PASSING CA SMOG with BORLA Headers?

[NeXJ]

Hi - Well I've read TONS of posts on the topic of passing the CA SMOG test and I've seen lots of ideas for solutions - and it seems to me that running aftermarket headers is a pretty great way to fail, since it seems to generate an excess of Nitrogen Oxides (NOx). Indeed - I just went for a smog and failed (only just - my situation isn't as bad as others) - but it's still a fail. Some clever member here remarked the coincidence between high NOx numbers and running headers.

SO - since I only have one more shot at this - and I don't want to pay someone off to pass me illegitimately - I'm in need of a solution. The last time I ran a bit (perhaps too little) ethyl alchohol in the tank (2-3 oz in a few gallons of premium).

HOWEVER I came across a few interesting posts about 1) disconnecting the t-stat sensor (also morally dubious - but hey) but also 2) disconnecting the battery RIGHT BEFORE the test so that the HO is running off computer fuel maps.

ANY SUGGESTIONS ON THIS? Can anyone guide me on this? Will killing the battery for ten minutes do it? How long does it need to run before running off of custom or 'learned' fuel maps again??

I have a 92 XJ with a 97 HO 4.0 with borla headers installed in 2000... high flow cat (magna? can't recall) etc etc. I think that's all the relevant tech info needed. Everything else is more or less in spec it seems. I'm not convinced a new O2 sensor is going to help much from what I've read.

ALSO- does anyone know if the fuel map trick is going to mess with my HCs and other numbers? I could kind of see that happening - even if it gets my NOs down...

 

[Darky]

When was the last oil change? Try running some Sea Foam through the engine first to make sure it's nice and clean. Was it up to operating temps when you smogged it? How old is the cat?

 

[NeXJ]

I gave it a full seafoam torture a few days before along with an oil change with Castrol GTX. The cat's about six years old but still seems to be working great - it only has 50K on it - as the CO and HC number are STELLAR - so I think that cat's working well. the whole problem is that the headers shoot the exhaust temp WAYYYYY too high and you end up super heating the cat and blowing lots of NOx out the exhaust... COULD be it's too soon after the seafoam and oil change - but still it really racks up at $80 or so per test... I'm not a rich man. The SMOG joints in this town are getting greedy - won't offer pretests and won't offer free re-checks.

 

[NeXJ]

I'd just like to find a way to be sure to pass fairly easily without spending another $4000 in parts and check fees. Because I know that road and don't want to go there...

 

[GrimmJeeper]

who is telling you high NOx has to do with having a borla header? NOx is directly related to high combustion chamber temps, high NOx is a common problem for the 4.0 aftermarket header or not.

 

[scottmcneal]

I found on mine it had a intake leak.Large one.Found it by using sea foam down the intake.

 

[souske]

are they smogging it as a 92, or a 97?
If you converted to OBDII, disconnecting the batt is a bad idea, the monitors wont be lit, and you can fail for that.

You may consider going to your local smog refferee, they charge much less than commercial shops, and are typically very knowlegeable. I found them to be excellent to deal with when i had to get a certification when i moved my 96 drivetrain over to an 87 body.

 

[NeXJ]

SOUSKE: There's really no issue with the different engine years - as it seems to be going unnoticed - just smogging as a 92...

GRIMM: If you do a search on the naxja forum for 'header' with 'smog' or 'emissions' - you will find that nearly ALL the posts with aftermarket headers are failing from high NOx - a few people have also remarked on the correlation... which makes some sense to me. If you have reason to believe the correlation is in error - please explain why if you can..

"who is telling you high NOx has to do with having a borla header? "

 

[NeXJ]

disconnecting the batt is a bad idea, the monitors wont be lit, and you can fail for that.

Why won't the 'monitors' be lit??? (not sure which monitors you mean??) - there would still be battery power. It's not like I'm not reconnecting the battery. I'm just trying to delete the user fuel consumption maps...

 

[NeXJ]

I'm SO close to passing anyway- I see no need for a referee - just looking for a sure fire way to squeak through.

 

[souske]

on OBDII (96+) the computer has to be on learned maps, not the baseline ones.
since you are smogging as a 92' disreguard

 

[NeXJ]

GRIMM - what would YOU recommend to help it run richer then (assuming lean mixture = high combustion temps)? I figured using one of the 'stock' fuel consumption maps would be the way to go..(?)

 

[NeXJ]

SOUSKE - ahhh ok i see your point. Yeah - it's ALMOST plug and play - though I never found a good solution for the incompatible engine temp sensors (for cabin reading only) - seems the only real way to deal with it is to tap into the block - but I was worried about hitting the water jacket or worse! But that's a side issue.

 

[Planetcat]

Aren't the borla headers 50-state legal? If they are, you can call them and get them to send you the sticker that has the exemption number that the smog guys use. I would think it's not the headers causing your numbers to be off. I would try to burn off more of that sea foam, if you can wait. Call Borla anyways and see what they say.

 

[NeXJ]

PLANETCAT -
Well it's not like I'm failing a visual inspection due to the headers... so I don't think there's a sticker needed - unless it's PROVEN that the headers are the weak link - I've passed with them before - but it seems possible that the scavenging effect of the headers is pumping up my NOx. Hence the others' remarks in the forum.

I can't see how losing more carbon in the engine cylinders/journals or whatever is going to help my NOx numbers... ? I suppose it COULD help things run a bit cooler maybe...

 

[GrimmJeeper]

what plugs are you running? I have to put stock renix plugs in my HO to get it to pass NOx, champion RC9YC.


also, disconnecting your temp sensor at the thermostat housing will trigger a CEL... don't do that.

 

[NeXJ]

oh they're probably stock champions - might take the plugs out for a cleaning but they only have about 10K on them. I used to be into fancy plugs and jacobs ignitions silliness but have grown up a bit since then...

 

[GrimmJeeper]

try the renix plugs, they are a cooler heat range. I have a set I swap in just for smog time. I've also had pretty good results with the "Guaranteed to pass" stuff that CRC makes, should be available in most parts stores.

 

[NeXJ]

oh i see... hmmm really? how do the renix plugs stay cooler than the post renix ones? I mean - they're getting the same voltage - same amount of energy passes through them. I could see it MAYBE if they had far more massive bodies made of steel or something and could act as a heat sink...

 

[NeXJ]

I think (from what I understand) that the 'guaranteed to pass' stuff only helps with HCs and CO ?? I don't think it does much for oxides of nitrogen...