The Semi-Unofficial Pistol-Forum Car geek, gearhead, hot rodder, and vehicle thread

[SecondsCount]

Was the GT40/Cobra race a modern classic car race? I kept thinking dang how many laps is this pass going to take? And the second GT40 never got by?

Yes, Goodwood is an annual event where the hold classic races.

The GT40 looks beautiful on the track. Makes the Cobra look really old in comparison.

[hufnagel]

I too immediately thought the green trace to be abnormal but I guess one could question at the places where the two traces vary widely which one is wrong. Do you know what happened at those spots? Change in throttle position? Change in engine speed?

sadly i didn't record things like vehicle/engine speed and throttle position that time..
given it's a honda, and I was forced to use EOBD for data, and i'm not familiar with how honda O2 sensor traces should look, I have to rely on the general theory of operations of most O2 sensors is that they're narrow band sensors, so they switch between lean and rich instead of reporting a smoother output curve (wideband.) since the green one is almost always showing some form of switching on its graph, I'm taking that one to be, for the moment, expected performance. you can see from the blue curve that, at random times it stops switching, and if you look at the first graph right near the end it goes COMPLETELY dead. it should also be noted that, the blue curve is for Bank 1 sensor 1, which is the bank that has the catalyst performance code being reported (P0420).

a note on Catalyst System Efficiency Below Threshold codes, specifically P0420 and P0430, for those who don't know.
those 2 codes come about generally come about because the downstream sensor (sensor 2) starts switching, or showing high levels of unburned hydrocarbons. the predominant cause of that would be a failed or failing catalytic converter, hence the the name of the code. HOWEVER, that also requires that the vehicle be in proper running order, and that includes the upstream sensor reporting correctly to the ECU about HC emissions right after combustion. If the upstream sensor starts performing badly, the downstream will start to see problems. Basically, a garbage in garbage out problem.

Since we have a vehicle here that popped a MIL, i'm going to assume the dealership read codes and came up with the P0420 as an active code at that time, and reported back "bad cats." HOWEVER, the light turned itself OFF after some additional driving, which would indicate the OBD saw expected performance from the downstream sensor, and assumed the fault was corrected, and put the code into a STORED state. This would indicate a still functioning converter, and leads me to believe we are indeed dealing with a GIGO condition. Further research indicates that it's apparently NOT uncommon for Honda 3.5L v6's from this era to need O2 sensor replacement around the mileage she currently has on the 'van.



typing all this, I just had a thought...
again not being a Honda guy, I'm having to rely on experience and general O2 performance specifications.
I know that in the Chrysler world I deal with predominantly, the downstream O2 sensor DOES contribute to overall fuel tuning, which is NOT common in some other worlds (GM and Ford from what I remember do not take downstream data and use it to tweak performance.) I experienced that first hand one time when the downstream on the Neon had damaged wiring, would occasionally wig out, and the computer would go bonkers leaning the engine out thinking "holy crap I'm pissing fuel out the exhaust!" and make it run so poorly it scared the crap out of me that the motor was broke.
I don't think that's the case here, as there was no experienced performance issues in the 'van during the test drive, but it's something I should look into I guess.

[CraigS]

I have no idea if there are joints there or not but if there is a joint near that cat have you looked for leaks? One generation of one model I used to work on had a propensity to blow out the gasket near one of the cats causing MILs on.

[awp_101]

Was the GT40/Cobra race a modern classic car race? I kept thinking dang how many laps is this pass going to take? And the second GT40 never got by?

Yes and the Goodwood races are fun in that the drivers are usually actually racing each other vs just a set of glorified parade laps to keep the cars safe.

It was suggested in the comments by a couple of people those are probably MKI GT40s with the 289. The implication being had they been MKIIs with the 427 the pass would have happened sooner regardless of how good the Cobra pilot was.

[CraigS]

Yes and the Goodwood races are fun in that the drivers are usually actually racing each other vs just a set of glorified parade laps to keep the cars safe.

It was suggested in the comments by a couple of people those are probably MKI GT40s with the 289. The implication being had they been MKIIs with the 427 the pass would have happened sooner regardless of how good the Cobra pilot was.

That makes sense. I believe Goodwood is a medium speed track so the GT40 aero advantage would not do as much as at a higher speed track. And a big block would have a pretty good chance of pushing the aero brick Cobra fast enough to stay ahead. I have watched Goodwood on TV many times over the years and it is always fun.

[camel]

sadly i didn't record things like vehicle/engine speed and throttle position that time..
given it's a honda, and I was forced to use EOBD for data, and i'm not familiar with how honda O2 sensor traces should look, I have to rely on the general theory of operations of most O2 sensors is that they're narrow band sensors, so they switch between lean and rich instead of reporting a smoother output curve (wideband.) since the green one is almost always showing some form of switching on its graph, I'm taking that one to be, for the moment, expected performance. you can see from the blue curve that, at random times it stops switching, and if you look at the first graph right near the end it goes COMPLETELY dead. it should also be noted that, the blue curve is for Bank 1 sensor 1, which is the bank that has the catalyst performance code being reported (P0420).

a note on Catalyst System Efficiency Below Threshold codes, specifically P0420 and P0430, for those who don't know.
those 2 codes come about generally come about because the downstream sensor (sensor 2) starts switching, or showing high levels of unburned hydrocarbons. the predominant cause of that would be a failed or failing catalytic converter, hence the the name of the code. HOWEVER, that also requires that the vehicle be in proper running order, and that includes the upstream sensor reporting correctly to the ECU about HC emissions right after combustion. If the upstream sensor starts performing badly, the downstream will start to see problems. Basically, a garbage in garbage out problem.

Since we have a vehicle here that popped a MIL, i'm going to assume the dealership read codes and came up with the P0420 as an active code at that time, and reported back "bad cats." HOWEVER, the light turned itself OFF after some additional driving, which would indicate the OBD saw expected performance from the downstream sensor, and assumed the fault was corrected, and put the code into a STORED state. This would indicate a still functioning converter, and leads me to believe we are indeed dealing with a GIGO condition. Further research indicates that it's apparently NOT uncommon for Honda 3.5L v6's from this era to need O2 sensor replacement around the mileage she currently has on the 'van.



typing all this, I just had a thought...
again not being a Honda guy, I'm having to rely on experience and general O2 performance specifications.
I know that in the Chrysler world I deal with predominantly, the downstream O2 sensor DOES contribute to overall fuel tuning, which is NOT common in some other worlds (GM and Ford from what I remember do not take downstream data and use it to tweak performance.) I experienced that first hand one time when the downstream on the Neon had damaged wiring, would occasionally wig out, and the computer would go bonkers leaning the engine out thinking "holy crap I'm pissing fuel out the exhaust!" and make it run so poorly it scared the crap out of me that the motor was broke.
I don't think that's the case here, as there was no experienced performance issues in the 'van during the test drive, but it's something I should look into I guess.

What do the catalytic converters look like. Are they purple? What tool are you using? Is it an autel that hasn’t been updated?

[rawkguitarist]

I’ve been thinking about getting a BRZ for a while. My son needed a new car, so I sold him mine and went ahead and grabbed this 2023. My old car was a Lexus Is350, and it made me appreciate an automatic with paddles. I found 6 automatics in the country and this was the closest at about 250 miles from me. Some feel it’s sacrilegious to not get a manual in these. But with 228hp and it’s so light and such low center of gravity it’s plenty quick. Even better, it handles like crazy.

Now I just have to be patient enough to have my EQ, amp and sub installed next week. The stock stereo is the worst I’ve ever heard.

[hufnagel]

What do the catalytic converters look like. Are they purple? What tool are you using? Is it an autel that hasn’t been updated?

grey. with a honeycomb matrix. and my autel is up to date.

[HeavyDuty]

I’ve been thinking about getting a BRZ for a while. My son needed a new car, so I sold him mine and went ahead and grabbed this 2023. My old car was a Lexus Is350, and it made me appreciate an automatic with paddles. I found 6 automatics in the country and this was the closest at about 250 miles from me. Some feel it’s sacrilegious to not get a manual in these. But with 228hp and it’s so light and such low center of gravity it’s plenty quick. Even better, it handles like crazy.

Now I just have to be patient enough to have my EQ, amp and sub installed next week. The stock stereo is the worst I’ve ever heard.

I was looking hard at BRZ a few years back before I decided I wanted a convertible and bought a Miata. I should look at these again.

[rawkguitarist]

I was looking hard at BRZ a few years back before I decided I wanted a convertible and bought a Miata. I should look at these again.

Funny, there's two cars that seem to be the standard to be judged against in the $30k to $40k sport car price point. The Miata and BRZ/GR86. One reason is twenty something dudes can have a reasonably priced base vehicle to tune into a really good "track car". But without doing anything they're both are legit drivers cars. I won't be spending money on a CAI, headers, exhaust and a tune on mine. I purposely chose this car to not spend as much as my Lexus. But soon I'm getting a better set of tires and brake pads. Eventually may put a strut tower bar and rear sway bar to tighten the chassis just a bit more.

But again... it's plenty quick. It's a little sluggish for some reason 1st gear to about 30mph. But in 2nd, 3rd, 4th in the 3-5k rpm range its easily as quick/responsive as my IS350.

NOW, the Miata... that super light/small car with a 180ish horsepower engine. A damn fast car.