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Misfires at startup only

8K views 16 replies 6 participants last post by  SwedishDoomGoblin 
#1 ·
I have a 2006 T5 V50 with about 150k miles on it. It runs well, but when starting the car with a cold engine I can feel it going into convulsions and shaking momentarily for 3-5 seconds off and on, until the RPM drops and settles into idle. From there the card runs and drives perfectly normally.

I took it to a shop (indie shop) and the CEL was for misfires at startup. He let the engine cool and replicated the issue, noting that every cylinder was misfiring. He pulled the MAF and the sensor (forget the correct name) that sits in the intercooler and replaced them for normal wear. It's still doing it.

Any thoughts or ideas?
 
#2 ·
Have you replaced the fuel pressure sensor?
 
#4 ·
No, but the fuel pressure was measuring good.
"Measuring good" how? With a gauge? What was the pressure, and did it change as the car ran rough and then smoothed out?

If you're just reading the OBD-II value the sensor is sending, that's not a useful test.
 
#5 ·
Most common misfire on startup I see is a bad fuel pressure check valve in the fuel pump. When faulty it allows the fuel in the rail to drain back into the tank. Usually a long crank is associated with it.
Second thing is leaking injectors. They leak down putting raw fuel in the intake runner, usually take s a few seconds to clear the fuel while they misfire.
Coils do fail as well but generally are not intermittent and if they are, they generally misfire when HOT and under load.
 
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#6 ·
Mine had this symptom. I started replacing things as I went.

Final cure was a bad MAF. I unplugged it, started the car - started up and idled like a champ. Plugged it back in and started up the car - would do it's normal sluggish ~500rpm lopey idle and then either die or pick up and go. I had a used MAF from a junkyard in my garage - replaced it and it has been good since, no more issues.
 
#8 ·
I've been having this issue too.

I documented some of my progress here: https://forums.swedespeed.com/showthread.php?626045-A-whole-bunch-of-CEL-codes

Based on another thread (link in my thread), I replaced the cam position sensors which seemed to help temporarily.

I still occasionally get a CEL during startup, but since I barely drive nowadays, fixing it hasn't been as big a priority as it should be.

For reference, my V50 has about 180k on the chassis, about 80k on the engine.

FPS was replaced about three years and 30k miles ago.

Spark plugs were replaced about one year and less than 10k miles ago.

Fuel injectors and coil packs are of unknown age. Probably never been replaced.



What did you replace before the MAF?
 
#7 ·
I'm sorry I don't have the exact figures but I asked the tech and he stated that he tested the fuel pressure and everything there was good. He put in a new MAF since mine was also suspect, but no change. We ran out of time since I was getting ready to leave for vacation, and driving the car about 12 hours in the process. He thought perhaps the valves were getting stuck at startup from carbon buildup, etc, so he put some fuel additive in. I've only had one cold start since, but it was drama free. I'm wondering if it really was just that simple. I'll see tomorrow morning as we finish the second jaunt if our road trip to Vermont.
 
#10 ·
Well my car started acting up again after a few days on vacation. Drives totally fine other than cold startups. So far no CEL from it, but it's there.

Other than the MAF my boost pressure sensor was replaced. My guy at the shop said he measured really high PSI (about 15) at cold startup which he though seemed excessive, and when he checked the BSS it had enough oil and gunk on it that it was worth putting a new one in. No dice. So I'm not sure where this leaves me. One step closer to a V90 or V60 perhaps, but I sure don't want a car payment.
 
#12 ·
Working on it now along with other issues.
 
#13 ·
Working on it now along with other issues.
Thanks. I got my other misfires at 3/4/5 sorted out (was basically a ground issue I think), but then all of a sudden I'm getting it at 2 & 4. New coils. New plugs. Doesn't move so I don't believe those are the issues. It runs a bit rough for a few seconds when I first start up the car in the morning, and only throws a CEL once every few days, but then it smooths out and runs great the rest of the day. Starting to get a bit spooked after reading some of the other threads! Haha. My coolant levels appear to have dropped slightly since I replaced my expansion tank recently, so I'm worried about head gasket or warped head. It would be ever so slight if it's an issue at all, so I guess next step is to pull those coils/plugs one morning and inspect for coolant on top of the piston according to one suggestion here. I don't get even a hint of smoke and there's no coolant in the oil, so maybe I'm ok, OR it's very, very miniscule. Either way, I'll be keeping my eye on this. Good luck with figuring out your issue too!

Overall, my car runs superbly, so hopefully it's just a hot weather fluke or something as simple as MAF, ETM, fuel system related. I dunno. I'm not seeing anything more than the simple misfire codes in Vida with a gazillion suggestions as to what it might be.
 
#15 ·
Lol. They sure can be. Thus why I eventually fired the dealer and rarely even go to my indie anymore except for stuff I don't want to deal with, but I enjoy fiddling around with my cars, trying to keep them running as close to perfect as possible.

But I hear ya. I too refuse to get a car payment. Got one of my Volvos 10 years ago and 150K miles ago (now has over 200K) for cash, and recently bought my little C30 for cash too. Since the car's in such great cosmetic shape and there are no payments, I'm willing to keep wrenching on it. Even if it's something as bad as swapping an engine. My thing is, any time something needs replacing, it's an excuse to go with the best part possible, with goals of upgrading with performancy bits as I can. If I end up needing to swap engines, then that's JUST the excuse I needed to put in a fresh one with shims/sleeves, and can then safely upgrade ye ol' turbo. Trans goes bust? Time to do AWD conversion! Haha.

The thing is, my wife and I were shopping around, looking at brand new Civics, the Kia Forte GT, VW GTI, etc. Our requirements were 6MT, compact, a back seat for the kids, and fun to drive. I gave up looking for used models of those because people wanted ABSURD money for used, clean examples. Anything quasi-affordable was rode hard, put away wet, thoroughly trashed. I know my C30's old and has some miles on it, but it looks dang near factory fresh, drives great, and came in at less than 1/3rd of what the stupid dealers are commanding these days with their insane "market adjustment fees." I figure with the $20K+ difference I saved, that could justify a LOT of repairs and upgrades. ;)
 
#16 ·
That's exactly how I continue to justify my repair bills. However it seems the repairs are stacking up more than usual, and I don't have the time or the know-how to wrench on them the way they require. So my requirements would be wagon, AWD, and definitely not a CVT. The only manual option would be a VW Alltrack, which I believe is a tad smaller than my V50 but similar, but not great to look at, a V90 CC/R-design which are great to look at but pricey, or an E400 wagon which are also pricey. And if I keep them long enough to pay them off and live without a car payment once again will any of them not have expensive repairs stacking up? Doubtful. That's my mindset and I'm quite torn to be truthful. But if the V50 becomes predictably unreliable it will have to go as it's the family hauler and we do long road trips a few times a year. Otherwise I still think it's a great looking car. The design ages quite well. My interior is still clean and in pretty good shape considering the age, etc. I don't hate driving it, even though it tends to crash over bumps terribly.
 
#17 ·
You're at least looking at some REALLY nice replacements, so I hear ya. Personally, our plan is to save up so we can replace our XC70 with a much newer (mid to late '10s) V60/70/90. Then the C30 gets kinda demoted to our "fun" car so reliabilty's a bit less of an issue. It IS our current daily driver, though but that'll probably change as we replace our trusty old steed.

If it makes you feel any better, our XC70 had us questioning things as we approached 200K. It was one thing after another, but certainly nothing unexpected for the mileage and age. Painful to spend the $$$ on a car that's worth only a couple grand at best, BUT we got over that hump and it's been pretty much problem free for the last 20-30K or so. Aside from my non-functioning radio that is, but that's been going on for even longer so whatever. Doesn't keep it from driving. Car's been a dream ever since we pushed through some of those issues. Especially since I invested in some nice Bilsteins all the way around! Drives ssoooo good.

Perhaps a suspension upgrade's in order for your V50 if it's riding too rough over bumps. You indeed do have quite a unicorn and personally, I would have a REALLY hard time parting with it altogether.
 
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