do I need an aftermarket fuel pressure regulator?
 

a few people saw/heard about my smog #'s, and mentioned that #'s suggest my car is running lean:

15mph @ 1807rpm:
%CO2 = 13.8
%O2 = 1.5
HC (PPM) = 193 (max 88, avg 21) --> failed!
CO (%) = .02 (max .52, avg .06)
NO (PPM) = 1102 (max 704, avg 150) --> failed!

25mph @ 2866rpm:
%CO2 = 14.4
%O2 = .7
HC (PPM) = 74 (max 53, avg 13) --> failed!
CO (%) = .03 (max .5, avg .05)
NO (PPM) = 494 (max 738, avg 136)

car is STOCK except for bonez downpipe and pettit (efini?) y-pipe

i talked to john @ mazdatrix today, who upon hearing the #'s muttered that it could be running lean, but then said at this set up it's impossible for my car to run lean. i then called rotary power and tri-point. tri-point said the CO suggests car is lean, said for me to bring in the car and pay 170 for diagnostic and go from there. then i talked to norman @ sidepex, who also said the car is probably running lean, and that the fix would be aftermarket fuel pressure regulator. all of them said it might also be a busted cat (cat has 74k miles on it; motor has only 1800).

so...is this a problem w/ the fuel pressure regulator? i'm unsure as to what i should do next. sidepex said they'd charge 65 to check out the car, making sure everything is working right, including compression check. i'm tempted to do that. is my car really running lean from these #'s? is this dangerous? the motor is new, i don't want to blow it!

guy at sidepex (not norman) also said the downpipe would cause it to run lean, but i think john at mazdatrix said it wouldn't. well?

take it in.for 65 bucks you also get hooked up with a compression check not to mention a diagnostic.The dealer here charges 80 bucks for a compression test alone.

sure a performance mod that allows for more airflow will lean out the map on the ecu.

But it doesnt mean that its too lean. We dont have emissions in florida so those #s are hard for me to interpret. I have a stock fpr with 51k miles off of my 94 if you end up needing one I know it's good because my car made 380rw on pumpgas using it. I dont think you want to be getting an aftermarket one with your little mods and the stock one is very expensive new.

Yanni

So you the one that made me hold for John on the phone, ughg! You should have done the tulune trick to pass smog (allegedly). I beleive the Efini y-pipe and DP will increase boost and is the reason they mentioned it being the possible cause. Do you have a boost gauge and a water temp gauge? ...could save your engine. You may need an upgraded ECU if your at 11lbs, or have John change the pills to jets or make a home depot boost controler (and limit to 10lbs).

what's the "tulune trick"?

no boost and water temp gauges yet; i've only owned the car for 3 weeks. but they're coming. i just got a pod for 'em...but first i need to get the car smogged and registered

1 part tulene to 3 parts gas will "allegedly" help you pass the test. It will lower the octane, so a bottle of octane booster wouldn't be bad. No turbo boosting while the stuff is in the tank. Get rid of the gas afterwards (drive it off), then fill with super and maybe more octane boost to flush it out. This may not be a california approved method but "allegedly" it works and more info can be found with a search since my info may not be exact or completely acurate ...and is intended for off road smog testing outside of CA "allegedly". :wink:

are you talking about toluene?
If you mean toluene, and you mixed it 1 part toluene to 3 parts 93 ocrane gas you would have 98.25 octane gas, not lower octane.

oops! sorry! i called twice, too =P

um...what does this mean?

so you think i need boost controller?

even with a dp the stock ECU can run lean, but keep it below 10 psi and you should be ok

so i just did a quick search and it seems the y-pipe can raise boost by 1~2 psi or so. is this true? if so then i'm probably boosting above 10 then. i don't have a boost gauge yet. dang! how do you keep boost down? is boost controller the only way? any cheaper way? =P

You can have the stock pills replaced with different sized carb jets.
You can make a home depot boost controler.
You can buy a boost controler - manual or electric.
...all those choices will restrict boost.

tootoolean, toelean, jimmy dean lean, the stuff in the paint section at home depot. Anyhow, I thought there were replies stating that it lowered octane levels. I don't know personaly and that's why I sugested the search to be accurate.

Bullshit. Show us your wideband testing results. Oh, you don't have any? Then don't contribute to spreading falsehoods about the FD.

FD_dave:
You're not running lean because of a downpipe and a y-pipe. Furthermore, running leaner results in cleaner emissions. Do some researching, it could be a lot of things. Your cat may be bad, your ACV may be bad, your air pump may be bad, etc.

so i'm not running lean? does TPS have anything to do w/ running rich or lean? if so, could adjusting TPS adjust the air/fuel ratio?

btw, just got my compression test done. numbers were:
front 105, 105, 105
rear 100, 100, 105
these numbers are good, yeah?

norman @ sidepex (real cool and friendly guy!) just checked out the car. everything seemed ok, including the air pump. changed spark plugs to ngk platinums 'cuz the previous mechanic put in non-platinum plugs. hopefully this'll do something. next week someone from the club is going to take a look at it for me, and hopefull smog it (and pass!). knock on wood... thanks for all the input

You could be running lean, but not from just the downpipe and y-pipe. The TPS can certainly effect the a/f ratio, make sure both the narrow and full range sensors are within spec (see Section F of the FSM).

I think we need to separate two concepts here that are getting confused:

1. Running lean on an emissions test under light load at low RPM.

2. Running lean when you are at full boost accelerating like mad.

-Max

GoRacer:

Toluene won't help you pass the emissions test - You are thinking of ethanol or methanol (Denatured Alcohol or Shelac Thinner). they both will boost Octane (though not nearly as much as Toluene) but unlike toluene burn much cooler than gasoline so help reduce NOx emissions. Toluene has both Higher Octane rating and Specific Energy content than Gasoline hence it's favored use as an octane booster for race fuels (turbo F-1 cars used 90%+ Toluene mixes)

^ yes, that's it. thank you for the correction. I was refering to "denatured alcohol" in the paint section and I thought the brand name was Tulene. I thought people posted that it lowered the octane level though and was the reason not to boost?

https://www.rx7club.com/search.php?searchid=103017

Oh the joys of FD emissions testing ;) From my recent experience, here's what your dealing with. High HC means that unburned fuel is making it's way through the emissions system. This usually means that your running rich. High CO means that combustion isn't completely burning all the fuel. This can be caused by a number of issues, but since your numbers are low, I wouldn't worry about this one. High NO is pretty easy, it usually means that your EGR isn't working properly.

Here's what I would try before testing your car again:

1. Change the oil, plugs and O2 Sensor.
2. Check the EGR.
3. Check the cat.
4. Check the air pump and the corresponding parts under the UIM.

If it don't pass after this, I'd try the alcohol.

oooh, that's good info. thanks a bunch!

i already had the plugs changed, ngk platinum tips. mechanic said the air pump was fine, though i feel he didn't check its function. i'm going in next week for someone from the club to look at, wish my car luck :)