dr1553

I have been searching and I cannot find a post that details the location of the coolant temp sensor on a 3.0 engine. My search fu must be weak because I know this must have been posted before.

Does anyone have a pic. of the location and sensor on a 3.0 engine?

The reason I want to replace it is because I believe my truck is running rich, low mileage at or less than 10mpg, smelly sooty exhaust. I know the coolant temp sensor has not been replaced in at least 10 years, probably never, so I figure it wont hurt to replace it anyways. I have already replaced the O2 sensor, cat, TPS, checked the AFM....new Toyota dist. cap and rotor, probably other stuff I am forgetting.

I just pulled the number 1 and 3 plugs to take a look, they look more like lean running plugs to me. These are NGK R BKR5EYA and have been in the truck for less than 10k miles.

Plug #3





Plug #1

myyota

The plugs don`t really look that bad. When you replaced the 02 sensor did you use a Denso 02 sensor ?, Bosch 02 sensors don`t work well in toyota engines. Another thing that`s effecting your mileage is the winter gas. I also se that you have 31'' tires, that more than anything will effect your mileage, have you ever considered regearing ?, that would help you a lot right there.

dr1553

NGK OE identical O2 sensor from sparkplugs.com

It has been getting bad mileage for a few years now. I used to get 15-18mpg and then one day I noticed the idle was rough and I have gotten 10mpg or less ever since and the idle has never returned to normal. The change was sudden and very noticable not gradual.

I have checked and changed just about everything except the coolant temp sensor. I have had running threads and followed threads of people with the same issues. Everything I have changed so far has made the truck a little better but nothing has fixed the low rough idle. The O2 sensor and TPS helped the most but there is still something wrong. It seems strange but whenever I put a new part on (O2, cat, TPS) the thing will run better for about two weeks and then it goes back to like before. It's like it WANTS to run bad.

I want to change the coolant temp sensor to check that one off the list too. I had thought that I was running rich but after seeing the plugs I dont know. Looks almost like its running on the lean side to me.

myyota

Ive read the most 3.0`s have problems with the EGR filling the intake with carbon build up, and after it builds up so much it can cause engine problems, ruff idle and power issues. I would recommend that you remove the upper and lower intake and clean them out, also clean the throttle body and EGR, that should help things a lot.

dr1553

Did all that recently also. :-)

RMA

its at the back of the intake , middle .. green plug i believe.

MudHippy

O.k., the suspense is killing me. See what happens when the residing 3VZE expert goes away on vacation? Nothing gets done in a timely manner regarding it.

Hint: Substitute the term 3VZE for 3.0, and try your search again(leave out the words "location" and "pics", the search feature didn't like it when I tried using them, too specific). I've answered this exact same question in FULL DETAIL on a couple of occassions recently. They'll be displayed at the very top of the list(first and third threads w/pics included).

HappyAdventure

this thread has the picture you are looking for:

http://www.toyotanation.com/forum/sh...d.php?t=346899

dr1553

Ok...got it now. Thanks for the search tips and link! I'll look for it on the truck in the morning, too dark now.

Sounds like it could be either the coolant temp sensor or the coolant temp switch causing problems. Are the aftermarket ones from O'Reilly ok to use?

spitfire4

any update? how much better did the cts help?

Team420

If that link dont help... i have an engine on a stand in the garage...... ill take sime pix later and post them up...

theMonch

Don't count the VAF meter (MAF) out too soon. Did you replace it or just check it with a multimeter as per FSM? I had a similar running problem that would be intermittent that I chased down for close to a year. It turned out being the VAF. It also has an air intake temp sensor integrated that also tends to get a bit wonky over time.

If you have a friend with another 3.0, try swapping VAF's and see if the problem gets fixed.

AkitaDog

iTrader: (1)

The plugs look good, a little worn. Might be a little on the lean side, I would check for a vacuum leak? imo

dr1553

I never got around to changing the coolant temp sensor.

The truck has been running ok but still getting only 10mpg or less where I did get 15-18 and then one day when I started it up the idle was not the same. Rough idle, slightly smelly exhaust, sluglish during acceleration....etc.

I'll try and list everything I have done and what the effect was but this has been going on since 2007 so I dont know if I can remember everything. This isnt in order, just listing as I remember things....

new spark plugs....dont remember if it made a difference

new o2 sensor....made it run a little better

new cat...seemed to run great for about 2 weeks and then back to normal

took off the intake and cleaned it out, new PCV...made it run a little better

new egr regulator since the old one was busted up...no difference

changed the cold start injector with one from a good running 3.0....no difference

new TPS....stopped the super low idle (450-500) and brought it back up to normal idle (800-1000)

Oreilly dist cap and rotor...ran worse so I put the original parts back on

checked the VAF per FSM and did the sweep test I read about somewhere, here is a video I took of that...




Recently my steering gear box starting leaking so I sprayed some degreaser on it and sprayed it off with the water hose to locate the leak. Right after doing that it ran awful so I pulled dist cap and there was alot of water under the cap. I got a new dist cap gasket from the dealer since no one else sells that gasket. The old one was in pieces, and let the water right in there. I cleaned and dried out the cap, sanded the rotor contact a little and it ran much better, maybe a little better than before but still a little rough.

I did notice oil under the cap so I pulled the dist to check for lateral play in the shaft. The bearings felt good and I cannot feel any play in the shaft side to side. There is some up and down play but I dont know if thats normal or not. Here is a pic of the oil under the cap...you can see it to the right of the rotor under those wires.




The truck is running pretty good now but it still has a slight miss and rough idle that very noticably smooths out at 2000rpm. With engine warm.

The truck still has the original dist. cap, rotor and spark plug wires. I dont know why I said in an earlier post that it had a new cap/rotor because it doesnt, they are original as far as I can tell

themonch, can you check out the video of the VAF and see what you think? I still havent counted it out as a culprit but its an expensive part to swap if its not bad. I do have a friend with a 3.0 runner, I'll call him and see if I can try his out. If his runs any better that is, seems like a lot of these 3.0's are having these same issues.

AkitaDog, I have checked for vacuum leaks many times and havent found anything...but...all the little hoses on the engine are getting old and mushy or brittle. There must be some vacuum leak somewhere considering the age of everything. I have sprayed starting fluid around the engine bay looking for rpm changes but nothing.

At this point I am thinking I need to replace the dist cap and rotor with new parts from Toyota, not aftermarket. I am also thinking I need to change the spark plug wires but the Toyota wires are $100. Whats an ok set of aftermarket wires or do I need to go original on those too.

I need to check the timing again, when all this started I tried to set it but the mark was jumping around all over the place.

Is it worth throwing a new ignition coil on there also? Oreilly sells a BWD for $60.

What about fuel injectors? Is there a chance that I have a bad one? Or they are all dirty? Engine has 178K on it now.

ZARTT

I know that you have tried swapping the cold injector for a known good one, but maybe it is being told to stay on thereby killing your mpg.
After the engine warms up try disconnecting the electrical lead to the injector and run that way for a couple of tankfuls to see if that is a factor.
You can hook it up to get the engine started when it is cold.
Also try to borrow a scanner from PEP girls to hook up while the engine is running.
This could indicate whether or not the ECU is ever switching over to closed loop mode.

dr1553

ZARTT I remember now that I did disconnect the cold start injector on the advice of a friend. I ran the truck like that last summer and only hooked it back up when the weather turned. No difference at all, I even forgot I had disconnected it until it was very hard to start that first cold morning.

No PEP boys (girls) around here that I know of. But I wonder if its something like that because sometimes when I am driving it or sitting at a light there will be a sudden change in the way its running. It will be running fine and then like someone threw a switch it starts running rough, and then back and forth a few times.....just like someone is throwing a switch. I think there may even be an audible click when it does it at idle, at a stop light. But I have never noticed it do it in the driveway so I wonder if it only does it once its warmed up.

Ok, you know when you turn on the A/C while at a stop and the RPM drops then there is a click and the RPM's pick back up. Its just like that, but it does it without the A/C being turned off and on.

What you said about closed loop mode made me think of that.

dr1553

A friend of mine has a good running 3.0 and in the next few days we are going to swap his VAF into mine and see what happens.

I'll be sure to post the results.

I think I need to keep searching for a vacuum leak also.

Wrenchinjoe

While you have a good running 3.0 donor diagnostic vehicle to play with, try swapping the distributor out to see if that could be the problem. Yours appears to be seeping oil and it also let water in from the cap... couldn't hurt to check that out. Just make some reference marks with a sharpie so you line them both back up after testing.

dr1553

Yes....good idea. I'll do that if he will let me. I already pulled my dist and it didnt seem to have any lateral play (slop) in the bearings but it wouldnt hurt to check. From what I understand if there is oil under the cap that means there is some wear in the shaft/bearings. Just because I couldnt feel it doesnt mean its not there.

At this point even if it turns out to be an expensive part like the distributor or VAF I dont care, I'll buy a new one just to have the truck running right again.

Wrenchinjoe

Please some one correct me if this is wrong, but I think the crank position sensor that sends its signal to the ECU is effectively in the distributor on this motor. So if that sensor was crudded up from oil seeping past the inner o-ring, you could get a faulty signal at the ECU. If the distributor bearings are worn and have even slight play, you could get an eratic signal at the ECU, in your case at low rpm. I am guessing here, but I have heard of a couple of poor idle situations being resolved with a new distributor so it is worth checking out.

Good luck.