Car Engine (1Az-Fse) Running Rich On Fuel

[syncview]

what about the afr sensor? can you show us the graph?

[syncview]

the fuel pressure seems to be low as it shouldn't go below 8 MPa

it should vary between 8-13MPa

[Vlado P.]

it only goes to 6 MPa when i select -25% pressure in techstream test.

the lambda sensors seem to be working fine, sinusoidally from 0.4 to 0.8 volts

[syncview]

also test the fuel pressure sensor itself

check the service manual

[Vlado P.]

i haven't performed this test, but will check the manual this weekend. is it something that requires special equipment?

[syncview]

drive the car with the tech steam connected.. graph the fuel pressure

see if it ever drops below 8

same time record the afr sensor graph and if possible post a picture here

the o2 voltage range seems to be on the richer side but still need the graph

[syncview]

i haven't performed this test, but will check the manual this weekend. is it something that requires special equipment?

i don't remember

check the service manual

[Vlado P.]

will do! i'll drive the car connected either tomorrow or sunday, and will post the graphs...

[syncview]

another thing for you to check: clogged EGR / stuck open... creating a vacuum leak

[Vlado P.]

ok, i still haven't had the time to scan the car while driving (hoping to do it this weekend), but what i did notice lately is this... namely, when the car is in the "half-warm" temperature stage (where the choking problems occur) the engine makes a strange noise when accelerating, as if something is loose and creating vibrations!?!?! this noise is not present when the car is cold or fully warmed up.

i know there is nothing loose, plus this really coincides with the period where the car hesitates when accelerating...

it seems the symptoms are multiplying, yet the ECU still does not display any error codes. so much for the ECU diagnostic abilities i guess...

[Vlado P.]

ok, i did scan the car while driving today, and from what i can tell the fuel pressure is normal...

also, it seems to me that all other parameters are normal too (as far as i can interpret them)....

however there is something that i noticed, it seems very unusual and i don't know what to make of this... namely, techstream lists the following parameters: O2FT B1 S1, O2FT B1 S2, O2FT B2 S1, but there is nothing to be found on O2FT B2 S2. not only that, but O2FT B1 S2 displays a constant value of 99.15%!!!!

from toyota's diagnostic manual for 1AZ-FSE, there should be values for all 4 parameters (O2FT B1 S1, O2FT B1 S2, O2FT B2 S1 and O2FT B2 S2) with min of -100%, max +100% and normal values of 0+-20% for all four of them. not only that, but missing from the list is also TOTAL FT#2, i am guessing because there are no values read for O2FT B2 S2?!?!

now my question is...why aren't there any values for O2FT B2 S2 and TOTAL FT#2? this does not seem normal to me, since fuel trim for bank 2 need to be monitored and regulated the same as for bank 1?

below are some comparative graphs i took today...

[syncview]

i will get back to you tonight

[syncview]

lets not worry about the 'missing' values for now

there is no total FT#2 - only TOTAL FT#1 - it is the average of both LTFTs.

looking at your graphs - specially the O2S Voltage - both B1 and B2 - are weird. as in, reeaallllly slow to respond.

now, since both are not working as they should, I would see what is making these act like this OR what has killed them.

What can kill them is coolant contamination - if you can one of those quick testers that you can put in your car's radiator to check the presence of combustion gases in the coolant system.

I would also make sure and confirm that the EGR valve is not stuck open.

Also, how many catalyst converters your car has?

[Vlado P.]

i think the graphs look weird because the cable i got is chinese crap, the refresh time is horrible.

i have previously scanned the car with another adapter and torque pro, and the values refreshed much better (you could see the sinusoidal curve of the S1 sensors).

as far as i can tell the car has a dual cat system (one for bank 1 and one for bank 2). the cat efficiency test in techstream also gives two values.

regarding the egr valve, about a month ago i tried driving the car with the egr hose disconnected and properly closed, and didn't notice any difference at all (the choking was still there).

according to toyota manual:

TOTAL FT#1 - Total fuel trim bank 1: Average value for fuel trim system of bank 1/ Min.: 0.5, Max.: 1.496

TOTAL FT#2 - Total fuel trim bank 2: Average value for fuel trim system of bank 2/ Min.: 0.5, Max.: 1.496

this is what confuses me, the manual describes parameters that techstream does not detect?

[Vlado P.]

OK, i finally was able to scan the car again (techstream and torque pro) and report back the graphs. unlike with techstream, the scans from torque pro nicely show the sinusoidal graph from the pre-cat O2 sensors, whereas the post-cat are fairly stable in the output voltage (shown data from one bank only, the other one looks very similar).

however the MAF values are quite lower than the specified values, both while idling and at 2500 rpm without load (confirmed with techstream and torque pro). MAF sensor was cleaned month and a half ago (not that it was dirty), so reported values should be accurate.

MAP seems normal....

[Primerr]

Hi, I have described the same problems, are there developments on the subject?

[Jhook]

Hi Vlado.

Did you solve cars broblem? I have a similar broblems and nobody dont know how to fix it.. 

Even Toyota importer says that it is feature and nothing cant do. 

Broblem is, maybe, in ecu and there can have a new program, but it does not solve the broblem wholly. 

So, if car is new and it runs normally, how i can reach that point again? (Buy a new car, i think) 

sorry to my bad english, i am from Fin and here is a lot of peoples who have a same broblem.. With car, no English speaking.. 

Best regards -Jhook

 

 

[Vlado P.]

i haven't found the issue to this problem... to be honest i haven't had the time to deal with it...

it's not the spark plugs, that's for sure...

[MarianB]

I have Avensis AZT250 2 VVT-i from 2005 with  exactly same problems. I will go to try this:

[Vlado P.]

don't bother... i have already had the fuel pipe replaced as per toyota's bulletin... nothing to do with the problem!

i have also cleaned the intake valves with absolutely no difference. so, all that is left is either some sensor malfunction or clogging of the catalytic converters...

[bootzey]

Hi Vlado P. Sorry about refreshing this thread.

I've got similar problems, though not quite as extreme but some similar and have started a thread.

I've got...low tick over, especially when the gearbox is engaged, high fuel consumption and a mid temperature flat spot whilst driving (though this depends on road speed).

While the car was ticking over it suddenly got better, tick over raised to a smooth 800rpm and simultaneously both post cat 02 sensors started to react correctly. I put this down to the engine and possibly the cat getting hotter due to the car being stationary. I put the heater on full blast, plugged in my scanner and the ecu coolant temperature started to drop hitting 80 degrees from a high off 98. However, the temperature gauge didn't drop and also didn't rise when ecu said 98 and the fans came on. I'm working along the lines of the same thing happening whilst driving and throwing the ecu fuelling into a wobbly confusion resulting in running rich.

Someone here said there's loads of similar symptoms in Finland and we're 2 here that are suffering in winter, wonder how many more there are that don't think of forums.

Yet to work out the cause. Could be a restricted coolant flow or inefficient water pump (I've got a grinding sound from the pulley/belt area) or even the thermostat not opening fully.

Cheers

Dave

[Vlado P.]

thermostat problems are not uncommon.... in your case this might be the problem.

 

in my case, i'm thinking that my cat might be clogged, since the symptoms disappear when the water reaches 90C, plus the MAF sensor records very low air consumption... maybe the car is choking????

[Konrad C]

You are going through all the electronic things, like the fuel injection, the O2 sensors and the catalytic converters, but what about the mechanic side of things like the inlet valves and carbon build up. Direct injection engines as most will know, is known for this and the fix is to remove the inlet manifold to use a suitable cleaning tool.

If you can get one of those scopes and look at the inlet manifolds and valves, you can get an idea how much carbon has built up. 

[Vlado P.]

i have done this in august.... i was convinced it was a carbon build-up, so i removed the intake manifold, cleaned the intake shafts (there was minimal build-up) and the vacuum operated flaps. there was absolutely no change in engine operation!

the car has only 82000 km, so i don't think that the inlet valves are the problem. i don't think it's the MAF sensor either, although i might test this if i find a replacement...

[bootzey]

I admire your persistence Vlado.

Modern engines are so heat sensitive and a lazy thermostat that doesn't fully open would restrict coolant flow.

My daughters corsa lost heat completely with the heater on full. The temperature gauge would also drop going down a big hill. A blocked heater matrix was the culprit. 

Did a 7 mile round trip the other day and plugged my scanner in when I got home. Ecu temp said 81, thermostat opens at 82, so it wasn't fully warm. Left the car ticking over and it took 5 minutes to get upto 88 then a further 20 minutes to upto 98 when the fans came on. This seemed a hell of a long time. The temperature gauge didn't budge at all and was even saying normal temp at 98! Couple this with the temperature dropping when the heater is on full blast suggest a coolant blockage or restriction somewhere. Would be interesting to how long it takes others to get up the point where the fans come on.

I took advantage of a euro car parts discount offer of 69% off and brought 2 bottles of Cataclean.  Put one in as they suggest, drove till the light came on then put 20 quids worth in. Put the other bottle in when I had just under half a tank, drove till I had under a quarter of a tank in the put a further 20 quids worth in. I've now done 220 miles and still have quarter of a tank left. This was two 80 mile round trips mixed with steady nontraffic town driving and one n half hours of ticking over. I now have a tick over of 750-800 revs which I never had before the Cataclean but only at stand still and not when stopping at junctions etc. I suspect the driving is cooling the engine to much, which then runs rich, reduces tick over and increase fuel consumption. 

The Cataclean would also of helped with what Konrad (thanks Konrad) is suggesting with the coking up of things. Though I've had the air filter box off and the throttle butterfly is clean.

My post cat 02 sensors are very high at 0.7-0.9 which suggests the cat isn't doing its job. The pre cat sensors are flipping nicely, even with a slight stop at 0.45 but do go up to 0.9 too. A scan says sensors are OK but giving a high voltage. I've never hat the EML come on and there's no stored codes.

I'm now waiting till all the Cataclean has gone through at which point I'll put some she'll ultimate in and plug in my scanner.

Thermostat will be changed but not sure when.

Hope this helps, give the Cataclean a go.