986 CEL on after storage
 

Hi!
Just fired up my 1999 986 2.5 after almost two years in the garage. It was fine when I parked it. On first startup the red light next to the temp gauge started flashing, and the CEL came on. Not flashing. I checked the coolant, and found it was a little low. Just under min. Added some coolant, changed oil and filter, and both lights were gone. That was yesterday. Today the CEL light came on again. Car pulls strong, and the oil looked fine. No water in it, and no bad signs in the filter either. Will hook it up and read the codes, but what do you think is the most likely cause of the CEL?

Hmm, intuition tells me you should replace all your fluids after sitting for 2 years. Maybe start with an oil change and complete coolant flush.

Thank you for swift reply. I changed the oil and the oil filter yesterday. The coolant was fresh when I put it away, so I just added enough to make the red flashing light go away.

The CEL could be from any number of things.
Read the code then you will know why the CEL is on.

Until you know the codes there isn't much help.

And then the brake fluid flush.

Incidentally, I had something similar happen. Granted, I didn't store it for a year, but I bought it from someone who had.

After I put about 150 miles on it after storage, I threw CEL and blinking coolant light. It was throwing 3 different codes, one of which ended up being a bleeder valve. Fixed that and the coolant system was right as rain. (...except for not having secured the reservoir cap tightly enough and blowing out about a gallon of coolant onto a parking lot, but we're not going to talk about that.)

You said it threw 3 codes but only told us of 1. So let's start over....what are the 3 codes? Code numbers ONLY please.

Finally found the time to hook it up!
Codes as follows: P0300, P0301, P0302 and P0303. My Bosch Estronic reports them to be ignition faults on cylinder 1, 2 and 3. When I cleared the codes it took about 5 minutes of eventless driving before the CEL came on again. Any suggestions?

Codes as read by my Bosch Estronic: P300, P301, P302 and P303. What is the most likely cause? I erased the codes, and drove it for a few minutes before the CEL came back on. It pulls strong, but the idle is a bit erratic at times.

Jesus, that'd be a misfire on four cylinders (you would know this if you took 2 seconds to google!). No clue what could cause that I defer to anyone else or otherwise if it were me I'd consult a shop. That's a lot of failure at once.

Well if you have no clue then maybe you shouldn't say anything. And if YOU googled you would have known that isn't miss fire on 4 cylinders.

It's actually misfire on cylinders 1-3. I would start with just pulling the coils & plus and replacing the plugs. clear the codes and then take it for a drive.

Woah there, calm down, I forgot about the general misfire 000 code. I actually have experience diagnosing a misfire I've just not yet bought/worked on a 986 and don't know if there's another common issue that could cause half the cylinders to fail, hence deferring to others :D

Misfires all on the same bank.
pull the coils a look at them for hairline cracks.
If there are no cracks the coils should be ok.
Replace the plugs as STI-986 said.
Also look for any oil on the coils or plug insolator.
Oil on the plugs or coils can cause issues.

Let us know if that fixes the issue.

Also, check for oil leaks around the spark plug tubes on the cam cover. This is typical of dry/cracked spark plug tubes. Ok to replace, cheap but just time consuming. These can cause misfires also.

for coils unless the crack is very obvious it will be hard to see them usually. cracked coils typicall cause misfires when driving in rain or getting them wet.

If you dont know when either were last replaced, it may be best to just replace all the plugs & coils, it isn't expensive.

Solenoid?
 

Both plugs and coil packs are fairly new. I could understand if one failed, but not all three on one bank simultaneously. There has to be another problem causing this. Read about a possible solenoid issue known to cause misfire codes on bank 1. Any information on this subject?

You would have other codes for a solenoid issue. I know, have a 2000 doing it.

if all you are getting is misfire for 1,2 3 then it's going to be plugs/coils....or wiring. Having sat for a while it's possible something got in and started to chew on wires.

I would still do new plugs. 1 hour of your time and under $40 in parts. Never hurts to do plugs.

You can just get it out and start driving it, put about 100 miles on it, clear the codes and then see if they come back.

I some what agree with your line of thinking.
BUT:D
The car sat for two years:eek:
So the best thing to do is go with automotive tried and true diagnostic procedures.
That means simplest things first then work your way up step by step.
The plugs, coils, and any oil that could cause issues is the easiest first step.
If there is no issues with them then there's no cost.
Go to the next step.
Next would be the wiring harness to the coils.
Rodents like to chew the coating on wires for some damn reason.
You can test that out with a common Digital Multi Meter.
If these prove out all good then it's time to look for other causes.

Sticking to the basics helps prevent chasing your tail:D

Let us know how you go.

If the above does not fix the issue perhaps we can help you find the issue.

Test drive
 

Will change the plugs and check the coils:)
Cleared the faults and took it for a test drive today. It drives well. No hesitation on acceleration and no smoke or misfire. Drove approximately 60 km. I then decided to check the brakes and floored the pedal. The brakes are very good. But the cel came on again immediately! Coincidence? Turned around and drove 60 eventless km back again.
Hooked it up again and the same codes were present: P 300, 301, 302 and 303.
It was stored for two years with little fuel in the tank. Any possible problem here that will affect bank 1 cylinders only?

Does your scanner show freeze frame data?
That is data showing the conditions or some of the conditions when the codes were set.
If I remember correctly most all OBDII scanners that show freeze frame data show data for the last code only.
But Since all your codes are related there may be a clue to whats triggering them in the freeze frame data.

Still need to look at the coils, plugs and wiring harness though.