luv2ride

My 96 993 just rolled 45k and consumes less than 1/4q per 1000m. I am dreading the day when I see the looming CEL light. Its a 2nd car that is garaged all winter and driven occasionally in good weather. Is there a proper why to drive the car to preserve the car and ensure it won't light up? suggestions?

Thanks
Ryan

epj993

A CEL related to the secondary air injection may ultimately be unavoidable. But good preventative maintenance would be change the SAI check valve every 10-15K miles and rev it high on a regular basis!

97Targa

CEL in respect to the SAI, is most often a result of worn valve guides. Do what you can to keep the cylinder head temps down.
Have you removed the engine tray?

luv2ride

I also have an anxiety about the slipery slope. But that can be another thred. And no craig. I havent removed it. That's a good thing to do?

97Targa

The engine tray traps the heat. That's a bad thing. Most experts (including Bruce Anderson) agree that the tray is designed to allow the car to pass noise restrictions.

Father of 3

Keep temps down, change check valve at 15k intervals. To keep temps down, remove engine undertray, make sure cooler fan is working, install cooler fan switch, and/or add an auxiliary oil cooler. Everything is pretty cheap except the auxiliary oil cooler.

mborkow

having been through a top end rebuild as a result of SAI, i can say that you'r anxiety is quite well founded (and i did not appear to have worn valve guides, or at least i wasn't consuming a lot of oil). that $6k bill hurt (a lot).

97Targa

Check out Robin's site @ www.p-car.com for info on the fan switch over ride mod. It's in the DIY section.

Mark Wilson

Just curious, is there any proof that running the engine hard helps with cel? I've read this several times, but it seems like an urban myth to me. No offense intended.

JasonAndreas

Based on what is written in the patent covering the 964 rear undertray its main function was to improve aerodynamics, any noise dampening was just a side-effect. The undertrays were designed by Michael Preiss (now head aerodynamicist at PAG) so I guess it would be possible for someone to call him up and settle this once and for all (he doesn't respond to emails -- I tried).

97Targa

Interesting. Did the factory use them on their 964 or 993 based race cars?

f_scaife

So did you do a top end rebuild just because of the SAI induced CEL? Upon teardown were your guides worn out?

C.J. Ichiban

engine tray removal is about an 8 minute one tool DIY. And if you're only running in fair conditions, and weather- you're not worried about getting salt or debris bouncing off the underside as much- i'd take it off.

aerodynamically? not going to really make a difference for any purpose for daily driving conditions- and it's going to trap too much heat to use on the track...right?

if you're really that worried go pick up an OBD -II scanner from autozone for 150 bucks or so. It also seems that our cars really just want to stretch the legs out, and the fuel injectors respond well to wide open throttle now and then puts enough pressure to keep them from accumulating too much carbon build up.

I'm in a similar situation mileage wise, although my car barely uses any oil between changes- must be the nice socal weather?- so when i'm in traffic i try to even put up the spoiler to keep it cool in the engine bay. most of the issues that come up with the engine maintenance are all based on accumulation, its going to take repeated abuse or neglect to wear down that $ 20,ooo drivetrain.

Terry L

This is my second 993 with the CEL issue so I guess that makes me an expert. I don't believe that any of the preventative measures mentioned here or elsewhere will help, although maybe they can delay the problem. If you have seen a 993 engine opened up, you will know that the carbon can actually clog the entire air line, not just the tip. I'm hoping that the cleanout will work but I'm not optimistic. BTW, neither of my cars was using a lot of oil. Unfortunately, we must build in the price of new valve guides when we buy or sell these cars.

brucec59

The main reason we care about the CEL is because it means we fail the smog test (in some states), right? But isn't there a limit to how much you are required to spend to attempt to fix smog-related problems?