HELP Engine Light w Many Codes
 

Took the 1998 Boxster out and the CEL lite up within the first 100 yards, multiple codes where read. Car did not want to exceed 2000 rpm. Turned around and put it back in the garage.

PO 300 - Misfire Detection
PO 304 - Misfire cyl 4
PO 305 - Misfre cyl 5
P1 316 - Refer to Manual
P1 317 - Refer to Manual
P1 319 - Misfire Detection

Car ran great the weekend before without issue. Plugs changed within the last 1000miles, EOS replace within the last three years and O2 sensor was replaced on drivers side ahead of cat last fall. Car has 46,000 miles. This car has had no modifications, any help would be much appreciated.

Ken

If my information is correct all the codes are misfire codes.
P 1316 and p 1317 are also for cyl 4 +5.
I would start by pulling the plugs and cleaning them on cyl 4+5 and also look very carefully at the coil packs on 4+5 if they have any cracks even if they are hairline cracks they could be the issue.
let us know what you find.

did these codes come up after driving through rain/puddles?

Car was not driven in rain when these codes appeared.
Replacing coil packs on #4 and #5... will update with results. Thanks for your replies.

When you replace the coil packs also look over the wiring to them the best you can for any issues.
Also pull those two plugs and check them over. They could be fouled due to the misfires.

getting those codes in the rain is classic coil pack issues. they develop cracks, that you can't usually see with the naked eye, but when wet it shows up. easy way to verify is with the engine running spray some water from a bottle in the dark and see if you can see any coil pack spark. If so...replace it

Replaced Coil Pack #4 and #5, this resolved the CEL and the car is running so much better.
1. Should i replace the other 4 coil packs ?
2. It seems like there is some hesitation which I believe could be a semi blocked Cat Converter. Will take some Temp Readings within the next few days to answer that questions. Has anyone here replaced there Cat with a Cat By Pass, which unit did you use and did the CEL come on?

Thanks for all your replies.

If it were me, I would replace all of the coil packs & plugs. Not all that expensive and then they are all replaced at the same time compared to trying to remember which was done when later on if doing any other troubleshooting. I look at this as just a standard tune up (like replacing plugs, wires, distributor cap & rotor). Can't hurt to replace them all, only help

You can also use a vacuum gauge to check for a restricted Cat Converter or restricted exhaust.
I am surprised at how many people don't have a vacuum test gauge in there tool box.
A very basic tool that can tell you many things about your engines condition.;)

Blue, could you please provide more details on how do you test a restricted cat using a vacuum gauge?

I bot a digital manometer (JFP's suggestion) to check the vacuum on the block and curious how you use it to check a congested cat.. thanks!

A digital manometer is different then a standard (old school) vacuum gauge.
So it will not work to check a restricted exhaust system.

With a standard vacuum gauge its the action of the needle on the gauge that is important.
So you do a "Snap throttle test" and a "Hold RPM test".
Cats have to be hot Ect. Ect.

It will be easier for me, and probably more informative for you if you google vacuum gauge testing catalytic converters.
You will find all the info you need to do the test.

Edit: A standard vacuum gauge only costs around $15.00-$20.00 and as I stated in my other post very handy tool.
There is lots of info on using them on the net just have to search around.