Emissions: my experience with Ethanol and Snake Oils
 

1989 RX-7 GTU with original engine (i.e. non-turbo, stock porting). 121,000 miles. Stock exhaust manifold, pre-cats deleted, stock catback, stock main cat, with split air pipe inlet flange at the exact correct location (so this cat is either a Mazda piece or an OEMish aftermarket design). Stock emissions rack, solenoids, ACV, air pump, etc.

Well, I knew it would happen eventually. HCs have been rising gradually over the years, so it was just a matter of time before the car started failing smog.
15 mph test: HC = 99 (2009), 112 (2011), 128 (2013), Fail, limit = 118
25 mph test: HC = 38 (2009), 59 (2011), 127 (2013), Fail, limit = 93

Sounds like I was close, right? Maybe, but just not close enough.

2nd attempt: Lucas Oil Deep Clean Fuel System Cleaner. And -- Changed spark plugs to new set of stock NGK (old plugs looked semi-ok, but the electrode had deteriorated noticeably on the leading plugs). The stuff in the blue label bottle. Bought the 16 oz bottle ("more is better," right?), dumped it into the tank. Burned through it. Among other things, it's supposed to "greatly reduce harmful NOx emissions". Ok, I'll give some credit where it's due. NOx emissions fell 10%. Whether you can call that "greatly" is subject to interpretation. Meanwhile, HCs went up.
Result: Fail
15 mph test: HC = 132
25 mph test: HC = 143

3rd attempt: Replaced ignition wires. No change. Replaced leading coil. No change. Replaced trailing coil. No change.
Result: Fail (no difference in HCs).

4th attempt: CRC Guaranteed to Pass . "Pass your emissions test or CRC will double your money back!" Whatever. Added to tank, burned through it. Retested.
Result: Fail.
15/25 mph test: HCs = upper 140s.
Smog pump connected directly to split air pipe - no difference.
The stuff is garbage.

5th attempt: Ethanol. Kleen Strip Denatured Alcohol S-L-X. Two gallons from Home Depot at $16 each. Smells like ethanol, tastes like ethanol (j/k). Not really sure what "almost empty" means in the directions given in the FAQ. I ran it down to under 1/4 tank. I guestimated "2.25 gallons" needed to dilute fuel to 33% ethanol at that point. Car actually idled fine and ran fine under load (never gave it > 50% throttle, stayed below 4K rpms mostly). It did seem to run a bit hot. Overflow tank started filling up when the car was on the dyno, although the stock temp gauge never budged above its "just south of center" position (i.e. 170* to 230* range).
Result: Fail.
15/25 mph test: HCs = upper 160s
Next: smog pump connected directly to split air pipe
15/25 mph test: HCs = upper 140s

6th attempt: More ethanol. And I mean, a lot more. Ran the tank "dry" -- only dead volume remaining (i.e. not enough to start the car). Dumped 2 gallons of ethanol into the tank. So we're at 60-80% ethanol at this point. The car didn't like it. It barely ran. It wouldn't idle most of the time. At 25-30 mph (2500-3000ish rpm), I could only drive it for maybe 30 seconds at a time. Then the check engine light would come on and the car would start bucking under acceleration. Ignition off / on would reset things back to normal for a while. I was hoping it would behave itself long enough to survive a test cycle. But to no avail. The dyno rollers greatly amplify the bucking effect and it was impossible to do the test (not to mention unsafe). Well this got my otherwise friendly neighborhood smog guy quite agitated -- basically told me never come back with this car until I get a cat. I tried to explain and reason with him, and even cured the running problems right there in front of his shop. With the engine running, I added about 1 gallon of plain 87 octane gasoline and you could hear the idle gradually stabilizing. Yup -- I was hoping this would convince him to get me back on the dyno for one final attempt. "Go home" was his response. I take some of the blame. I should have added enough gas to the tank
Result: pissed off dyno guy, temporarily 86'd from the premises

7th attempt: A bit less ethanol. I'm guestimating 50% ethanol at this point. Car running ok. I added just enough gasoline to ensure the check engine light and semi-limp mode didn't activate. Basically, the fuel had the highest proportion of ethanol the car would tolerate. I waited two days for the smog guy to cool off, and, to his chagrin, returned for another check.
Result: Fail, but for a different reason
With smog pump connected directly to split air pipe
15 mph test: HC = about 110, passable
25 mph test: HC = about 90, passable (barely)
But there was a new problem. NOx went sky high. 1200+ in both tests.
Yeah -- the extreme lean condition of running on ethanol is causing high NOx. So I'm thinking -- with HCs ok, maybe try reducing the supply of oxygen (less available for reaction with nitrogen) by disconnecting the split air pipe.
15/25 mph test: HCs = same, passable. But NOx still too high at ~900. Damn. So close.

8th attempt: Old spark plugs. The smog tech claimed he's seen a car that started failing after new plugs were installed. Go back to the old plugs was his recommendation. There may be some hope in this: My first attempt was the only one with the old plugs -- and the car ran cleanest. I knew the NOx were due to the excessively lean AFR. So I thought -- dilute the ethanol with a bit of gasoline. Went home, added a bit over 0.5 gallons, put the old plugs back in, and connected the smog pump directly to the split air pipe. Drove to the smog station the next day, and.....
Result: Fail.
15/25 mph test: HCs = upper 140s

9th attempt: Bönez High-Flow Catalytic Converter from Rotary Performance. This is the single cat system "for use with Racing Beat Street Header", so I had to get a proper connecting pipe fabbed to reach the stock exhaust manifold.
Result: Pass
15 mph test: HC = 87 (limit = 118), CO = .04 (limit = .75), NOx = 13 (limit = 799)
25 mph test: HC = 15 (limit = 93), CO = .02 (limit = .63), NOx = 52 (limit = 738)

My take-aways from this:
The parts store snake oils are ineffective. Assuming everything else is functional, your best bet with an aging cat is getting it very hot -- but even that may not be enough. You can try air injection (either directly from the smog pump or by capping the ACV vac line per FAQ), but stations may fail you due to air dilution.
And -- making use of the alcohol trick is no guarantee. My car wouldn't run acceptably with >50% ethanol on the stock ECU. The resulting lean AFRs caused high NOx emissions. It's possible that the right proportion of alcohol/gas would have achieved a passing result -- attempt #7 with 50% ethanol came close when I deleted the air injection. But the range of usable proportions is narrow. 33% (1 alc:2 gas) is not enough to lower HCs (maybe the ECU compensates for lean AFRs by adding fuel) whereas 50% (1:1) is too much.

(With a standalone or RTek -- I suppose it's theoretically possible to run higher levels without leaning out too much.)

Why anyone would want to live in a state that subjects it's citizens to that treatment is beyond me.

Glad you got it figured out (although some people would have let logic prevail and jumped straight to an aftermarket replacement cat for $75 plus installation and called it a day) and posted helpful info here for others who have to deal with this clusterf*** of an ordeal simply to drive an older vehicle.

Found my old emissions story from end of 2009:
The entire time, I had a the leading coil going bad. Took a long time of diagnosing (the summer after) that it was the coil. So even with all the miss firing...


"New York here, figured I'd share a story
Well it passed ... after 5 fucking tries. But... my car isn't stock, and it may not be the best tune:
Street ported with a Haltech

The cat was used, and it probably needed to be run and cleared (we installed it at the shop), so the first attempt wasn't going to work anyway. Also, the car wasn't fully warmed up the first try, and we forgot to switch on the air pump (off a vette) until half way through.
The numbers were a disaster
HC: 7.8 out of allowed 0.8 (YIKES)
CO: 30 out of an allowed 15 (again, YIKES)
NOx: passed EASY by whatever huge amount. Everything passes NOx

second attempt... Fully warmed up and air pump on
HC: 2.8 (still failing badly)
CO: passed
NOx: passed

At this point I'm told taking out timing will help to drop the HC

third attempt...
Took timing out all over my maps, same as usual for the rest
HC: 1.8 still failing to beat 0.8

fourth attempt...
Took out even more timing all over the place. Poured alcohol into the gas tank.
The sniffer fell out of the exhaust duct half way through and the test failed

FIFTH attempt...
Said "to hell with this, not taking any chances". Locked the timing at -5 degrees
HC.... 0.67 out of 0.8. FINALLY PASSED

NOW... there is a bit more to this. These old Haltechs have known issues with crank signal, and I really want to redo my CAS lines with nice new shielding. So throughout all these tests, I was having misses. Not horrible, but they were there and they don't help.

I didn't give the engine a good redline either before doing any of the testing (d'oh!)

Also it was 26 degrees this morning when I went to start my car. My doors were frozen shut. Last weekend I had to jump the car with a jump pack to start it. The week passed and we had some pretty cold days.... so my battery is not very healthy. I tried this morning to start without assists and it was cranking SLOW. So I threw the jump pack on. It's a little better, but not great and now all I am doing is flooding it. So I cut the fuel and crank. It caught, idled up for 5 seconds, died. Try again and I'm flooding. Try un-flooding again and then another attempt. No good, and my crank is weak again. At this point I'm cranking too slow, flooding even worse, and killing my jump pack. Laptop is telling me I'm at a pathetic 8 volts when cranking. Now I have no hope to start this car. So I hop in my trusty Honda and run to autozone to buy jumper cables.

Thank you Honda!

I was able to get strong cranking a few times without fuel to be sure of un-flooding.
A little more swearing and cranking and it fired up.

After all that I went and did my testing. On most certainly fubar plugs...

Final passing results:
HC limit: 0.80 Result: 0.67
CO Limit: 15.00 Result: 4.32
NOx limit: 2.00 Result: 0.08

That was my fun day, figured I'd share. Now I know what to do next year."

yea the first time i passed smog i had what was left of an aftermarket cat and one of the pre-cats still intact. I had only about one or two gallons in the car at most and right before i went to the smog shop here in ca, ghetto part of salinas. I poured a whole bottle of seafoam in the car and swerved a lil bit to mix it up with the gas before i went to the shop. this ended up in me passing. So i was good for a year .

This next time i luckly sourced a full stock set of cats and i still added the full bottle of seafoam prior to going to the smog shop and luckily passed. Also make sure that your fuel injector air bleed hose is properly hooked up to the upper intake mani this was not hooked up and i failed numerous times until i found out it was capped off. Also a properly hooked up o2 sensor is crucial. might wanna set your tps prior to smog also. oil change helps. and seafoam is awesome!!!

My take-aways from this:
...it needed a new cat in the first place.

I call it *Hope-In-a-Bottle*
 

The state didn't do that, after the first time it was all self-inflicted.:lol:

Emissions test passing is extremely well documented on this site.

From the FAQ:
https://www.rx7club.com/attachments/...onsfailure-jpg

Plus I've been documenting my annual emissions tests since 2005:

https://www.rx7club.com/2nd-generati...-style-465422/



I will restate my stance from 2005 on this subject:

Fix your car and it will pass emissions!:icon_tup:

while i can see a 25 year old cat being bad, i really only check the TPS, and the ACV before i go smog.

port air is KEY.

.....I was hoping I could make ~30 ppm go away without replacing the cat..... :icon_tdow

.....didn't work. all relevant maintenance recently done. oil had ~250 miles when I started.....

ACV, solenoids -- all operational per FSM.

The Texas emissions thread is helpful, and I have been able to use the air pump trick to good effect while living in another state.

Bonez cat from Rotary Performance -- will fail visual in California (even though it will reduce all measured emissions to state-legal levels). Doesn't have the right numbers stamped on it. Conversation with RP and my own experience have confirmed this. (Just for giggles, I might put it on the race car and see what the sniffer says later this year.)

Zero difference in mileage on my car. I will dyno the car eventually and check the difference in power. FTTB, the butt dyno says there isn't any difference.

this one time i had to smog a 1990 Mercedes, and it failed miserably (380ppm HC's), not wanting to spend any money, or actually even open the hood, i got the cat hot. since its a POS, i just went around the block with the gas pedal on the floor, and modulating the speed with the brakes.

i pulled up, in a cloud of smoke, and it passed. heat is important.

this other time i had a 79 Rx7, with the THERMAL reactor. i got it warm, and did a pretest, and it passed easily, the smog guy turned it off (which is BAD) and then turned it on to do the test and it almost failed.

its a THERMAL reactor, heat is important

pretty sure there is a CARB legal magnaflow. if not magnaflow there are CARB legal cats for these cars.

Sucks you had to go through all that, but it made an entertaining story.. so thanks for that.

The Bonez cat is a nice piece. Just put one on my GTU to get rid of the smell (previously had no cats). Made the exhaust note a lot nicer too..

Of course it didn't work. You didn't fix your car. You didn't replace your failed cat. People keep trying to pass a sniffer with failed cats and it doesn't work pretty much every time.

You put on an expensive cat that won't pass Cali visuals? :facepalm1: Again self-inflicted pain.

Good Luck, hope you get your car back on the road legally.

-J

Does that mean I can buy a failed RX7 FC in California and import it into my part of Canada where sniffing is regarded as impolite and is not done?
Might there be a deal for me on a TII?

That piece of information is mainly for the benefit of other California residents. I have other plans for it. ;)

It should pass as most of those guys aren't as old as the car. Who knows what OEM cats looked like(I know, but I ain't talkin'). My high perf aftermarket cats pass.

thats a good point actually, there is no number on the stock cat, as a cat was a cat until very recently

and actually the Rx8 just has a part number etched into it, which wouldn't be hard to duplicate

Which do you have?

the Bonez cat does have a number and it's not on the "allowed" list; the smog tech showed me a booklet published by CARB. He was lenient, but experience will vary from one station to another.....

The ones made by Magnaflow, the pre-cat and main cat. The previous owner had them both replaced in order to smog it to sell it to me.

high HC with ok CO is going to be misfiring or bad cat almost every time. These stock cats were not designed to last very long.

remember that CO is basically your AFR coming out of the tailpipe. It can easily be under 1% if the AFR is ok. Even though the cat converts CO, there's basically nothing to convert if your air pump & port air system work right. NOx is only bad if you have a very lean engine-out AFR.