96 LS 400 done 320k been serviced well,was running rough ,tested leads 3 were no good,replaced with OE set,ran on 8,test drive it pouring blue smoke out of left exhaust twin pipe.starts instantly but overfuelin massively,can put finger in exhaust and unburnt fuel,no engine check lite at all?!Anyone any idea wrong with it,have never seen a 1uz-fe smoke.!
mechnificent,
Sep 29, 8:54am
Oiled up O2 sensor and someone has modified the ecu so the trouble codes don't log ?
The smoke and the unburnt fuel are two different problems.
Was it smoking before you changed the leads ?
You can test the O2 sensor using a simple analogue volt gauge. Use two pins to back-probe the O2 sensor's plug and then with the engine running measure the voltage at the pins. The voltage should fluctuate between about poing 1 and point 9 of a volt. If the voltage is out of range, or not fluctuating, then there is a problem with the system.
mechnificent,
Sep 29, 8:56am
It could also be a leaking injector. too much fuel washing the bores and causing the oiling. It should set the light on and set a trouble code though.
Have you tried pulling the trouble codes out ?
ema1,
Sep 29, 8:57am
Possibly if it had 3 dud leads as you say there might be a bit of oil collecting in a muffler over time so I'd give it some time to burn off any likely oil in muffler by going on a decent length drive. Other than that I'd suspect a PCV fault. or an O2 sensor fault get both checked out plus any other likely cause. Also check for if any changes from standard ECU settings have been made? . Get it checked anyway if your unsure?
flack88,
Sep 29, 9:00am
Yes did start smoking before the crook leads,the ECU has never been touched know previous owners,the overfueling has happened since the smoke,its got correct oil and still clean.thanks for info.
ema1,
Sep 29, 9:02am
Have you noticed any big use of oil showing gone down on the dip stick and what amounts have you topped it up by/distance traveled? Wonder if cold start circuitry is faulty or there is a temp sensor fault upsetting the ECU? This needs seeing to quickly as over fueling is detrimental to engine life and fuel economy.
flack88,
Sep 29, 9:05am
Yeah last 500k trip when smoke started,changed oil still smoke,and scoffing gas .
flack88,
Sep 29, 9:06am
Temp gauge not reading either,used to.!
ema1,
Sep 29, 9:07am
Major check of all sensors etc related to ECU and fuel system check required. Toyota service required to sort this one, have the car checked for possible vac leak as that will make for big increase on fuel usage. you'll probably be down on power too marginally? The ECU might also be at fault as in faulty/leaking capacitors or crack in circuitry try another ECU that's known to be a good one the same type just to see if there's any change, won't do any harm trying?
flack88,
Sep 29, 9:09am
Burned sump oil in 450k trip.
ema1,
Sep 29, 9:15am
PCV fault likely?
flack88,
Sep 29, 9:16am
Theres no blow by or fumes,didnt have compression tester that was long enough to test,pulled hose off rocker and it ran rough with air leak to manifold,but came good when put back on,so Toyota to get scan then.thanks for advice.
ema1,
Sep 29, 9:18am
I very much point my finger at PCV not functioning, it's a fault they can happen just out of the blue. Replace the PCV with a new one. betcha that's your problem right there.!
thejazzpianoma,
Sep 29, 10:27am
Start with this! If the car thinks it's cold it will over fuel. Doesn't necessarily account for blue smoke on one bank (although could be due to bore wash) but start with testing the temp sensor and getting it sorted. Some cars use the same sensor for ECU and gauge some do not. Either way, you really want this sorted before carrying on with your diagnosis.
thejazzpianoma,
Sep 29, 10:59am
Top right of page is the coolant sensor, rather than me explaining how to test there are no doubt millions of articles and youtube videos on the subject.
Cleaned the PCV was ok ,can smell fuel in the oil on dipstick ,oil still very clean,massive amount raw fuel out exhaust at idle,Thanks jazz
thejazzpianoma,
Sep 29, 3:55pm
You are most welcome. As above, sort that then come back if it still has the issue. No point in continuing until that is sorted though IMO.
yz490,
Sep 29, 4:34pm
if the oil's been diluted with fuel is re-breathing fumes of the oil & umm, running on the smell of an oily rag. Only partially relevant but had that on early Yamaha 4 stroke 3 wheeler's where via a carb float valve fault they'd empty the tank into the sump through the breather into the crankcase from the air filter box. Didn't half cock up the carburation, rich idling being so bad they'd just stop. Change the oil & re-route the breather & all good. Simple old stuff compared sorry. Think you said your temp gauge isn't working. Is it way way low on water for some unknown reason & not touching the sensor causing it to think it's cold then making it run rich. Maybe not or it would be complaining in other ways by now. Modern stuff is beyond me so ignore me lol. Just to Edit that, an old guy i know [even older than me] has a late model Lexus V8 & developed a radiator fault so got a new aftermarket one of ebay & has been good for a couple of years. Not relevant i know but! .
elect70,
Sep 30, 9:01am
Had a similar experience with a BMW V8 . wasnt firing on 3 . new leads & ran ok but smoked . big time , petrol in the oil , changed it & all Ok
flack88,
Sep 30, 9:32am
Has already been changed,burnt a sump of oil,but wasn't over fueling like now,just 2ton hunk of jap scrap metal at the moment!
elect70,
Sep 30, 12:22pm
Has it got an OB2 socket on it garage man can plug a scan into ? Only way or otherwise do a swapatron onall components until its fixed i had early EFI range rover had no way to scan for faults but with a bit of searching found the relevant values for all the sensors & air flow meter & injectors . Couldnt diagnose faults in the ECU though . Luckily used parts dime a dozen --unlike my BMW crank & cam sensors $250 each
thejazzpianoma,
Sep 30, 2:44pm
If the problem remains after fixing the coolant sender/gauge issue then and only then in my opinion is it time to move on to obd etc.
If it has a round plug there are ways of checking the codes, but hopefully yours might have a rectangular plug. I say hopefully as the Americans implimented OBD2 from about 1996 but yours is likely ex Japan so different rules can apply (sometimes they switch them all early sometimes not).
Anyhow, if you own an android smart phone it would be worth grabbing yourself one of these. It's about the cheapest way to get a basic OBD2 read. You just need that and the "torque" software that costs next to nothing. Because you have an engine/fuel problem this basic setup will likely work perfectly (as opposed to transmission or airbags etc).
1429231595 - listing number for obd adaptor
This article shows you what the round plug looks like which hopefully yours does not have. If you have the rectangular version go ahead and order the above if you want to proceed further (or just want to have one handy for next time which would be very wise IMO).
Incidentally. if you really wanted to see for yourself that it is over fueling due to the temp sensor issue. Order the adaptor and let me know. I can walk you through where to look that will show this fairly definitively. It's always fun as then you get to see the parameters change after the repair is done.
rlr29,
Sep 30, 4:45pm
I had a Falcon do this. Filled the sump and exhaust with fuel and then backfired. People came from two streets over to see what happened.
mechnificent,
Oct 1, 5:12am
The trouble codes for that vehicle may be accessible without a scan tool. If it's pre obd2 it should have the toyota style rectangular plug under the bonnet in which case you just jump two pins and the codes flash on the dash light. If it has the obd2 plug it may still be possible to access the codes by using a jumper and reading the code on the dash light. In the process of phasing in the obd2 protocol some manufacturers installed the obd2 plug but didn't follow all the obd2 protocol. They sometimes used the plug with the manufacturers scan or assembly line tool to access the data, but they also allowed a jumper to be used on what's known as the manufacturers pin. There are two pins in the plug for each of the five protocols used. One pin delivers the mandated emission sensitive data which standard obd2 readers(or factory tools) get, and the other one, known as the manufacturers pin, gives access to all of the cars control units(such as body, aircon, trans, abs), either with a factory tool or a well set up laptop. In the phasing in stage they often allowed a jumper from the manufacturers pin for the relevant communication protocol(iso, pwm, can etc), to earth, so workshops could access trouble codes without the code readers.
Google will tell you which protocol that car uses, and you can then look up which manufacturers pin to try jumping for that communication protocol. It wont cause any problem to try it. The communication pins are all able to be earthed without damage. If you short the twelve volt pin it will blow a fuse of course.
Hope that all makes sense and helps. if not, ask, or google " obd2 plug manufacturers pin", or something like that.
flack88,
Oct 1, 5:23am
Yes has standard rectangular Toyota plug.
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