baja is right about it being fuel related.

Run some BG 44K cleaner through the tank, may be injector related.

 

[changedsoul]

I took it for a short drive, first 5 min or so it idled pretty rough, but after that it smoothed out again and has been idling smooth since. For the sake of knowledge, I went out an got me an OBDII scanner because I have had a check engine light come on and go off periodically for the past few years, lol. Anyways, last time I tried to investigate the engine light itself came back as something with some fuel rail 1 bank 1. Couldnt find any real info about it then, and the car was running normal, so i blew it off.
Perhaps this issue from way back has gotten worse and is causing more issues now. That being said, when I was tinkering with my idle problem, I created a few bogus error codes and wasnt sure which was caused by me vs my actual engine problem, so I cleared all the codes in hopes the light comes back fairly soon along with a snapshop of my engine sensor data. Perhaps armed with that info, I can post back here in hopes someone can help trouble shoot this with me before I am stranded where I dont want to be

Also, the plugs, other than some carbon on 3 of them, didnt look all that bad. Not really warn all that much. Its been about 6 years since i changed them, I guess I could just go for it. Also, this truck doesnt have wires. Seems its all controlled electronically and each plug has its own coil sitting over top of it.

Since you guys are leaning twards a fuel issue, and the fact that I had that fuel bank error code few years back off and on till now, I am thinking it might be there too. Ill post back some data when the light presents itself again.

Thanks for all the help.

 

[LittleCaesar]

Ever changed the O2 sensor?

 

[changedsoul]

No I have never changed the O2.

Ok, So It just came on, and the computer spit out these codes:
P1135 ( Air / Fuel Sensor Heater Circuit Malfunction)
P1130 ( Air / Fuel Sensor Circuit )
P0171 ( Bank 1 System to Lean )

Seems the only code the computer grabbed a snapshot of the engine data was P1130
The values for that are as follows:
: Trouble Code - P1130
: Eng Speed RPM - 1013
: Calc Load% - 20.4
: Coolant Deg F - 165
: Intake Air Temp - 100F
: Short Term Fuel Trim% Bank 1 - 19.5
: Long Term Fuel Trim% Bank 1 - 10.9
: Vehicle Speed - 29mph
: Fuel System 1 loop Status - clsd1

Anything of interest in there?

 

[steezemcqueen]

Clean your MAF sensor

 

[SRSRunner]

sounds like an 02 sensor- delete the code, get some electronics cleaner and clean our your MAF see if it comes back on again. I would do what the others have said about plugs/wires as that's a cheap and easy job. If none of that is an issue- start with the injectors next. I doubt that's what it is if its only minimal buildup on the plugs- however if it does turn out to be the injectors- replace the check valve on the line also.

 

[t4r4life]

a/f ratio 02 and vaccume leak

 

[changedsoul]

Ok, So I changed my plugs, cleaned my MAF(was dirty but not bad), changed my Air Filter. While changing my air filter, i noticed a hose disconnected that went to the air filter cover, same cover the MAF is on. I connected it. I also dumped some of that sea foam down my tank.

All this done, I cleared my codes, and headed out on the road. It was going good for a while, i thought I fixed it, but the light came back on. This time with a different code along with the original.

P0125 ( Insufficient coolant Temperature for Closed Loop Control)
P1135 ( Air / Fuel Sensor Heater Circuit Malfunction)
P1130 ( Air / Fuel Sensor Circuit )

Snapshot values for P0125:
: Trouble Code - P0125
: Eng Speed RPM - 1656
: Calc Load% - 44.3
: Coolant Deg F - 185
: Intake Air Temp - 91F
: Short Term Fuel Trim% Bank 1 - 0.0
: Long Term Fuel Trim% Bank 1 - 14.1
: Vehicle Speed - 34mph
: Fuel System 1 loop Status - OPEN2

Also I took some real time reading while the car was idling:
MIL Status = on
ABSLT TPS% = 11.0
ENG Speed(RPM) = 701
CALC Load% = 18.0
MAF(LB/M) = 0.43
Coolant(degF) = 190.0
IAT(degF) = 108
IGN ADV(deg) = 8.5
Short Term Fuel Trim% Bank 1 = 0.0
Long Term Fuel Trim% Bank 1 = 0.0
Fuel System 1 loop Status = OPEN2
O2S11(V) = .655 (this never changes)
O2S12(V) = .065

While I was out driving, the car started to idle rough again at a stop. I placed my foot on the brake and pressed o the gas and brought the rpm's up to 1k. The rpms started to bounce between 700 and 1000 untill i took off from the stop. This only happened once, and after driving down the street from this time, each stop the idle was ok again. Something must be borderline failing maybe?

Anyways, with this new info, can someone suggest what might be wrong now? I understand two of the codes seem to point to the O2S, but one code says the heater malfunction, but the scanner connected says the heater is OK and the O2S testing is incomplete. I am confused on how all these sensors tie together. Anyone got another suggestion?

 

[changedsoul]

I been doing a bit of reading about O2 sensor checking and symptoms and I came across soemthing that mentioned possible thermostat issues?

Correct me if Im wrong, but after driving on the freeway for a few minutes, shouldn't my fuel system loop be closed and not open?

I read that monitoring doesnt happen untill its closed loop? is this correct? Reason I ask is while driving and monitoring the scanner, seen that fuel system loop switching back and forth between open and closed. In fact in my first post, I have it losted as it being closed.
Few years back, I cant remember entirley, but I faintly remember changing to a cooler one to get heat faster in the winter. ( when i lived in wisconsin ) Could this cooler thermostat be not alowing my engine to get hot enough to go into a closed loop?

 

[Gerdo]

Mine had a rough spot in my RPMs. it was bad plug wires.

 

[changedsoul]

Wish it were that easy. I already changed the plugs, and mine doesnt have wires.
I pulled out the Air / Fuel Oxygen sensor and bench tested it. Heated it with a propane torch and voltage went up, took flame away and voltage went down within a sec or two. Heated it for two minutes and seen no drops in voltage the entire way, took flame away and voltage dropped fast. So it seems the sensor is good.
Got some carb cleaner and sprayed around all my vacume points and the rpm's didnt change.

Anyone have ideas to these codes I am getting?

P0125 ( Insufficient coolant Temperature for Closed Loop Control)
P1135 ( Air / Fuel Sensor Heater Circuit Malfunction)
P1130 ( Air / Fuel Sensor Circuit )

Snapshot values for P0125:
: Trouble Code - P0125
: Eng Speed RPM - 1656
: Calc Load% - 44.3
: Coolant Deg F - 185
: Intake Air Temp - 91F
: Short Term Fuel Trim% Bank 1 - 0.0
: Long Term Fuel Trim% Bank 1 - 14.1
: Vehicle Speed - 34mph
: Fuel System 1 loop Status - OPEN2

Also I took some real time reading while the car was idling:
MIL Status = on
ABSLT TPS% = 11.0
ENG Speed(RPM) = 701
CALC Load% = 18.0
MAF(LB/M) = 0.43
Coolant(degF) = 190.0
IAT(degF) = 108
IGN ADV(deg) = 8.5
Short Term Fuel Trim% Bank 1 = 0.0
Long Term Fuel Trim% Bank 1 = 0.0
Fuel System 1 loop Status = OPEN2
O2S11(V) = .655 (this never changes)
O2S12(V) = .065

 

[changedsoul]

Ok, I know I am posting allot, but now I am just confused. All though I tested my O2 sensor and found it to be good, I didnt check the heater. So I crawled back under my car and probed the heater wires ( disconnected ) and found it to be open. Thinking it was bad, I went to my local parts store and checked theirs as well and found it to be open.

I checked my down stream O2 sensor and found 13ohms on the heater.

So my question is this...My down stream is labeled as an O2 sesor, but my Upstream is labeled as an Air / Fuel Oxygen Sensor, Do these have different ways to check heater elements?

Based on the down stream checking 13ohms, and my upstream reading open, I would think my upstream was bad....but then the new store upstream also read open.
Could I have checked a bad one in the store as well?

 

[LittleCaesar]

If the store is nice enough to let you check their O2 sensor, ask if you can just plug it in your 4runner and attempt to clear the codes.

If your 4runner is California spec, then you do have an Air/Fuel sensor pre cat. I think this is still your problem. But how to thoroughly test it, I can't tell ya past what the FSM can provide:

Toyota Tacoma/ 4Runner/ Tundra/ FJ Cruiser Factory Service Manual Page

 

[Cuffs]

I had the same physical symptoms recently (but not the same codes you got). Turns out mine was a bad coil pack. Pretty simple and cheap fix.

 

[Gerdo]

Wish it were that easy. I already changed the plugs, and mine doesnt have wires.

All 3.4L 3rd gens have plug wires. If you didn't have to pull and plug wires then you only changed 3 of the plugs. The passenger side has coil packs on top of the plugs. These feed over to the 3 plugs on the drivers side. These are the wires that can go bad. Also there are 3 plugs to be changed on the drivers side.

 

[02SE]

All 3.4L 3rd gens have plug wires. If you didn't have to pull and plug wires then you only changed 3 of the plugs. The passenger side has coil packs on top of the plugs. These feed over to the 3 plugs on the drivers side. These are the wires that can go bad. Also there are 3 plugs to be changed on the drivers side.

From his description in his first post, I'm thinking he has the 4 cylinder..