TobiasRX

Hi

I have recently tried to pass emissions here in sweden without success. CO is 2.6 and HC 116
The emissions is only bad at idle, at increased idle (3000rpm) i have CO 0.0 and low HC
My engine is recently rebuilt and i have driven it 60km.
I have a slight idle issue where when i turn on the lights in the car the idle jumps + - 50rpm
If i dont have the lights on it idles fine.
Also when the engine is cold it struggles to get to 3000rpm. So it frels like something is stuck and barely manages to open. Not sure what though.

Can any of this be related to bad emissions? Im Thinking yes but unsure what to look for.

Also, but this is a longshot, at both times i have been to the car inspection to get my emission readings i have had a turbo pipe to the IC alittle loose so when the turbos spool up i can hear air being blown into the engine compartment.
Can this affect the emissions?

Would really be great to get some answers to my problem asap cause in a few days i wont be allowed to drive the car because i failed to pass the emissions inspection.

KrisD1

What kind of value do you need in Sweden. Do you have a airpump and cat?
When your car is cold you cannot go wot until the car is warmed up.

TobiasRX

We need to have CO 0 and HC under 100

What i ment with the cold engine is when you start it and its supposed to go up to 3k rpm to warm up faster. This is a feature Mazda built in to the car to get better emissions during startup.
Just ment that it doesnt work properly on my car.

wstrohm

Idle speed when warm (and the engine should only be tested when fully warm) should be 700 - 750 rpm with all electrical accessories off. Is that your idle speed? If too low, you could fail emissions. Are you sure that outside air is being injected into the catalytic converter? That is needed to burn off HC in the converter.

I think idle speed may very well rise when an electrical load like headlights is added. There is an "Electrical Load Unit" which affects idle speed according to load on the alternator. Page F-82 of the 1994 RX-7 workshop manual states that with electrical load ON, idle speed should be 775 - 825 rpm. Also if A/C is ON, idle speed should be 875 - 925 rpm. On our '94 FD, whenever the air conditioning compressor comes on, the idle speed rises. It also happens when the heater fan/AC blower is on high speed. When set correctly, the PCME and IAC valve work to hold idle at 720 rpm, unless heavy electrical loads cause the ELU to compensate to a higher idle speed.

(For what it is worth, here is a link to our '94's current emissions requirements and results in California. There is no idle test here; tests are done on a roller dynamometer at 15 mph and 25 mph.)

TobiasRX

The problem for me is that the idle jumps alittle when i get the lights on. It cant hold it steady. Otherwise the idle is fine. Maybe the elecric load unit is faulty or stuck. The car has bern sitting for 3years.

Iam actually not sure if the air pump is working correctly. It costs money for me just to ser if the emissions will get worse if i disconnect the airpump. Maybe i will try that anyways this week.

arghx

iTrader: (3)

The accelerated warm up system is to reduce cold start emissions on the LA4 emissions certification test cycle in the USA. It's not going to have a real-world effect on anything else. Japanese cars didn't have it.

If it's not just a bad cat, this sounds like a secondary air injection (smog pump) issue to me. Contrary to popular belief, the smog pump only pumps air directly into the cat under a narrow set of conditions. It's usually pumping air right into the exhaust port.



Here's a little background on how this works. The FD requires a rich (richer than 14.7:1 , the stoichiometric ratio) mixture at idle and low loads to stabilize combustion and prevent misfire. The smog pump dilutes this rich mixture at the exhaust port when the port air system (built into the air control valve) runs. Some of the fresh air recirculates back into the engine, but most flows into the exhaust system where it assists the oxidation process in the catalyst.

There are effectively three cats on a non-Japan spec FD. The closest converter is the pre-cat. This warms up first and operates on a cold start to assist performance in an emissions certification test more than anything else. The second cat is really the front portion of the main underfloor converter. This is an oxidation catalyst; it converts HC and CO and requires assistance from the smog pump when the engine runs under low loads. The third cat is actually the rear portion of the underfloor catalyst; it is a three way cat, meaning that it converts HC + CO (oxidation) and NOx (reduction).

Assuming there aren't any basic mechanical issues (messed up idle speed, exhaust leak, etc) failing an emissions test is usually the result of a secondary air injection problem or poorly performing converter.

I don't think a small leak in the intake air system (as long as it's not an actual vacuum leak) is going to have an effect because this engine does not use an actual airflow sensor. You should check for vacuum leaks and try doing the idle adjustment procedure in the service manual (fuel and emissions control section). Basically you put it in diagnostic mode and turn a screw on the throttlebody.

TobiasRX

Thanks for all the info.

I dont think the cat is broken since my lambda values is over 1.0
Also i didnt mention that i am using a racing cat and i havent connected the pipe from the air pump to it. Have never needed it before.

Is it a good idea to measure the emissions with the airpump connected and during test disconnect it? Or am i wasting my time and money doing this?

CloudPump

iTrader: (2)

Ding Ding Ding

-Geoff

TobiasRX

Perhaps you should read my entire post before writing such remarks. I have never under 7 years needed to direct any air into the cat. Shouldnt need it now either. i wrote that in my post.

CloudPump

iTrader: (2)

Seven years of gunk building up in the cat because of not getting extra air sounds like it's caught up to you.

I read your entire post.

If nothing ever changed over time no one would ever fail emmissions ever.

-Geoff

TobiasRX

I am not using the cat when i drive, only to pass emissions. So again. Not an issue with the cat.
If you read the entire post you would know that its only at Idle i have bad emissions not when driving

CloudPump

iTrader: (2)

And at idle is when the air pump pushes air into the cat through that tube. At speed it does not. It is only at low speed or idle that air needs to be injected into the cat as the car runs too rich.

Why are you fighting this so hard?

-Geoff

TobiasRX

Because all of the things I have listed.
I shouldn't have good emissions when revving if the cat is bad.

It's more likely the air pump or the acv

CloudPump

iTrader: (2)

Ok...

So you have too much CO at idle.

Your catalytic coverter converts CO to CO2 (amongst other things)

You have an air pump that is designed to pump air into the catalytic converter at idle in order to facilitate the conversion of CO to CO2 (amongst other things) because at idle the engine does not breathe enough air to compensate for the very rich idle mixture.

You do not have connected the tube that pumps air from the air pump into the catalytic converter to facilitate this reaction.

Yet you won't accept that this may be the cause of your problem?

I mean really? The car was designed to pump air into the cat at idle to solve THIS EXACT ISSUE and because you're not pumping air into the cat you're having the exact issue it was designed to correct...

This is like you complaining that your headlights aren't working and refusing to acknowlege that the bulb may be burnt out because the bulb has always worked in the past.

-Geoff

TobiasRX

And you keep ignoring the fact that the cat has been working on all the emission tests over at least 7yrs and just a few miles earlier than the latest test.

Please just ignore my thread and let someone else help me.

CloudPump

iTrader: (2)

You said previously the car has been sitting for 3 years.

You also said this is a rebuild with 60km on it.

A lot has changed in those 7 years you were passing emissions... Must have been tough pushing the car to the emissions facility the past 3 years.

If you're too stubborn to accept help, then go help yourself.

-Geoff

TobiasRX

No nothing really has changed over the past 3yrs other than that things may have gotten bad over time.

But if I direct air into the cat or not is not the issue since it has worked so many times before and I haven't driven the car with the cat all this time.

Have I made myself clear now on this?

CloudPump

iTrader: (2)

I wash my hands of this.

Maybe someone else will chime in and tell you what you don't want to hear.

-Geoff

TobiasRX

Hey It wouldn't be a big deal if the cat was broken. At least then I would be sure what the problem was.
But I'm gonna go on arghx tip. Seems more likely.

wstrohm

If this FD has the original lower LIM gasket made of fiberboard, it could have burned through in places causing a vacuum leak. If you have noticed a slight increase in idle speed over time, that would be one symptom of a vacuum leak. At idle, the vacuum is at a maximum, and consequently a leak would be most noticeable there. For some reason, a leak there can cause poor emission performance... I don't know why.

I would also agree with CloudPump regarding need for air injection into the catalytic converter. If there is insufficient O2 in the cat, it cannot burn off the residual HC and CO from the exhaust.

arghx

iTrader: (3)

While your argument makes sense at first glance, you are missing some critical points. The secondary air injection system doesn't work the way you think it does.

At idle, the port air system works, not the split air system. In fact I can't think of a single mass production vehicle with secondary air injection, piston or rotary, that pumps air directly into the cat at idle. It goes into the exhaust manifold or exhaust ports, especially because there's a precat that is meant to oxidize HC and CO during cold start.





Now that doesn't mean you will fail a California sniffer test if you just run your air pump right to the cat. These tailpipe tests are tough for old cars but they're nothing compared to certification tests, even with the old standards from way back in the day. That's why you can pull your precat, run the airpump right to the main cat (even an aftermarket one) and still pass if the cat can stay hot. The tests aren't that difficult in the scheme of things.

One misconception is that a cat is either "good" or "bad," when really it degrades over time. On 96 and later (OBD II) cars the ECU can figure out whether it's degraded too much based on how much oxygen breaks through the cat as the engine cycles from lean to rich. On an FD, you can't know easily because it's OBD I. The OP's cat could be worn out. That's well within the realm of possibilities. But if the secondary air injection system isn't working the way it was designed, you are already fighting an uphill battle on an old cat.

So to pass (at idle condition) you need

1) mechanically sound vehicle--no vacuum leaks or other basic issues

2) secondary air injection system working, preferably working like stock so that air goes into the exhaust ports and then into the cat.

3) a cat with some life left in it that is up to temperature during the emissions test. It's hard to say what that really means... the better your cat is working, the more it masks other problems. The cat can't be too aged (heat breaks down the converter over time) and in the case of an Rx-7 at idle it really needs a lean mixture entering it.

TobiasRX

Thank you arghx.
I ofcourse cant rule out the cat entirely but i never drive with the cat. I only put it on for the yearly emissions tests wich i have written before.

I am going to try running the test without the airpump and see what values i will get.

TobiasRX

ok, so i disconnected the hose going from the airpump to the acv and it is working as it should.
gonna check the acv when i have more time.