gserep1

Hello,
I recently took my 99GS4 in for the mandatory biennial emissions test here in the good ol' state of California. I know that MOST states do not have mandatory scheduled emissions testing.

I have never had a MIL or "check engine" light come on in the car. It passed in every respect other than "high nox. It is borderline high.

NOX is formed when the combustion chamber is excessively hot during driving. On other cars, this condition is handled by the EGR valve, that puts burned exhaust back into the combustion chambers to cool it down, and then close back.

Problem is: the IUZFE engine does NOT have an EGR valve, or so I am told.
The Lexus technicians said that I should pay attention to the check engine light, and they cannot do anything as long as the check engine light is going out after a start.

I get a light ping on full throttle acceleration...( not supposed to get that, I think). This happens regardless of the type of premium gasoline I put in. The sound comes just after "tip in", and onlylasts a split second.

The technician recommended a good intake cleaning using something like "BG" or the like, and then an injector cleaning to get rid of deposits on the valves. He says that this will effectively lower the compression ratio to normal. and the knock sensor will not activate and lower the timing, which takes away the power by retarding timing 10 degrees. I have used BG products before on older cars, so I may try it on mine.

First I have to be sure there was no EGR valve on this engine. This car has been sluggish in comparison with the first GS4 I had in 2003. This one appears to have been BABIED by some older owners who bought it new, and used it for weekend trips only, hence the low miles after 6 years. It has had every Lexus service on time since new, but has always burned more gasoline than the one I had before.

I called a few Lexus Dealers trying to buy an EGR, and they all say that the engine in question does NOT have an EGR

Does anybody have a solution to my dilemma?

Thanks in advance.

joshoowa

iTrader: (1)

if i am right EGR is old school

lexus motors are more efficient where they burn everything intially no recycling... if i am correct

chuckb

I don't know, but I think there has to be some exhaust recirculating going on. I wonder what the difference between a LEV GS4 and a ULEV GS 430 is.

gserep1

Good question. There has to be something different, but I do not know what it is.

Since my last post, I bought a kit from BG, and installed the contents:

1. One can of fuel injector cleaner in the tank to mix with 20 gallons of fuel.

1 small aerosol can of spray for the throttle body...I used it while running. The engine barely ran with the mass air sensor off, but I got it all in. The inside of the throttle body and intake manifold were dirty again after just 5 thousand miles of driving. By the way, the throttle body will NOT open with the cable assembly UNLESS the ignition switch is turned ON. Since it is the MOTOR on the other side of the throttle body that opens the butterfly plate. GS430 owners will have to find a way to open the butterfly plate manually, since there is nno cable arrangement on their engine.

1 can of upper intake and valve cleaner that is administered into the intake behind the throttle body very slowly while the engine is running. Many times we spray stuff through the throttle body and move dirt, but where does it go? Down on top of the valves and the air passageway.

This stuff has to be installed with a special adapter and hose assembly with a restrictor fitting on the end to "meter" the solution through the intake. Engine vacuum sucks it in slowly and the car actually runs on it, until the can is empty. I will get a few pictures of the kit and the tool, and post it tomorrow.

The engine smoked from both exhaust pipes somewhat until the can was empty, and it smoothed out afterwards. I went out and filled the tank, put a can of octane booster in the tank as well, and now the pinging has gone away for now

Everything is much smoother, including idle, but I have to see how long it wil last. I think I got rid of some built up carbon way deep down inside the engine.

TIME WILL TELL. I will drive the rest of this week, and THEN go back and see if my NOX problem has been resolved.

Thanks again for the responses.

TAMR_GUS98

Gserep1,
If the previous owner "Babied" the car, then chances are, the high Nox readings are from excessive carbon deposits in the engine. That would also explain the ping even with premium fuel.
The EGR valve does not exist on an engine with vvt-i. The exhaust gas is recirculated into the engine when the valves overlap during vvt-i operation.
I will say that you are headed in the right direction when you decarbed the engine, cleaned out the intake and injectors. I would also recommend getting the catalytic converters checked to cover all bases.
After you pass your emissions test, you might want to reset the ECU memory. So it can forget the driving habits of the previous owner and learn yours. You can reset it by pulling the ecu fuse, disconnecting the negitive battery terminal or any tech from the Lexus dealer can reset it with a scan tool. Just make sure you do this after you pass the emissions test. You will fail it again if you reset it before the emissions test. Also, if you disconnect the battery terminal, you will need to reset the radio station presets and seat memory. Good luck on your next emissions test.
Will

TAMR_GUS98

Hey Chuckb,
LEV=Low Emissions Vehicle, and ULEV=Ultra Low Emissions Vehicle. The ULEV passed stricter/tighter emission standards. Your right, there is EGR function built into those engines.
Will

gserep1

THANKS for all the good info. I knew some of it, but it helps to get validation. Having some smog certification experience certainly helps too. I have my own scanner as well, but did not know if this engine had an EGR valve or not.

You are also right about NOT resetting the computer until AFTER the test, because to do so will wipe out the I/M MONITORS function of the computer. This function is used by the smog test folks to determine if all the sensors on the vehicle are "talking" to computer, or MONITORING everything as you drive.

Many cars only use MONITORS instead of actually running the car on a treadmill, or putting the sniffer in the tailpipe. My daughters' 2000 Beetle is a prime example of this. All they did was plug in the data link under the dash and put the sniffer in the tank and idle the engine. Everything was fine, and I was done in 15 minutes.

I made this mistake last year with my wife's 97 Explorer before smog time. I cleaned everything up, and reset the computer just before the test. It passed the emissions test, but failed the "monitors" test because I just erased all the info when I reset it. Bottom line was, my wife had to drive the car for about a week so all the monitored functions had a chance to work normally and record their usage.

Things like: O2 sensors, Heated O2 sensor, catalyst, EVAP system, and much more. In the end, it passed after a week of cold and hot starts and normal driving operation. They wanted to see open and closed loop function as well. It cost me double to have the tests run again...LESSONS LEARNED! There is much more going on with these computers than most folks realize.

My car is runnng great now, but I seem to have another problem. My scanner indicates that all the monitors are functioning properly with the exception of the EVAP system, yet I have no check engine light. Only the EVAP system says..NOT READY, while all the others say READY. On the EGR function, it says NOT APPLICABLE. I am wondering if it is possible to have an EVAP problem, yet NOT have a check engine light. I am going to do a bit more research since I have the scanner, and see if I can induce a fault by disconnecting the electrical impulse to the evap module on top of the engine. If so, I can reset, and assume all is well. If not, then I will have to dig deeper.

The car runs stronger than it did, but the mileage is not as good as my other GS4 of the same year and miles, plus it is not as strong as the other car. I can't wait until the weekend to get on the road and open it up a bit after all the cleaning of the intake this week.

Thanks for the tip on the catalysts, I will check them next. I hope all the crap I got out of the induction system and valves don't clog up the catalysts.

Time will tell, and THANKS AGAIN! I will keep you posted.

gserep1

Hello,
I started tooling around the net after making my last post, and found out some intersting stuff.

It seems that the "Monitors" for the EVAP is one of the hardest to set, and may take days of driving to accomplish. So I am sure my car is okay, especially since it runs so well. My scanner is accurate, and if it says that the EVAP system is NOT READY, it really isn't, and I should wait before digging further. ESPECIALLY since there is no check engine light to trigger it.

This delayed phenomenon is "built in", so I will just drive it, and keep checking with my scanner until it kicks in.

By the way, I got this info from these 2 articles on the web. You can find them at:

http://www.babcox.com/editorial/tr/tr60244.htm

AND

http://www.babcox.com/editorial/us/us20212.htm

I hope you can find them....makes for some very interesting reading.