Help Passing Emissions Tomorrow

[Rom3BreaK]

UPDATE: I passed emissions barely, but I'm having some knock issues. Please see 2nd page for log file (post 19) I would really appreciate it!!

Please :)

92 VR4

So I failed emissions at idle and am looking for a little advice on how to pass this thing.
Idle mode limits are: 220 HC (PPM) and 1.20 CO (%). I failed with 372 HC (PPM) and 0.58 CO (%).

I don’t know if it matters but I passed at “cruise” which means just revving in neutral due to being un-testable on the dyno. Limits were the same but passed with 56 HC (PPM) and 0.47 CO (%).

Now I don’t know what any of that data means, besides the obvious that I’ve exceeded a limit for something (hydrocarbons???) and thus failed. Now I’m hypothesizing that the problem is my very rich condition at idle. Low fuel trim is around 82-84% at idle, while mid and high fuel trims are in the mid-high 90’s. I don’t know how I can fix this rich condition. I currently have a hot wired fuel pump WITH an AEM AFPR. I installed the AFPR to correct this issue and after installation it did bring the high fuel trim down from ~120% to ~98%, but the low trim remained the same.

Other potential causes: I have gutted pre-cats, but still have my main cat. I have a vac redux including EGR delete. I’ve passed emissions despite these things in the past. My oxygen sensors are cycling well, but never seem to spike above .9 V. Again, I’ve passed like this in the past although it’s something I think needs to be worked out.

On top of this, the car WAS sitting for maybe 20-30 minutes before the test; I’m thinking this may have been enough time for the main cat to cool down and not work as well during the test?

Now if you have any suggestions to help me out here I’d be very grateful. The ideas I’ve come up with are to make sure the car has been running more recently to make sure the cat is hot; to lean out the fuel via AFPR (by the way pressure IS correct according to my gauge); or to get to the inspection location and remove the battery negative connection in order to reset the fuel trims. Feel free to critique these ideas. I plan to test again tomorrow morning.

Sorry for the novel, and thanks!

[Steve '92ES]

I wouldn't re-set the fuel trims, as I understand it 82-84% is actually trying to lean out your rich condition.
Fresh plugs, good wires, and a clean air filter might help.
Leaning it out a bit might help as well but be careful not to go to far or you could spike the Nox.

Just for fun, what happens if you hook the pump up as stock, with the hi/low resister? Does that affect the low trim?

[EvanH]

I dont know how true it is, but I know at autozone, there is a bottle of fuel additive. It states it will guarantee you passing emissions. Something like CRC or something.

And IIRC, sitting and idling is the best way to heat the cat up. Driving cools it off. So sit and give it a little extra gas to heat it more?

[Rom3BreaK]

Thanks for the responses. I think you're right that this means it's trying to lean out a rich condition, the problem is that a rich condition does exist and at around 82% you reach the maximum correction (maybe I'm wrong?). As far as plugs, wires and air filter, all have very recently been changed/cleaned. I was also wondering how much is safe to lean out using the afpr if anybody has any idea.

I'm not really sure how to hook the pump up as stock... when it comes to electrical work I can follow directions, but don't really know what I'm doing. I'll look into giving it a shot as I want to correct this issue with or without a passed emissions test.

I don't feel comfortable using any kind of mystery fuel additive, it seems impossible that you can guarantee a pass, and if it somehow does work I would imagine your engine wouldn't much agree with it.

The guy who tested said this wasn't a bad fail, more like I barely failed. Of the advice given so far I'm thinking that if I make sure my car was running for a bit before the test I'll have the best shot.

[Steve '92ES]

Thanks for the responses. I think you're right that this means it's trying to lean out a rich condition, the problem is that a rich condition does exist and at around 82% you reach the maximum correction (maybe I'm wrong?).
Yup, that's what I'm thinking. The problem is that if you re-set it you'll go back to NO correction making the problem worse, not better. As it is 372 isn't too bad. A little tweek and you're there. Re-set the trims and you're likely to blow a 1200... :0

That CRC stuff isn't bad. It's just a pretty good injector cleaner. CRC is a major company and they're studies show that the majority of failures are caused by dirty fuel systems. Of course they only studied bone stock cars so that may not be true in your case. Then again it wouldn't hurt to try. I've used it, not to pass inspection but just as a fuel system cleaner and it does work and had no adverse affects. Plus it has a Stealth on the box so what's not to love?

Of course you do have to run at least one full tank through so if you're going to do this tomorrow you'll need to find an all-night Walmart and spend the rest of tonight cruising... ;)

[Rom3BreaK]

Bah! Failed again after decreasing fuel pressure 2 psi and making sure the car was warmer. It was better this time though at 302 HC. Looks like I need to explore new avenues. Ill have to see what I can do with the fuel pump wiring. Something i've been really wondering about; shouldn't my afpr be able to handle a fuel pump hotwire?

[zapman2000]

if you can get your hands on pure ethanol fuel you can pass no matter what shape your car is in the additive from auto-zone just thins out the gas with bio-fuel elements so it works just like gasoline but with out the harmful effects basically you would be thinning out the gasoline
me and a friend used 5 gal of pure ethanol fuel to get a car that was smoking as it took the test to pass, guy giving test couldn't believe that it passed and ran it 2 more times before giving us our emissions report which showed 0's across the board for all tested elements it was pretty funny

[Erron Spalsbury]

What kind of test is it? Is it the two speed idle test or dyno roller test?

I pass with flying colors with just the main 4" cat. A little loud, but it passes with flying colors. I am running e85 though. If you have a way of watching your AFR you could blend in some to help.

[Rom3BreaK]

It's the two speed idle test which is the problem; that's the only time my car runs really rich. I'm HHH logging and that's it. I'm willing to try fuel additives as a last resort, however I'd like to figure out why my LFT's are so rich. After having installed the AFPR I expected to bring in all the trims right around 100, but unfortunately that's only the case with my mid and high trims. Does this sound like something that indicates a faulty FPR? Last time I passed emissions with a dead oxygen sensor, gutted pre cats, and egr system deleted. The only real difference between this and last time is the Fuel pump hotwire and AFPR. I haven't heard of anybody having trouble passing with these mods so that's why I suspect my FPR. Does anyone think re-installing my egr system would mend this issue? Or should I re-wire my fuel pump somehow?

I'm really stretching for a solution, something here definitely seems off to me. Does anyone think some log files would be helpful?

[BlackStealth]

The AEM AFPR comes with a few different sized internal parts. These parts regulate how much fuel is returned to the tank, I think the one you have in your AFPR needs to be switched out for the next larger size. The reason I say this is because your low fuel trim is indicating rich, and you're probably overrunning the FPR slightly.

There's also another way to fix a rich idle condition -- raise the base idle. Raise it to 950 or 1000 rpms (I think 1200 rpms is the max allowed for idle for emission testing). A higher base idle has two bonus:
(1) an engine at higher rpm tend to combust more completely...at idle it's more difficult (from an emissions stand point of view).
(2) higher rpm demands more fuel, this will slightly fix/mask the problem of having too much fuel pressure at idle.

Also, do not reset your ECU fuel trims. You want your fuel trims to be as low as possible considering your rich idle problem. 82 fuel trim is better than 100.

So how do you know when you're ready for your next test? When your low fuel trim is not maxed out (indicating too rich). So look for a number of 83 or higher. Ignore the other fuel trims for now.

[Rom3BreaK]

The AEM AFPR comes with a few different sized internal parts. These parts regulate how much fuel is returned to the tank, I think the one you have in your AFPR needs to be switched out for the next larger size. The reason I say this is because your low fuel trim is indicating rich, and you're probably overrunning the FPR slightly.


Awesome! The one installed is indeed the smallest one, looks like I'll try out the medium sized (.150") one instead.

The manual sold with the FPR says to remove it before swapping the orifice; is it safe to swap these out with the FPR still installed or should I stop being lazy?

On another note - anybody know where I can get a decent torque wrench that reads in-lbs (10) and is cheap in cost? I don't have one and it looks like I'll need one for this job (and can't think of another job I'll ever need it for).

[BlackStealth]

I think you will be fine as long as there's no fuel pressure sending parts everywhere, another words, get the fuel pressure to zero before disassembling it.

I took my AEM FPR apart before, just note the "tightness" of the screws as you disassemble, as that's probably the 10lbs of torque you need.

[Rom3BreaK]

I swapped out the orifice for the next larger one on Saturday, now just trying to get my trims dialed in so I'll report back when they're as good as can be. Something odd that's happening after I did this work is now my car holds fuel pressure for MUCH longer than it did previously. Now after a half hour + I still have around 20psi of pressure whereas before it would drop to near zero in less than two minutes of turning the car off.

[YoshiBishi]

I dont know how true it is, but I know at autozone, there is a bottle of fuel additive. It states it will guarantee you passing emissions. Something like CRC or something.

And IIRC, sitting and idling is the best way to heat the cat up. Driving cools it off. So sit and give it a little extra gas to heat it more?

Theres a bottle with a 3000GT on it.

[Rom3BreaK]

ECU still seems to be figuring out the fuel trims. Low is ranging from 82-89, mid is staying solid at 86.7, high is ranging from 112.5 to 111. Looking better but things still seem off...

[Rom3BreaK]

Just thought I'd offer an update. I ended up passing emissions on my 3rd try. After having switched out for the next larger orifice, my LFT's had much less of a tendency to stay maxed out rich, but still lingered around the same numbers. My final trick? Rather than adjusting the base idle, I simply turned on the AC. This of course had a similar effect making it idle higher and I passed with around 212 HC IIRC.

[BlackStealth]

Rather than adjusting the base idle, I simply turned on the AC. This of course had a similar effect making it idle higher and I passed with around 212 HC IIRC.

My emission testing place turned off my A/C, that's why I didn't suggest that as an option. :)

[Rom3BreaK]

haha yeah I knew it was a bit of a risk. I was feeling 50/50 on the different orifice doing the trick so I figured it was worth a shot. I made sure to turn off any vents that would blow on someone in the driver seat :biggrin:

[Rom3BreaK]

Driving around last night logging, encountered some high knock counts which have been plaguing me. I don't always get these counts when I step on it, but sometimes I do. ~21 counts doesn't make me feel safe. If you guys could take a peek for me and clue me in on what may be going on I'd really appreciate it. I have new O2 sensors, hot wired fuel pump, AEM FPR, vac redux. Boost controller is zeroed out (waste gate pressure)!! I have a feeling that what ever is wrong helped contribute to my emissions issues. I think my O2's aren't cycling exactly how they should be but no sure what to do about that (think its a symptom not a cause). I tested for fuel leaks with UV dye and everything seems good.


I attached a zipped file which should open fine in an excel sheet. I tried to organize data for easy viewing, and highlighted high knock areas of concern.

[BlackStealth]

Are you using a fuel controller? Perhaps you're knocking because of timing induced knock (side effect from piggyback).

p.s. Which datalogger are you using to collect data?

[Rom3BreaK]

I'm not using a fuel controller. Using Hand Held Halo data logger.

[BlackStealth]

The problem you have is tricky. You need to find out if it's real knock, or false knock from aging components.