Source
r/240sx•
DemizeDesigns

Need help from the cali smog techs

I took my car to go get a smog test today and I am a gross poluter. engine is a bone stock single jingle.as I got home my cel popped on for code 32 which is egr function. The timing is way retarded and the tech told me to check my o2 sensor because my car is running rich. I've lost a majority of my life reading forum posts and the fsm. Since my cel is on for the egr, I am going to take of the egr and all the little parts to clean them and check the charcoal canister valve. Here are my results https://i.imgur.com/tyUIs68.jpg anything helps!

list of stuff I've recently done before the test:

- new spark plugs and wires

- new rotor

- new cts

- Replaced all cracked and leaking vacuum lines, basically the whole car all the way to the gas tank

- replaced some old corroded wires

-timed at 750rpm at 15 degrees with tps removed

- I used a multi meter on most smog parts

- new fuel

- seafoam

- fuel injector cleaner

- replaced orings for injectors and leaking fuel pump

- cleaned leaky solenoids which fixed the leaks

​

I'm debating pulling the engine and trans, doing a manual swap since I have all the parts in my shed besides the pedal and ecu and its easier with the engine out, clean and paint the bay, clean egr and intake ports, and installing a solid steering bushing and polyurethane rack bushings. Would be my first time pulling a engine but I am wanting to know how to do it for future purposes.

Posted Sep 28, 2019, 9:46 PM UTC · edited

110
nistech30•

You're on the right track with the egr equipment. Before taking apart the egr equipment, I would start with inspecting the elbow shaped hose at the bottom of the EGR-BPT (one of the saucer shaped things in the back of the engine). If there's a hole in the hose or feels thin, then replace it. Also inspect the hoses going to and from the egr +egr-bpt.

When the engine is running at normal idle, push up on the diaphragm and see if the engine stumbles. If it does nothing, then the egr may not be getting enough vacuum. You will need to vacuum test it. There's resources online on how to do. If the egr passages are clogged, you would have to spray carb cleaner and let it soak over night. Hopefully, all you need to remove is the egr-bpt. The egr (other saucer shaped thing) is a complete pain to remove.

As for the timing, I think it is retarded too much. I can't remember the threshold, but may be it's 18 btdc. The timing +- limits should be labeled under the hood.

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DemizeDesignsOP•

I have tested the egr before when I push on the diaphragm it stumbles. I have replaced the bpt with one from a pick a part and sprayed carb cleaner in it. As for the timing it says in the fsm and on my hood 15+- and with the tps unplugged its sittin on 15, therefor im thinking its the computer setting the timing to 0. I just snapped off the bolt on my tps so maybe I don't have that set right but right before I blew the fuse on my multimeter it was at .45 volts closed throttle.

1
Banandana•

There's the metal vacuum lines that run next to the intake manifold. There's 5 on the front, 3 that stick outwards and 2 that face downwards. Make sure to check the vacuum diagram to ensure the lines aren't swapped, or else the EGR won't receive vacuum under cruising conditions.

https://i.imgur.com/RUxItDI.jpg

Throttle body (12) -> EGR Solenoid (12, 10, 11) -> Hard metal vacuum lines (10, 7, 16) -> BPT Valve (16) -> EGR (15)

There's another line from the same metal vacuum line connecting to the bpt valve, which also connects to the EVAP canister. Follow the vacuum lines and make sure you didn't switch anything; you can find the diagram in the FSM, maybe your numbers are different.

I spent hours trying to determine why my EGR wasn't passing the california functional test only to find out I swapped the vacuum lines 10 and 11 or something, on the metal lines.

If you have a vacuum leak the AFR will be off. If your EGR is working correctly and the BPT valve input receives vacuum at 2400ish RPM after the car is warmed up, the EGR should be receiving vacuum just fine.

The EGR solenoid is closed until the engine is warmed up. Hope this at least helps, I know diagnosing this stuff is a bitch but you'll get it.

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DemizeDesignsOP•

So I took apart the intake manifold and cleaned the egr runners on the intake which made my car run all funky with all the air flowing through now. So I unplugged the battery and stood on the brakes for 10 mins. Definitely helped resetting the map. My car seems like it is running rich and I am getting vacuum to the egr and the bpt works. I adjusted my tps to the correct voltage before and got it to sit at 15btdc. After I decided to clean the intake it is retarded back down to 0. One of the solenoids behind the valve cover I think may have a bad connection since it’s all corroded and when I put on the connector the car starts running g differently. I know I am close but this has just been a frustrating rabbit hole lol I was able to get the idle to 750 before but now it’s sitting at 900 with the tps disconnected and around 400-500 plugged in

1
Banandana•

I'm pretty sure none of the EGR related vacuum lines run to the rear solenoids behind the valve cover. Those solenoids are responsible for the torque flap actuators and the vacuum to the AIV system iirc.

Make sure you torqued the intake manifold to spec with the right torque sequence. Don't forget the long bolts that bolt the head to the manifold under the fuel rails. If you have a manifold leak, your car will run like shit, potentially burning coolant as well.

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DemizeDesignsOP•

So I think I had the lines 2 and 3 swapped and my egr was also leaking. I cleaned it and now my car is running much better and is not rough anymore. I can't seem to get my idle under 1200 when adjusting the idle speed and timing. My idle screw oring was torn and leaking so I replaced it, the timing with the tps plugged in now is -15. So it seems as I'm on the right track but I cant get the idle lower. I am thinking about finding a local mechanic to see what they say. I'ts probably something simple that's flying over my head :(

1
Banandana•

I am not sure if lines 2 and 3 are related to the EGR function.

Looking back at your first post, I notice you mention the tech suggested you check your oxygen sensor. If it's a high mileage sensor or you've been running rich for a long time, those sensors will start to foul up and read lean, which causes the ECU to run the engine richer. I would suggest if yours is old to consider replacing it, as the o2 sensor can affect how the engine will run. There is a diagnostics mode you can put the ECU into which will report the o2 sensor readings; it might help you check the fuel trims, but if the o2 sensor is questionable it might not be helpful.

You also mention cleaning solenoids fixing leaks in your first post. I'm not sure what that means.

Another observation, high HC and CO output can be a symptom of an inefficient catalytic converter. It might not be worth replacing the catalytic converter until other issues are resolved, because it isn't surely the cause of the issue, but if everything else is fixed, and your HC and CO output are still high and the ECU is reading within 5% of target AFR (via the previously mentioned diagnostics mode) the cat might be the culprit. Something to note.

The high NOx reading is definitely EGR related.

These are difficult problems to solve without being in front of it, but if this was my car, I'd replace the o2 sensor if it's questionable; the o2 sensors are fairly cheap on rockauto, etc as it's an older 1 wire sensor. Just a generally good idea if it's old.

Check all the vacuum lines for leaks; easier said than done but the EGR related vacuum lines can get hot, and crack over time. It's some work, but it is worth replacing lines if they're questionable.

FYI, sucking on the 15a vacuum line to the EGR at idle should cause the car to stall out. I understand you checked this already to some capacity, but this might rule out the case of the vacuum signal to the EGR not actuating the EGR.

If that stalls the engine out and the EGR is operating via vacuum signal properly, then I'd check the BPT valve. You mention you bought one at a junkyard or something; they aren't complicated even though it sounds like it, and I've paid for a new one when it turned out mine worked fine. If there's positive pressure applied to the bottom port, the two ports on the top should be able to keep vacuum. If the larger, bottom hose connected to the BPT valve is ruptured or broken, the EGR will not function. The hose gets hot, so there is potential for it to crack.

Make sure the EGR temp sensor is connected and intact. It's the small sensor connected to the top of the intake manifold. Looks like https://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/SU6670/image/4/

The EGR solenoid controls vacuum to the BPT valve via the EGR vacuum solenoid. It's the solenoid with the 3 vacuum lines connected to it under the intake manifold kind of near the alternator. Make sure the solenoid is plugged into the wiring harness and the vacuum lines there aren't cracking either.

If the engine is running and after warming up, you can disconnect line 16, the one that sticks up on the metal vacuum lines. Feel that with your finger and rev the engine a little using the spring contraption connected to the throttle cable, not sure what it's called. If you feel a slight vacuum on your finger at around 2200rpm ish and the engine is fully warmed up, the EGR solenoid is working, and your lines up to the BPT valve are all functioning properly. If there's no vacuum at this point (basically gently rev the engine a little bit and feel if there's vacuum signal when you let go of the throttle), either the EGR vacuum solenoid isn't working, or there's a leak before/after the solenoid, or the vacuum lines are hooked up incorrectly. You have to use what you know to deduce where the problem might be with these vacuum lines, as confusing as they seem.

If you're getting vacuum to the BPT valve at cruising rpm as mentioned above (fully warmed up), and the BPT valve is working (you can finger test the vacuum after the BPT valve but it's more subtle), and the EGR stalls the car out at idle when messing with line 15 as mentioned above, the EGR should be functionally working. If all the vacuum system is working as expected, I would question if the EGR is actually flowing exhaust gasses through the intake manifold and/or if the EGR temperature sensor is working properly.

If everything there looks ok, and you're still not able to figure out the root cause, it might be worth taking to a mechanic as you had mentioned. Diagnosing car issues over the internet can be quite difficult and the right mechanic should know how to diagnose vacuum and EGR issues. Hopefully some of this information is helpful.

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