Check engine light is killing me!

[NismoDan]

So here's the deal:

Got the car, no check engine light. The day I go to get it smogged (after buying it), check engine light comes on. Unfortunately, I move 400 miles from home (and my tools) the next day.

Finally got around to using the ECU's self-diagnostic LED thingy, got codes 32 and 33, O2 sensor and EGR.

Replaced the O2 sensor this last weekend, didnt reset the ECU, drove 350 miles with the light still on.
Got back to the Bay Area, reset the ECU, light didnt turn on.

Today I finally go to get my smog done, and about 1.5 miles AWAY from the bloody smog place the light turns on again.
I am then reassured by everyone working there that it wont pass with the light on.

Any ideas? Anyone?
Pretty please?


By the way, the car has driven perfectly the whole time the light's been on; no stalling, sputtering, etc.

[kingsol]

check your codes again

[ghostuss]

Hmm EGR? Your EGR might be bad too. Man good luck with those lights. I hate them, I have one on right now, it's the EGR and I just ignores it unti I have to smog this bitch.

[wootwoot]

clear your codes in the parking lot of the smog shop for a quick fix. chances are it is egr but if you dont feel like getting to it yet

[idlafie]

Download a Factory Service Manual from here.
http://www.ffdet.com/members/rich/Nissan/nissan.htm
Follow the diagnostic procedures listed for the appropriate Diagnostic Trouble Codes.
Before you start though, check to see that the vacuum line that runs from the secondary BPT valve to the EGR valve is not cut / split / melted / disconnected OR pinched. If it is then take the appropriate action to repair it. You might also want to take a can of carburator cleaner & spray some of it in the little metal tube that's on the top side portion of the EGR valve. While you are spraying it into the little metal tube, take your other hand & place it palm down on the top of the EGR valve. Curl your fingers around the EGR valve till your fingertips are underneath the bottom "hat" portion of the EGR valve. GENTLYsqueeze your fingertips upwards...you should feel the bottom diaphram portion of the EGR valve rise slightly as you apply pressure to your fingertips. You're using the carburator cleaner to help get rid of some of the carbon buildup that's stuck in the EGR valve by spraying it with carb cleaner.
Anyhow, hope this helps...
ID

[ghostuss]

I heard you can just block it off too.

[NismoDan]

Ok, so i finally got around to checking my codes again.
Pulled a 34....got angry....tried again, pulled a 55, the "everything's OK" code.
Check engine light goes off.
Go to the smog place. Smog guy tests it 3 times, fails every time.
What's going wrong is my NO...I'm getting readings of 4000.
So, since he's a nice guy, the smog dude doesnt input it into the computer, so I'm not a gross polluter yet.
The check engine light turns on during the tests.
At the smog place we check the EGR again. Turns out the thick bottom hose from the BPT to the EGR is screwed. We replace that. Check engine light is still on.

So by this time i come home and start messing around on my own.
Checked the EGR by pushing up on the diaphragm and it makes the engine bog/stall....which means the EGR is working
Next I put carb cleaner in the throttle body as well as in the top EGR valve hose.

Check engine light is still on....

Any suggestions?

[aznpoopy]

34 = knock sensor

check the ground on the upper right side of the valve cover (with you facing the front of the car). iirc that one hooks to the knock sensor. its always shaking since its on the engine and gets weak over time. might want to clean / resolder to keep it from popping up during the inspection.

going over your old issues:

high NO can be caused by

malfunctioning EGR system :(
bad catalytic converter
carbon desposits inside engine
alot of timing advance

might wanna see if you can clean some gunk out of the EGR. also maybe the material in the cat is fuxord or the cat itself is a bit clogged? have you timed the car? then again if it was that advanced i bet you'd notice...

finally i heard if theres alot of moisture in the air, it can reduce your car's nox level; try going next time on a rainy day if you can keep the check engine light from coming on.

[Phlip]

Removing the check engine light bulb could do a world of good here too.

... oh, and move the hell out of California, I got my car inspected with the check engine light on once

[Id-]

uh you could leave california :)

[idlafie]

Checked the EGR by pushing up on the diaphragm and it makes the engine bog/stall....which means the EGR is working

Check engine light is still on....

Any suggestions?

Recheck the EGR valve, except this time do it with the engine running. Place your left hand on top of the EGR valve & curl your fingers underneath towards the bottom of the EGR valve. Let your fingertips touch the bottom diaphram under the EGR valve. DO NOT push on the diaphram...just let your fingertips feel it.

Take your right hand & reach over to the throttle body. Pull on the gas cables leading to the throttle body a few times. You should feel the diaphram on the bottom of the EGR valve raise by itself. By pulling on the gas cables, you be revving the engine hard & fast a couple of times - you're creating a vacuum to the EGR system. You'll feel it cuz the diaphram on the EGR valve will raise by itself without you pushing it.

If you don't feel that vacuum, then you need to trace the vacuum lines to see if any more vacuum lines are cut or melted. Best way to do this is to get your hands on a vacuum gauge & follow the procedures listed in the FSM. The smog guy found a bad vacuum line already, you may have another one or two that you haven't found just yet.

While you are at it, also check & clean the secondary EGR solenoid valves. You're gonna need a S13 FSM to find the location of each of them.

And as for your faulty Knock Code sensor, check the subharness - it's probably a bad or shorted out pin connector in the harness. Also resolder a new ground grommet where the wires connect to the engine block, (directly above the Oxygen sensor towards the rear of the engine block on the driver's side).

Hope this helps....

ID

[idlafie]

Removing the check engine light bulb could do a world of good here too.

... oh, and move the hell out of California, I got my car inspected with the check engine light on once

Removing the Check Engine Light Bulb may not help. Depending on how competent, (or incompetent), the smog technician is, he is supposed to check your dashboard as he turns the key over on your ignition & starts your car for the test. If the Check Engine Light does not come on with all the other bulbs, (alternator, oil, seat belts, etc) as it should, then the smog tech can fail you for not passing the VISUAL portion of the smog test.

This site gives a pretty good description of how a smog test is done..good reading:
http://www.valvoline.com/carcare/articleviewer.asp?pg=ccr20040601st

Anyhow, hope this helps...
ID

[idlafie]

going over your old issues:

high NO can be caused by

malfunctioning EGR system :(
bad catalytic converter
carbon desposits inside engine
alot of timing advance

might wanna see if you can clean some gunk out of the EGR. also maybe the material in the cat is fuxord or the cat itself is a bit clogged? have you timed the car? then again if it was that advanced i bet you'd notice...

finally i heard if theres alot of moisture in the air, it can reduce your car's nox level; try going next time on a rainy day if you can keep the check engine light from coming on.

Aznpoopy is correct in all of the above....one thing he may have forgotten to mention, but is known to happen on our 240's......

You may have a partially plugged exhaust passage that feeds the EGR valve. It's the metal tube that goes from the exhaust manifold, runs behind the engine and then connects to the EGR valve. You're gonna have to disconnect the exhaust passage tubing & run a wire or something else thru there to clean out any carbon buildup and debris which could have built up inside of there.
ID

[NismoDan]

You think shooting some carb cleaner in the EGR hardpipe would help clean some crap out?

[NismoDan]

Recheck the EGR valve, except this time do it with the engine running. Place your left hand on top of the EGR valve & curl your fingers underneath towards the bottom of the EGR valve. Let your fingertips touch the bottom diaphram under the EGR valve. DO NOT push on the diaphram...just let your fingertips feel it.

Take your right hand & reach over to the throttle body. Pull on the gas cables leading to the throttle body a few times. You should feel the diaphram on the bottom of the EGR valve raise by itself. By pulling on the gas cables, you be revving the engine hard & fast a couple of times - you're creating a vacuum to the EGR system. You'll feel it cuz the diaphram on the EGR valve will raise by itself without you pushing it.
ID

Ok, so I just did this and yea, the EGR doesnt move on it's own.
I'm going to go see if someone can help me find the leak.

And the thing about the EGR hardpipe from the exhaust mani...I would open it up and clean it out, but when I do the EGR manually it opens right and the gas comes through, so that pipe isnt clogged. Thanks for the help though.