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Discussion Starter #1
I walnut shelled my 2008 S5 with 40k miles on it, and in 10k miles I'm again getting random misfires cylinders 3, 6, and 8. I plan to swap the coil packs and maybe look at the spark plugs. They're the right heat range and size but they are the cheapest NGK R's I could find at a hair over a dollar each. Not sure if it's relevant.

Two weeks ago I did a cold start with the a/c on and it shook the car missing hard on at least one cylinder. This was the third day in a row, so I gently raised the revs and it cleared, and no check engine light. This time I had enough, and went to the nearest parts store and dumped 32 oz of techron into the tank, gently drove while near Empty the 15 miles it took to get to the 91 ethanol-free gas pump I frequent (Here in Utah 5k feet that's high octane) and filled up. The next day and following days, no problems with misfires. It's 12 years old and relatively low mileage, maybe fuel was getting gummed up.

Two tanks later I did my 5k oil change, last weekend. Which is usually suggested after such concentrated PEA has gone through the system.

So maybe it was a fuel issue, the car just kicked over 50k miles.

But yesterday the car started with the check engine light on. And I peeked at the codes, there they were. This time I cleared them, and drove to work. Drove home, no problems. But I noted much better throttle response and power, filed it away as notes.

This morning I started and surprise! The check engine light is back. This is starting to turn into an actual problem! And so I'll divert the work from the 2002 S6 I'm rebuilding and my roommate's 2001 S8 I'm also rebuilding.

Anyways, I did the walnut shelling myself and it came out great. The little flaps weren't an issue on an 08 so there was no way to put the intake on wrong. All the little inserts went in correctly. Everything was great and I was contemplating building a catch can for the PCV to try and lengthen the time it needs to go before being blasted again.

If it's not the coils/plugs it's the injectors?

ALSO on the list of projects for this car is a custom LED retrofit for the tail lamp housings. I've done all the legwork, or at least, I thought I did. I've converted a few other cars and motorcycles over the years, and it's just something I rather enjoy doing as opposed to buying off-the-shelf replacements. But I did one last signal analysis and realized.... the four bulbs that comprise the turn signal/tail lamp/brake lamps operate by DIMMING and BRIGHTENING. Not multiple filaments, no, no, it repurposes the same bulbs. My only solution is to run signals from up front to have true turn signal activation, as I am separating the brake lamps from the turn signals and going with amber. The end result will be pretty awesome, I've never seen someone do this so you guys are in for a surprise. But. All this talk about pre and post facelift LED housings and recoding the comfort module 46, what are the results of that? Do I gain dedicated signals for the turn signal and brake lamp bulbs, that is, with isolation? Or should I not bother playing with it and just run a few extra wires to some relays? I've already got a stainless bracket I built to attach to the nav dvd system in the trunk, to attach 10 power resistors safely and neatly to fool the system for every bulb I swap. This was just an added layer of complexity and I'm looking to reduce that if possible. Any insights would be appreciated.

Sincerely,

Keman
 

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I plan to swap the coil packs and maybe look at the spark plugs. They're the right heat range and size but they are the cheapest NGK R's I could find at a hair over a dollar each. Not sure if it's relevant.
The plugs would be the first thing I would look at here. I couldn't even get one that cheap for my lawnmower surely they can't be the right ones?
 

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Discussion Starter #3
Ok, I pulled the coilpacks and plugs tonight, and noticed a few coils weren't plugged in "all the way" .. if you know what I mean. Those connectors aren't exactly easy to make click. So I swapped #2/#3 for measurement sake. Cleared all codes. And while I was in there, I took Deoxit D5 and shot it at every connector in sight, loosened the two grounds on the engine top, put some there, put it into the connectors for the MAF, and both fuel injection pumps, as well as the ground near the firewall with the big - on it, the ground lug for jump starting I think. That thing was a little loose! For how long? No idea!

End result? Holy cow. I start it and it purrs and is quiet and no more shaky idle. It used to be BAD and I always just attributed that to it being a bit of a hot engine, but no... now I remember when it was new. Now I remember this smooth quiet perfect idle like a precision machine.

I can't wait to try it on the way to work tomorrow. Test drive felt good. Bad grounds? Bad connections? We'll see!

Also, for the plugs I got them confused with another engine. I pulled out dual platinums, and they were gapped correctly and nice and clean. I dunno what I was thinking. They're fairly new. Maybe it was the cheapos I stuck in my 02 S6.

-- Keman
 

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Keman mate pleased to hear that you are making good progress with the car!! Lets see some pics please!!!
 
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