Prado 1KZ-TE Starting and Idling Problems

[jsbautista08]

Hello everyone! I recently just joined the forum but have been reading posts since I acquired my 120 Prado. I’ve read all the posts that are relevant to my problem and have gone to the auto shop with the information and had repairs/inspections done accordingly but have had only negligible improvement.

Here’s what’s wrong with my 120 (auto transmission):

1. Engine turns but takes time to actually start. We’ve changed the fuel filter assembly & primer, the inlet air temp sensor, turbo sensor and crank position sensor. There have been improvements, but it still occurs intermittently. Sometimes it can go a whole day without problems, sometimes it acts up the entire day. There is a loud clicking sound coming from the engine bay when it turns too long. Have no idea what that is.

2. Idle drops when the vehicle stopped, on drive with my foot on the brake, but only when the ac is on. It gets worse when when I turn the steering wheel, sometimes when I’m in the process parking, the engine actually dies due to the idle dropping too low. But switch the AC off and it idles fine! So just to be safe and to save myself from embarrassment, I just switch off the compressor when I'm parking. No dropping idle.

Mechanics have ruled out the heater plugs. Those have been inspected and everything is in good working order. We’ve also inspected the spill valve with a multimeter and the ohm reading is within spec.

I'm thinking the fuel pump is next on the list, but that's gonna cost a small fortune. Is there a way to diagnose the pump before having to go the calibration route?

We are all dumbfounded, plugging in the diagnostic tool shows no error code. I desperately need your help guys!

 

[Deleted member 13129]

Hello everyone! I recently just joined the forum but have been reading posts since I acquired my 120 Prado. I’ve read all the posts that are relevant to my problem and have gone to the auto shop with the information and had repairs/inspections done accordingly but have had only negligible improvement.

Here’s what’s wrong with my 120 (auto transmission):

1. Engine turns but takes time to actually start. We’ve changed the fuel filter assembly & primer, the inlet air temp sensor, turbo sensor and crank position sensor. There have been improvements, but it still occurs intermittently. Sometimes it can go a whole day without problems, sometimes it acts up the entire day. There is a loud clicking sound coming from the engine bay when it turns too long. Have no idea what that is. when blocked or cracked it gives the symptoms you have .

2. Idle drops when the vehicle stopped, on drive with my foot on the brake, but only when the ac is on. It gets worse when when I turn the steering wheel, sometimes when I’m in the process parking, the engine actually dies due to the idle dropping too low. But switch the AC off and it idles fine! So just to be safe and to save myself from embarrassment, I just switch off the compressor when I'm parking. No dropping idle.

Mechanics have ruled out the heater plugs. Those have been inspected and everything is in good working order. We’ve also inspected the spill valve with a multimeter and the ohm reading is within spec.

I'm thinking the fuel pump is next on the list, but that's gonna cost a small fortune. Is there a way to diagnose the pump before having to go the calibration route?

We are all dumbfounded, plugging in the diagnostic tool shows no error code. I desperately need your help guys!

Hi
Have you looked at the MAP filter at the throttle body side of the intercooler it is a small barrel with two vacuum pipes it filters the air pressure before it reaches the air pressure sensor , it can get blocked with oil vaper coming from the rocker box going through the intercooler , give it a good spray through with carb cleaner so it blows through clean at both ends , also check its not got any cracks in the body as the plastic barrel can get brittle with engine temps as it ages , this map filter fits in a C spring clip at the side of the rubber throttle body and is black on top and gray in the rest including the bottom outlet and fitted upright in a C spring clip , don't confuse it with the vacuum valve on the EGR valve which is smaller and fitted side ways . if the map sensor filter is dirty after cleaning it check for blockage and dirt going toward the sensor fitted to the side of the intercooler at the end facing the front of the car , its all a simple check and clean to do yourself . when blocked or cracked it gives the symptoms you have . also try cleaning the MAF sensor on the air box with alcohol spay see if that helps .

 

[jsbautista08]

Hello TONYCY11, thanks for the reply! I totally forgot to mention that I did pull out the MAP Filter and sprayed it through and through with some carb cleaner. Wasn't dirty at all, carb cleaner came out clean even after shaking it in the filter. Checked for cracks as well and it looks to be in pretty good shape. Even tried to blow into one end with my finger plugging the other end to check if air was leaking and nada. You think it would be a good idea to try and change it to a brand new one?

She actually performed quite well after that for a whole day, she started fine, idle was smooth, I thought everything was fixed...until the symptoms came back again the morning after. Same thing, long cranking with some clicking, rough idling when the AC is on. Been scratching my head about this whole thing really.

 

[StarCruiser]

If all that TonyCY has said doesn’t fix it, I would say this has all the hallmarks of suction/spill control valves. To eliminate everything fuel related before the pump, run from a can straight into the fuel filter, ideally through a separate known good filter into the pump though you may need a priming bulb to do this. Also check/change your air filter and check for any splits in intake pipework.
If it’s still giving trouble it could well be worth changing SCVs, I’ve read on here that they seem to be the major thing to fail with these and changing seems to be the only cure.

 

[jsbautista08]

Hello StarCruiser! Great idea running from a can as an elimination process. I ought to check the intake pipes as well for any cracks. I do remember reading somewhere on here that though the SCV shows normal ohm readings, it can still be busted. So that's worth a shot.

The only problem here in the Philippines is that the SCV is only sold as part of the fuel pump, can't get it separately. I'm gonna have to find one somehow just to event test it

 

[StarCruiser]

Hmm, try either Amayama.com, Partsouq or Megazip or failing that Roughtrax here in the UK have them and might be able to ship if you ask them. After all, they are small fairly lightweight parts.

 

[Deleted member 13129]

Hello TONYCY11, thanks for the reply! I totally forgot to mention that I did pull out the MAP Filter and sprayed it through and through with some carb cleaner. Wasn't dirty at all, carb cleaner came out clean even after shaking it in the filter. Checked for cracks as well and it looks to be in pretty good shape. Even tried to blow into one end with my finger plugging the other end to check if air was leaking and nada. You think it would be a good idea to try and change it to a brand new one?

She actually performed quite well after that for a whole day, she started fine, idle was smooth, I thought everything was fixed...until the symptoms came back again the morning after. Same thing, long cranking with some clicking, rough idling when the AC is on. Been scratching my head about this whole thing really.

If the map filter is clean and not cracked it don't need changing like starcruiser said it very well could be SCV problem , but also try cleaning the MAF sensor on the air box with MAF spray if you haven't already done so before you start spending big money .

 

[MarkW]

Is there not a system that increases idle with the AC on? And something similar with the power steering. If it idles fine without the AC or turning the sterlering wheel it has to be something connected to those systems

 

[jsbautista08]

@MarkW , my thoughts exactly. Actually, it idles fine even if I turn the steering wheel as long as the AC is off. I just don't know where to look so I can try to adjust the idling.

 

[jsbautista08]

If the map filter is clean and not cracked it don't need changing like starcruiser said it very well could be SCV problem , but also try cleaning the MAF sensor on the air box with MAF spray if you haven't already done so before you start spending big money .

My 120 doesn't have a MAF sensor on the box, what it does have is an Air Inlet Temp Sensor located on the throttle side. I changed that to a new one and had some improvement but it didn't completely solve the problem.

 

[jsbautista08]

Hmm, try either Amayama.com, Partsouq or Megazip or failing that Roughtrax here in the UK have them and might be able to ship if you ask them. After all, they are small fairly lightweight parts.

Thanks for the sources @StarCruiser , that'll come handy once it's determined that it really is an SCV problem. I'm gonna have her fuel system diagnosed on Tuesday at a reputable auto centre, hopefully we can get to the source of the problem soon.

 

[StarCruiser]

@MarkW , my thoughts exactly. Actually, it idles fine even if I turn the steering wheel as long as the AC is off. I just don't know where to look so I can try to adjust the idling.

The thing is, your OP and title outline starting problems, not simply the idling problems that would occur if the ‘idle up’ Control were faulty. I’ve no idea how this operates on a 120 but under normal conditions there should be a slight change in tone each time the compressor kicks in. If correct, two things happen, the clutch on the AC compressor is energised and the engine is given a little extra throttle (the idle throttle stop is raised slightly) to compensate. This can be checked if you unplug the AC compressor at the magnetic clutch lead (single wire) and then switc on the AC, the engine should increase its idle speed as there is no load (compressor) for it to drive.

Good luck on Tuesday.

 

[Deleted member 13129]

Thanks for the sources @StarCruiser , that'll come handy once it's determined that it really is an SCV problem. I'm gonna have her fuel system diagnosed on Tuesday at a reputable auto centre, hopefully we can get to the source of the problem soon.

One thing to try that costs nothing is take off the MAP filter and temporary join the pipes with a unrestricted tube if it runs well with AC on in idle buy a new MAP filter .

 

[jsbautista08]

The thing is, your OP and title outline starting problems, not simply the idling problems that would occur if the ‘idle up’ Control were faulty. I’ve no idea how this operates on a 120 but under normal conditions there should be a slight change in tone each time the compressor kicks in. If correct, two things happen, the clutch on the AC compressor is energised and the engine is given a little extra throttle (the idle throttle stop is raised slightly) to compensate. This can be checked if you unplug the AC compressor at the magnetic clutch lead (single wire) and then switc on the AC, the engine should increase its idle speed as there is no load (compressor) for it to drive.

Good luck on Tuesday.

This seems like something that I should seriously look into. Upon observation, there is no change in idle speed when I switch the AC on. Idle is at 700 rpm upon starting the engine and remains at 700 even as I switch the AC on. Should the rpm go up to about 800?

 

[jsbautista08]

One thing to try that costs nothing is take off the MAP filter and temporary join the pipes with a unrestricted tube if it runs well with AC on in idle buy a new MAP filter .

I'm gonna try this today @TONYCY11, I'll report back if there's an improvement.

 

[StarCruiser]

This seems like something that I should seriously look into. Upon observation, there is no change in idle speed when I switch the AC on. Idle is at 700 rpm upon starting the engine and remains at 700 even as I switch the AC on. Should the rpm go up to about 800?

Sounds like it’s working, as it would drop the idle speed if the idle up wasn’t working due to the load of the AC compressor.

 

[jsbautista08]

Sounds like it’s working, as it would drop the idle speed if the idle up wasn’t working due to the load of the AC compressor.

I need to correct myself, it’s idling at 700rpm without the AC and around 800rpm with the AC. So I guess it’s fine. I took a video of how the rpm drops as I turn the wheel, I’ll upload as soon as I get the chance.

 

[jsbautista08]

Here are the videos:

AC On

AC Off

 

[jsbautista08]

Also, here’s a photo of my fuel pump. The SCV part looks nothing like the ones I’ve seen on other photos. And a photo of my fuel filter (is there anything I can try to adjust there that would make a difference?)

 

[StarCruiser]

How did you get on running from the can Jay? This should eliminate anything upstream of the pump.