Phantom check engine light. - Toyota Nation Forum : Toyota Car and Truck Forums

Ace2424 · 09-02-2010, 10:21 AM

So I have a '99 5sfe and about 2 months ago, the check engine light came on. So naturally I take it to work and plug it in. Comes back with an "Engine gas recirculation insufficient flow."

Ok, so I took it home and pulled apart the egr valve. It was horribly clogged due to the car having 214k miles on it. Cleaned it out with engine cleaning tools and throttle body cleaner. Got it all shiney, cleaned out the egr tube, which wasn't clogged, threw a new gasket on and put it back together.

I cleared out the code and drove it about 30 miles, then it came back on. Ok, so time to check that the egr diaphram is still holding pressure. Again I return to work and borrow the vacuum pressure tester kit and slid it on the top vacuum attachment. Held pressure perfectly when compressed and didn't release... Ok... So I gave up for a while and then one day noticed the light went out.

I was really happy because I thought it just had to run it's cycle. Next day, back on! At this point I'm wondering WTF is going on. Then again a day later it turned off. So I thought to myself, what was different about that driving time that might have been the same as last time. I then turned on the air conditioning. Within 30 miles, it was out. Holy shit!

So I run a couple more times with it alternating on and off to see if it's consistent. It is. Whenever the check engine light is on, the car is running without ac on. When it's off, the ac is on.

What I'm wondering is if it really does have anything to do with the egr valve at all? Has anyone come across this problem with the gen 4 5sfe?

**TOYOPARTSMAN** · 09-02-2010, 10:32 AM

Did you by chance take apart the modulator and clean the small white filter inside. The modulator gets carbon build up as well from the egr valve, which in turn can affetct the egr VSV.

I am not a tech, but I do know that some of that is all vacuum related, so I don't know if the amount of vacuum the a/c might be pulling is enought to throught that off or not.

someone who is really knowledgeable about that stuff is a member named NERVOUS. You may want to find his posts, I believe there is one called is the EGR VSV the same as solenoid, or something like that.

Nervous · 09-02-2010, 10:33 AM

Is it the famous P0401 code? Welcome the club then.
1) Check for vacuum leak in rubber hoses coming to and from EGR, modulator and VSV.
2) Did you clean the air filter in vacuum modulator?
3) Check the VSV (resistance, apply voltage, check the air flow through it). However, even with all of these tests it still may intermittently fail.
4) Search here for P0401, there is a TON of info about it.

Ace2424 · 09-02-2010, 10:40 AM

Whereabouts is the VSV and modulator located?

Nervous · 09-02-2010, 10:42 AM

See item #4 in my list above.

**TOYOPARTSMAN** · 09-02-2010, 10:45 AM

Follow one of the vacuum hoses to it, it should be real close to the EGR valve with a part number of 25870-74090 on it.

***fenixus*** · 09-02-2010, 11:55 AM

I would replace the modulator for starters (it has filter in it and also sort of diaphragm in bottom part IIRC).
also you should check VSV for EGR if it operates correctly, at least do the testing per FSM. check SFI manual for gen4 camry:
http://www.camrystuff.com/manuals/Gen4/SFI.pdf

you should also check all EGR vacuum lines if they can hold vacuum (plug one end and test the other with a hand vacuum pump) and if they do not restrict the flow (check if air blows through them easily).

Chris Crash · 09-02-2010, 02:58 PM

The intermittent trait that your problem has points me to the ECU/electrical problem. Maybe a switch somewhere in the ECU is fried or a wire is shorted. Any splices anywhere?

Nervous · 09-02-2010, 03:01 PM

I would consider this as the LAST possibility. BTW, does anybody know which OBD software allow to control the EGR VSV? For example, ScanMaster allows only to read data, not to send commands. But which one can send commands? That could help in diagnostic of VSV and EGR (and ECU!).

Ace2424 · 09-03-2010, 05:31 PM

I have made plenty of splices as I have a whole LED interior and truck lighting system going on. However, I haven't done any incorrectly. I don't use the pinch "quick splices" and I have covered and water-sealed all my wires correctly with shrink conduit, so there is no possibility for it to touch metal anywhere. I also haven't done any LED or neon work on it for almost a year now so it wouldn't make sense for it to just go off and short out now.