Emissions Test Help , Fuel Mixture Questions , Making Progress...

[VTEC_Inside]

Ok dokie, here are my results from Feb 2004.



I was told at that time that the cat was bad, but since I had reached the repair limit, I ended up with a conditional pass in the end.

Test is comming up again now. I've already bought a new cat and mid pipe with resonator cause mine broke off at the muffler flange.

After searching and reading on here for an hour I've come to the conclusion that my cat probably wasn't the problem back then.

I've recentley replaced my thermostat which I now believe may have been my problem all along as the car was never heating up fully until on the highway and I was having all kinds of cold idle trouble.

However as you can see, I had no trouble with the idle part of the test.
My main problem would seem to be running rich while driving. I found nothing about adjusting that though. Could that have been as a result of the lower than normal operating temp?

[VTEC_Inside]

Also, while we're here. My car also visibly burns oil on cold starts when the ambient temperature gets closer to 0 degrees celsius. I'm almost certain that its dried up valve seals as it won't blow a puff of anything when the weather is warmer.

Will that oil burning off damage my new cat?

[A20A1]

If the fuel is cold it will puddle and you'll either get raw fuel in the cylinder which is harder to burn or less fuel cause the air just blew over the top while the fuel remained in the manifold and you run lean.
In any case if your fuel isn't warm enough, meaning in VAPOR form then it will decrease performance.

If coolant isn't flowing properly things like your choke and thermovalve will not work correctly... This means you choke may still be closed when it shouldn't which would cause you to run rich.

Always heat the car up fully before doing an emissions test.

The engine itself will still get hot... just because your coolant temp doesn't show a change doesn't mean your engine isn't heating up. The coolant sensor is in the carb manifold, if you were having coolant issues that wasn't letting the coolant build pressure which would alow it to reach a higher temp before boiling... or flow problems keeping the coolant from reaching the sensor all together.

[RamThis]

I was a state inspector here in Tx a few years ago. I learned in alot of classes that if you do a full tune up, change the oil, put in some Berrymans B-12 Chemtool to the gas tank, and make sure your timing is set, it shouldnt have any problems passing the sniffer test. sometimes throwing a new cat on, driving the car till it warms up, and bringing it right in for inspection will work as well, did this on many a car to get them passed.

Just make sure as mentioned before, DONT BRING THE CAR IN COLD. Make sure its been running for a while. If you are not the next in line for inspection and the car would have to sit for a while, either come back at a different time, or, if the wait isnt more than about a half hour, just wait in your car and keep it running and hot. This helps to keep the car running leaner and cleaner.

Also, if you have an O2 sensor, and its been more than 60K or so since its been replaced, put in a new one.

There were few cars I couldnt get to pass with some minor tweaks or catching up on some fogotten maintenance items. Hope this helps....

[A20A1]

I dunno if you guys have seen this thread... add or change info if you've got it.
https://www.3geez.com/showthread.php?t=46572

[dalinxz]

change your pcv valve $4 fix and not that hard to change

[VTEC_Inside]

change your pcv valve $4 fix and not that hard to change

I plan on that actually. I tried once before but I couldn't get the damn thing out of the manifold... Any suggestions?

I'm putting my new exhaust parts on this weekend as well hopefully.

[dalinxz]

tug you really have to tug the thing out I thought I was going to break something but it eventually comes out whilse your pulling jiggle it at the same time and eventually after much deliberation it will come out.

[VTEC_Inside]

I just changed the PCV valve. Strangely it came out pretty easy. I wonder wth was up last time I tried.

Anyways, it was still working, ie clicked when I clamped the hose. The bottom was covered in a light coating of oil. The new one I put in is just from Partsource. The top opening seems smaller and the the spring doesnt seem as stiff, but it still clicks when clamping, a little louder perhaps.

Now my weekend rides on being able to use my aunt and uncles garage with a pit. If not I'm stuck jacking up the car in the driveway.

[VTEC_Inside]

Ok, my '89 failed the etest again today with high CO and HC at 40kph.
I've since replaced the O2 sensor and to my suprise the car seems to be pulling harder when I punch it now. This may be indicitive of a better mixture thanks to the sensor. However I am not entirely sure of its role in the a/f mixture. I want to tackle any other possibilities before I go for a retest.
I've been reading on here that the idle a/f mixture screw is basically in effect to 3000rpms. Is this true? I've never touched the mixture screw and my car passes idle emmisions with .02 CO and next to no HC. Is it possible to pass with next to no emissions at idle, yet fail running 1900rpm@40kph if this screw needs adjustment?
I've never touched the air jet controller either, but I read that I could potentially lean it out using that. I'd rather not as this car has passed emissions in the past as it is.
I've had thermovalve A replaced. After reading I think I want to replace B as well.
As of right now the following describes my car:
- choke works perfect once the car starts. it usually takes 2 tries as it dies the first time unless I gas it a bit. (fast idle problem???)
- the idle controller seems useless to me. It gets wicked vacuum and holds very well, but it doesn't ever seem to back off so I've got the screw adjusted such that it does nothing.
- it has a light studder on light throttle application, but that has just started recently (last couple days) and I think its cause of bad gas, but I will rule out a distributor issue soon
Any thoughts/opinions/suggestions are greatly appreciated as always.

Forgot to include this wonderful tidbit.
I changed the plugs last night before the test, and the O2 today after the test.
All the plugs look about the same, which is a light WHITE ash coating. The O2 looks about the same. Now doesn't this indicate a slightly lean condition?

[A20A1]

when the idle controller gets vacuum it's supposed to put less resistance on the throttle linkage and lower the idle speed. If vacuum drops, it rasies the idle speed because the spring over powers the vacuum and pushes on the throttle linkage. If the throttle stop isn't set right there could be problems... if there was a vacuum leak then it would constantly want to up the idle. But usually the idle controller is in constant contact with the throttle linkage... only when you press the throttle does the idle controller fall out of reach, and at that moment you're no longer idling so it doesn't matter.

https://www.3geez.com/showthread.php?t=46572
https://www.3geez.com/showthread.php?t=45880
https://www.3geez.com/showthread.php?t=44074

Yeah the A/F screw is not for mixture at Wide Open Throttle... it's mostly for idle mixture, it's not so much RPM dependent as it is throttle position dependent... how far your throttle plate is open will determin where the carb gets a stronger vacuum signal from. I'd say a steady 2,000 rpm and you're still in range of the A/F screw.

What did you fail? HC or CO or what?

Supposedly the carb runs rich so the O2 sensor is there to let the computer know how much air to add behind the carbs back... so the carb doesn't meter any fuel to support the air... and you end up with a leaner mixture on demand.

I would check your booster venturi... just in case.
https://www.3geez.com/showthread.php?t=8972

[VTEC_Inside]

Would you happen to know what point the Idle A/F mixture screw becomes irrelevant? Could one assume that at 2000rpm the idle a/f screw is not really affecting anything?

when the idle controller gets vacuum it's supposed to put less resistance on the throttle linkage and lower the idle speed. If vacuum drops, it rasies the idle speed because the spring over powers the vacuum and pushes on the throttle linkage. If the throttle stop isn't set right there could be problems... if there was a vacuum leak then it would constantly want to up the idle. But usually the idle controller is in constant contact with the throttle linkage... only when you press the throttle does the idle controller fall out of reach, and at that moment you're no longer idling so it doesn't matter.

Problem in my case is that the throttle control doesnt seem to move at all until the engine dies.

I failed HC and CO.

HC limit: 68ppm Reading: 102ppm [Those are the exact numbers]

CO limit: .38 Reading 1.2 [I have to look up the exact numbers, but those are close]

I would check your booster venturi... just in case.
https://www.3geez.com/showthread.php?t=8972

Already tried moving it. They don't seem to budge, but I will check again.

[A20A1]

It could be you have a rich mixture.
Or poor ignition, or both.

A vacuum leak would effect both the carb and the ignition timing.

Since idle speed adjustment is dependent on a good ignition system... a faulty ignition system could lead to improper carb adjustments.

The lean mixture would cause the higher HC, but higher CO is from a richer mixture, a richer mixture could effect ignition and that could lead to higher HC.

The plugs will tell you what your engine was doing shortly before it was shut off... not specificly what your car is doing at 2,000 rpm.

So you may have an overly rich or poor combustion at that engine speed / throttle angle/position, but everything else is okay.

The powervalve operates off of low vacuum signal... if vacuum were to drop off too early then the spring would lower the power valve plunger, open the valve and introduce a richer mixture.
A vacuum leak, leaky power valve, or sticky power valve may cause this problem.

If the float setting was too high. It would take less effort for the carb to pull fuel from the float bowl, that would lead to a richer mixture overall.

You may want to replace the carb 'Top Hat Gasket'. This will keep the internal air and fuel passages sealed and free from interference.

https://www.3geez.com/showthread.php?t=5350

that link will take you to a printable image of a usuable 'top hat' gasket.

print it on a thin sheet of gasket paper, it's best to use an exacto or quality single hole puncher to make the needed holes in the gasket material.

[Kabuki]

OH! DON"T MESS WITH THE A/F MIXTURE (also known as Lambda) SCREW! It's set at the factory and cannot be reset correctly once moved! Also, check each of the vacuum diaphragms on the Carb and other places. The hot air diaphragm, the vacuum advance, the Choke Opener, and the charcoal canister vent are the most common to fail, and usually in that order. We've been doing a lot of those lately. Check all of your vacuum hoses too. Last thing, you mention the plugs... What brand and model did you install? What about your cap and rotor?

[VTEC_Inside]

I hadn't planned on touching the A/F screw. Idle is not my problem.

The hot air door leaks a bit, but nothing severe.

I think my Thermovalve B is toast because I only get vacuum to the inside port of the distributor advance when its cold. I'm about to start reading up on what else that could effect. I believe that is only a problem on cold idle situations. I think I am going to change the distributor tommorow. The one on the car is the TEC one and oil is slowly leaking through it. I have a Hitachi unit that belongs on the car anyway so...

The choke opener is working fine.

I'll have to read up on checking the canister. The only thing I know as far as that is concerned is that I seldom if ever get an air whooshing as I open my gas cap.

I've visually inspected pretty much every vacuum hose and replaced a few suspect ones.

The plugs I put in are the NGK ones that the underhood sticker indicates. The cap and rotor are OEM and only a week or two old.

I really appreciate all the help and suggestions. The people on here have undoubtedly saved me hundreds of dollars in diagnositic fees.

[VTEC_Inside]

Man, this car should come with a vacuum pump/guage.. lol...

I think I'm going to have to invest in one.

[A20A1]

A vacuum leak is a vacuum leak servere or not.

The vacuum on our carb system is spread thin enough as is between all the valves and such.

The #25 is supposed to get vacuum only when cold, that is why it is called the cold advance.
Your thermovavle is working.

[VTEC_Inside]

I meant that #25 is not getting vacuum on my car when cold.
I should have referred to the #'s sorry.

[VTEC_Inside]

Ok, my car failed E-test last wednesday, over on CO% by 1.xx%.

I replaced the O2 sensor and had the exhaust sniffed again today. CO% dropped by a full 1.0x percent!. I'm still .08% over the limit though.

This challenge is remaining enjoyable for now....

[VTEC_Inside]

I believe I have found the final problem.

After tightening the boosters [thanks A20], replacing a couple more vacuum lines, and verifying the IAT sensor operation, I decided to check the coolant temp sensor.

I haven't checked its operation yet (ie resistance), but I can tell you that it doesn't matter thus far as IT WASN"T HOOKED UP!!!!!

I can't reach far enough from the top to put the connector back on, but as soon as I can get under it, I'm going to verify its operation and reconnect it.

[A20A1]

You mean the sensor on the block?

[VTEC_Inside]

You mean the sensor on the block?

Yes.

[Honda-Master]

lets see u are failing at cruise correct??? try something..make sure the secondary air system works properly... under the air cleaner there is the secondary valve it has a vacc hose ( #5 ) disconnect hose..raise engine rpm to 2500-300 you should get vacc there ,if not secondary air is not working.....try a test,, disconnect hose # 5 and plug it ,, hook up a t-fitting to distributor # 2 hose the inner hose of vacc advance unit ,, hook up a vacc hose to the t-fitting and hook it up to the secondary valve it will lean out the mixture at cruise.. i have done this 100 times to correct emission failure at cruise running rich,, try and post results..



With Air Suction Control Solenoid Valve
(Manifold Vacuum -> #24 -> AS Solenoid -> #5 -> AS Valve)

Bypassed Air Suction Control Solenoid Valve
(Manifold Vacuum -> #24 -> AS Solenoid -> #5 Plugged -X)
(Manifold Vacuum -> #2 -> T-Fitting -> New vacuum line -> AS Valve)
(Manifold Vacuum -> #2 -> T-Fitting -> #2 Continued -> Distributor Advance)

[VTEC_Inside]

After I replaced the O2 sensor all emissions fell drastically.

At my last test I was within the limits for HC, and NO. I was only slightly over on CO%. As I mentioned, the coolant temp sensor was completely disconnected at the time. I have since checked its function, ie watched it go from 7k ohms down to 2.5-3ish as the car warmed up, and reconnected it. I'm almost certain I will pass the test now.

If not I will move on to troubleshoot the air control system.

[A20A1]

Thanks for the info.