98 ES300 Problems..

[AptNull]

Okay, so my 1998 ES300 is acting like it's starving for air, or some other issue.
I'm going to name off what I've already replaced & my initial thoughts and what's been done.
(This engine & transmission has been rebuilt, and should have 0 carbon on any components; however the EIM (Exhaust Intake Manifold) has carbon all inside of it.

So far I've replaced the Downstream O2 sensor and Bank 1 Sensor 1 O2 Sensor (1st one, at front of engine).
I've bought a fresh, IAC valve from RA along with a Oil Pressure Sensor Switch (because there was & still surprisingly is; a oil drip leak coming from the OPS area. A mechanic told me it was the OPS so I replaced it, still leaking.)
I have checked MAF sensor, there is 0 carbon anywhere on it from what I can see.
I've adjusted throttle cable, to try to achieve higher idle to prevent the car from stalling & then reverted the cable back to how it was as best as I could once I realized this would not help (from another forum).
I've checked all vaccum hoses along the air intake, and today just finally said *BLEEP* it and threw an entire can of TB cleaner through the TB into the engine intake mainfold & alot of carbon came out of the TB.

The Radiator or Overflow tank keeps leaking... alot of coolant all over the ground. I mean alot.
I've tried adding coolant, finding the leak, etc. Keeps leaking at random times. (When engine is hot.)
The Radiator Fans (No.1 & 2) do not turn on unless I disconnect the temperature sensor cable at the top of the fan (not bottom of radiator); so I am thinking this is why due to steam & pressure build up it keeps pouring into overflow and coming out of overflow.
I'm considering it maybe the radiator cap failing as the rubber doesn't seem like it's useful anymore on the cap.


PLEASE HELP!! I have no idea what to try next. Someone on another forum told me to try replacing my EFI switch. I checked all radiator fan relays too but mainly I need help figuring out why my car is having so much trouble idling, etc. It does seem alot better after taking a whole can of TB cleaner though. (didn't stall or idle too low).

[RX400h]

So the coolant is leaking from the overflow tank? Air in the cooling system could cause a high temp condition, resulting in burping of coolant. The temperature sensor could be bad. Do you have a factory service manual? That would guide you in testing various components and subassemblies.. 

[AptNull]

4 minutes ago, RX400h said:

So the coolant is leaking from the overflow tank? Air in the cooling system could cause a high temp condition, resulting in burping of coolant. The temperature sensor could be bad. Do you have a factory service manual? That would guide you in testing various components and subassemblies.. 

I do not have a factory service manual and I was planning on replacing temp sensor, would this also fix the radiator fans not coming on unless I unplugged the connection?

[RX400h]

Based upon the possibilities below, it can also be a fan relay, if you have one. There should be a way to test the sensor. If it is outputting the signal to trigger the relay, then the relay is probably bad. It's always to good to test before replacing.

If the Fan does not Come On at All

What is the problem if my radiator fan wont come on?

If you notice the fan does not turn on at all, it may be caused by a number of problems but here are the most likely 3 reasons.

• The temperature sensor is bad. Generally located by the thermostat housing, this should be the first thing to check and replace since it is easy and inexpensive.
• The fan relay may have failed. If the fan relay is stuck open, the fan will never turn on even if the sensor signals that it should. Replace the fan relay.
• The fan motor may be bad. This can be tested by unplugging the fan and directly connecting a power source to it.

[AptNull]

3 hours ago, RX400h said:

Based upon the possibilities below, it can also be a fan relay, if you have one. There should be a way to test the sensor. If it is outputting the signal to trigger the relay, then the relay is probably bad. It's always to good to test before replacing.

If the Fan does not Come On at All

What is the problem if my radiator fan wont come on?

If you notice the fan does not turn on at all, it may be caused by a number of problems but here are the most likely 3 reasons.

• The temperature sensor is bad. Generally located by the thermostat housing, this should be the first thing to check and replace since it is easy and inexpensive.
• The fan relay may have failed. If the fan relay is stuck open, the fan will never turn on even if the sensor signals that it should. Replace the fan relay.
• The fan motor may be bad. This can be tested by unplugging the fan and directly connecting a power source to it.

Okay so then it's highly likely it's just as simple as a temperature sensor... now are you speaking of the Coolant Temperature Sensor? It is 2 pronged and is long and skinny & bronze in color?

 

Also, I'm thinking EGR valve is reason for rough idle but my friend used his computer and it's not giving any errors. It had a small problem with IAC so I just installed a fresh one to rule that out and did new O2 sensor B1S1 and Downstream.

[RX400h]

I'm not sure what it looks like but there should be mention of it in your service manual. I believe the advice above is referring to the coolant temperature sensor. Is your idle still a bit low?

[AptNull]

2 hours ago, RX400h said:

I'm not sure what it looks like but there should be mention of it in your service manual. I believe the advice above is referring to the coolant temperature sensor. Is your idle still a bit low?

Yes it is still low, and it will stall eventually. Works slightly better with the EGR disconnected from power from what I can remember. There's also alot of hesitation and the car stalled while I was driving the other day.

[AptNull]

Update - I have replaced the following 
All 3 O2 Sensors
IAC Valve
Air Filter
Bought new Clamps for Air Intake Hosing
Cleaned TB & Intake Manifold
Fan Relays for 1 2 & 3 even though I don't have a 3rd.
RAD Fuse in Cab Fuse Box.
Oil Pressure Sensor Switch
Coolant Temperature Sensor

Car runs alot better, no stalling or rough idle except when the P0300 code returns.
I keep getting P0301, P0303, P0305 along with P0300 and P0171 System Too Lean even though I replaced all O2 sensors & disconnected Battery for 5-10 minutes.

I feel like I'm so close, but so far. Anyone have any ideas? Radiator fans still AFAIK do not come on during any operation.
I've been using my scantool to keep a eye on ECT Sensor Graph and highest temperature it's gotten to (while driving, 185F; while idle; 208F).

 

[RX400h]

At what temperature are they (fans) supposed to come on?

[AptNull]

7 minutes ago, RX400h said:

At what temperature are they (fans) supposed to come on?

I believe around 200F. They did actually kick on earlier today which surprised me. Had the car on, and ECT was reading around 210 I think and I had AC running IIRC.
So atleast I know it shouldn't overheat. It did once before, but I think that's because I have a failing radiator cap and there was bubbles in the lines. (Replaced IAC Valve, so had to unhook coolant line & air got into system.)

[RX400h]

Ah, so you may be able to scratch that off the list.👍