Smog/Emissions Problem

[kings1527]

I went to get my car smogged today and it failed pretty badly; gross polluter status for my California car. The numbers are as follows:

Ignition timing problem: I'm idling at about 1000 RPMs

15mph test:
HC - measured 269 (Max allowable 141)
CO - measured 2.56 (Max allowable 0.99)
NO - measured 724 (Max allowable 1148 PASSED)

25mph test:
HC - measured 153 (Max 113)
CO - measured 2.21 (Max 0.79)
NO - measured 736 (Max 978 PASSED)

From the paperwork I have from the previous owner, it looks like the O2 sensor was replaced about 5 1/2 years ago but only driven less than 100 miles since it was installed by DMC in Garden Grove.

Any thoughts? Bad O2 sensor? New cat?

I appreciate the help!

Alex
6575

[thirdmanj]

Find a guy qualified to smog test cars, take him out for drinks and become really good friends. Then mention to him that you've got a car that needs to be smogged! Problem solved!!


j/k... I'm really not too sure. Could be your cats not doing its job anymore.

[Bitsyncmaster]

Is your frequency valve buzzing. You should check the mixture setting as a first check. Why is it idling at 1000 RPM? It should idle at 775 RPM. Sounds like you need some adjustments.

[jawn101]

Agreed, an idle that high is symptomatic of something else misconfigured in the fuel/air system, that would definitely hurt your emissions.

[kings1527]

Is your frequency valve buzzing. You should check the mixture setting as a first check. Why is it idling at 1000 RPM? It should idle at 775 RPM. Sounds like you need some adjustments.


Thanks for the replies, guys.

Dave: I'm not sure where or what the frequency valve is. I'll have to look it up. I have no idea why it's idling at 1000 RPMs. I'm going to do a little investigating in my manuals and online over the weekend and see if this is something I can tackle on my own.

With numbers this high and that way off, do you guys think it could solely be related to the idle/mixture or could the cat converter be bad, too? How can I get a good/bad reading on the O2 sensor? My Lambda light isn't on.

I definitely wouldn't mind finding a Volvo guy in the Southern Cal area that's comfortable working on the car. I took it to one Volvo place today and they didn't want to work on it.

Thanks!

Alex
6575

[jawn101]

Frequency valve is an electronic fuel injector bolted to the passenger side valve cover towards the back. You'll find it by the presence of two fuel lines running to it and an electrical connector with a white plug. Start up the engine and touch this injector, you will feel if it's buzzing independently of the motor. If it's not, that's a big problem.

No sense in investigating your cat until the mixture is set properly. If the FV isn't buzzing that means the mixture is way, way off, or the valve is bad, engine computer is bad, O2 sensor could be bad, bad grounds, you name it. Lots to check. Look around for vacuum leaks as well. Check the electrical connector on the vacuum advance solenoid (bolted to the back of the intake manifold at the center, just to the right of the distributor)

The Lambda light on the dash is not related to any measurement, just to a mechanical counter that reminds you to change the sensor every 30k miles. So it's not part of the diagnostic process at all.

Check into that frequency valve and we'll go from there. There are TONS of threads on here about troubleshooting and correcting a high idle. Bring the idle to 775RPM +/- 50 RPM and then have your smog check again. If it still fails it could be the cat.

[deloumis]

Frequency valve is on the passenger side valve cover. Has hoses going off to the FD and a plug. While the car is on you should hear it buzzing. Lambda light is only for the counter, just a reminder to change the O2 sensor every so many miles. Has nothing to do with the readings.

[mluder]

You may also be looking at a problem with injectors. If the spray pattern is bad you could be dumping too much fuel which would result in high hydrocarbons and that could foul the o2 sensor. This could also be a causation for a high idle.

I would test the injector spray pattern first.
If that checks out, adjust the mixture with a dwell meter.
Next try o2 sensor.
Finally Cat.

This is what I had to go through with my car. I had a rough idle and terribly high HC in my emissions. I replaced my injectors which were not sealing properly. I also replaced my o2 sensor and my cat which turned out to be completely destroyed inside.

Once all that was done I dialed in the fuel mix and passed emissions with flying colors and it runs so smooth now.

Cheers.
Steve

[kings1527]

Alright guys, making progress. Thanks for all the help.

Steve - thanks for the info. The PO had the injectors placed maybe 5 years ago but the car had been run only about 70 miles since that time. I drained and cleaned out the fuel tank and never had any issues with the fuel system, per se. Possibly still a bad spray pattern?

My idle is right at about 750 when I first start it up, but increases to 1000 when it's at operating temperature. I'm guessing it's because the oil gets heated up at that point and less resistance.

Thanks for all the help, Jon. So here's what I found: I'm 99.9% certain I located the FV located here:11014

I unplugged the electrical connection with the engine running and the idle dropped off considerably, almost completely dying, and then kind of fixed itself but idled poorly. As soon as I connected it again, it went back to its normal idle and running smoothly (but still a high idle). When I disconnected it, the buzzing stopped. When I reconnected it, the buzzing started up again. So it seems like we're good there, right? I hope so...it's a $350 part.

As far as vacuum leaks go, I don't see anything but I think I need to take some ether and spray around to see what I can find. What would be the best points to hit?

While looking around the engine compartment, I came across this electrical connection that was disconnected:11015

I can't find the vacuum advance solenoid but I'm wondering if this is the connection to it? I'm still rooting around the engine bay trying to locate that solenoid.

Where should I go next? Thanks in advance...

Alex
#6575

[deloumis]

Vacuum advance solenoid is on the firewall.
Look at this diagram and follow the vacuum hoses to locate it.

[Bitsyncmaster]

My idle is right at about 750 when I first start it up, but increases to 1000 when it's at operating temperature. I'm guessing it's because the oil gets heated up at that point and less resistance.



That is correct that the oil heats up and causes the idle increase. It may be a simple back the curb idle screw out. My car had the same problem but was bad deceleration valve springs.

[kings1527]

Vacuum advance solenoid is on the firewall.
Look at this diagram and follow the vacuum hoses to locate it.

Thanks deloumis. Can you try posting that diagram again?

Alex
#6575

[Ron]

http://dmctalk.org/showthread.php?1156-Vacuum-Hose-Diagram


Distributor vacuum solenoid #27 here (http://store.delorean.com/c-275-2-4-0-evaporative-control-systems.aspx)

[deloumis]

Thanks deloumis. Can you try posting that diagram again?

Alex
#6575

Sorry about that, Idk what happened.

[kings1527]

That is correct that the oil heats up and causes the idle increase. It may be a simple back the curb idle screw out. My car had the same problem but was bad deceleration valve springs.


Thanks Dave. I found your old post where you talked about your decel springs and it sounds like a very similar problem as mine. I tried looking up that part on the parts list and in the forum and I can't locate exactly what the deceleration valve springs are and where they're located. You also mentioned the "W pipe" in your old post and I don't know what that is. Can you help me out on that?

Thanks,
Alex
#6575

[Bitsyncmaster]

The W pipe is the pipe you see that bolts to each runner on the intake manifold and joins them into the throttle body. You need to remove that W pipe to see your deceleration springs. From what I've seen, when the springs are bad, you can see the uneven spacing on them.

Here is a shot of the bad ones.

[kings1527]

Golden. Thanks Dave. I'll check it out today.

If anyone else has any ideas, please keep them coming.

Alex
#6575

[kings1527]

On another note, I started it up this morning and noticed on a cold start, the FV would buzz for 3-5 sec, turn off for 3-5 sec, and then turn on again etc. This happened for about 2-3 min or so until it was a little warmed up.

Is that normal?

Alex
#6575[/QUOTE]

[Bitsyncmaster]

On another note, I started it up this morning and noticed on a cold start, the FV would buzz for 3-5 sec, turn off for 3-5 sec, and then turn on again etc. This happened for about 2-3 min or so until it was a little warmed up.

Is that normal?

Alex
#6575No. Durring a cold start to warmup, The FV should buzz continuously running at 50% duty cycle.

[David T]

If the FV stops buzzing that is either a bad connection or your mixture is way off. Probably due to a vacuum leak and/or bad spray pattern on the injectors. The best way to find vacuum leaks is with a smoke machine. Typically the areas to check are the injector seals and the air pipe under the mixture unit. Recheck that the vacuum hoses are routed correctly to the vacuum advance and the CPR and the vacuum advance solenoid is hooked up electrically. Best way to check the mechanical and vacuum advance with a timing light. That way you KNOW they work and are hooked up correctly.
David Teitelbaum

[Bitsyncmaster]

During the warm up, the lambda is not running closed loop. It is waiting for the O2 sensor to warm up and start supplying voltage. Therefor the FV runs fixed at 50% or if it's really cold 60%.

So it will only stop buzzing after that warmup if the mixture is way off. Actually it never stops buzzing but with the mixture way off you may not hear or feel it buzz. If it truly stops buzzing then the lambda ECU or FV has lost 12 volt power.

[kings1527]

If the FV stops buzzing that is either a bad connection or your mixture is way off. Probably due to a vacuum leak and/or bad spray pattern on the injectors. The best way to find vacuum leaks is with a smoke machine. Typically the areas to check are the injector seals and the air pipe under the mixture unit. Recheck that the vacuum hoses are routed correctly to the vacuum advance and the CPR and the vacuum advance solenoid is hooked up electrically. Best way to check the mechanical and vacuum advance with a timing light. That way you KNOW they work and are hooked up correctly.
David Teitelbaum

Outstanding info Dave, thanks. I'll check that stuff out. On a whim, I tried to see if my CSV was having any kind of issues tied into this problem so I jumped it with the grey connection from the CPR and instead of cranking about 4-5 seconds before starting, it starting right away. So maybe there's something going on there, too.


During the warm up, the lambda is not running closed loop. It is waiting for the O2 sensor to warm up and start supplying voltage. Therefor the FV runs fixed at 50% or if it's really cold 60%.

So it will only stop buzzing after that warmup if the mixture is way off. Actually it never stops buzzing but with the mixture way off you may not hear or feel it buzz. If it truly stops buzzing then the lambda ECU or FV has lost 12 volt power.

Thanks Dave...I think I'm looking at a mixture issue as opposed to it not working right, per se. It felt to me that it completely stopped buzzing; it was very distinct. But we'll see. The saga continues...

Alex
#6575

[kings1527]

The W pipe is the pipe you see that bolts to each runner on the intake manifold and joins them into the throttle body. You need to remove that W pipe to see your deceleration springs. From what I've seen, when the springs are bad, you can see the uneven spacing on them.

Here is a shot of the bad ones.


Dave M - I've looked absolutely everywhere for the part number/part diagram that includes the deceleration springs and I can't find them. Can you give me the Parts Manual page or part number? Thanks!

Alex

[Bitsyncmaster]

Dave M - I've looked absolutely everywhere for the part number/part diagram that includes the deceleration springs and I can't find them. Can you give me the Parts Manual page or part number? Thanks!

Alex

I don't think you can buy the springs from our parts list. I bought another used throttle assembly. I thought about finding new springs but you would need to create a test jig and set the springs to open with higher vacuum than you get at idle (guess about 20")

[dmc6960]

The springs are not replaceable. The spring retainers will snap if you try to remove them. You'll need a new throttle assembly if they are collapsed.

[David T]

If you have an automatic you do not really need the decel springs to work. That means they can stay closed so the springs can be much stronger or you can glue them shut. On the 5-speed you can experiment with different spring pressures to modify the exhaust note. BTW, you can remove the retainers if you are careful. The springs need to be at least strong enough to hold the valves shut when the throttle plates are closed and the motor is idling. The other thing you can do is a dash pot. It hooks up externally to "catch" the throttle arm and settle it slowly to idle so the throttle plates don't snap shut quickly. You can adjust it a lot easier and quicker than the decel springs.
David Teitelbaum




The springs are not replaceable. The spring retainers will snap if you try to remove them. You'll need a new throttle assembly if they are collapsed.

[dmc6960]

BTW, you can remove the retainers if you are careful.

I was plenty careful. Have you removed the springs on any throttle plate?

[Bitsyncmaster]

I was plenty careful. Have you removed the springs on any throttle plate?

You can remove them by heating with a soldering gun. I used solder wick to remove the solder but if you can spin it while it's still hot that should work.

[kings1527]

Thanks for the info, guys. Good to know about the decel springs. After learning more about them, I'm hoping it's just a dirty throttle body (as was one car's case) as opposed to the decel springs. But for some reason, I thought the butterfly assembly (part 102856) was more expensive. At $86, I'd much rather replace it with NOS instead of messing with the springs.

I'm going to be doing a water pump real soon so once I get the intake manifold off, I'll take a look. Thanks again Dave M for the pic you posted on the springs.

DavidT - Thanks for the info. I have a manual.

Alex
6575

[kings1527]

This was a long work in progress, along with a lot of other things but I finally got the high idle/smog issue taken care of. The high idle at 1000-1100 RPM was my decel springs. I installed a new throttle assembly and all is well.

With my smog situation, I adjusted my dwell and the numbers were still way too high across the board. The guys at DMC CA said that it was the catalytic converter. So I ordered a new cat, gasket, nuts, and new O2 sensor and installed everything. I took it back to DMC CA and they smogged it, and the numbers came out amazing. They said this was one of the cleanest burning DeLoreans they've seen. That made me feel good! I attached my paperwork for a bad cat but properly adjusted dwell, and then the paperwork for a properly adjusted dwell, new cat, and new O2 sensor.

1646816469

[Chris 16409]

Here's something I just thought of. My car failed a SMOG inspection the last time I did it. I messed with the dwell and it passed the second time. However, I'm thinking the first time around, I don't think the technician allowed the car to warm up long enough for the lambda system to switch on. After start up and with the car running open loop, aren't the exhaust gasses less "clean"?

[jawn101]

Most smog places I've used will tell you to leave the car idling while they get ready to take your reading. I assume this is the reason why?

[kings1527]

Here's something I just thought of. My car failed a SMOG inspection the last time I did it. I messed with the dwell and it passed the second time. However, I'm thinking the first time around, I don't think the technician allowed the car to warm up long enough for the lambda system to switch on. After start up and with the car running open loop, aren't the exhaust gasses less "clean"?

That's the reason, as I understand it. The car needs to be completely warmed up in order for the emissions system to be working 100%, along with the O2 sensor and a pre-heated cat.

[David T]

It is absolutely essential that the car be at operating temperature before and during emission testing. There are systems that operate during warm-up to warm the car up more quickly that will skew the emissions badly. ANY shop MUST be sure the car is completely warmed up before trying to measure exhaust emissions. Usually the drive to the shop is enough. If the car is already at the shop then it must be warmed up.
David Teitelbaum