EduardoForesti

I am a P030X sufferer and HATING it. NOTE: I did review other threads, and in particular "I could use some diagnostic help on misfire codes"

Car: 1997 993 C2, cabriolet. 100K miles

Useful info. The P0303 started about 150 miles after a big maintenance job, which included:
- Plugs, wires, caps, rotors, distributor belt
- Upper and lower VC gaskets
- Clutch, DMF (don't judge me ), etc
- SAI ports spa treatment (port clean/flush re: 0411 0410 codes)
- Clean ISV
- Air filter, fuel filter, alternator, oil and filter
- Engine (plus cats/exhaust), got a bit of an (external) bath given all of the accumulated oil from leaky gaskets
- Note: It has Porsche / OEM belts on it from before the above job (noting this because non-OEM belts are a known culprit for misfires)
- It has a fresh tank of gas

Other Symptoms (beyond CEL and code) and other info:

• No issues with starting. No issues with stalling.
• The engine definitely sputters at idle and in driving (it is really misfiring), but when I drove it last, the sputtering was intermittent for parts of the drive (like it had gone away, but...it came back). There are moments in a 5 mile drive the missing isn't happening, but it is mostly missing constantly. It is PARKED now as I don't want to risk damage.
• When the P0303 first popped, it popped with a P0411 and P0410 (freaked me out), but I've reset twice now and the P0411 and P0410 have NOT appeared again.
• Plug wires for cyl 3 are set/tight at plugs and d-caps and the wires from d-caps to coils are tight.
• OBD stats attached -- July 17 Bank 1 definitely looks out of whack - but only via inference given the huge difference to Bank 2; not because I know any better)
• OBD Stats attached - July 21 Shortly after the P0303 first hit, now I'm getting: P0303, P0300 and P0304 (issues have moved to bank 2); these stats are from that set of errors.
• For some reason I looked at the DME Relay (I probably read in a thread somewhere) when I parked it last and it was 'hot' - not so hot you couldn't hold it, but pretty hot... Is that a possibility?
  • I just re-read this post (probably is what lead me to the DME Relay in the first place!!!) -- so tonight I will pop the cover of the DME Relay and look for issues (and will report back).

I think the recommendations from the other threads is now for me to (net of all the work performed to date)?:

• Find and fix any VRAM vacuum leaks. I don't have any testing equip other than a OBDII reader, so I can look for disconnected vacuum lines?
• Figure out to test the hall / Pulse sensor https://rennlist.com/forums/993-foru...op-manual.html (I responded to that post looking for the procedure to test)?
• Check the grounds https://rennlist.com/forums/993-foru...l#post10388201?

Given other's experience and expertise and the attached OBD stats, is there anything glaring that would you lead you to "the source"?

Is the hot DME Relay a clue? Is the fact that the misfires are somewhat intermittent a clue? Is the mountain of recent work and the engine baths a clue (other than painfully frustrating)?

I have a service manual, but it is incomplete and is totally missing section 28 ("ignition system")...ugh...

Many thanks for any insights!

- Edward

PS: The shop (that I love) that did the recent work is +/-90 minutes from me, so if this can be fixed from home, I'd be a happy camper...hence my reaching out to "the Rennlist brain-trust"...

pp000830

Before digging in too deeply;

• Verify the plug wires go to the correct plugs and the plug and rotor boots are fully seated.
• Check that the distributor belt is not broken by unplugging the center distributor wire on the right-hand cap and see if the engine starts runs on the left-hand distributor only.;
• Then plug it back in and unplug the left-hand cap center wire and start the engine to see if it runs on the right-hand distributor alone to validate system spark through that distributor..
• If it runs at all on each of the caps alone the ignition spark and the belt is intact.

After these simple items prove to be OK, get back to us to look more deeply into the issue.

Knowing the exact codes thrown in the P030x series tells a bit more. A general code or codes thrown from multiple cylinders suggests it is a centralized issue that impacts multiple cylinders such as a vacuum issue or a distributor spark issue. If it is consistently one cylinder's code than the focus of the investigation should be on that one cylinder's spark or fuel..
Andy

Mr.Woolery

Do you still have the dual mass flywheel? If so, how many miles would you estimate on it? Does the car run a bit smoother with the AC on?

Sometimes a failing dual mass flywheel will cause misfires on all cylinders. Depending how bad it is, sometimes turning on the AC will help by adding a little bit of load to the flywheel and prevent it from "jiggling the timing". I had that issue with mine before replacing the DMF--would throw codes and wouldn't pass smog as a result. Turning on the AC would smooth things out and let it pass smog easily...then I replaced it with a LWF.

Sire

what he said:
Verify the plug wires go to the correct plugs and the plug and rotor boots are fully seated.

pp000830

Here is a page that discusses testing a dual-mass flywheel:
Dual Mass Flywheel

Hope this helps,
Andy

95_993

Eduardo,

From your original post, I see you have already replaced the DMF so it's a lower probability the new one is failing (no DMF judging here as I stayed with DMF as well during my last clutch replacement). One thing I did not see on your above list is cleaning of the fuel injectors. I am not sure how long the engine sat for the engine out maintenance you just did but it is possible you have stuck or sticky injector(s). Try running 2 tankfuls of BK44 Or Techron and see how it does. It's easy, inexpensive, burns no bridges and the best part is you can drive the heck out it.

pp000830

I'm a big fan of Techron, run two consecutive tanks treated with it once a year.
Could be a contributing factor but probably not a root cause, can only help.
Andy

il pirata

As stated, the problems started after the work was done. The factory manual for troubleshooting a misfire code will lead you though checking most of the work done (plugs, wiring, distributor , etc.).

Edit: You should also have the shop check that the gap between the speed reference sensor and the flywheel is 1mm +/- .2mm.

Where all of the parts used Porsche boxed parts?

You also mentioned the engine, etc. got a "bit" of a bath. Was this with a power wash?

You may just need to send it back to the shop. Do they have the On-board Diagnostic Shooting ) ODB II Manual?

EduardoForesti

Thanks Andy.

• Plugs/Wires. Confirmed 3 & 4 were seated. Have not confirmed all are seated and haven't confirmed all are routed properly (but the wires and plugs were just changed by a qualified mechanic and it did run clean for 150'ish miles.
• Dist Belt. It too was just replaced, but I did confirm (via the pull wire/start/repeat test) it is still good.

Current codes:
P0303 - this is what it started with and hasn't changed.
P0300 and P0304 - these came 2-3 days later and have persisted.

EduardoForesti

Many thanks to Andy, Bob (il pirata), Sire, 95_993, and Mr. Woolery!

Updates and answers.

• Current codes:
  • P0303 - this is what it started with and hasn't changed.
  • P0300 and P0304 - these came 2-3 days later and have persisted. I will reset and see what I get tonight.
• Plugs/Wires.
  • Confirmed 3 & 4 were seated.
  • Have not confirmed all are seated and haven't confirmed all are routed properly (but the wires and plugs were just changed by a qualified mechanic and it did run clean for 150'ish miles).
• Dist Belt. It too was just replaced, but I did confirm (via the pull wire/start/repeat test) it is still good.
• DMF
  • It was just replaced. Sachs. New in box. 95_993, thanks for your comment on DMF...I almost did the LWF, but went for the 'known' vs. unknown....
  • Looks like the DMF sensor test requires Porsche tool, so will have to hold on that one (and hope the new Sachs DMF is good to go).
• Fuel Injectors.
  • I do see in OBD readout (attached) that bank 1 and 2 lean results are very different.
  • I do have some Lucas fuel injector cleaner. Is that good, or do I need to get the Techron or BK44?
  • Will run the Lucas or Techron/BK44 ASAP
• DME Relay
  • Popped open and looked okay (but didn't look w/ magnifying glass, etc.).
  • Replaced with spare just for CYA. Since the spare was not a new one, I ordered one and it will be here Wednesday.
• Recent parts replaced. All the parts listed at top were new and were either Porsche, Sachs (clutch, DMF), Bosch or Beru (e.g., plug wires) -- basically OEM or OEM quality.
• Turning AC on. Tried, no impact / change to idle.
• Engine Cleaning. Can confirm, but I believe was steam bath (vs. just pressure wash). I had brought it up thinking maybe it triggered something like a ground fault (e.g., there a ground under the fan above bank 1 that is related to ignition).
• RE: going back to original shop. They'd jump on it in a heartbeat, but they are a 90+ min drive away, 1-way (and I don't know if it'd be a quick fix or if I'd need a ride back, or need to bring a tent and sleeping bag). And, importantly, given how it was bad it missing one day (recall the missing is less/worse at times), I don't know if the voyage would cause problems (someone mentioned running too long/hard with misfires could mess up the cats...a bill I don't want to touch....).

pp000830

Hi Eduardo,

• haven't confirmed all are routed properly (but the wires and plugs were just changed by a qualified mechanic and it did run clean for 150'ish miles).

Need to verify the plugs are wired correctly, should be able to see this with a flashlight and take a little time. Your implied logic that it ran 150 miles without issue may allow one to infer the routing of the wire worked correctly, however I would check it anyway.

• Engine Cleaning. Can confirm, but I believe was steam bath

Take the rotor caps off and look for pooled water or condensation in the distributor base under the spark shields or on the cap internals. Could explain the intermittent nature of the issue as the engine warms up.

Andy

95_993

I would go with Techron or BK44 for 2 tankfuls and skip the Lucas.

samurai_k

I would confirm both sets of wires from the rotor and spark plugs are going to the right place. It's a dual plug setup so the engine will start and run even if you have one of the plugs in the wrong cylinder.

samurai_k

Here is a visual

https://rennlist.com/forums/993-foru...utor-caps.html

Look at each wire and make sure the number matches the location on the pics above. The same on the spark plug side for each cylinder

EduardoForesti

Thank you for continued insights!!

• Checked routing of wires; all looks good
• Added Techron. I realize it could take some time before it could take effect.
• RE recent bath and condensation. The bath happened before the distributor was rebuilt and caps/rotors replaced.
  
• Anything else to do?
• Also, the misfire and rough idle / awful performance seems pretty consistent now (NOT intermittent)
• Since there is a new DMF, is there a way for a mortal to test the crank sensor (with limited tech)?
• Are the fuel/air mix results in the OBD readouts a tell re: other diagnostic work?

Thank you again.