Firstly, misfire issue on a 2003 Audi A4 1.8t, AMB engine with 104,000 miles. Bone stock.

It has been a rough year: it started with someone side swiping my car ($4,800.00 in cosmetic damage, fully covered thank god) and diagnosis of cancer (super high survival rate, don't worry )

But then two weeks ago, the notorious rear coolant flange finally blew out, along with the accompanied hose. Got everything fixed at my local dealer for $100, including new G12 and coolant flush.

Since, aside from an airlock issue making my heat go on the fritz (THAT I understand and can do myself, so many DIY articles, thanks fellow members!), I have been misfiring at start up.

RPMs shoot up anywhere to 1200 and drop as low as 400. Pretty random as well, but I'd assume more so on the high idle side. The idle fluctuates and sputters rather hard, CEL blinks as it does for a misfire, I turn off the car and turn is back on and everything evens out to normal (sometimes it takes maybe three attempts, but I digress)

Now, when I scanned the car I got three codes: for cylinder 2 misfire initially, but eventually also cylinder three misfire and multiple cylinder misfire (obviously) error codes popped up.

I bought and replaced all four coil packs (all of which were pretty corroded due to the coolant I'd assume?) and changed spark plugs 2 and 3; both of which were worse than I've ever seen.

Complicated issue as to why I didn't change all four plugs (long story, short: two out of four in the box had hairline cracks and were blowing my ECU fuse and can't return for new ones because they are past warranty/return policy.)

Initially, the car fired right up like it should and I assumed "mission accomplished!"

I just turned on my car to deal with airlock issue and the car did the same thing: hopped to 1200RPM, sputtered, restarted the car, back to normal idle.

The kicker: I have cancer and have to start chemo tomorrow. Anyone familiar with chemo, working on my car outside in a central Wisconsin winter isn't the best plan for someone with a newly weakened immune system. I'd like to atleast get a solid idea as to what I have to do before tomorrow morning.

So, does anyone have any educated guesses as to what could be the culprit?

I've been looking at a lot of Forum posts and can't really seem to find anything that fit the timeline of what has happened in my situation with the car )if I am wrong, sorry and please forward me the link).

This is my second Audi and my second 1.8t. I'm fairly familiar with the engine and the engine bay, though not as techy as most here, unfortunately.

As mentioned before, I live in Wisconsin so the winters are kinda cold, but in the past 4 years with 1.8t's, I've never had such a hectic problem with cold starts and misfiring.

Thanks to anyone who has the time to read and help on Oscar/TWD night.

Any other questions, my phone will be here at my side for speedy replies.

 

Also: using NGK laser platinum plugs. For nearly a year. Changing every 20k

Gapped at .032.

 

Could the coolant leak have taken anything out? Oil was just changed (0w40 module synthetic), I don't know.

Not trying to reply to myself, having an issue editing via mobile device.

Thanks again.

 

More likely a vacuum leak. Maybe you didn't get everything back together well or accidently broke something in the process. I had a broken nipple on the check valve that has a "t" in it just back and left of the reservoir. No misfires, but lots of tach needle bouncing around. Since a lot of the vacuum system was removed or pushed around to get to the flange, start it and listen for the telltale hissing and / or double check all the check valves in that area.

And good luck with the chemo. Sister just went through that and it is no fun

 

Much appreciated. I think I am ultimately going to have to have it taken in to have it looked at. But at least I can throw some ideas out to my mechanic.

Just hate not being able to do much diagnosis or maintenance myself.

Also thanks for the support in the personal aspect of my post