Low idle sometimes stalls (1 Viewer)

[BOB F]

View attachment 1355120

Got it thank you.

That is one clean engine!!

I am assuming the RR on the fuel filter is straightforward?

Thank you

 

[2001LC]

Pull EFI fuse and crank engine to release fuel pressure first.

 

[BOB F]

An update and request for help.

I never had a chance to clean the TB as I was going away. The day I was leaving I was going to take the LC to the airport and I started it in the morning just to see if everything was OK. It started fine and idled ok. Dummy me, I forgot to turn it off and took my DD to work. When I came home midday to go the airport, the battery was stone dead. I think it stalled and lights were on. I left on my trip.

I came home and charged the battery and it started right up. As I sat in it, it would occasionally on revving, drop the idle and stall. I planned on getting into the TB cleaning this weekend.

The next day I tried to start it and now it wont start. There is some ignition like its trying but it won't fire up. This is not the EFI fuse issue in which there is no ignition, it is occasionally getting fuel and spark.

Where should I start? I am thinking fuel pump. Fuel filter?

Thank you for any help

 

[Julian Stead]

What is your battery condition like, could you have a bad battery. See what the voltage drops to under crank? Also try keeping your foot flat on the gas pedal to allow more air in as the engine might be flooding due to a faulty throttle body.

 

[BOB F]

What is your battery condition like, could you have a bad battery. See what the voltage drops to under crank? Also try keeping your foot flat on the gas pedal to allow more air in as the engine might be flooding due to a faulty throttle body.

Battery is less than a year old. It cranks like crazy. I don't think it's the battery.

I'll try the pedal. You mean flat to the floor?

 

[Julian Stead]

Yes flat to the floor. If the idle control is sticking then this could cause the engine to flood, Pedal to the floor might help it fire up as you allow more air in.

 

[BOB F]

Yes flat to the floor. If the idle control is sticking then this could cause the engine to flood, Pedal to the floor might help it fire up as you allow more air in.

I just went out my foot to the floor and it started on the first fraction of a turn.

I honestly don't think it was the pedal position that did it. I think it would have started right away anyway.

Left it running. See if it stalls again. I'm going to start by cleaning the TB this weekend.

I don't trust it to use it like this.

 

[2001LC]

Why don't you think pedal position?

 

[BOB F]

I just went out my foot to the floor and it started on the first fraction of a turn.

I honestly don't think it was the pedal position that did it. I think it would have started right away anyway.

Left it running. See if it stalls again. I'm going to start by cleaning the TB this weekend.

I don't trust it to use it like this.

It stalled and on trying to restart it's acting like it's missing.

Water in the fuel?

Why don't you think pedal position?

on restart try that wouldn't work. It sort of started with a miss.

 

[2001LC]

Water in fuel, dam. Unfortunately 100's don't run on water, nor have fuel tank water drains like aircraft.

You asked where to start; drain fuel/water and replace with fresh 91oct.

Toyota OM recommend two things not to do, that you've done. Avoid prolong idling, don't leave key in on position when not running.

 

[Julian Stead]

I would get a fuel sample, that would rule out or confirm water in fuel. Water in fuel will normally affect more than just idle though, but you do have to rule it out. After it cuts out you could pull the spark plugs to see if they can give you a clue to whats going on. But cleaning the throttle body would still be no1 on my list.

 

[BOB F]

That will be my first task.

In watching some videos on cleaning the TB , in one he unbolted the TB and cleaned it outside of the car, replacing the gasket, etc.

Do you guys do that or just clean what you can access through the throttle plate?

 

[2001LC]

In aircraft they have a drain at bottom of fuel tank. During pre flight inspection we drain a little fuel off with plastic tube. We then inspect the fuel for water. Water sit at bottom, fuel on top. We've no way do this with cars. Why did you even bring up water?

Clean Throttle Body in place.
Read post #18 again.
I'm still very concerned with your EFI fuse mod and why you did it.

Here step by step for minor tune up. It's important to eliminate the simple stuff before moving on.

1. Remove EFI fuse. Then crank engine to relieve fuel pressure. (If replacing fuel filter)
2. Disconnecting battery (negative post first), cleaning & greasing both post. Leave battery disconnected (for minimum of 30 minutes), to rest ECM. NOTE: The very last thing you do is reconnect battery.
3. Replace fuel filter. Put EFI fuse back in.
4. As you remove air box; Clean MAF sensor with a spray can of MAF Sensor Cleaner & inspect air filter. Don't touch thin internal wires or get anything like grease or oil on them. Use a little dielectric grease on connection in hardness.
5. Inspect all vacuum hoses for cracks and tight fit.
6. Remove PCV and soak in solvent.
7. Clean throttle body in place. I use Sea Foam lube, tooth brush & brass brush along with dental tpye mirror to clean. Avoid getting excessive amounts of solvent like sea foam lube into axle holes of butterfly. Some feel this can damage throttle body motor/gears.
8. Test and replace PCV (air passes one direction only). PCV Grommet on pre 2003 must have tight fit or replace. Replacing both PS & DS PCV hose if loose fit.
9. Remove spark plugs, inspect, clean & test. Use spark plug cleaner, test resistance & gap. Note: Do not change gap of used plugs.
10. Reassemble in reverse order.

You'll here a hum coming from throttle body motor with key in on position. IDK but it may be possible to damage the TB motor, when key on static (engine off). What do you think @Julian Stead ?

 

[Julian Stead]

I don't think it will damage it as it is designed to constantly run. If the car runs perfectly other than cutting out at idle, then TB is most likely to blame. I would suspect water in fuel only if it cuts out whilst driving for no reason not just idle. If you had a vacuum leak, I would expect the idle to raise and the engine to run lean. Poor oil change intervals and clogged PCV valves affects throttle bodys due to crank case pressure rising and fouling the intake which inturn fouls up the throttle body.

Start at the air filter, check if its clean and change if required.
Check MAF and clean if required.
Check throttle body and clean.
Check condition of vacuum hoses.
Change PCV valves if throttle body was very oiled up.
Change engine oil and filter if it hasn't been changed.
Disconnect battery and relearn ECM.

To check for water in fuel just put a fuel sample in a bottle from the pipes in engine bay, just use the fuel pump to extract some fuel from the tank. Might aswell change the fuel filter at this stage if you haven't done it in a while.

 

[2001LC]

I don't think it will damage it as it is designed to constantly run. If the car runs perfectly other than cutting out at idle, then TB is most likely to blame. I would suspect water in fuel only if it cuts out whilst driving for no reason not just idle. If you had a vacuum leak, I would expect the idle to raise and the engine to run lean. Poor oil change intervals and clogged PCV valves affects throttle bodys due to crank case pressure rising and fouling the intake which inturn fouls up the throttle body.

Start at the air filter, check if its clean and change if required.
Check MAF and clean if required.
Check throttle body and clean.
Check condition of vacuum hoses.
Change PCV valves if throttle body was very oiled up.
Change engine oil and filter if it hasn't been changed.
Disconnect battery and relearn ECM.

To check for water in fuel just put a fuel sample in a bottle from the pipes in engine bay, just use the fuel pump to extract some fuel from the tank. Might aswell change the fuel filter at this stage if you haven't done it in a while.

Good idea you have for checking fuel

 

[BOB F]

Poor oil change intervals and clogged PCV valves affects throttle bodys due to crank case pressure rising and fouling the intake which inturn fouls up the throttle body.

Ok.. Hopefully I am not being premature here but...

I am somewhat embarrassed but this is my wife's car and when some of this started a couple weeks ago, she said to me, "whenever it ran funny I would go get the oil changed and it seemed better. Do you think that might be it?" To which I of course replied, "No, there is no relationship"

Reading Julian's quote above I thought, hmmm... I went and got the oil changed and...all symptoms have disappeared, Car starts perfectly, no dropped idlling and runs great. I drove it about 25 miles with a few stops and engine off, a bunch of lights, even had it inspected in which she started and stopped it three or four times. Perfect!

So where is that crow my wife will serve me??

I will still clean the TB but at this point I think Julian nailed it with just a thought. The car was only 1500 miles over its 3000 mile oil change. We do change it regularly. I am wondering if this car is sensitive to what Julian said and in the past my wife actually was spot on!

2001LC... the fuse box repair issue was a separate problem which I believe I have resolved with my mod. That had been going on intermittently for a few years and has been discussed at length in this forum.

I am hopeful that this issue is behind me and I thank you guys for your quality responses and help.

I checked my records and I had serpentine belt, fuel filter, plugs and air filter done 11 months ago.

Thanks again. I have an issue with the drive that ill post in another thread. But I am mostly confident in taking the car out and about.

I just made an appointment to have the timing belt, etc. done as well.

 

[Julian Stead]

I would still clean MAF and Throttle body. Also renew PCV to get the engine breathing better, it might not be so sensitive to oil change intervals after that.

 

[BOB F]

I would still clean MAF and Throttle body. Also renew PCV to get the engine breathing better, it might not be so sensitive to oil change intervals after that.

Thank you Julian. Good stuff. Been around cars all my life and this is a revelation to me.

 

[BOB F]

Cleaned MAF and TB. Runs beautifully!

DC battery and have a CEL. P0115. Coolant temp circuit? I'll see if it comes back.

 

[DirtDawg]

Cleaned MAF and TB. Runs beautifully!

DC battery and have a CEL. P0115. Coolant temp circuit? I'll see if it comes back.

How dirty was the TB?

Amazing how such a small amount of grime can reduce the airflow that much.