 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Toyota / Toyota Trucks / June 2009My smog numbers are getting rather high.
I just passed my smog check, but it was *very* close this time, so clearly it is time to do some work to clean things up or replace something. This is a 1999 Tacoma 2.4L w/automatic. Here is the history of the last 3 smog checks... 2005: (27,252 miles) 15mph HC=3 (max 60) CO=0 (max .75) NO=30 (max 552) 25mph HC=2 (max 43) CO=0 (max .90) NO=12 (max 805) 2007: (33,190 miles) 15mph HC=24 (max 60) CO=0 (max .75) NO=22 (max 552) 25mph HC=10 (max 43) CO=0 (max .90) NO=20 (max 805) 2009: (36,825 miles) 15mph HC=58 (max 60) CO=.16 (max .75) NO=541 (max 552) 25mph HC=22 (max 43) CO=.05 (max .90) NO=407 (max 805) Possible factors to consider: Earlier this year I had to replace my catalytic convert (stolen). Recently I have done little more then short trips since my commute is only to the local train station. The smog station guy gave me a $241 estimate for: "Fuel / Air Induction System Service", $175 labor. Parts are: "Air Intake Cleaner", $18 "Fuel Injection system Carbon Cleaner", $26 "Power Enhancer 44K", $15 So, what do 'ya all think? Can I do this myself with some fuel additives and maybe a spray in the intake flow? Should I stop using cheap low grade gas (I don't notice any pinging)? Might something more major be needed?  SignatureDoug Herr doug*at*wombatz*dot*com Doug Herr <nntp@wombatz.invalid> found these unused words: >I just passed my smog check, but it was *very* close this time, so >clearly it is time to do some work to clean things up or replace [quoted text clipped - 39 lines] > >Might something more major be needed? "Recently I have done little more then short trips since my commute is only to the local train station." "Fuel Injection system Carbon Cleaner", $26 And take a couple fully warm high speed [60-70] jaunts of 50 miles. It's also nearly time for spark plugs, perhaps one is fouling? > I just passed my smog check, but it was *very* close this time, so > clearly it is time to do some work to clean things up or replace [quoted text clipped - 43 lines] > Doug Herr > doug*at*wombatz*dot*com The high HC means unburnt fuel. Therefore suspect spark plug fouling or possibly other ignition faults. The low CO and high NO implies very high combustion temperatures. NO production is very strongly temperature dependent. The likely cause of the worsening combustion temperatures is poor EGR performance. It may be that the EGR valve is shut closed or, more likely, the EGR passageways are clogged. Either way an EGR service is needed to restore EGR function and get combustion temperatures back down to normal. The prescribed services are good to do but won't solve the problems at all. The most important BG service you need (in addition to replacing the spark plus and/or wires) is the BG EGR service vice the 44K and induction cleaning. Good luck. Al > 2009: (36,825 miles) > 15mph HC=58 (max 60) CO=.16 (max .75) NO=541 (max 552) 25mph HC=22 > (max 43) CO=.05 (max .90) NO=407 (max 805) Thanks much to both of you. I checked the plugs and all 4 show good signs, so we seem fine there. I will do an additive regiment to make sure the innards are all clean, but the EGR inspection has found a problem... http://wombatz.com/img_1429a.jpg I took pictures to make sure I did not put things back out of order, but I happened to have my vacuum meter connected when taking the pictures. The red line shows where the EGR gets a vacuum "signal" from. Even when nice and warm I was not getting any vacuum to the EGR, so we clearly do have a problem here. During idle I can kill the engine by applying vacuum to the EGR itself, so I guess that the EGR itself is working and has a clean enough gas route. Clearly it is the control stuff that is having trouble. If I blocked the hose marked with a blue X, I was getting good vacuum "signal" to the EGR during high revs. Does this mean that the vacuum modulator is good, but that the gas temperature sensor is bad? I have not gotten all the way down to that valve (the truck is still cooling back down), but the electrical connection *looks* fine it does seem that the hoses are connected ok. SignatureDoug Herr doug*at*wombatz*dot*com >> 2009: (36,825 miles) >> 15mph HC=58 (max 60) CO=.16 (max .75) NO=541 (max 552) 25mph HC=22 [quoted text clipped - 28 lines] > cooling back down), but the electrical connection *looks* fine it does > seem that the hoses are connected ok. I got to the valve!!! The "bad" news is that it is working. I say bad since I could have figured this out via creativity if I had been thinking. It is closed when the truck is off and opened when the truck is running, so it obviously works. It is just a open/close valve. This means that the troubled part must be the gas temperature sensor (or connection). Anybody know if that is the dealy-bob right near the EGR valve? This is going rather well so far, I am hardly bleeding at all and the truck still runs. SignatureDoug Herr doug*at*wombatz*dot*com > >> 2009: (36,825 miles) > >> 15mph HC=58 (max 60) CO=.16 (max .75) NO=541 (max 552) 25mph HC=22 [quoted text clipped - 49 lines] > > - Show quoted text - No vacuum to the EGR implies no EGR action and explains the high NO. You need to trace the EGR vacuum line back to its source. It originates from a thermostatic vacuum switching valve (TVSV) which is screwed into the intake manifold somewhere and looks something like a sending unit except that it has no electrical connections to it but will have one or more vacuum lines coming out of it. It opens at a specific temperature (typically around 160 F) during engine warm-up (of course you don't need EGR action during engine warm-up). Above that temperature the valve is open and the vacuum lines coming from it should show manifold vacuum. When you find the TVSV connect a vacuum gauge into the line from it feeding the EGR and verify that vacuum appears at a specific temperature during warm-up. Keep checking vacuum between the TVSV and the EGR valve to locate where vacuum is getting lost. Since the EGR valve seems to be working and I doubt that either the modulator valve or the TVSV is bad (although those are certainly possibilities) it may be as simple as a cracked vacuum hose at one of the vacuum hose connections. You're on the right track. Good luck. Al > I just passed my smog check, but it was *very* close this time, so > clearly it is time to do some work to clean things up or replace [quoted text clipped - 39 lines] > > Might something more major be needed? Do you have an OBDII scanner? Are there any stored CODES? ...and, YES!, you can clean the Throttle Body, and save $241! |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.