1999 Toyota Camry fuel injection system

  • 6 CYL
  • FWD
  • 140,000 MILES
I have a 1999 Solara V-6/5-speed with 140000 miles.
The engine develope a miss (check engine light came on also) while driving on a long trip about a month ago. Brought the car to the dealer, they had it a few days, but didn't seem to make much progress or have much confidence in any diagnosis. The two trouble codes described cyls 5&6 misfiring. The dealer replaced the spark plugs and cleaned a sensor, but felt the car may need new fuel injectors $1500. Finally, they advised me to try the car and that it seemed to be running correctly. The car ran well for a month, now the problem has come back. Took the car back to the dealer, they said the next step was the fuel injectors, but could not guarantee that would fix the problem. Needless to say, I didn't OK the work. I bought another can of injection cleaner and a few more spark plugs from the dealer, have decided to try to tackle the problem myself. I wrestled all the plugs out, they all appeared normal and looked the same. I can see that replacing the injectors will probably require removing the air plenum and plumbing. There is an air hose coming from the throttle body that Ts into both intake manifold injector rails.I am confused as to the theory of this system. But, I decided to spray some engine tuner/dearbonizer down into both of these intake air runners that house the injectors in the hopes that this may help clean the injectors. I am not sure whether this helped or not, because the problem seems heat related, the engine seems to run fine cold, the miss comes in only after the engine is well warmed up. But, the engine did seem to run better after "soaking the injectors", it started running a little rough just as I got back home, but only at idle.
So, if anyone has some experience with this engine, please let me know. Just have a few more questions:
I don't see any return fuel line, how is the fuel pressure "regulated".
Could this engine decarbonizer spray damage the catalytic converter or O2 sensors?
Thanks for your advice. Don
Do you
have the same problem?
Tuesday, September 16th, 2008 AT 4:45 PM

1 Reply

Hi Don,

Circuit Description
ECM uses signals provided by crankshaft and camshaft position sensors. If engine speed rate has changed enough to equal a preset number, a misfire is detected and MIL is illuminated. If misfire rate is high enough, and driving conditions will cause catalytic converter damage or overheating, MIL blinks when a misfire is occurring. DTC is set during any particular 200 revolutions of engine during which misfiring is detected which can cause catalytic converter overheating and/or damage, or during any particular 1000 revolutions of engine during which misfiring is detected which can cause a deterioration in emission levels.

Possible causes are:
Ignition system malfunction.
Defective fuel injector(s).
Improper fuel pressure.
Defective EGR system.
Defective engine compression.
Improper valve clearance.
Improper valve timing.
Defective Mass Airflow (MAF) meter.
Defective Engine Coolant Temperature (ECT) sensor.
Open or short in wiring.
Poor contact at ECM or component.
Defective ECM.

Fuel pressure regulator is located in fuel tank so the output pressure is already regulated.

You should check the label to see if the spray is safe for catalytic converters.
Was this
Sunday, September 28th, 2008 AT 10:05 AM

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