'91 Comptech SC CEL and codes 1 and 2

[drudolf]

Hi All,
I am the new proud owner of a '91 Comtech SC NSX. :biggrin: 42K miles. It also has the Comptech headers and exhaust. This is an early kit with the whipple SC.
Picked it up in Baltimore a couple of weeks ago and drove it the 7 hours home. (I live in Ohio). About an hour into the drive I got a CEL. The car had a hesitation on light throttle application that got worse until the CEL and them got really bad. Turning the car off and on made it better for a while. Codes read out as 1 and 2 which are O2 sensor problem. Nursed it back home (Well nursed it might not be entirely true. It ran best above 3500 RPM or with 3/4 and above throttle so I made darn good time home) When I got home I ordered a set of Denso O2 sensors and swapped them out. Also replaced the air filter. Reset the computer by pulling the clock fuse. It got better, but not fixed. Driven it about a week. Sometime it's OK with only a slight hesitation when gently accelerating, most time a little worse. Couple of times the CEL came on. Today it ran pretty badly and the CEL came on. I read the codes and... 1 and 2 again. It's not the wiring to the O2 sensor. Looked like new. Does anyone have advise on the next step?
Thanks!
Dan

 

[BTL3.0]

try cleaning the throttle body yet?

 

[drudolf]

Nope. Not yet. I was going to swap fuel filters and try see if the fuel pressure is OK. I'll try the throttle body cleaning too.... Any hints on best way to do that?

 

[Larry Bastanza]

You should check the fuel pressure at all RPM's, under load. The SC requires up to 90 PSI when on boost, and although the Code 1-2 does not always mean "lean" you need to make sure this is not the issue. Lean is bad, and can have very damaging consequenses. Code 1-2 means 02 sensor "out of range" i.e. too lean or rich, and when the ECU trys to make it right, is cannot get it into range, and throws the code.

HTH,
Happy Holidays,
LarryB

 

[G III]

check fuel pump,,short it out so it will be in2nd stage,,drive car to see if cel light comes back on,

 

[drudolf]

Well I went out and was going to buy a fuel pressure gauge but couldn't find anyone (3 different stops) who had the small size tap out connection for the top of the fuel filter. I looked around more on NSX prime and it seemed like that even if I find that the pressure is wrong the next step would be look at the A/F ratio and adjust the pressure based on that. Versus buying a lot of equipment and messing around way too much at this point (I just want to be able to drive my new car) I made an appointment with Justin at Source1 on the 7th. I'll let everyone know what the result is. Thanks for the feedback.

 

[drudolf]

Just got back from Source1 and my car runs great!!!! Justin found that the supercharger wasn't grounded properly and someone had turned up the fuel pressure to maximum (probably to try and fix the symptoms) He fixed both and I was charged a total of $131.25 for both the diagnosis and the fix. Source1 is HIGHLY recommended!!!

 

[racer9x]

Now that's good news, do you know where exactly it wasn't grounded properly?
Just curious as I am getting ready to install one on my car and it is nice to be able to do a search regarding a problem and find a possible solution.
thanks

 

[SOURCE 1]

Just got back from Source1 and my car runs great!!!! Justin found that the supercharger wasn't grounded properly and someone had turned up the fuel pressure to maximum (probably to try and fix the symptoms) He fixed both and I was charged a total of $131.25 for both the diagnosis and the fix. Source1 is HIGHLY recommended!!!

Thanks for the recommendation! Glad it was a simple fix. Now get out and enjoy that beautiful car!

 

[drudolf]

Now that's good news, do you know where exactly it wasn't grounded properly?
Just curious as I am getting ready to install one on my car and it is nice to be able to do a search regarding a problem and find a possible solution.
thanks

Justin said the supercharger is powder coated and that you must make sure that the powder coating is removed under the GND lugs. There is one GND lug on one of the bolts on top of the supercharger. Don't know if that's the only one.