BesideTheBox

I have that image printed out and I refer to it constantly. I have checked wires numerous times over the last weeks.

I would be happy to post a picture. Not sure what you are looking for. Lower plug wires (II-xxx) at the plugs? or lower plug wires (II-xxx) at the distributor caps?

BesideTheBox

When I put the muffler back in, should the tab that is welded on the muffler be touching the top of the bracket?

The reason I ask is that when I do that (tab above the bracket), the union with the catalytic converter is good, but the muffler sits quite a bit forward (into the wheel well) than it does on the other side.

I should have taken a picture before taking it apart, and I could not find one on rennlist. I'm sure one is there, just not able to find it.

Mike J

The tab on the backside of the muffler is a hanger - it supposed to be used to hang the muffler on the support bracket. So the bracket should be "inside" the hanger, so to speak. The muffler's position is set by two points, it has to meet the cat convertor, and hang on the hanger....

geolab

The way I would proceed personally.
From the video, it sounds mechanical tapping, but you have the misfire code.
1- I would remove both mufflers on the floor.
Check both muffler brackets on engine, by hand, and by tapping with rubber mallet.
For the right side bracket, you could tap it and bend it a few centimetrs to the rear, so that your muffler align with the left one, no problem.
Check the catalytic converter from its outlets if it rattles, by hand and rubber mallet.
Go under car and tap with the rubber mallet both heat exchangers, small quick soft strikes to try to initiate rattle.
After, I would go under engine, and check the tightness of the exchanger bolts. The hex and round bolts.
Re-mount mufflers with welded tab hooked on muffler bracket.
Mount muffler to cat connections without tightening hard.
Mount muffler straps and adjust muffler position for final tightening.
Tighten muffler to cat. Tighten muffler strap, do not bend muffler core.

Start engine...if sound popping persist, please do the following:

Push the driver seat to the front Maximum position, remove rear left passenger carpets,
under the seat, reach for the ignition module electric serial plug.
pinch the metal plug tab, and remove the rubber plug in the picture below.
check if the plug prongs are not rusted.
re-plug the ignition module and start engine to check for PoP......if it still pops ?

Order part number 993.602.706.00 , from porsche here it is around 120 euros.
Bosch part number 0227 100 200.
If on tight budget, try Not to buy a chinese cheap copy, commonly beru, just stick to Porsche or Bosch from a reputable source.

to install for testing first:
Seat to the front, unplug the mounted module, and plug the new one.
Stick the new one with a cloth, between electronics aluminum shield and metal floor, next to the mounted module.
let the metal of the module touch the metal floor.
Test the engine....
If it does not pop, I will follow-up how to replace the module...
If it pops, I will buy the module from you at the price you paid, zero cost for you.
regards

ps: in the picture, you could see the module plugged with the metal lock tab.
In your car, all the picture stuff will be covered with an aluminum shield. The shield does not cover the rear for you to access the module

IXLR8

George,

Brad and I were on the phone for quite a while yesterday.

I have the same module on my BMW motorcycle (but for one coil) and related how I was getting a hesitation. Sure enough, when I pulled back the rubber boot on the connector, removed the SS retaining clip and pulled the connector off, one of the pins (the one from the kill switch) was not locked into the connector. A simple bend of the tab on the pin had it snap back into place.

The fact that he uses his 993 as a daily driver and that it sees lots of salt, who knows he may have slightly corroded pins.

Mike J

Great ideas guys! Lets see how the diagnostics go...

BesideTheBox

Here's a picture of the left and right mufflers. I'm assuming that they should be mirror images of each other? The right muffler has been "repaired". Perhaps from a steep driveway angle. The chrome tip on that side is scraped good and bent slightly, so I'm guessing that this is what happened. The tube to the muffler may have been bent and they cut & welded in a patch. But it looks to me like it is 1.5 inches longer than it should be.

Anyone have a spare stock Gillet muffler, part # 993.111.046.12?

TMc993

Also looks as if the other pipe on that muffler is bent as well. The muffler is bent where the pipe is welded in and the pipe appears to sit at a slightly different angle than it should. That muffler took a pretty good hit. I wonder why they lengthened the exit pipe?

Mike J

Either sloppy work or they wanted the tips to stick out further. Maybe someone in the past backed into ta spot and really hit the tips...

You can find mufflers for sale here all the time - or post asking for a set, or ping Fister and get some Stage III's. You will not not hear that noise again (just due to sheer volume -- haha).

I wonder what the internals are like? It does not look like they have been split, but a good job is quite transparent.

cheers,

Mike

BesideTheBox

Maybe they couldn't figure out how to get the muffler on the hangar and figured the easiest thing to do was to lengthen the exit pipe!

I take that back. You would have to have the muffler completely off the car to do that welding job.

The tips were reasonably close to the same angle and stuck out about the same distance before I removed the mufflers.

This muffler exercise had given me the opportunity to address 2 things from the ToDo list:
1. Put a rivet into the trim above the left muffler tip - done!
2. Replace the heat shield above the left muffler input pipe - done! - Thank you to JLUinAZ for sending me his unused set for the cost of shipping.

BesideTheBox

Yes. I looked again. Sloppy weld where the input pipe has been reattached to the can. And the angle is wrong. Easier to see after I flipped the pair over and matched them up. Amazing that you saw all this from that picture.

BesideTheBox

geolab,

Thank you for the detailed diagnostic procedure. I could not find any rattles, all bolts were tight.

I am not clear what "The hex and round bolts." referred to, but all the nuts holding the heat exchangers up to the engine were tight.

As I outlined in my previous post(s) in this thread, the right hand muffler has been smacked and repaired. I still was not able to make any noise with the rubber mallet though.

I installed the muffler and started her up. After 15 minutes of idling, I went to check on the exhaust tone. Still popping. The pops are accompanied with significant puffs of air out the exhaust.

Then I went to look for the ignition control module under the seat. It is not in the location suggested by the picture. My car is a '97 C4S, is it located elsewhere under the seat?

I did have the seat out yesterday or the day before. I wasn't sure how to get at the components under there as everything was covered in metal, so I cleaned and reattached the grounds as that was the only thing easily accessible down there.

IainM

Do you get puffs of air out of both exhausts?

Mike J

hmmm - you know I hate to say this, but this was very similar to when I was diagnosing my Targa misfires - you get a sort of **popping** erratic sound. The video sound was more metallic than I had, my sound was definitely more exhaust. I was also getting misfires too - after a whole bunch of diagnostics, I ended up rebuilding the engine, and when it was all back together, no more putting and smooth idle.

I prob just freaked you out - but again the noise from the video is more metallic, the noise I was getting was pure exhaust unsteadiness and sort of like poor combustion. It was hard to tell from the rebuild that fixed it, I did everything (new rings/valves/guides/bearing/etc) and also cleaned the injectors.

Can you do another video at different distances and perhaps some visuals so we can see the distance, etc. That might help.

**just listened to the video again - it sure sounds like a loose piece of metal somewhere - maybe someone can lend you a pair of mufflers so you can at least get that part out of mind

Cheers,

Mike

BesideTheBox

The popping and the associated strong puffing only comes out the right side.