DFW RX-7 Club March 6, 2010 Meet
#51
#52
Thread Starter
There were no survivors
Joined: Aug 2004
Posts: 2,475
Likes: 1
From: Grand Prairie, Texas
#54
My 87 did the same earlier in February. Blew over twice the limit. Keep meaning to do some research but haven't yet.
#55
What's your gas mileage like? Hydrocarbons usually mean you're running pig rich or your cat(s) is/are gone. When I first got my FC I was getting 7 mpg, after a new O2 sensor, I jumped up to like 18 or so with no other tuning.
The Mustang on the other hand blew like 1200 hydrocarbons (200 allowed) and after tuning and adjusting timing and chasing our tail for 4 months, it turned out the person we bought the x-pipe from had gutted that cats. Even without the cats though, the RXP Guaranteed to Pass stuff dropped HCs down from 1200 to 300, but as Frankenrex pointed out, not sure if it works the same on rotary. Don't know why it wouldn't though, combustion is combustion.
The Mustang on the other hand blew like 1200 hydrocarbons (200 allowed) and after tuning and adjusting timing and chasing our tail for 4 months, it turned out the person we bought the x-pipe from had gutted that cats. Even without the cats though, the RXP Guaranteed to Pass stuff dropped HCs down from 1200 to 300, but as Frankenrex pointed out, not sure if it works the same on rotary. Don't know why it wouldn't though, combustion is combustion.
#56
Sunday I replaced the plugs and O2 sensor (the center electrode on the plugs was pretty worn after only 4K miles, and the O2 sensor was only $20) and changed the oil. My wife took it back to the inspector today, and it blew even worse, at least on the NOx, according to her. I'll check the numbers this evening.
Looking and posting in this thread tells me that high HCs can be a failure mode for the cat on RX-7s despite the inspectors advice and the usual diagnostic charts for emissions. Rotaries are apparently low in NOx to start with, so that part of the cat doesn't have to work hard, but the high HCs inherent make that part of the cat go nuts. So the HC part burns out, but the NOx part doesn't.
As far as I can tell, the car is running right. My gas mileage is poop (9MPG,) but until this week, I only drove neighborhood streets for a couple miles, and tended to drive with my foot to the floor. Exhaust didn't smell overly rich, as far as I can tell.
Whelp, a Magnaflow cat is ~$95 on eBay or $122 at O'Reilly's.
Looking and posting in this thread tells me that high HCs can be a failure mode for the cat on RX-7s despite the inspectors advice and the usual diagnostic charts for emissions. Rotaries are apparently low in NOx to start with, so that part of the cat doesn't have to work hard, but the high HCs inherent make that part of the cat go nuts. So the HC part burns out, but the NOx part doesn't.
As far as I can tell, the car is running right. My gas mileage is poop (9MPG,) but until this week, I only drove neighborhood streets for a couple miles, and tended to drive with my foot to the floor. Exhaust didn't smell overly rich, as far as I can tell.
Whelp, a Magnaflow cat is ~$95 on eBay or $122 at O'Reilly's.
#58
Only one free retest, unfortunately. We were almost $200 into it when the Mustang finally passed.
Also, I have a brand new magnaflow cat in the garage from my TII build, but I have a sneaky suspicion it's 3"
Also, I have a brand new magnaflow cat in the garage from my TII build, but I have a sneaky suspicion it's 3"
#59
Old gas can be a problem but if your only getting 9 mpg old gas is probably not an issue...
Only one retest? I thought you had 30 days. Maybe they have changed the rules (again)
Recently I had an old car I was unsure of passing. I didn't want to go to the trouble of registering and insuring it if the car would not pass emissions. The tech said they can run their machine in 'calibrate' mode and it doesn't report the results to the state. He ran mine in calibrate mode and it passed, so I registered & insured it then went back, paid him the $40 for the 'real' test and he stickered it.
Only one retest? I thought you had 30 days. Maybe they have changed the rules (again)
Recently I had an old car I was unsure of passing. I didn't want to go to the trouble of registering and insuring it if the car would not pass emissions. The tech said they can run their machine in 'calibrate' mode and it doesn't report the results to the state. He ran mine in calibrate mode and it passed, so I registered & insured it then went back, paid him the $40 for the 'real' test and he stickered it.
#60
EJ....
#63
Some shops apparently will do a calibration, or "pre-test" if you ask. Wish I'd known that before I sent the wife to Kwik-Kar. Now I have to pay another $40 on top of the $100 for the cat plus whatever the muffler shop will charge me for welding it in.
Just ordered the cat - should be in before the weekend. Meanwhile, I get to keep an eye open for da cops...
#64
Old gas can be a problem but if your only getting 9 mpg old gas is probably not an issue...
Only one retest? I thought you had 30 days. Maybe they have changed the rules (again)
Recently I had an old car I was unsure of passing. I didn't want to go to the trouble of registering and insuring it if the car would not pass emissions. The tech said they can run their machine in 'calibrate' mode and it doesn't report the results to the state. He ran mine in calibrate mode and it passed, so I registered & insured it then went back, paid him the $40 for the 'real' test and he stickered it.
Only one retest? I thought you had 30 days. Maybe they have changed the rules (again)
Recently I had an old car I was unsure of passing. I didn't want to go to the trouble of registering and insuring it if the car would not pass emissions. The tech said they can run their machine in 'calibrate' mode and it doesn't report the results to the state. He ran mine in calibrate mode and it passed, so I registered & insured it then went back, paid him the $40 for the 'real' test and he stickered it.
#65
You know, it stinks that you are required to pay more than once for a legally-required test.
Some shops apparently will do a calibration, or "pre-test" if you ask. Wish I'd known that before I sent the wife to Kwik-Kar. Now I have to pay another $40 on top of the $100 for the cat plus whatever the muffler shop will charge me for welding it in.
Just ordered the cat - should be in before the weekend. Meanwhile, I get to keep an eye open for da cops...
Some shops apparently will do a calibration, or "pre-test" if you ask. Wish I'd known that before I sent the wife to Kwik-Kar. Now I have to pay another $40 on top of the $100 for the cat plus whatever the muffler shop will charge me for welding it in.
Just ordered the cat - should be in before the weekend. Meanwhile, I get to keep an eye open for da cops...
Of course if they pulled you over for 100 in a 35, then they might be less so.
I couldn't help but notice that this came after the 'bad gas' comment.
Last edited by mar3; 03-11-10 at 12:07 PM. Reason: Merged back-to-back posts...
#67
When I failed I had 15 days starting the day after the failed test to return to them for a retest. That retest would have been free and I had to bring along paperwork indicating what work I had done to correct the issue. I've also been told that the state had been cracking down on running pre-tests on cars and that the only way you're supposed to be run is in actual testing mode.
I do know that something isn't right with mine as I backfire heavily after WOT when the secondary injectors are on. Also since I run pre-mix i can lay down an excellent spy hunter smoke screen just letting the car run at 5k even at partial throttles. lol Emissions testing is done at RPMs below secondary injector engagement though. But I still suspect something isn't right. However it has been doing this since I got the car and has passed in the past. Now it's quite possible that the cat is toast in same way shape or form. There is the possibility that I hadn't gotten low enough on fuel before refueling and not adding pre-mix to contaminant the numbers but last year it passed by the skin of it's teeth on my normal pre-mix levels. Plugs and O2 sensor isn't that bad to replace so I'll give that a whirl. I've got a spare known good exhaust system laying around to so I might as well just put that on and give it a go.
I do know that something isn't right with mine as I backfire heavily after WOT when the secondary injectors are on. Also since I run pre-mix i can lay down an excellent spy hunter smoke screen just letting the car run at 5k even at partial throttles. lol Emissions testing is done at RPMs below secondary injector engagement though. But I still suspect something isn't right. However it has been doing this since I got the car and has passed in the past. Now it's quite possible that the cat is toast in same way shape or form. There is the possibility that I hadn't gotten low enough on fuel before refueling and not adding pre-mix to contaminant the numbers but last year it passed by the skin of it's teeth on my normal pre-mix levels. Plugs and O2 sensor isn't that bad to replace so I'll give that a whirl. I've got a spare known good exhaust system laying around to so I might as well just put that on and give it a go.
#68
Bah. $150 cat + $40 new test and all I got was this shiny new FAIL. That's $305 so far, including the testing.
Everything went down, but HC is still 300 on low speed, even more on high speed (I think he had it in the wrong gear - it's higher HC than previous and lower RPM.)
O2 id 0.0%, so I think maybe the ACV or air pump are not doing their thing - not enough O2 to the cat to completely burn the excess HCs. Wish I'd have checked all that before throwing money at it that I didn't really have...
All in all, I can't complain much - I've still got less than $2000 in the car so far. Fairly cheap for an S5 in decent shape, as far as I can tell.
Everything went down, but HC is still 300 on low speed, even more on high speed (I think he had it in the wrong gear - it's higher HC than previous and lower RPM.)
O2 id 0.0%, so I think maybe the ACV or air pump are not doing their thing - not enough O2 to the cat to completely burn the excess HCs. Wish I'd have checked all that before throwing money at it that I didn't really have...
All in all, I can't complain much - I've still got less than $2000 in the car so far. Fairly cheap for an S5 in decent shape, as far as I can tell.
Last edited by Frankenrex; 03-13-10 at 07:57 PM. Reason: added detail
#69
#73
#74
#75
Kevin, I'm really surprised you're having that hard of a time passing it.
It passed (barely, but passed) when I had it and I was premixing with marvel mystery oil since the OMP wasn't hooked up.
Also, the Mobile 1 shop in Richardson off Plano, north of Arapaho, didn't mention a retest limit when the Jetta failed. I was always told that you kept going until it passed. Heck, the time it barely passed with the 7 the guy ran two tests back-to-back until it did.
It passed (barely, but passed) when I had it and I was premixing with marvel mystery oil since the OMP wasn't hooked up.
Also, the Mobile 1 shop in Richardson off Plano, north of Arapaho, didn't mention a retest limit when the Jetta failed. I was always told that you kept going until it passed. Heck, the time it barely passed with the 7 the guy ran two tests back-to-back until it did.