Now I have a Cylinder 1 Misfire!

I've been reading the thread about the X51 engine with a cylinder 1 misfire. Very interesting stuff. Mine is not like his, but here is the issue that has just started: I drove the car 1200 miles from Chicago to Daytona last weekend. I changed the water pump and thermostat a few weeks prior to that, did some shake down cruises in Chicago, with no issues. Starting a few days ago, the car misses when coming off of idle until it gets under load....almost not noticeable. This morning it started hunting about 100 RPM at idle at a stop light (never did that before), rev the engine a little, it goes away....get it going, it runs like a beast, like it normally does. So I went out and did some troubleshooting.....there was no check engine light after the morning drive....but then the check engine light came on within 30 seconds of starting the car....here is what I got: So I plugged the Durametric in and started snooping around. I don't know how to capture the logs.....but what I did see was misfires on cylinder 1. They were only at idle, normally ONLY when I give it gas from a stop. It will log 1, 2, 4, or up to 10 (if I start and stop a few times in succession) and then the Durametric clears it after some period of time, like 60 seconds, so the count starts again. If I drive down the road, there are NO misfires. It's only when I come off of idle and start going down the road, my car is a six speed. So coming back to my condo, I do an inspection of the engine, the intake is tight (assume no air leaks), take the oil cap off, it is easily removed and the idle goes up slightly, put it back on, no problem. Coolant is pink, oil is black. No nasty stuff between the two. Then I look and see there is some coolant leaking, the underside of the reservoir is wet, has a drip or two. Then I look at the barb fitting that I replaced with the Home Depot barb when I did the water pump and it appears it is leaking from that fitting and potentially spraying upwards to the bottom of the coolant reservoir tank. I replaced the reservoir tank last year, so it should be good. This is the barb I am talking about, I was not able to use the OEM hose clamp, just used crummy old hose clamps....I think the bottom one is loose, but without tools it's very hard to get to with the intake in place: And now I remember smelling coolant slightly since I have done the water pump including my drive down to Daytona at the gas stops. The coolant in the reservoir is at about the "low" level mark. Is there a possibility that the coolant has dripped down and gotten to the coil pack for cylinder 1? I don't know if that's the aft cylinder or not. I plan to go get some tools and try to tighten the hose clamp, and then run the engine until it is hot to see if it is still leaking.... Thanks for any advice. DB Joe: You out there?

I think you may have answered your own query. I'd stop the leak of water first, then see what happens. I think you'll find no more misfires.

Possibily. Can't dismiss the possibility coolant leaking has not affected the coil. (Just had new coils/plugs installed in my 996 Turbo less than 1K miles ago. Yesterday upon cold start the engine misfired. The same error codes: P0300, P0303, P0306; it would produce before the coil change. There is some sensitivity to dampness. Oh, since I parked the car after last using it Tuesday the weather turned off a bit muggy/cooler as we are getting some cold fronts moving through with teh promise of rain to come.) Address the leak. I like to flush the cool engine with a bucket of hot water after to flush/rinse away any anti-freeze residue as one can continue to smell anti-freeze for a while after the leak is stopped. If any error codes come back then you'll have to post them. I note there is one code related to sensor aging. I doubt any coolant leak played a role in that so there exists a possibilty one (or more) O2 sensors are about at the end of their service life. If you elect to replace a sensor my advice is to replace all 4 at the same time.

My guess is a bad cyl #1 coil. A coil in good condition is water proof so it should not be affected by coolant pouring over it. You may want to check out the Norma hose clamps. I only use Norma or Oetiker type. Norma has round edges and don't cut into the rubber hose. Oetiker is a one-time use but it's tight and anit-vibration (won't loosen itself due to vibration). To diagnose the O2 sensor codes, you can log the O2 voltage of all 4 sensor and during a cold start for 2 minutes using Durametric (or any generic OBDII scanner).

Upon further inspection of the engine bay, there is coolant pooling (albeit a very small pool) in the left hand engine mount, and looking underneath the car through the exhaust opening, I can see the residue on what appears to be wiring loom to the coil pack. I went to Walmart, got some tools, went to Napa, got some coolant and clamps, will address the leak, top it off of coolant and scrub the harness with a brush and some clean water. We'll see what plays out. Thanks for everyone's response....maybe if I need a new coil pack I could head over to DB Joe's if he is around and change it! Will report back.

i had coolant leak dripped on cyl 1 coil pack, misfire cyl 1. fix leak first. i suggest replace all coil packs. they go bad with time. save yourself the headache.

I agree with the others. Address the coolant leak, but I think it's time for new coils too. The misfires will probably go away, but they'll probably come back again when the engine gets wet.

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You'll be in good hands

Here's the update....removed the air filter, cleaned things up, put a new hose clamp on....drove it....still had some misfires.....but the problem is that the coolant expansion tank is leaking. I drive the car....and then I see coolant all over again.....but then I see this....see the droplets at the bottom of the plastic tank? I wipe it off, if it sits and idles it takes a while for one drip to show up, at least 4 or 5 minutes....but drive it around the block and it has drips all over it. I had to put 1 liter of fluid back in it. I can't tell where the tank is leaking.....I did replace it last year, but now I think the next step is to just replace it. The coolant is perfectly pink....just curious, could this be the beginning of an intermix issue?

Stant pressure tester time.

If you replaced with a genuine Porsche part, it should have a 2 year warranty so the replacement should be free...but you're on your own for labor if you did it yourself. Good Luck, DS

I just happened to be at the local Alfa Romeo shop in Daytona, hang out with the owner, he had the Stant tester, plus the stuff that measures if you have combustion gases in your coolant....that test was negative, but when I put it in front of the exhaust, it turned color, so I know the chemical was good. Will post the results with some pictures tomorrow. Could not get the coolant expansion tank to leak unless I am driving it. I called the local Porsche dealer, they can get a tank in next week....they said the cost was $106! I asked them if they thought that was correct, and they said yes....it won't matter if I order it tomorrow or Monday.

At what pressure and for how long you pressurized the tank? You need 18PSI for 20min or longer. Also need inspection mirror to check the bottom of the tank. Also need to check the CAP at 21 PSI but from your photos, it looks like the tank itself...cracks at the bottom.

Ahsai- Thanks for your input...I should of asked what the procedure was when I was over at Rick's place yesterday....I can tell you that when the tank was still hot, the gauge would decrease when I pumped it up to the high blue area, which was about 14 PSI. You could see it go down very slowly, it would decrease to the bottom of the blue area from the top in about 2-3 minutes. Once it cooled down, it seemed to hold. I then attached it during operation of the car to see how high it would go, once again, I pressurized the tank to the low/middle end of the blue zone, then warmed the car up and it was idled at about 3,000 RPM for 3 or so minutes, the gauge went up to the blue/black overlap, and then when we came down to normal idle and put the AC on to get the fans going, it would basically return to where it started. I was at the right place at the right time, Rick had this tester: Here it is during the high RPM testing: During all of the testing at the shop, I could not get the tank to leak....but then drove the car back about 5 miles to my condo and the bottom of the tank was wet again, I drove the car gently, it was wet, not dripping. One other test we did was to measure if HC's were in the coolant....and there was none. Here's the tester.....but when I put it in front of the exhaust after the test, the color changed right away, so the chemical was known to be good. The coolant is perfectly pink in the reservoir: And after looking at the pictures of the engine compartment on my PC....it sure looks like it's coming from the top, not from the barb fitting. It's interesting that I replaced my coolant expansion tank CAP last April based on it being an old one, my original tank cracked within weeks. I replaced it last year with a "German" brand from Pelican and now it cracked! I will be replacing the tank and the cap.

Anytime, Paul. Forgot to say, the test should be performed with engine off. Hard to tell an accurate PSI from your friend's gauge but 14PSI is not enough. The tank CAP doesn't start to open till 18 PSI. BTW, the procedures I mentioned are per Porsche. I added the 20 min based on my personal experience and others. I don't think you have intermix. Looks more lke a leaky tank. Your old tank started to leak after you replaced the CAP could be because the old cap couldn't hold pressure so it was easy on the old tank. Getting a new OE tank and CAP is the way to go, unless the current cap tests out fine. Although an OE tank is not cheap, at least yours is easier to replace than the mkII's.

I ordered the parts from Suncoast....got the OEM parts, they are only about 50 miles down the road from me....I did call their dealer parts department: Expansion Tank Suncoast online: $295 Suncoast parts counter: $446 Cap Suncoast online: $23 Sucoast parts counter: $56.30 However Suncoast online will not allow a pick up, but I'm sure it will be 1-2 day UPS when they do ship them.

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Sunset has the tank for $264 + shipping.

Update: So I put the new tank and cap in today, took me a little more than 2 hours, the last time I did it, I remember it took me SOOO long to get the tank into the little holder at the top, this time, it slipped right in. I ended up doing it over at a guy's shop in Daytona that does Alfa Romeo's. Will post a few pictures of that later. This is what I believe happened, don't know if it's true or not, but this is what I believe. April 2015: Read the forum, replace the old expansion tank cap on tank with a latest version one, the original tank cracks within days. I believe I added some coolant at the same time to "top" the level off. April 2015: Buy new "German" brand tank, install it, all is good. February 2016: Replace water pump and thermostat housing, fill the system with new coolant. Filled the system in 40 degree F weather to the "low" line on the tank. Drive it around in 40 F weather for a few shake down cruises, all is good. March 2016: Drive 1,300 miles to FL, all is good, it's cool out. Drive in FL in 70 F weather with no AC on and the coolant gets hotter than it has since I changed the water pump. The tank pops a hole in it. There was VERY little room for coolant expansion in the tank in 70 F weather with the coolant warmed up. Caused high pressures in the tank, and the cap did not relieve. If I was to guess, the new cap that I got either lifted at too high of a pressure, or was "high in the range" from the factory. When I added the coolant after doing the water pump, I filled it to "low" when the engine was cool. I think that's too high. In the end, it over pressurized the tank, and popped it. Today when I filled the new tank (and I bought a new cap also), I filled it to about 2" below "low" when it was cold. I started it up, let it idle for 25 minutes, everything was warming up, and once it came up to temperature, the level in the tank was 1/2" below "low". I drove it around, it was about 80 F, stopped at a gas station, the level is just at or slightly above the "low" level. I think the cap had an issue, plus the lack of air volume in the tank caused my issues. With the lack of air volume in the tank, the pressure increases to a much higher pressure when the coolant heats up, in my case, the cap wouldn't relieve the pressure, the tank would crack. I could be wrong, but this is what I think in my head. After driving it 30 minutes, there were no leaks, all is good. When I was idling it, I could tell I still had a misfire on cylinder 1, every once in a while it would miss. Then it started slowing down on the misses, they were coming about once every 30 seconds, then it would go minutes without missing. Driving it, I did not notice any misses. I don't have to have the computer hooked up, it's very easy to tell if it's missing at idle and when you accelerate away. Thanks for everyone's advice!

Here's a couple pictures of the shop....OMG, a dream shop. An office in the front, storage for a bunch of Alfa Romeo's in the front, and a shop in the back with a lift, room for two other cars and you can still work on stuff in the back. I am lucky to have meet Ric. This is RML Automotive in Daytona Beach, FL. He has so many people come by his shop every day, he has a lot of friends! https://www.facebook.com/rmlautomotive/ This is pretty much from outside where my car is looking in to the shop, you can see the entrance to the show room on the left. Ric is old school and AWESOME. This is a 50's Alfa....it's got a brand new paint job and is being built back up: Here is the show room, there is a desk, office and bathroom behind this shot. That's 9 cars in there and at least one scooter. The entrance to the shop is on the left past the red Fiat.

Ahsai- You were right, I had a failing coil pack in addition to my coolant leak. When I ordered the replacement tank and cap I did not order a new coil pack, I believe I just forgot. Anyways, the car was still misfiring on cylinder 1, and yesterday I installed a new coil pack. All is good. I will be replacing all of them this summer.

Great outcome Paul! Give me a shout when you install the coils!

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Glad you got it sorted out! Question though.....when you filled the coolant (first time) and then drove around, did you have the burp valve open? If not I wonder if that started the whole scenario.

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I did not have the burp valve open during driving. Sounds like I need to do that now with the new tank. I could not find a procedure in the manual...I know it's in there, but couldn't find it. I thought I saw it before.

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Look at the pic below. The green arrow point to the black cap with the silver metal piece. Move the metal piece so it stands vertical. That opens the valve. http://www.pelicanparts.com/techarti...lant_Flush.htm

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Glad it was something simple. You can leave the valve open and drive the car for a few days. Remember that valve does not vent out to the atmosphere. All it does is letting trapped air vent into the tank. If you manually open it, this internal venting will happen earlier before the coolant is hot, at which point the coolant will force the valve open anyway.