A miss and a stall, a bodgey idle and a big puff of smoke

[**Anyhow]

I have a 1uz in my 4runner work car and have so far done about 25k kms on it. But i have an ongoing problem which is atarting to drive me crazy. Starta fine every time and some days can be started 20 or 30 times. But every 6th start, on average, one hell of a puff of smoke comes out of it. smells like fuel, but almost white. and there is a miss... usually under power, and much more noticible when cold. and after a heavy boot in first(usually, sometimes second) there seems to be a total loss of spark for about a second.
and pulling up at the lights i have to keep an eye on the tacho as it seems to have a tendency to stall after jumping on the picks, usually after having the idle bounce between say 400 and 800 rpm a couple of times. as soon as the key is touched she fires back up and the idle stays constant. sometimes the idle can be all good and then it will just start to bounce up and down for no apparent reason.
i have had several mechanics look at it, but seeing as there never appears to be a fault code and everyone is stumped.
i have...
replaced plugs
leads
coils
cat
had the fuel system cleaned and tested
ignition system too... supposedly

going shopping for new O2 sensors next

and failing that will have to seriously consider and aftermarket emc

all of these issues seem to be intermittant... all suggestions greatly appreciated

Kane

 

[Zuffen]

Check your idle control valve is doing it's job.

Sounds like it's sticking.

Let me know if you need a replacement.

 

[XR8tt]

If its runing rich or the 02 sensers read that it is ??
The ECU open up the ISP to lean it out which [can] cause this
erratic idle..
Is the TPS voltage set low enough at idle ??

 

[earthman]

**Anyhow,

Not sure about a lot of your symptoms but one of them sounds familiar. Here is what I wrote for another post:

http://www.lextreme.com/forums/showthread.php?t=8926&highlight=alternator+idle

"My idle bottomed out (and bounced between 400 and 800) when slowing down and stopping for about 2 months. Very strange symptom. Could not work it out for ages and tried everything from least expensive thing to fix to the most expensive, of course it ended up being the most expensive: the alternator.

I tried cleaning ISC, changed AFM, cleaned throttle, checked for vacuum leaks, checked coil and ignitor wiring, checked ECU plugs for corrosion, changed the ECU water temp sensor and the alternator was last on my list but I did not get to it before it died and it left me stranded. I got a new one and have not had the problem since."

basically the alternator was not working at low RPM. Others have found similar: http://lextreme.com//forums/showthread.php?t=6186&highlight=low+voltage

hope this helps and let us know how you go.

 

[**Anyhow]

XR8tt... i have no idea... sorry... im not that far into it

Earthmann... i had the alternator checked and it is apparently doing its job. could the alternater be having this intermittant issue???


and i should say that its more of a surge then a miss while accellerating... and sometimes after restarting it will idle around the 1500 mark for about 15 seconds then slowly drop back to normal

 

[XR8tt]

Hmm ?? Check things that measure / calibrate tune like air meter, 02 sensors, fuel reg and delivery...
I had a charge issue in another brand like this...
It was a faulty cell in battery and alternator overcharged..
If ECU can be checked for faults?? Through a dealer etc??
Could be another option, it at least reads all the sensors are within calibration and working.

I would suspect a blown head gasket ??

 

[**Anyhow]

found one problen to be the battery... as you said... a bad cell. but the alternator seemd to be ok. was told its not the O2 sensors or a blown gasket. have a new AFM on the way.
fingers crossed at the moment

 

[earthman]

Thanks for getting back to us mate. It is interesting that charge (alternator and battery issues) can cause problems with the idle. Hope your vehicle is running OK now.

 

[**Anyhow]

ahh... yeahhh.. the battery has fixed a problem that i didnt mention in my origonal post. Namely... flat battery... regularly... but thought it may have had something to do with the alternator, not a dead cell. DOH

all symptoms still exist, hope hinging on the afm at the moment

 

[XR8tt]

Strange as it MAY seem ???
I have seen engines run like this when fuel filter is blocked...
Seems ECU is over compensating for low fuel pressure ????
Exhaust leaks can cause strange fuel mixtures also...

 

[**Anyhow]

Fuel filter was done last service... and i had a new sports exhaust put on only about 6 months ago. will get that checked the next time i go past the shop where i had it done.
still waiting on that afm... how hard can that be???
and about to install a new icv... thanks again Rod

 

[XR8tt]

Check anywhere coolant can leak into inlet manifold ??
Sounds like a head gasket problem ??
White smoke and engine miss explained as said seems to point me in that direction..

Depending on what sealant they used on exhaust??
They often use silicon which can stuff up 02 sensors ??
Check they are connected properly..

 

[**Anyhow]

ok... since replacing the IACV i have not seen the regular puff of smoke (more like a smoke screen). the miss/surge is still there as is the occasional stall. still trying to source the AFM...

 

[**Anyhow]

ok... since replacing the IACV i have not seen the regular puff of smoke (more like a smoke screen). the miss/surge is still there as is the occasional stall. still trying to source the AFM...

i spoke tooooo early... nearly killed the pensioners whose driveway i was in when i started it this afternoon

 

[earthman]

Hey man, Any Updates?

 

[**Anyhow]

WELL... now that you mention it...

Since getting my hands on a replacement AFM things seem to have picked up.
The regular stall has has pretty well disappeared. The smoke screen has not repeated itself. the dodgy idle still has its moments... but very rarely.
Im thinking that a combination of replacing the IACV an the AFM has solved there issues.

The surge is still there under flat to the floor stuff, and is more promonent the larger the load. But it IS better...

The one problem that has not changed... when shifting to 2nd (or occasionally 3rd when merging onto the highway) after full throttle, almost redline, i find that if i try for a quik gear change (quik clutch and juice off and on) i have one hell of a dead spot. a second, maybe 1 and a half, where there is absolutely nothing. as if all electrical power has been shut off. going for a not so quik change, easing off and on the juice i dont seem to have the problem, and it is quite smooth.

I think half of my problem is that i used to have real tough street machines and even though this thing sounds like one... it is still a 4WD and should be driven like one

 

[earthman]

Hmmmm..... this is purely a guess, but if it is struggling when revving high could that be a fuel pressure or fuel starvation issue? Maybe the pump or relay? what sort of pump is it?

 

[**Anyhow]

it still has the standard v6 fuel pump that 4runner came with. when i had the injectors cleaned they did a full check on the system and said that there was heaps of room to move and plenty of pressure. its funny because it has done it at low revs as well. not very often but...

still open for suggestions

 

[earthman]

Yeah, mine still has the old V6 pump too and it works fine with no issues.

geez.... don't know.... sticking or loose throttle cable tension maybe?

 

[**Anyhow]

yeeaaaahh.... nah. checked that the other day while i was in there. was talking to a bloke the other day who said it might have something to do with the 4WD suspension extra travel etc. dont suppose you have ever noticed anything like it with yours...