Chug chug go broom..hesitation - Air flow?

[RutHunter Junior Member Find all posts View Profile Close RutHunter]

Hi All,

Firstly I'd like to say that the problem happens on Petrol and LPG so we can rule out fuel.

it starts and idles fine with a slight miss now and then.

But when I press the accelerator it coughs for a bit and then catches on and goes but not great like it used to. The problem started a while a go and has slowly gotten worse.

no lights coming up on the dash and nothing specific coming up in techstream when I plug in the computer that I can see or understand.

I can hear the throttle opening through the snorkel sucking air. I think what may be happening is it is not supplying the correct injections to the air and therefore may be the air flow meter might not be supplying the correct current? I have just changed all plugs and all new genuine ignition coils.

your thoughts please?

[Corigator Avid PP Poster! Find all posts View Profile Close Corigator]

Have you tried cleaning the MAF sensor?

[RutHunter Junior Member Find all posts View Profile Close RutHunter]

Well just cleaned the MAF sensor this morning and the coughing seems to have gone away. There is still slight hesitation when the accelerator is pressed but this may go. Had to disconnect the negative from the battery for 10 minutes to reset the ECU as once I put the air flow sensor back in the idle went up to 1200 rpm. Obviously needed a clean even though it looked like new. Can't wait to see the difference in fuel economy. Very easy to clean. By the way the guy at Repco said that the contacts cleaner is the same as the Mass Air Flow Sensor cleaner, they just rename it and make it double the price.

I am selling the original coils for spares for just $30 each incl shipping if anyone wants them, I paid almost $200 each for the new ones. see the for sale threads. Only selling 5, keeping one for a spare my self.

[MidLifeCrisis Out of control poster! Find all posts View Profile Close MidLifeCrisis]

My thoughts
"terrible thread name" Sounds like boy band song title.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

My thoughts
"terrible thread name" Sounds like boy band song title.

I thought it was a great thread title, made me laugh

Cheers Andrew

[Wal01 Junior Member Find all posts View Profile Close Wal01]

I have a similar issue, usually after it has been serviced. Like its running on half rat power. Where is the MAF located so I can give it a clean?

[ratsack Member Find all posts View Profile Close ratsack]

I have a similar issue, usually after it has been serviced. Like its running on half rat power. Where is the MAF located so I can give it a clean?

If it's anything like the 90/95 series, you'll have your air filter which then follows some hosing into the intake of the engine. Between the 2 will be a small thing held by 2 screws into the pipe that has a cable running to it. Unplug the cable and unscrew the screws. It should come out, give it a nice clean spray with the right cleaner, let it dry and then put it back in.

At least, that's what I do...

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

I have a similar issue, usually after it has been serviced. Like its running on half rat power. Where is the MAF located so I can give it a clean?

Have look on top of your air cleaner box, there will be some wires going into the MAF, just remove the 2 screws and pull it out, make sure the O-ring is in place when you replace it.

Cheers Andrew

[Cardinal Fang Lurker Find all posts View Profile Close Cardinal Fang]

Beyond cleaning the MAF, the PCV valve (positive crankcase ventilation valve) is always worth looking at/cleaning/replacing. Easy and inexpensive solution to many engine ills. It should be replaced intermittently for many vehicles but usually gets overlooked during servicing. Here is a reasonable summary:

http://www.agcoauto.com/content/news/p2_articleid/197

[RutHunter Junior Member Find all posts View Profile Close RutHunter]

Do you know where this PCV valve is located on the 1GRFE?

By the way, after cleaning my MAF Sensor I am getting 3 litres better per 100klm on LPG.

[Cardinal Fang Lurker Find all posts View Profile Close Cardinal Fang]

PCV ventilation Valve location and replacement

It is on the very top-rear corner of the passenger side engine valve cover and has a hose leading to the intake. I just rang 2 Toyota dealerships in Sydney to get a part number and price.

The first dealership said the Toyota policy was they do not give part numbers over the phone, but was happy to give me the price - $32.44. They said they had to order it in – 2-3 weeks.

The second (friendlier) dealership gave me a Toyota part number straight up - 12204-31110. They said the price was about $30.00, and had to order it in – 2-3 weeks.

A quick search on the internet has this Toyota genuine item at around US$5.00 elsewhere. So that's a 600% (approx) mark-up by Toyota Australia. They continue to disappoint. You could probably also get it faster from overseas. (anyone tried this mob before? http://www.toyotascionpartsdirect.co...ve/12204-31110)

If you replace or clean this ventilation valve the manual gives the following torque specs for reinstalling: 27Nm (275kgf cm, 20ft lbf).

Hope this helps get you a few more litres per 100…

[RutHunter Junior Member Find all posts View Profile Close RutHunter]

Finally got a chance to check this PCV valve and yes it was full of shit so I cleaned it out with brake cleaner and all good. It still does let a little air in on the reverse cycle which I believe it shouldn't so I will probably replace it altogether. Good tip thanks.

[Wal01 Junior Member Find all posts View Profile Close Wal01]

My problem has almost gone away...........? Leaves me puzzled. I bought new coils thinking they might be the issue but before installing them it improved to the point I thought why waste $600. The problem only occurred after the vehicle was serviced and at 1800 - 2000 rpms either at slow or highway speeds. I have put a petrol injector cleaner in the tank and replaced the gas filter (petrol was replaced at service along with new plugs).

The tappets have not been re-shimmed. Toyota wanted $800 to look at them and a further $1200 to replace them. There is no valve noise so I'm thinking it's not the issue. Surely these issues do not remedy themselves. I have a scan gauge but no codes were listed. I'm starting to think possibly valve recession? Has anyone rebuilt the heads with hardened inserts, if so what cost (the old man just had his 2006 Territory head done for $2000 including disassembly and reassembly)?

The issued occurred on LPG and Petrol but LPG was worse.....mmmmmm

[RutHunter Junior Member Find all posts View Profile Close RutHunter]

What exactly does you engine do at 1800 - 2000 rpms? chug?
If it was valve recession it would happen at all speeds I would think. If it is happening on Petrol and LPG then it is not a fuel supply problem therefore wont be the filters or injectors. From what you are describing the first thing I would do is clean the MAF sensor. Then I would look at the electrics like coils. Remember that LPG is much more touchy than petrol, so for example if there is a problem with a coil it will be more noticeable on LPG. My old 4runner started missing once, but only on LPG, found out it was a lead, on petrol it was fine.

[Wal01 Junior Member Find all posts View Profile Close Wal01]

What exactly does you engine do at 1800 - 2000 rpms? chug?
If it was valve recession it would happen at all speeds I would think. If it is happening on Petrol and LPG then it is not a fuel supply problem therefore wont be the filters or injectors. From what you are describing the first thing I would do is clean the MAF sensor. Then I would look at the electrics like coils.

It was more like lurching like an electrical fault hence the coils. If you had the cruise set at 100 km and 2050 rpm whenever the engine came under load, like a small incline, the engine would miss or shudder (jerk) the whole car on petrol and LPG. Back off ever so slightly so it wasn't under load and it would be fine. My thoughts were a coil breaking down under load.

The plugs were replaced at the recent 175000 km service, MAF sensor was cleaned but the half rat power and lurching remained. I booked it in with an autoelec to check the coil load but it has come good......puzzling. I cancelled the autoelec and thought I'd just replace the coils as the cost was similar but the problem has now gone.

Today I cleaned the throttle body, MAF again, checked the PCV valve. Throttle body was very dirty on the engine side of the butterfly valve (oily carbon deposits). Put it all back together and it revved at 1500 - 2000 rpm at idle. Weird.

I took it for a drive and it was running on and staying high longer in the rev range like a sticking throttle. When rolling and out of gear and the RPM was fluctuating between 1200 - 2000 rpm (needle bouncing between the two numbers). Back to the drawing board.....

Took off the inlet manifold again to make sure no air leaks and no sticking throttle body. All seemed fine. I disconnected the battery to reset the ECU. Now back idling at 700 rpm. Crazy stuff

With the old mans Territory, the only sign of an issue was it would miss (fluff) on one cylinder for about 15 seconds first start in the morning. He did the same stuff as I'm doing now hence why I'm concerned about the valve recession. His motor did 170000km all on LPG.