Just took my truck to smog... I have only driven about 50 miles in the last week, and in the 6 months before that not at all. It passed (just barely) on the 15mph test, but was way over two out of three tests at 25mph. In particular, my HC and CO(%) were 202 and 2.52, while the max acceptable for those was 90 and .77 That was 25mph at 1448 rpm

at 15mph, 1518rpm, the HC and CO(%) were 110 and .35 which means the HC is exactly as highg as possible, and hte CO(%) is about .2 under (the max at 15mph is .58) What the hell can I do? I can't afford to keep spending money on this thing, in the last year I've spent well over 2500 in repairs. (the motor was rebuilt...)

I'm trying to sell it to someone who may know how to fix it, but If nobody wants it, and i have to sell it to joe schmoe, tehn I would like ot at least have it pass smog.

What causes the HC and CO(%) to be so high? Would a tuneup be enough to fix that? ANyone have any ideas? They want way too much to diagnose it at the shop, and I just can't afford it. Wah. I know, enough rambling and whining...

oh yeah, I forgot, I didn't know how much gas was in it, 'cause the gauge is broken, so I put 10 gallons of supreme in it, and a bottle of injector cleaner, could that have made a difference, and if so, why so much difference at the two speeds?

Thanks,
Cabe
916-201-8303

can you give any info on year miles, cid etc??

go to kragen and get some stuff called crs pass smog(might be another brand but its in a blue box) do what exactly what it says on the bottle...

replace your cat.

Plain and simple, if NOx was cool, HC and CO, rich running. Adjust the Air Fuel ratio, you want the CO and O2 to be within 1% of eachother. Anything else shoot me a PM!

Thanks for all the suggestions! here's what I left out
88 suburban
350, TBI
175000 miles
engine rebuilt with only about 1000 miles on it (long story)
My question to K5MonsterChev; how do I adjust the ratio on a TBI that is completely controlled by the computer? I thought I was pretty much at the mercy of the ECM.
Any more ideas are very much appreciated

Cabe

make sure you have no vaccum leaks also did you replace the o2 when you re-did the motor ?? lastly orginal cat ??

AHH yes, TBI, theres one small detail.

Is there anyhitng that would make it run lean, so the O2 sensor would sense lean and richen up the mixture, leading to higher CO and HC? Dirty Air Filter could also make it run rich.

sticky egr maybe?

Charlo

EGR would have a big effect on NOx

I think the cat is original, I've never changed it...
I finally got it retested after doing the following...

replace 02 sensor
replace coolant temp sensor
replace spark plugs
change oil/filter
replace air filter

so I took it in today to get it retested, and this time it failed both!!! (15mph and 25)
this time here's how it looked

%CO2 %02 HC (PPM) CO(%) NO (PPM)
max GP MEAS max GP MEAS max GP MEAS
15 mph 13.6 .8 110 297 165 .58 1.88 1.05 970 1736 340
25 mph 13.0 .7 90 247 212 .77 2.07 2.32 830 1536 186

So next is EGR? Also, there is a small hole in Left hand side exhaust manifold, could it be allowing air in and throwing off 02 sensor (it's about 6 inches away, just ahead of last plug)??? My dad has a friend that might swap in a motor (he has tons from old business) cheap, so I don't want ot throw too much more money at it, but whaddaya think???

It did better before I changed all the parts!!! SUCK!

Thanks in advance,
Cabe

by the way, the formatting looks good when I put it in, nice and easy to read, but in the post it's all just rammed together, sorry...

replace 02 sensor
replace coolant temp sensor
replace spark plugs
change oil/filter
replace air filter

how much did that cost? now how much is the diagnosis. if you have no idea how to fix it but your broke why would you throw money down the drain by fixing what you think needs to be done. i see people that do this all day long and they end up spending more money than the rich guy that drops his car off and says "what ever it takes, just fix it."

this was free advice from a friend, who has a shop in placerville (has for about 15 years). I would have taken it to him for normal stuff, but since it won't smog, it won't register and I can't drive it up there. All of the above cost 50 bux (plus about an hour of my labor, which is normally 1500, but I don't charge me), and the retest was free. All of the reputable shops I've called want at least 135 to diagnose (2 hr shop time, for the most part) and that doesn't include parts or repair, just diagnosis... Also, since I took it to a "test only" center the first time, I have to take it back there after the diagnostics and repairs are performed somwhere else. So, assuming any of the other parts need replacing, (egr for example is 40 bux at kragen, I'm sure a shop would mark it up, plus charge for install) I'm ending up spending a lot of money on this thing, and I want to avoid that... 50 here or there doesn't matter, but I'm not going to give a shop a few hundred to tell me how to fix it, especially not when I have it up for sale for a grand!!

Did you have any ideas? Do you work somewhere that I could bring it and get it diagnosed? If so let me know (I noticed you're in SAC, if so HOOK ME UP!).

Thanks

I would try to help you but I can't make heads or tails of those numbers....can you give just the measured/actual limit for the 4 parameters?

sure, I'll just write it out this time, that's ugly up there!

C02% at 15mph 13.6 at 25 13.0
02% at 15mph .8 at 25 .7

(it doesn't specify a max for the above, it just gives the measurements at the two speeds)

HC (PPM)
at 15mph MAX is 110, mine is 165
at 25mph MAX is 90, mine is 212

CO (%)
at 15mph MAX is .58, mine is 1.05
at 25mph MAX is .77, mine is 2.32

NO (PPM)
at 15mph MAX is 970, mine is 340
at 25mph MAX is 830, mine is 186

Thanks!

make sure you have no vaccum leaks also did you replace the o2 when you re-did the motor ?? lastly orginal cat ??


Did replace 02 last week, but haven't checked for vacuum leaks, I'll check it out tonight!

Also, mechanic friend said HC could be high from natural passage of gas into oil over time, I changed it, but would it be a good idea (for the 9 bux it costs) to change it again??? You know, kinda "poor-man's flush" job???

what about timing? is it set right, and if not, would it cause it?

replace 02 sensor
replace coolant temp sensor
replace spark plugs
change oil/filter
replace air filter

how much did that cost? now how much is the diagnosis. if you have no idea how to fix it but your broke why would you throw money down the drain by fixing what you think needs to be done. i see people that do this all day long and they end up spending more money than the rich guy that drops his car off and says "what ever it takes, just fix it."
This is free advice from a test only smog technition, I must suggest you do what he says. it would possibly only cost 120 for any decent shop to diagnose the problem. And if it is simple they may just fix it for ya.

well if you have a hole in the exhaust manifold.. ..

fix it..
kragen has a very hi temp repair kit for the manifolds..

about 10.00


change the cat....
about 50-80.00 for one


change the o2 sensor again..

that should do it..

Depending On The Situation The State Will Also Help Pay For Some Of The Work To The Vehicle.

Depending On The Situation The State Will Also Help Pay For Some Of The Work To The Vehicle.
Low income, repairs over 500, and must be on a renewal and not a change of ownership.

This is free advice from a test only smog technition, I must suggest you do what he says. it would possibly only cost 120 for any decent shop to diagnose the problem. And if it is simple they may just fix it for ya.

Do you know of a shop that is trustworthy in the area? I'm between roseville and rancho cordova (live in roseville, work in rancho) every day, so if you know of a good shop nearby please let me know! Like I said, I'm only asking a grand to sell it, so I want to avoid paying 120 for diag. and then another (enter amount here) for parts and labor...

Thanks!

Blaz----is the engine actually getting warm....actually hot? You still have the thermostsat in there right?

yep, put in new thermostat not too long ago, takes a while to heat up, but runs between 190-200 for the most part, according to my temp gauge. Could it be something choke-related?

some of the tbi engines have an air bypass valve. It gets clogged with carbon and won't close all the way. creates a lean mixture.

don't know if mine has got one or not, I'll check. if it does, can I just take it off and clean it?

This is free advice from a test only smog technition, I must suggest you do what he says. it would possibly only cost 120 for any decent shop to diagnose the problem. And if it is simple they may just fix it for ya.



OOOHHH thats illegal, tset only are only allowed to test, and give you a list of test and repair stations.

For a repair cost wavier, the cost of the repairs has to be atleast $450, with proof of it.

Dont waste your time replacing EGR, thats not it.

yeah just pull it out. spray with some wd-40 and wipe off. be sure to check the air passage where it seats and make sure it's clean as well.

Looks like it's going to placerville this weekend, dropping it off and leaving it with a friend, got it all lined up to do whatever it needs to smog, and fix the knock (all the way up to replacing bottom end of motor, if necessary) so it looks like I'll be waiting a bit while someone else does the work! Thanks for all the help everyone!

beyond any dought you must fix the upstream exhaust leak. O2 sensors really compare oxygen inside to outside of the pipe. If your drawing air in at this leak and you almost have to be by some measure that wonderful E.C.M. is going to push fuel. Also the E.G.R. valve is calibrated to that engine and the spring rate in the valve is crucial so I would do junkyard.