1996 993 check engine light.

[almico]

I recently had the car in for service: new suspension and post purchase inspection.

At the same time I had them install a pair of Fister Stage IIIs that I had Darin do for me.

When I went to pick up the car it suddenly would not run. After two more days I got a bill for a fuel pump relay and a new MAF sensor. Car is running great now but I'm popping a check engine light. My slick new Autel scanner is too slick for a 993 and it doesn't decode the VIN.

I brought it by the tech and his scanner said misfire on all 6 cylinders. He reset the light and said if it comes back it's new plugs, wires cap etc.

But he loves throwing parts at a problem. The plugs/wires and cap were done 30k miles ago. Shouldn't be that bad.

My thinking is that since I wasn't getting a CEL before the exhaust and new MAF, that plugs, wires and cap are not the answer.

Could it be the Fisters?

[Marine Blue]

I tend to agree but to help with diagnosis, how many years since the plugs and wires were done?

[almico]

Originally Posted by Marine Blue

I tend to agree but to help with diagnosis, how many years since the plugs and wires were done?

30K miles.

[Marine Blue]

How many years?

[almico]

Originally Posted by Marine Blue

How many years?

2008 @ 72K miles. A little over 100K now.

[almico]

For yucks and giggles, I called my local P dealer to get a quote for a plug/wire and cap change.

5 hours @ $225ea to change the plugs
8 hours to changes the wires
$27 x 12 for the plugs
$127 x 12 for the wires.
Didn't bother to ask the price for the cap.

From what I've read, 11 plugs would take about 2 hours for a fairly handy, "first time doing this" home mechanic. It's the last one that might be 4-5 more.

I have a good floor jack and stands, but I'm thinking this might be my opportunity to divert some funds that I would pay someone else and invest in a compact lift system (I have a '76 911 also). I can't get too crazy; I have just enough room for two cars and the ceiling is only 8'. Does getting a car 3 feet off the ground make that much difference to 18". I'd still be on my back with not enough room to sit up straight.

[Marine Blue]

I’ve heard similar regarding plugs, I had mine done by a local shop when the valves were adjusted.

Regarding the lift, I purchased a Quickjack scissor lift last year and I do feel that the additional height it provides makes working underneath the car significantly easier. More height the better! More importantly I fee much more comfortable under the more substantial lift than I do a small jack stand. I’ve done a couple of oil changes and two brake jobs and it’s paid for itself already.

Going back to the original issue, did your shop provide the error code for the CEL? I don’t think the Fister would impact it since its downstream of any of the emissions stuff.

[Gspin]

Get a Durametric to analyze it or better yet someone with a PIWIS. Agree, highly doubt the plugs went bad as they're known to last for years especially on normally aspirated cars. Any tech that is part swapper is nothing more than that,run. Where are you located?

[mysocal911]

Originally Posted by Gary Spinella

Get a Durametric to analyze it or better yet someone with a PIWIS. Agree, highly doubt the plugs went bad as they're known to last for years especially on normally aspirated cars. Any tech that is part swapper is nothing more than that,run. Where are you located?

The OP indicates he has an Autel scanner, but it can't read the VIN. It's not necessary to use the VIN reading function on an Autel to utilize the OBDII functions for diagnostics.

[shahram]

Check engine light on 993 (96 and late) comes up most of the time due to clogged SAI ports. Secondary air injection. Check on Rennlist how to clean the ports.

[samurai_k]

Connect your reader and dump out the specific error codes from the ECU. The check engine warning light is a consequence of other errors being triggered.

The error codes will then point you to the right place to diagnose and rule out as root cause of the fault. Throwing parts or service at the problem and not understanding what the root cause is just wasting money on service and parts that is not resolving the cause of the issue to begin with.


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[vax]

Hey Almico, Any progress on this issue? I'm also getting the same misfire CEL on my 96 suddenly. The only work that was done recently was swapping out belts (and I did use the genuine porsche belts).

On one particularly hot day here, the car actually stalled. Luckily, it restarted instantly.

[Traveller]

Originally Posted by almico

But he loves throwing parts at a problem.

Because having diagnostic skills takes some grey matter. And exactly why nobody touches my cars and motorcycles.

[mdm1053]

Hi Almico, have you had any luck with your issue? I have a '96 C2 with Fister stage 3's (done under previous ownership) and I'm having a very similar issue. CEL comes up every 150 or so miles with random cylinder misfire. It goes away after a bit of time and then the cycle repeats. I've taken it into a reputable mechanic and they haven't found anything of concern. Their guidance was, "keep driving it and come back if anything changes or gets worse." They were reluctant to throw parts at a problem they felt may just be a faulty sensor. Would love to get thoughts from other on how to narrow things down a bit.

Here's what I've tried:
- checked timing belts (were replaced but OEM)
- cleaned MAF and ISV
- changed fuel filter
- new DME relay

[Traveller]

Originally Posted by mdm1053

Here's what I've tried:
- checked timing belts (were replaced but OEM)

I take it you meant timing chains on your 993.

[mdm1053]

Sorry, I mis-typed. I meant belts (fan, AC, alt).