3VZ-FE unburnt fuel...

[Peka]

Having some issues with my Camry, have taken to the dealer and been left with no confidence in them since they haven't fixed it after 3 attempts.

When it is running badly, unburnt fuel comes out of the exhaust, sometimes enough that a cloud of white smoke fills the garage. It is not temp related as it can run roughly even when warmed up.

When it first started doing it, we found that the leads were arcing, so replaced them, along with the plugs (due for replacement anyway at 200,000km) and the distributor cap. It was ok for a few weeks after that, then started doing it again, at which point we took it to the dealer.

They found a cracked rotor, which has been replaced. According to them the compression test was fine, and they have narrowed it down to cylinder 3. They found that the injector on cyl3 was gummed up but swapped it and say that it has been ruled out. Injector may just have been gummed up due to the fuel not being burnt properly? They also tell me that there is plenty of spark.

They also did a "TK" test for cylinder head leak which showed "no evidence of any leak".

Their diagnosis is that is a possible crack in cylinder head allowing water to enter into cyl3. Despite no evidence to support their diagnosis - leak test was good, compression test was good, not loosing any coolant.

We have run injector cleaner through the fuel a number of times.

Today a mate and I had a look at it. We pulled the intake runners off and saw that the intake to cylinder 3 was very clean while the others were dirty. Spark plug for cyl3 was also dirty (black soot). Cyl3 intake is directly under the cold start injector so we thought it must be something in the cold start system - injector stuck open or maybe bad ECT sensor telling the ECM to open it. Cleaned everything up, ran some intake system cleaner (appears to be same type of stuff as Seafoam) through it. It ran fine for a while then started running rough again. At this point we pulled the cold start injector and put it in a bottle. It was not squirting any fuel while the engine was running rough so that rules out the cold start system.

What to look at next? Unburnt fuel tells me that either the plug is not firing when it should or the injector is squirting when it shouldn't....

[bigbird]

that sounds like a bad plug. if the cylinder is clean while the others are dirty then theres a good chance that the fuel being unburned is "cleaning" the walls of the cylinder. heres a good way to test. just pull the plug out and insert a screw driver or somthing into the sparkplug sleve. turn the car over, watch to see if the plug wire arches onto the screw driver. this way ull know if its the plug or not...im bettin it is. personally id get a replacement sparkplug anyway and then test it. that wawy ull know if its somthing else in the ignition system and not the plug.

P.S. dont hold the screwdriver in there, rest it on somthing so it doenst give u a shock...i learned the hard way

[Toysrme]

The CSI is only like a 15-25hp injector anyways, and it's split between all the cylinders. It's very little fuel. (75-125cc)
Change the plug again, check the injector yourself.


It's not a crack in the cylinder head. If it was you'd be boiling over inside a minute. And the combustion chamber, along with the plug would be 100% spotlessly clean.

[Peka]

Originally Posted by Toysrme

It's not a crack in the cylinder head. If it was you'd be boiling over inside a minute. And the combustion chamber, along with the plug would be 100% spotlessly clean.

That's what I thought

Thanks for the tips, I'll let you know how I go. Might not get another chance to fiddle with it until next weekend....

[Peka]

I had a fiddle with it today, plan was just to move the plug,lead and injector from cyl 3 to the front bank so it's easier to get to for troubleshooting. I measured the resistance between the terminals on all the injectors. The manual says ~13.8 Ohms, all injectors measured between 15.3 and 15.8 Ohms. Is this far enough out of spec to cause me grief or is it nothing to worry about?

Is this normal for the injector holes?



All the injectors were dirty, two had the holes on the 'shaft' part of the injector completely blocked. I cleaned them up before re-installing them, the two bad ones are now on the front bank (as well as the spark plug and lead from cyl 3).

This is what they looked like:

REAR BANK



FRONT BANK



It's still blowing unburnt fuel out the exhaust so cleaning the injectors made no difference. Does the state of these injectors indicate that it's not just one cylinder playing up? When I parked it after a decent drive, it was still running rough, so I pulled the injector connectors on the front bank, one by one, to see if it ran worse or the same. Each time it ran worse.

Any advice on the state of those injectors appreciated

[Peka]

Checked resistance of a bunch of things:

Volume Air Flow Meter - all good
TPS - all good
IAC Valve - all good
IACV VSV - 60-70 Ohms, spec says 33 - 39 Ohms but says to replace if there's no continuity
Fuel Pressure VSV - all good
ECT sensor - not tested properly gave a reading within range after running the engine for a few minutes
CSI Time Switch - as per ECT sensor

Is that IACV VSV too far out of spec? Would it be causing issues?

[Peka]

*bump*

Anyone got any comment on those injectors?

[davemac2]

why do you say it is unburnt fuel coming out the exhaust? Is it a strong smell of fuel or something. White smoke usually implies coolant, smell is usually sweet.

I don't have a lot of experience with injectors, but those look pretty dirty to me. Can you bench test them maybe to make sure they have a good spray pattern? You should at least clean the intake and TB with an Amsoil treatment or seafoam to rule that out.

A clean intake on #3 sounds to me like the dealer diagnosis may be close on a coolant leak there somewhere on the intake manifold. The manifold has all the water passages that takes in water from the rad on the left and exits on the right with the bypass valve/connections, as well as passages into the 2 sides of the engine. You may have a slow leaking intake manifold gasket near #3 or a crack in that manifold, or as the dealer has said, maybe the cylinder head itself. I know you have said you are not losing coolant, but the only other thing would be maybe gas getting into the intake from a leaking fuel regulator vacuum diaphragm.

This engine also has EGR valve cooling I think. Don't know exactly what that looks like, but could it be a source of coolant getting into the intake? Other source might be the IACV valve which also has coolant hoses connected to it.

dave mc

[Peka]

Originally Posted by davemac2

why do you say it is unburnt fuel coming out the exhaust? Is it a strong smell of fuel or something

Yes, you can smell it. It's definitely fuel. If there's anything else in the exhaust that shouldn't be there, you can't smell it over the fuel

I've just used nearly 3/4 tank to do 94km!

Fck it, I'm getting the injectors serviced. They look pretty dirty to me, I'd have thought they should be fairly clean...

I learnt how to check the codes last night, there are none stored. I pulled the fuse for the ECM, then set it in diag mode (short E1 and TE2) while I took it for a drive, but still no codes coming up. I would've thought the O2 sensor would register a code for being too rich?

[Peka]

OK, I've had the injectors serviced and the car runs better, but if it sits idling (eg. traffic lights) for long enough, or with very small throttle openings the problem returns. It took about 10 minutes of hard driving to clear it out and then it ran fine until I had to stop at multiple lights close together.

Of interest was something I found when I removed the injectors. The car had been sitting for a day and a half and there was almost a cm of liquid sitting on top of cyl 3. It wasn't the same colour as the coolant and the screwdriver I dipped in it smelt like fuel. This indicates a fuel leak. The injector dude said they weren't leaking, but one was not outputting the same volume as the others. They are all good now though.

So, the next possible culprit would be fuel pressure reg? Fuel Pressure Control VSV (resistance on terminals is in spec)?

[toyomania]

Your problem sounds similar to mine. I did a compression check and found cylinder 3 with zero pressure! My other pressures were at 145 -150psi. I had raw gas coming out of the exhaust and had wasted my time checking the multitude of sensors and solenoids to try to narrow down the problem. The idle of my Camry was rough, but at speed, the car had enough power to lead me to believe that it was an idle only problem. This is a quick check to see if you can avoid spending more money on your injectors.

[Peka]

Thanks for the tip. The Toyota dealer checked the compression and told me that it is fine. I don't have the tools to check it myself so I'm working on the assumption that they checked it properly and all is OK as far as compression goes.

I had to fill it with fuel last night - in the last week 123km used 53L !!

Took it for a good drive and if it's running rough I just have to drive it hard for a while (maybe 5mins) and then it runs perfectly, with no smell of fuel coming from the exhaust, instant response etc. If I then drive it around on light throttle openings, or have to idle for a while at lights, it starts to run rough and I can smell the fuel in the exhaust again.

BTW - I don't mind having spent the money on getting the injectors serviced, it was obvious they were going to need doing soon anyway

[Rdizzle]

well if you have that much fuel sitting on the cyclinder, it is obvious that something is leaking fuel pretty bad. Only at idle or when it is stops implys to me that the low pressure allows fuel to escape whereas spirited driving raises the pressure against some seal that is probably going bad. Check the fuel system around the area.

[Peka]

Originally Posted by Rdizzle

Only at idle or when it is stops implys to me that the low pressure allows fuel to escape

So the Fuel Pressure Reg could cause this? Is there a way to test without having a pressure guage?

Originally Posted by Rdizzle

Check the fuel system around the area.

There are no obvious leaks when looking under the engine bay. The only places I can see where fuel could get into the intake are the injectors or the EVAP lines - I wouldn't have thought a problem with the EVAP system would put that much fuel into the intake though? I will be checking EVAP and EGR etc on the weekend.

The guy that serviced the injectors tested them before cleaning them and there were no leaks. The car will be sitting for a few days so I might pull the intake plenum off on Sat pm/Sun and see if there's fuel on top of the cyl again.

Any other ideas on where the fuel could be leaking in?

[Peka]

I found that the hoses going to the IACV vacuum tank were crimped due to bad routing of the hoses. I fixed that and took it for another drive (wasn't expecting a cure though...). When I got back it was running crap again so I pulled the plugs to have a look. Sure enough, cyl 3 plug is wet with fuel, the two either side not quite wet but pretty sooty. The front bank look ok (please correct me if I'm wrong, I'm no expert ).

Rear Bank:


Front Bank: