93 Camry V6 fuel? ECT? help!

[hydroman]

Hello everyone. My 93 Camry V6 with AT has 90,000 pampered miles on it. Over the past several months it has started running intermittently very badly – will suddenly be gutless when trying to accelerate. It is worst when cold, but it is starting to do it when hot also. It isn’t misfiring, and the engine seems smooth even when the car is struggling to get moving. It isn’t showing any error codes. Here’s what I’ve done to try to fix it so far:
· New spark plugs, wires, distributor cap, rotor, fuel pump, fuel filter, PCV valve
· The following check OK according to Haynes: engine coolant tem sensor, cold start injector impedance, EGR valve operation, fuel pump relay
I have noticed a few strange things that I was wondering if someone has ideas about:
· I drove to work with my front O2 sensor unplugged, and it didn’t make any difference in how it ran, but to my surprise the CEL didn’t come on! Does this mean there is a problem with the ECT? The voltage from the sensor checked out OK.
· I unplugged the vacuum line from the fuel pressure regulator. Lots of vacuum in the hose, but it made no difference in how the car ran. Does this mean the regulator is bad?
I would really appreciate any ideas on what to try next. My budget and my wife’s patience are getting thin. Thanks!

[Toysrme]

All of your list was probably wasted money.
Whatever plugs you bought, swap them for NGK, or Denso only. Aside from that grab a vacuum gauge & check the vacuum in the intake manifold (There is a testing port on the ACIS side of the intake manifold).
Drive the enigne until warm & then do a compression check.


Tell me the numbers recorded on both.





I bet you slipped your timing belt, or there is a massive vacuum leak...





Quit throwing money at something blindly. That's how you live when you own a Ferrari. Troubleshoot first...

[hydroman]

Thanks for the response. Vacuum checks steady at about 16.5 inches. I'm at an elevation of about 1200 ft above sea level, so according to Haynes manual this is within normal range. I havent done a compression check as I dont have the guage, but half the time the car runs excellent, so I dont think it is a low compression issue. I've checked all the vacuum lines, and havent found a vaccum leak anywhere.

A few other things I've checked that I was wondering about:
1) Voltage at the front 02 sensor swings from about 7.8 to 9.5 at idle. Is this on the rich side? Or is this normal for this car?

2) Even though I thoroghly cleaned the IAC and the ohms checked OK, I'm suspicious of it because sometimes the idle shoots up to almost 2000 rpms when I start when cold, other times it just goes to about 900 rpm. Other times it goes to 1300 then drops quickly. Given the cost of a new IAC, I thought I'd get some opinions before replacing it. Could a slow/sticking IAC cause the car to run rich/sluggish when either cold or warmedd up? Seems like the car runs great when just warming up, only loses power when cold or fully warmed up (and only some of the time then).

3) Sprayed plenty of Seafoam Deep Creep into the EGR valve and the air intake of the IAC. The car ran great afterwards - until the lag started again.

4) I've checked and rechecked the ECT under all temperature ranges, and it seems fine.

5) I havent bought a timing light yet to check the timing, but wouldnt the car run bad all the time if the timing was off?

My next thoughts are to either replace the IAC, replace the fuel pressure regulator, or take it to a mechanic. I hesitate to do the former because I dont want to throw money unless I'm confident I have found the problem. But for the cost of going to the mechanic, I can replace several parts (which seems like what they do anyway). Thanks for any help.

[Peka]

Gday, did you end up finding the problem? I have a 93 Camry V6 with very similar symptoms and the Toyota dealer have not been able to diagnose it.

In addition to the symptoms you have described, when mine 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 with another cyl and the problem stayed on cyl3. 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.

Any help would be greatly appreciated!

*edit* I should add that it's a 3VZ-FE not a 1MZ-FE