Lumpy vvti idle and stalling...?

Hi chaps,

Is there any way to increase the idle speed of a vvti? I'm running stock ecu and maf sensor. And the idle is around 550rpm when warm, which makes my dash lights go a little low and some vibrations creep in. If I feather the throttle and hold it at 650rpm (where it should be) all these problems go away.

My first step would be to reset the ecu. Then check all your remaining vac hoses.

This is a really common issue, without a single known fix. The vvti throttle can be the cause, but these are hard to come by and very expensive (why i went for the Whifbitz porsche dbw conversion).

Apparently doing the permanent 12v fuel pump mod (bypassing the stock fuel pump controller) can work.

Maybe worth also getting a compression test done. As you're still running a stock ecu, it's conceivable it's run lean on boost at some point and damaged the block/ head/ piston/ring in one or more cylinders. This is obviously the worst case scenario so I wouldn't get too worried yet. Is it smoking much on idle?

Hey Jason, thanks for the reply, it doesn't smoke at all when warm, sometimes smokes a bit until it is, white smoke. I already have the 12v mod.

I'm just trying re-setting the ecu as we speak but I've noticed the idle hunts a bit, and the afr goes from between 13.5 to 16.5 on idle. Usually sitting somewhere in the middle at 15. What's it supposed to be?

Do vvti have iacv? I seems to remember people with idle problems cleaning them?

No I dont think so, I think they use the stepper motor on the throttle body to regulate the idle. That s also why there isn't an idle screw to adjust.

Nope no ICV. I had problems with mine after the battery went flat it forgot how to idle, just kept stalling.

The fix for me was turn the key to on but don't start the engine. Then push accelerator to the floor and hold for 30secs. A beep and some whirring later and the idle was back to normal

How weird, who told you to do that and why would that work?

It resets the throttle body

Post 5 in this thread I started when I had problems.

http://www.mkivsupra.net/vbb/showthread.php?339649-ICV-stuck-Car-won-t-idle

I have also found mention of it in another thread via the search function.

Thanks mate, I'll try in the morning and report back.

Tried the throttle reset this morning and nothing happened. Tried a second time to be sure and heard no beep and no whirring noise

Any other choices?

Strange, have you tried looking for any fault codes?

BTW because you have a VVTI car a Bluetooth OBD2 adaptor and the "torque" app can be used .

Just checked them and have a whole host of error codes

12: No "NE" or "G1" and "G2 signal to ECM for 2 sec. or more after cranking.

41: Throttle Position Sensor Signal

43: Starter Signal

I also got 44, 45, 49 and 51 but none of those seem to be codes according to this: http://www.mkivsupra.net/vbb/showthread.php?35920-How-To-Check-the-diagnostics-codes thread.

Are VVTI codes the same as non-VVTI?

I also just reset the ecu by disconnecting the battery and removing efi fuse no.1 for 5 mins (overkill i know)

I checked the codes once more without even starting the car and none of them went away.

The throttle position sensor could conceivably be the cause of your idle issue. Presumably this is replaceable on it's own, though you may have to look around as Toyota may not supply them separately.

Just checked them and have a whole host of error codes

 

12: No "NE" or "G1" and "G2 signal to ECM for 2 sec. or more after cranking.

 

41: Throttle Position Sensor Signal

 

43: Starter Signal

 

I also got 44, 45, 49 and 51 but none of those seem to be codes according to this: http://www.mkivsupra.net/vbb/showthread.php?35920-How-To-Check-the-diagnostics-codes thread.

 

Are VVTI codes the same as non-VVTI?

No, and with all those codes it wants crushing....

Meany

Do you know where I can find the vvti fault codes Chris?

I'm no expert but followed this thread to get the torque app to work.

http://www.mkivsupra.net/vbb/showthread.php?275824-Real-time-info-from-standard-VVTi-ECU&highlight=Custom+init

I swear when I looked for fault codes on my car it both found one and gave the description of it

They seem to be hard to come by, that's a disadvantage of the VVTi, the lack of English manuals and details like this. All I can suggest is Google, there may be some info out there, but I have no definitive list, sorry Mike, I'd post it if I knew.

I'm no expert but followed this thread to get the torque app to work.

 

 

http://www.mkivsupra.net/vbb/showthread.php?275824-Real-time-info-from-standard-VVTi-ECU&highlight=Custom+init

 

I swear when I looked for fault codes on my car it both found one and gave the description of it

That's fantastic Sam thank you very much mate. Just ordered one.

They seem to be hard to come by, that's a disadvantage of the VVTi, the lack of English manuals and details like this. All I can suggest is Google, there may be some info out there, but I have no definitive list, sorry Mike, I'd post it if I knew.

No worries mate, tried Google several times and came up with nothing. Hopefully the thing Sam linked to works.

So....i bought an OBD 2 adapter to check my fault codes and even though i have some stored in the ecu the adapter said i had no faults, whilst reading all other sensors from the engine just fine.

Whilst i had this adapter plugged in the car nearly stalled...came back to life, but the engine check light came on and the car went into limp mode, so accelerator did nothing until last 10% of it's travel. I've never had this happen before and it happened twice in a row with this adapter fitted so i'm presuming it's an adapter fault. The car then threw up fault code P1633 which is ECM malfunction: ETCS circuit. But again, i'm presuming that's only down to the adapter fault.

Car is running fine under normal driving but at idle and only when warm (idles perfectly steady when cold until water temp gets up to about 85ish degrees and idle naturally drops.) the idle is uneven and the AFR goes up and down between 13.5 and 16.5, idle drops as low as 400 sometimes and usually sits around 500-550 which is too low.

What is the connection to the stock water temp sensor like?? I had this on my non VVTI, Was getting a very bad signal from the Stock temp sensor. Its odd it happens when the car gets up to full temp.

And that would make the car idle poorly mate?

And that would make the car idle poorly mate?

Certainly, as would a drive by wire throttle body potentiometer issue, which is sadly now common as the VVTi's age.

If you are going for a decent standalone ecu cry at some point, I would ditch the stock throttle assembly for a Whifbitz true dbw conversion. The throttles are pretty common, reliable, support big power, and can be had used from £50 (or £150 brand new)