Build Thread - Project Navi

Short Version: Thanks for having me, and here is my new to me 04 C4S! Long Version: This build won't be the quickest, nor the most interesting, but would love to document the journey and have a place to see the slow steady progress. Several years ago I built a 97 XP from stock up to moderate crawling abilities and I had a severe lack of progress photos along the way, this is my way to right that wrong. After learning my lesson painfully through a 986 S, I spent the last several months searching for a C4S and struck a deal with someone local to me in Lexington, KY. She checked all the boxes of what I was looking for including a great service history from approx. 20k miles onward (sitting at 102k now). While a lot of the maintenance has been done there is still plenty more to go, especially at 100k+ miles. this list is not exhaustive and I'm sure will change along the way. I'm happy to entertain opinions and expertise alike particularly when it comes to the order of operations. I know I need to focus on the not so fun projects before I can really start on the personalization. *Edit to Add* IMS retrofit installed in 2015, so looking to go IMS Solution since it's been past 4 years. Clutch and RMS were done at 96k miles, will inspect for wear and leaking but hopefully won't have to replace. Maintenance - Oil change with analysis (Planned Mobil1 5W40) - Drop sump and inspect bores (No visual or audio symptoms. Just want an annual baseline) - Replace Spark plugs and coil packs - Replace Fuel Injectors - UAOS - Would like an opinion here on which model to install. I don't plan on any track time. - Replace Catalytic Converter (Have intermittent CEL) - Replace front wheel bearing - Replace motor/transmission mounts - IMS Solution Upgrades - Install new speakers - Source/Install 997 heated seats - 3.8L Airbox (Maybe hold out for new LN Carbon one) - Ohlins (or KW) Coilovers - OZ Wheels - Professional interior & exterior detail, including engine compartment - Paint correction and PPF - Retrofit PSE - Hardtop garage lift - 997 Short shifter My end goal is a backroads cruiser that I can drive year round without nagging in the back of my head that something will explode any minute. I have been reading up on previous builds and learning as much as is thrown out there. Thank you everyone thus far and in advance as I go along!

Congrats Ghost. Good list. I would also include replacing the water pump so you don't run the risk of a piece of the fan blade breaking off and lodging somewhere that you don't want. Any idea what cats you are running and the last time your oxy sensors were replaced? Sure, you may need new cats or just new oxy sensors, or if you are running after market cats, you may just need oxy sensors extensions. Worth a look at the service history which may save you quite a few bucks. Regarding UAOS, I would go with the track version, even for the street because it can run a quart of extra oil. You won't need an extra quart if you are just tooling around on the street, but the benefit to you is that you will never have to worry if you accidentally over fill it. Imho it's worth the couple dollars more. We do get alot of threads from time to time from guys that are worried about overfilling. I would rather have the industrial strength version on my car. I am sure there are other things I will think of, but you have a good starting list. Add: I would also consider (1) making sure that you have fresh ignition coils, spark plugs, fuel injectors and MAF and (2) getting the Durametric software for your laptop. (3) change your trans and brake fluid as well.

I love build threads!!! I�m with you on LN airbox.

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Should be fun, parts and tools start showing up today!

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Good call on the track UAOS, I hadn't thought about overfilling, thanks! The water pump and thermostat were done in April '21, I'm content with that, but if I'm in there one day I will definitely be installing a low temp thermostat. Lucky for me a Durametric came with the car when I bought her, it has been fun to play around with and I'm looking forward to a fun drive soon with a data logging session.4 For you data nerds a thought came to mind last night. Does anyone have a set route they drive for testing pre/post new equipment or parts install? Do you log data such as fuel trims, air flow, fluid temps? As a follow up question (I haven't looked yet) is the stock MAF still the recommendation if the TB and IPD plenum have been upgraded to the GT3? I was lucky enough that the P.O. has these installed already. Stock cat. converters from what I can tell by looking right now. Last night I pulled codes P0430 (Cat. Conv. Bank 2) & P1109 (TB voltage above range) Would those 2 combined lead you towards a faulty MAF or individual problems to address? On the fun side of it, for those who have asked, I can confirm a rear facing child seat and my wife (Under 5'-2") fit perfectly. We have a family Porsche!

I would change transmission and differential fluids and inspect the front differential flange oil seals. Replace the coolant tank with. Genuine Porsche tank and blue cap. Check the shocks/struts and bump stops, after 20 years they are probably ready for replacement You might want to investigate the Fister muffler mod, it is an alternative to PSE. Good luck with it. You have a very nice car! Mark

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+1, Mark knows his stuff.

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Thanks Mark! Will do on the fluids. Another project done by the P.O. new B6 Bilsteins and HR Lowering springs in April '21. I have a feeling I'll be chasing down the rubber components over the next several months though. On the exhaust, I might have to go back to sound clips again. I like the sound of the Fister mod, but I really love the idea of being able to turn volume down around town. I've got access and limited welding skills that I can fab either the Fister or PSE, but still considering if the effort is whorthwhile. As of now, I'm guessing that is a next winter project.

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Yep. I run the plenum and GT3 tb as well. You want the oem MAF. Alot of cels tie into the MAF. As an example, last year I started getting a cel for my cats of which it could have been oxy sensors or even the cat. Tied into the cel was also a reference to the MAF. I figured it was about time to put a new Maf in nevertheless and it eliminated the codes. I would have to check my records to see what code numbers.

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Yes, stick with the original MAF.

Finally got some wrench time on her last night. Oil change was uneventful, and nothing found in the oil filter, but will send off a sample for analysis. I also tracked down a grinding sound up front, what I thought was a wheel bearing I think is going to turn out to be lack of grease in a CV boot. After pulling the cover I noticed on the inner driver side boot, someone used a zip-tie instead of a metal crimp, will be adding grease and replacing shortly. Now the real fun part of what I was after, data to help tracking down some CEL's. I have the following codes P0430 (Cat. converter bank 2), P1109 (input charge variable high), & P1341 (variocam). I'd like to really narrow down what's causing it before I start throwing parts at her. I took a quick 10 minute drive and collected the following data at idle: MAF - 17 kg/h FRA Bank 1 - 1.05 RKAT Bank 1 - 0.06 FRA Bank 2 - 1.09 RKAT Bank 2 - 0.61 I know RKAT bank 2 should be close to 0 and I have a problem there, does that indicate O2 sensor? Or do I need to collect additional information? Also used the durametric to test function of the variocams, she died immediately after activating. My understanding was that she should have struggled to idle, but not outright turn off. She then fired back up as soon as I turned the key. Any insight? Or just replace the camshaft actuators? As a whole, is the best place to track down nominal values and problems in the service manual? Is there any type of flow chart in there for troubleshooting?

Long overdue update! From the previous CEL's all of those have been resolved. The P1109 was fixed with a new MAF, P1341 fixed with a new variocam solenoid, and the P0430 hasn't returned in about 1k miles of using top tier fuel. I have gotten to really enjoy driving her and got spoiled on a work trip a few weeks ago. I am lucky to live in KY and had a work trip down to Oak Ridge, TN. If anyone is visiting in the area there are some incredible roads between there. The icing on the cake was a free afternoon in Oak Ridge where I took off and drove both the Tail of the Dragon and Cherohalla Skyway for about a 200 round trip joy ride. And what a joy ride it was! Weekday afternoon with no traffic and no one to wait on with temps in the high 70's was pure bliss. Then the not so fun part... a couple days after getting home I noticed a hesitation in the idle, then followed up with an oil leak and a CEL reading P0507. I already planned to pre-emptively replace the AOS with the UAOS, and now I'm thinking it's required. Plan to start there along with a smoke test to find any and all vacuum leaks. Tedious, but hopefully that solves most of the gremlins for the time being. Hopefully I can get it done sooner than later and get back to enjoying the early summer driving weather around here. Cheers!

After the last episode of CEL's, I THINK they are all sorted. I had a high idle and hunting idle at times as well, those both were solved with a UAOS with Track Drain and a brown camshaft plug. Last I check all fuel trims were perfect! I've been able to knock some more items on my list slowly but surely. The emphasis this summer has been driving more miles. The second oil change under my ownership is due this month, defiantly looking forward to UOA results about about 3k miles so far this year. Maintenance - Oil change with analysis (Planned Mobil1 5W40) - Drop sump and inspect bores (No visual or audio symptoms. Just want an annual baseline) - Replace Spark plugs and coil packs - Replace Fuel Injectors - UAOS - Would like an opinion here on which model to install. I don't plan on any track time. - Replace Catalytic Converter (Have intermittent CEL) - Replace both upstream O2 sensors first, no return of the CEL yet. - Replace front wheel bearing - Replace torn inner boot and added bearing grease - Replace motor /transmission mounts - IMS Solution Upgrades - Install new speakers - Source/Install 997 heated seats - 3.8L Airbox (Maybe hold out for new LN Carbon one) - Ohlins (or KW) Coilovers - OZ Wheels - Professional interior & exterior detail, including engine compartment - Paint correction and PPF - Retrofit PSE or Fister - Hardtop garage lift - 997 Short shifter Got to combine fun time with the afternoon nap. Love it when a plan comes together.