94 q wont pass smog

[kevinpaigeking]

all readings went up after injector and ks replacement. i know i need to get new code readings but want some self help advice

[maxnix]

Did you clean plenum, lower runners, TB, IAC and EGR valves? New gaskets, hoses?

Just replacing KS, harness, and injectors should not cause that.
Modified by maxnix at 8:22 PM 5/24/2009

[qsiguy]

I failed emissions when I had bad knock sensors, check your codes now and make sure everything got hooked up right and that the new sensors are ok, no loose connections, etc.

How is it running compared to pre KS replacement?

[Rex]

My first thought when reading "replaced injectors" is a possible pinched o-ring or other issue.

[texasoil]

how does it run? My '92, 178K, original cats, '95 purple top injectors, idles so smooth it's scary. Emission numbers are still like they were 10 years, 90,000 miles ago--well below limits. KS will not effect emissions unless you are running cheap low octane fuel--and if you are, it will probably never pass the emissions test. If would be lots more helpful if you would include the before and after emissions test numbers.

[kevinpaigeking]

it runs good. plenty of power. Idle is not perfectly smooth. Also, check engine light will come on after extended driving, but does not stay on. Lastly, every so often the car will have abrupt loss of power for a micro second. this never continues after 2 or 3 hiccups.I was running 87 fuel when i had it smogged. will 92 really make such a difference? What about my O2 sensor?

[lexrob]

Ok this is going to sound crazy but it you have brief power loss randomly .... GROUNDS=(put big thick wire to frame-go drive!!Fixed).....alternator bad.. ICM.

All can be tested pretty quick just throwing it out there ive seen a crx,civic,teg,and 240 all go crazy from bad grounding. I also tested and searched forever on my buds 99 Z28 and ended up being alt. putting out to much. Im talkin MAF code, all O2's, bat. light flicker once, cd player shut off crusin..... anyways good luck.

[Rex]

it runs good. plenty of power. Idle is not perfectly smooth. Also, check engine light will come on after extended driving, but does not stay on. Lastly, every so often the car will have abrupt loss of power for a micro second. this never continues after 2 or 3 hiccups.I was running 87 fuel when i had it smogged. will 92 really make such a difference? What about my O2 sensor?

The CEL you describe sounds like o2's, but you have tro stop running 87. Bad things will happen if you do not run premium all the time. They may not habppen today, they may not happen next month, but they will happen.

If you consider premium is too expensive and unnecessry, then you're driving the wrong car. Sorry to say, but it's true.

[mxr662]

http://www.nicoclub.com/articles.php?id=60332

That's what my check engine light did with a bad 02 sensor

[qsiguy]

...KS will not effect emissions unless you are running cheap low octane fuel--and if you are, it will probably never pass the emissions test...

It certainly can/will. As soon as the ECU see's a knock code it switches the knock maps (fuel and timing) which are very different. If the emissions place does the "dyno" test it will most likely fail. I was not running low octane. I always run 91 (best we have unless you buy race fuel which I do occasionally). All I had to do to pass was bypass the faulty knock sensor with a resistor and it passed with flying colors.

Kevin, have you determined what code is triggering the CEL? BTW the knock code will not trigger the dash CEL.

[trajanH]

It certainly can/will. As soon as the ECU see's a knock code it switches the knock maps (fuel and timing) which are very different. If the emissions place does the "dyno" test it will most likely fail. I was not running low octane. I always run 91 (best we have unless you buy race fuel which I do occasionally). All I had to do to pass was bypass the faulty knock sensor with a resistor and it passed with flying colors.

Kevin, have you determined what code is triggering the CEL? BTW the knock code will not trigger the dash CEL.

How did you wire a resistor to bypass the knock sensor? I would really like to know that cause I have a knock sensor code triggering and that part seems almost impossible to replace on my Q. Thanks.

[kevinpaigeking]

thanks for the info. her is one last history fact of my q45 problem. Originally the check engine light was always on because i had bad injector (#6) and ks. I had smog check prior to replacing them and it failed. (of course) But after having the two replaced, and the car running much better, the re-smog showed even worse readings, almost doubled in a few stats. I can replace O2 sensor but these smog checks are becoming a crap shoot. what do you think?

[3Q Jay]

WE CAN'T TELL YOU JACK WITHOUT DATA.

[qsiguy]

How did you wire a resistor to bypass the knock sensor? I would really like to know that cause I have a knock sensor code triggering and that part seems almost impossible to replace on my Q. Thanks.

A new knock sensor is about 500-600K ohms. Check your current sensors and determine which one (maybe both) are bad. My bad one would measure all over the place depending on engine temp. I saw readings from around normal all the way up to 25M ohms. I clipped the knock sensor input near the ECU and wired a 560K ohm resistor from the ECU sensor input to ground. You could also wire this up out near the plenum. Just make sure the wire coming from the sensor is not still wired up with the bypass resistor.

Check your FSM (factory service manual) ECU diagrams to determine which ECU wires are for the knock sensors. To replace the knock sensors the intake plenum has to come off...big job. Several writeups on the site explaining process. Cost to do it right ~$900-$1000 if you do it yourself.

[thejapino]

Qsiguy, that's interesting. Email sent!

[unknown007]

thejapino you got mail too.

Like the others said nothing can be said without data. I say get your codes read with a diagnostic device and post.Maybe that'll help.

[jimbyjimb]

After you fix your issues put some 92 in with an octane boost and go on the freeway in 2nd gear and rev that biotch up to 5 grand for a few miles. Clear the crap out of it, you know. Carbon on the valves and such.

Sarcasm aside, what readings were highest?

[q45j30guy]

"go on the freeway in 2nd gear and rev that biotch up to 5 grand for a few miles. Clear the crap out of it, you know. Carbon on the valves and such."

what I use to call an Italian tune-up

[maxnix]

A new knock sensor is about 500-600K ohms.

A little closer to 550K to 565K Ohms.
Modified by maxnix at 9:21 AM 5/29/2009

[elwesso]

Yeah we really cant tell you much until you provide some data.... Its possible maybe you're failing your NOx emissions would wouldnt have anything to do with injectors...

Could it be maybe you missed something on the install, maybe a vacuum leak or something...? Im thinking the rough idle will explain some of it.

Also, what makes you think its a good idea to run 87 octane, especially when going for an emissions test?????????????????????

[jimbyjimb]

Hence forth, from this day forward it shall be known as the Italian Tune-Up. Q45tech must recieve all due credit for the 2nd gear on the freeway, or the aptly named Q45 "Italian Tune-Up," as it was his word I accepted as gospel.

But elwesso's points stand valid. It's a pretty well known pratice to run through emissions tests with high octane fuel and a hot engine. Work it out, let it breathe hard first for a bit. But there are many categories that can fail an emission test, and specifically which portions failed and by how much can help greatly in determining and pinpointing the cause of such failures.

[maxnix]

Also, what makes you think its a good idea to run 87 octane, especially when going for an emissions test??????

Actually, that should be ever. Emergency use only, small quantity, and replace ASAP with Tier 1 Premium.

[kevinpaigeking]

what aftermarket O2sensors do you trust (94 q45)

[maxnix]

OEM from Joe or correct NTK ones from sparkplugs.com.

For the latter, call to order to make sure you get the correct ones with the correct leads. Let them know you are from NICO in either case as they are both sponsors. Natasha I think was our contact at sparkplugs. Anyone at IoS can help you.

No other brands or eBay offers!


Modified by maxnix at 8:30 PM 6/3/2009

[qship96]

Brian, it is NTK!!!! TDK makes audio recording magnetic tape!!!!! Get that Revox off your mind!!!

[maxnix]

Maybe I was thinking of the CD-ROM blanks.

[kevinpaigeking]

HC (PPM) 15mph 82 1st time 113 2nd time

25mph 58 1st time 105 2nd

NO (PPM) 15mph 1285 1st time 2119 2nd time

25mph 1171 1st time 1989 2nd time

The 2nd values are the ones after fuel injector and ks replacement

[elwesso]

I edited your post to make it a little easier to read, I tried to decipher what was going on and I couldnt make any sense of it..

Next time you need to be a little bit more detailed.

It looks like you are failing on both NO and HC's which means that your EGR is plugged and you're running rich...

Please post the max values for your car, because your HC numbers could be close but certainly your NO numbers are way high...

Clean the EGR and you should be in business.

[kevinpaigeking]

ThanksMax on HC are 80 at 15mph and 45 at 25mph Max on NO are 679 at 15mph and 683 at 25 mph

[elwesso]

Did you let the car warm up fully? That should take care of your HC problems.. Right before you go to emissions take the car and drive it hard (few runs up to 5000+ RPMS) after its fully warmed up and when you're waiting don't turn the car off...

But for sure, you're going to need to clean your EGR and you should be all set!