Snabb T5M Posted June 24, 2015 Report Share Posted June 24, 2015 So I've been struggling to get my 1998 S70 T5M to pass emissions. Because of the OBD II issues with the 1998 S70s, the emission place has to do a sniff/dyno test. The testing facility plugged their Snap On diagnostic tool in and took some readings. Evidently she's running lean with a 30% correction going on by the ECU (whatever that means). The rear O2 sensor has the spacer on it and while the tech was testing the car he noted that "the rear and front O2 sensor readings are the same which might mean a degraded CAT." Also, in the guy's readings he noticed what seems to be a misfire at low RPM when first taking off. No CELs are being thrown though. My AFR gauge is showing the normal range of between 14.4-15.4 while hunting for the ideal 14.7. HOWEVER, at initial startup and until she gets warm, the AFRs are hovering around 13.5, which is weird. I replaced the front O2 sensor hoping this would help. Also cleaned up the hi-flow air filter. Prior to this recent test, the car had excessive hydrocarbons and carbon monoxide. She passes the nitrogen limits.The car has an IPD Stg 3 tune with 18T, 3" DP with hi-flow CAT, big bore throttle body, etc. The DP/CAT has 25,000 miles on it. The car isn't driven much, perhaps 500 miles a year. Might the CAT have degraded from minimal drive time?Any ideas for what I should be looking at or for replacing? New MAF?Would running 87 octane gas with a high performance ECU screw things up like what I'm having? (Figured lower octane would burn quicker/cleaner than 93 octane). So frustrated with this! Link to comment Share on other sites More sharing options...
Wesdunns70t5m Posted June 24, 2015 Report Share Posted June 24, 2015 If the cat isn't gutted and is exactly the same as ipd sent, I'd try runnin the car without the o2 spacer and see what, if any, changes happen or, just move here to Maryland! Only hook up the obd and scan for CEL's and monitor readiness for these (I have a 98 t5m also) Link to comment Share on other sites More sharing options...
troyhyde Posted June 25, 2015 Report Share Posted June 25, 2015 +30 LTFT? I think these cars throw a CEL at + or - 20 LTFT. I would work on addressing the fuel trim issue before worrying about the catalytic converter, it is not your primary issue in my estimation.Make sure your front O2 sensor is the correct part for the car and monitor it via the OBD port, verify it cycles normally. Odds are rather good that you have a large vacuum leak which is screwing up the fuel trims. MAF could certainly be bad. How does the car run? Link to comment Share on other sites More sharing options...
Snabb T5M Posted June 25, 2015 Author Report Share Posted June 25, 2015 +30 LTFT? I think these cars throw a CEL at + or - 20 LTFT. I would work on addressing the fuel trim issue before worrying about the catalytic converter, it is not your primary issue in my estimation.Make sure your front O2 sensor is the correct part for the car and monitor it via the OBD port, verify it cycles normally. Odds are rather good that you have a large vacuum leak which is screwing up the fuel trims. MAF could certainly be bad. How does the car run? The car drives awesome!! No stumbling or anything. I would hope FCP sent me the correct front O2 sensor. If it was a massive vacuum leak wouldn't I hear it? Link to comment Share on other sites More sharing options...
S8ET6 Posted June 26, 2015 Report Share Posted June 26, 2015 Lee, race gas will degrade your cat's performance over time. Link to comment Share on other sites More sharing options...
Snabb T5M Posted June 26, 2015 Author Report Share Posted June 26, 2015 Lee, race gas will degrade your cat's performance over time.Meh, and I haven't been running race gas in over two years. It'd be a waste to put race gas in a car that isn't driven. Link to comment Share on other sites More sharing options...
S8ET6 Posted June 26, 2015 Report Share Posted June 26, 2015 My pont is that, considering how often you used to use race fuel, the likelyhood of reduced efficiency from your cat should be expected. Link to comment Share on other sites More sharing options...
Snabb T5M Posted June 26, 2015 Author Report Share Posted June 26, 2015 My pont is that, considering how often you used to use race fuel, the likelyhood of reduced efficiency from your cat should be expected.Even though it was unleaded? DAMNIT!!!Was just checking around the different race gas websites, and they all say their unleaded race gas won't harm sensitive O2 sensors or CATs. I know enough not to use leaded race gas in Red, that's reserved for the Super Bee. Link to comment Share on other sites More sharing options...
SlapShot Posted June 29, 2015 Report Share Posted June 29, 2015 CT must have far less stringent requirements. I passed years back with an exhaust leak and a removed air pump. They just plug in their tester and check for a CEL. Honestly I was pretty sure the OBDII readiness checks were exempt for the 98's. Link to comment Share on other sites More sharing options...
washdup Posted June 30, 2015 Report Share Posted June 30, 2015 Try passing a '98 in California. . . . I dread every other year when the "smog check" notice comes in the mail. Aside from replacing the original air box, I have to swap in my original ECU, but that's mostly to get the NO emissions down (not the problem for your car, apparently). I have also found that the MAF can make a big difference in passing smog, even if the car seems to be running perfectly. Try replacing with another known good MAF. Link to comment Share on other sites More sharing options...
Snabb T5M Posted June 30, 2015 Author Report Share Posted June 30, 2015 Try passing a '98 in California. . . . I dread every other year when the "smog check" notice comes in the mail. Aside from replacing the original air box, I have to swap in my original ECU, but that's mostly to get the NO emissions down (not the problem for your car, apparently). I have also found that the MAF can make a big difference in passing smog, even if the car seems to be running perfectly. Try replacing with another known good MAF. Yes, purchased a brand new MAF and will swap out. Need to buy a cigar and do a smoke test on it and make sure no vacuum leaks. Final straw is going to be buying a new 3" hi-flow Magnaflow CAT and cut up my EST DP and stick the new CAT in. I have one of early EST DP's where the CAT was welded into place. Beautiful unit and I really hate to cut it up, but gotta do what I gotta do to make the car driveable. Link to comment Share on other sites More sharing options...
Burn-E Posted June 30, 2015 Report Share Posted June 30, 2015 You and I could always swap down pipes Lee. I have an original IPD 3" DP that has no CAT attached. Link to comment Share on other sites More sharing options...
Snabb T5M Posted June 30, 2015 Author Report Share Posted June 30, 2015 You and I could always swap down pipes Lee. I have an original IPD 3" DP that has no CAT attached.Hmmmm.........that's an idea. Though mine has an extra bung welded in for the AFR gauge. Link to comment Share on other sites More sharing options...
Burn-E Posted June 30, 2015 Report Share Posted June 30, 2015 How many bungs do you have? Mine is an IPD SS 3" piece with an added wideband bung. Link to comment Share on other sites More sharing options...
Snabb T5M Posted June 30, 2015 Author Report Share Posted June 30, 2015 How many bungs do you have? I think mine has 3 also. Would need to take a look at it again. It's not currently installed on the car.Hmmmm....front O2 bung, AFR bung, SAS bung, rear O2 bung. So 4. The IPD should have the 3 required bungs (O2 and SAS). Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.