Intermittent and Inconsistent rough idling, stalling, and smoke

[shredsobad]

hi everyone.
i've searched hi and low in this forum and others for the problem i'm having. i've found a few of the same scenarios but no solutions or answers. please help if you can.

the car is a 1993 camry v6. everything was running just fine until after i took apart the intake plenum to change the valve cover gaskets. while in the process, i changed the spark plugs, cleaned the cold start injector, and cleaned the throttle body (attached to the plenum). i washed the engine and surrounding areas after the job was done.

the problem:
the car started and ran fine that day after the job was completed. a few days later after being driven a few miles, the car began to run roughly and there was a presence of raw fuel smell and white smoke (not vapor) associated with all the happenings. the car was parked and rested then started back up and driven back home with no problems or smoke.

i changed the dist cap and rotor, which didn't help, and i checked all the connections as best as i could. i pulled the three front spark plugs to check condition. besides the # 4 plug being wet with fuel, they all looked new still with no other signs of contaminants. now currently, the raw fuel smell is gone but the car still smokes and runs rough but not at all times during the duration of the engine being run.

the car will run fine on the first start of the day then will start having problems as it is driven. if the car is shut down and restarted after some time, it will be fine and then get worse over time.

as soon as there's a hint of roughness and as it progresses, the smoke gets worse. if the problem goes away, so does the smoke.

i'm still doubtful that oil is the cause of the smoke because the car can be a chimney and die and then after a while of rest and started, the smoke is gone. there should be residual oil if so. to me, the car acts like its being flooded but i expect fuel smoke to be brownish/black it the mixture is too rich.

i'll start with that and i'll give any other info as needed.

all you help is very much appreciated!

[Stillrunning]

If it's thick white smoke that usually indicates anti-freeze.

[shredsobad]

Originally Posted by Stillrunning

If it's thick white smoke that usually indicates anti-freeze.

So anti-freeze will smoke rather than vaporize?

[Stillrunning]

Absolutely. If you stand in the cloud it'll smell like anti-freeze. Did you disconnect any part that had coolant running through it? If so I'd try to re-torque the fasteners as it may open up when hot. The one wet plug may be a clue.

[davemac2]

What did you use to clean the TB and cold start area? (hope it was oxygen sensor safe?) Did you touch the cold start injector at all? Are you sure you put the cold start stuff back together ok? It sounds like maybe you are dumping raw fuel into the engine, possibly from the cold start injector or you messed up something in the TB. What was your procedure for cleaning it? Did you wash your engine while it was cold/warm and not hot? Check the air intake hose carefully for any cracks/holes since it is old and you had it off for the cleaning. Check your vacuum hose connections carefully to make sure the EGR system is hooked up ok if you removed those hoses. I'm assuming you are not losing coolant and your engine temp is stable when the smolke and rough running occurs?

dave mc

[shredsobad]

thanks for the help guys. keep it coming!

i've been smelling the smoke thats been coming out and right now, the smoke doesn't really smell sweet like anti-freeze or anything although i'm not ruling it out. it actually smells like an exaggerated version of what normally comes out of the exhaust when the car runs fine. does that make any sense? i know what burning oil looks and smells like and the smoke coming out isn't really convincing me that its oil.

i had to remove the coolant lines going to the TB when i removed the plenum and the upper radiator hose to get the valve cover off. i noticed that the small TB lines were rusty inside......not a good indication of the rest of the internals. i guess it could be leaking water due to corrosion. i'll try disconnecting and plugging those lines to see if that helps. it stays pretty warm here in hawaii so hopefully the TB won't freeze up.

i cleaned the TB and cold start injector with spray carb cleaner. i've used the same stuff on many other cars with o2 sensors and never had problems so i stuck with it.

the cold start injector, i just removed the two nuts and cleaned the probe of carbon and gum. i didn't do anything else to it. its straight forward remove and install so i know its installed correctly.

with the TB, i didn't remove it from the plenum but the plenum was removed from the engine when i cleaned it. i used the same spray carb cleaner and a toothbrush with the throttle plate open to get the inside areas around the plate seat and all the little vacuum holes. i didn't notice anything abnormal with that whole process.

i had to disconnect the egr pipe and three small vacuum lines which one of them belonged to the egr.
all that looks ok as i can see. i reconnected all those to be sure.

engine parameters are all normal...... so far. no rise in oil consumption but i haven't checked the coolant level cause the car is usually hot so i'll do that and note.

btw - there is no CEL associated with all this

[Stillrunning]

Disconnect the electrical connector from the cold start injector (CSI) once the engine is warm, see if smoke stops. You may also be able to clamp the fuel line to the CSI which would totally take it out of play.

[shredsobad]

I tried disconnecting the electrical connector when cold and hot with no change. Haven't tried clamping the fuel line which I'll try.

Quick update. I tried disconnecting the water lines to the tb and the same problems existed so we can rule that part out. Also I noticed today that the fuel smell came back at first and the smoke was darker this time telling me that I possibly have a rich mixture. On a side note, I tried removing the Pcv valve to clean and it broke apart. I pulled out the remains from the valve cover and plugged the vacuum line. The valve was very gummed up and possibly inop. Started it back up and it smoked very slightly but the engine ran fine. I then took it out for a drive and floored it more than a few times and all seemed ok. Car ran great for the 15 min I drove it around. I went home and stopped and restarted and all is ok.

What would be the relation between a pcv valve and rich mixture?? Could the o2 sensor have gotten contaminated and caused a rich mixture from the valve not operating properly?? If so, shouldn't I have gotten a engine light?

[shredsobad]

Well, it was a tease... Car has the same problem again. I'm going to tear the thing down again and replace the back 3 plugs and all the wires to be safe. I'm thinking I could have a new bad plug. It seems as if I loose a cylinder when it starts smoking and running rough. Maybe the plug builds resistance when it get hot...??? Anyways, I'll post what I find... If anythng.

[cj0609]

A bad new plug was my problem. It took me days to finally come to that conclusion. Car was bogging down, that is now gone. I still have a rough idle.Almost like a pulsing, esp in reverse.I can deal with that for now. Car is running great otherwise.I replaced the strut ass all around.Made a world of difference.Still have a creeking sound over small bumps,might need bushings or to tighten down the tower bolts. I think I am going to put back my stock air intake. Wife is complaining car is too loud. Good luck.

[shredsobad]

update:

the car still has a rough running problem after duplicating the job as far as removing the plenum and associated components. i also put another new set of plugs in for safe measure. i checked to see all vacuum passages were clear. i didn't notice any obvious abnormalities as far as i could see even as i looked more closely for possible culprits.

as i kept troubleshooting and as i stated before that the #4 plug was wet at one time, i removed and made sure the plug was dry then removed the injector elec connector then ran the car. i pulled the plug and it was wet again with fuel. if i don't completely understand how injectors work, someone please school me on this. i thought logically and suspected that the injector should not be releasing and fuel in the the cyl without a signal from the ecu. i shot-gunned it and replaced the injector. the wet plug never returned after that.....yet

ALSO, i noticed one of the pins on the #4 injector connector was being pushed back cause the plastic clip inside the connector housing broke. i could duplicate the rough running problem as i pulled and pushed the loose wire in and out. the engine was running smooth after all this but was emmiting dark smoke extremely bad. tried reseting the ecu with no joy to the fix.

after a bunch of engine cycles, the car now has the original problem except now i know the smoke is a rich condition for sure.

i've been using a snap-on mt2500 to help with diagnostics and data monitoring. i noticed the Vf values (o2) indicate that the ecu is trying to constantly compensate for a rich condition. this tells me that since there is no associated code and the ecu is obviously trying to correct the mixture and the problem lies within something that the ecu has no control over as far as mechanical failure.

this car will be fixed one day and when it does, the solution will be posted.

any advice up to and beyond this point is and will be very much appreciated.

Thanks!

[davemac2]

Try running it without the intake hose attached (after it is warmed up) and see if it makes a difference with your rich running problem. Otherwise I would start looking at the O2 sensors as a potential failure point.

dave mc

[shredsobad]

I'm willing to try anything I haven't yet so I'll see what happens with the intake hose disconnected. The o2 sensors passed their test. I'm getting the 8 voltage fluctuations within 10 seconds so I pretty much ruled that option out...for now.

[jbutcher]

I have been following your thread and was wondering if you have made any progress. I am having the same problem. After putting in a lot of time and money into to it, I took it to the Toyota shop in Bryan, Texas. They had it for the day, and concluded that I had leaking head gaskets. But that doesn't stand up to the evidence. I ran a head gasket test, which came out fine. Can a blown head gasket allow raw gas to get into the exhaust? Raw gas is actually dripping out of the tail pipe.
Thank you all.

[shredsobad]

For everyone following this thread, i'm sorry that i have not updated it recently as i have fixed the problem!!

after spending a lot of time troubleshooting, i went back to the basics and refreshed my thoughts. i did the good ole' screwdriver listen test on each injector and to no surprise, the no 4 injector wasn't pulsing. this is obviously a ground or power problem. being that there's a raw fuel smell along with a full tank that was now a half tank after just a few days of testing, basic electrical knowledge told me that there could be both power and ground going to the injector causing the injector to stay open.

[quick camry injector refresh/lesson; the fuel injectors all are powered through the same circuit as the ignition coil's power source which uses the same 30a fuse. the injector circuit is controlled by a switching ground DIRECTLY from the ecu's injector driver. this means that each injector signal wire is directly connected to the ecu and there should roughly 12v at every white/red striped wire pin in the injector connectors 100% of the time with the ignition switch in the "on" position depending if the car is running or not.]

you can confirm the injector is staying open by a simple test that requires no special tools besides what you have already if you're this deep in. first figure out which injector is suspect by NOT hearing a pulse with the screwdriver while the engine is running. stop the engine and remove that spark plug. then, turn the ignition switch to "on" without starting the car. with the spark plug removed you will be able to hear the injector spraying fuel into the cylinder. NOTE: THERE SHOULD BE NO FUEL BEING INJECTED INTO THE CYLINDER WITH THE KEY "ON" ENGINE "OFF"! if you hear fuel being sprayed into the cyl at this time, remove the injector connector and confirm that the spraying stops. if this proves true, then you have the same problem that i had along with others on this forum. knowing that with the key "on" there should ALWAYS be power at the power wire in the connectors, proceed with checking for shorts in the signal (GROUND) wire from the connector to the ecu. you will have to gain access to the ecu connections to isolate the problem. if you can make and break a "ground" at the injector signal wire in the engine bay when you turn the KEY ON to KEY OFF, then you have confirmed that the injector driver in the ecu is the prime suspect. just to seal the deal, remove the biggest connection on the ecu first and try again. if the "ground" is removed with no relation to KEY position, REPLACE ECU. if you have a constant "ground" whether KEY ON or KEY OFF, you have a short along the signal wires path to the ecu. you will then have to tear apart the wiring harness and find the short to ground.

QUICK REMINDER: YOUR BODY HAS RESISTANCE. if you don't have the proper multimeter clips and probes for hands-free testing, be sure NOT to allow both multi-meter leads to come in contact with your hands or any other part of your body. depending on what type of multi-meter you have, it most likely will read your body's resistance and give you false indication of a short.

before i came up with this solution, i previously replaced the ecu with a used one from an ebay-er. it wasn't the exact number but it was cross referenced to my make and model. needless to say that i had the same problem, or i thought i did. i didn't have in place this troubleshooting procedure so i really couldn't confirm that it had the same problem. by the grace of the seller, he allowed me to refund my money. after i figured out what i needed to know and that the ecu was in fact the culprit, i tracked down another ecu with matching numbers and has since fixed the problem.

just a side note: without confirming the problem is fixed though some for of troubleshooting such as the one i posted, you may think that the problem still exist after you install a new ecu. reason is, all the carbon and residual fuel that has caked and flooded the cylinder will need some time to burn off. you may notice that after a while of running the engine, that it may smooth out but still smoke like hell. this is normal in the healing process. it will eventually go away. you can aid in the cyl clean up with maybe some seafoam or other type of upper cylinder cleaner.

you can ref this post also for comparrison: 3VZ-FE unburnt fuel...

let me know if anyone needs more info about what i did.

HOPE THIS HELPS!