Need FSM CEL code help - P116 (1 Viewer)

[landtank]

Status update:

After the diag reading the CEL was reset and it drove fine the rest of the day.

Went to start the beast today and saw tons of white smoke with an extreemly rough idol. It didn't smell sweet like anifreeze, more like gas. CEL came on again.

Crap!

You either reset the CEL when the truck was warm and it drove fine the rest of the day because it was already warm!

Or the next day was the second time starting from a dead cold state and it had a problem.

There really is no sense posting back here until that aftermarket T-Stat is replaced and confirmed to be installed correctly.

You really need to base line the system first with OEM parts to rule out an aftermarket issue.

 

[RedmondCruiser]

I brought it into the shop and I just heard back.

They seem to think it is a problem with my replacement t-stat. I bought a Prestone (pn 704180) t-stat @ $25 on my second CEL event. I bought the t-stat affter work at Schuck’s after running their CEL diag. tool and installed the t-stat that night. THe 2 local Toyota parts dealers were closed.

The Prestone thermostat was a standard 180 degree (F) and the shop seems to think that the rig needed ~195 degree (F) OM part BTW…it only cost $17.

Why would Schuck’s sell a t-stat that doesn’t meet engine specs?

I have not received the truck back yet, so we will see if the shop is correct. I’ll post back tonight with (what I hope will be the final thread.)

$25 1st replacement t-stat ( + 3 hours of my time)
$65 probably unneeded temp sensor ( + 2 hours of my time )
$315 part and labor from the shop because I am a dumb ass
----------------------------
$405

Lesson learned: buy the $17 Toyota parts and save ~$390 bucks

 

[landtank]

whether or not the T-stat is 180 or 195 has no bearing on the error code you have. It's not about operating temperature but the rate the engine is warming up.

Hopefully the T-stat fixes it.

 

[aamiggia]

I've had this code in the past on very cold mornings and not so cold mornings. I've never had abnormal temp. readings. I have a new t-stat, but have yet to install it.

Each time I got the MIL I just reset it and it never came back. The frequency of the light in my case is once every six months. I chalk it up to wierd things happening to the truck when it's cold.

 

[Beowulf]

I was curious to see if the original t-stat was bad or not. So I did the t-stat boil test that is recommended in the FSM EG-175. (Picture a saucepan on the stove with a thermometer.) The t-stat opened at about 185 (F) and fully closed at about 140 (F). So it appears that I didn’t need to replace it.

Based on the above post, I still think you have a temp sensor problem. I hope your shop is correct in their diagnosis but it's not looking good from where I type.

-B-

 

[landtank]

Based on the above post, I still think you have a temp sensor problem. I hope your shop is correct in their diagnosis but it's not looking good from where I type.

-B-

Come on -B-, that's a pretty lame test for this type of problem. How do you know that the valve is sealed tight?

I'm hoping the T-stat fixes it as I don't think he or his mechanics have clue to what is not happening on the truck.

 

[elmariachi]

I stand by my early post. I think if he installs a Toyota t-stat and new o-ring properly it'll cure it. But I hate to see these situations cost people $405.

Regarding his question about why parts store sell parts that may not be suited for certain applications; they sell whatever their distributors send them. Unfortunately, a lot of aftermarket parts manufacturers cut a lot of corners when representing what their parts will fit. This is why there are certain corners that you don't cut.

A word of advice from someone who has owned 6 of these (including a totaled 40th sitting in my dark garage tonight).....if you own a 60,000 actual mile 1997 FZJ-80, its the last of a rare breed and as such deserves to have nothing but Toyota parts used on and in it, IMO.

 

[Beowulf]

Come on -B-, that's a pretty lame test for this type of problem. How do you know that the valve is sealed tight?

I don't but it was working for 60k miles, then he got the temp sensor code, then he put in a new thermostat and got the same temp sensor code, then he tested the original thermostat and found that it opens and closes (i.e. it wasn't stuck open.) It seems unlikely that the first one would fail to close completely and the new one would also fail to close.

Getting a new Toyota thermostat and gasket is a good move but I just don't have any confidence that is his problem. I've been wrong many times though.

-B-

 

[RedmondCruiser]

I picked up the rig this afternoon and drove it home.

I get the impression that the tech didn't seem to be confident that the problem is completely solved with the new Toyota t-stat because they called late in the day and said that I could pick it up but suggested that I leave it overnight so that they could start it up from a completely cold start.

They also said that I had a misfire logged on cylinder #6 p0306. They tested the ignition system and did not see a misfire issue. I think the misfire came on Sunday with the rough idle and all the white smoke.

I didn't have a way to get into work tomorrow on that short of a notice. So the plan is for me to bring it in again if there is a problem and they would not charge for any additional troubleshooting. I thought that was fair. I am leaving the cruiser out of the garage tonight and it should be in low 40s tomorrow a.m..

I also think that I have something worse than a "bad" t-stat. That might explain the p0116 code but doesn’t seem like it is related to the idle and smoke issue.

Time will tell. I’ll keep everyone posted.

Dave

 

[RedmondCruiser]

It's back!

Beowulf was correct. The new Toyota t-stat did not fix the problem.

Started my rig up after work and CEL came on again. Haven't run the code.

This is starting to get fun.

Dave

 

[landtank]

looks like it was part of the problem as you went 4 days without the code, if indeed it's still the code you were having.

If it's a wiring issue with the sensor the book indicates if you short out the two wires at the sensor, an OBDII reader should indicate a temp reading of 140* C or more. If this reading is lower than that then you move onto the ECM and short the leads there. If the reading is different then the issue is with the wiring, if it's the same then you need to check the ground and supply lines to the ECM and if they are good then look int a new ECM.

If you can't do that testing then a simple check would be to check the resistance between the BR-B wire at the sensor to ground. It should show continuity and if it doesn't then that would give you a false low temp reading. From that you could move to the ECM and check the ground state there.