Hi, I'm completely new to Toyotas, loved them for years but have just recently purchased a used 95 , 3 liter, 270,000 k. Anyway this is the first used vehicle I've ever bought and it failed the e test. the reading are:
LIMIT RESULT

HC ppm 52 27
CO% 0.29 0.01
NO ppm 735 962 FAIL
RPM 1710
DILUTION 14.6
There is a very noticable sucking sound (vacuum leak) would this cause my high NOx reading? The motor also seems quite sluggish which I'm also thinking may be caused by the vacuum leak, am I correct in thinking this.


Derek

 

Anybody?

 

bump...GL

 

When combustion temperatures exceed 2500 degree F., atmospheric nitrogen begins to react with oxygen during combustion. The result is various compounds called nitrogen oxides (NOX), which play a major role in urban air pollution. To reduce the formation of NOX, combustion temperatures must be kept below the NOX threshold. This is done by recirculating a small amount of exhaust through the "exhaust gas recirculation," or EGR. valve.

The EGR valve controls a small passageway between the intake and exhaust manifolds. When the valve opens, intake vacuum draws exhaust through the valve. This dilutes the incoming air/fuel mixture and has a quenching effect on combustion temperatures which keeps NOX within acceptable limits. As an added benefit, it also reduces the engine’s octane requirements which lessens the danger of detonation (spark knock).

maybe check the egr

have you done plugs and all that fun stuff yet??

 

I haven't yet swapped out the plugs and stuff . I'm hoping that correcting the vacuum leak will reduce/ curethe problem before I have to sink any more money into it right now. As I understand it the lean mixture will burn quite hot and produce these high NOx reading.

Derek

 

DEF change plugs and run the car on the high way to get it hot before the test and a oil change the week before!

i have knowledge on the 22 re but not so much the 3.0

 

Definitely track down the vacuum leak, that will lean out the mixture as well as affect the EGR functionality both of which will increase NOX. The EGR is operated by a vacuum diaphram.

Since your HC's are not very high yourO2 sensor should be good to go. You *could* have a bad catalytic converter but it's too soon to tell with that air leak.

I would say do a tune up and run some Seafoam through the engine. Search on the Seafoam and you can see how to let the brake booster vacuum line suck some of it into the engine. You can poor the rest into the tank.

These trucks are not rockets but a bad vacuum leak will rob you of performance.

Frank

 

Thanks for the info folks, I'll keep you posted as I go. It'll be a day or two before I have time for any of this but I'll be back.

 

Changed plugs, oil, tested egr valve and fixed the vacuum leak yesterday. I'm hopingfully heading back to the E test center this afternoon. I'll keep you posted.


Derek

 

Well failed again today...My allowable NOx is 735, I came in at 823, getting better. Pulling the Cat today and having a look inside, mine sounds hollow the truck is fairly loud, muffler is new. Hoping a high flow cat will solve the problem don't know what else it might be, timing good, o2 sensor is good.

Derek

 

Passed today, third time tested and passed....yea !!!!!!!!!!
After the new cat my NOx came in at 622, with an allowable of 735.