Long crank when cold start problem

I just bought a 2003 996 Carrera2, car has only 26000miles. First day I pick up the car already has this problem, the car will start for sure but need to step a bit on gas to get it start in the morning first start, but it will be fine after the first start. Then problem will back after sitting for few hours. I change the spark plugs and coils since found one coil is actually broken. After changed, it start easier without touching gas but long crank when cold. Again, it will start for sure and idle seems normal. When is cold it took around 5 sec crank to get the car start, then after first long crank and shut off then start again will just be normal. Anyone can give me a help or have the same problem before? Thanks

HI Guys,, I have a problem that my dealer doesn't want to solve due to my modifications on my car.. In cold weather only on first cold start up only, but not everytime, The engine idles very rough for the first few minutes ,like missing almost,,and then the light comes on and the drive to shop memo comes on. BUT after another several minutes when as it warms up it smoothens out and the car runs perfect and perfect normal power,,It was data logged to verify when fully warmed up that what was checked was in range. The code is misfires in most of the cylinders...I know its not this, coil and plugs were changed before and I put a new battery in also. I almost believe its maybe a lean condition of some type? Maybe something related with secondary air pump? Thanks for any input..

I know this thread is 8 years old but I'm wondering if you ever solved the problem as I have just come across this problem within the last few months. I changed my coils and plugs as well as well as starter and battery for the warm start issue. I see no one ever replied to you but hopefully you figured it out.

When did the problem show up? Plugs and coils swapped but with what? New plugs that are perhaps too cold might still have issues for instance. No misfire under load warmed up?

A similar issue happens to early 997s with the carryover engines. Apparently the alternator wire can't carry enough current in certain conditions. It will always start but feels like you're in a horror movie when the car cranks too long. You can replace the wire with a heavier gage or try cleaning the contacts. Otherwise do what I did in my old 997 and live with it. It never left me stranded.

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Quote: HI, No problems ,no miss fires ,,runs great after several minutes from cold start idle...Data logged confirmed everything was fine after warm up. Plugs+ coil replaced recently... Thanks

i would imagine johns running one step hotter plugs? but agree.. if not? .... weird that nothing shows up in logging. i would immediately go right back to plugs n coils tho.....

Does your car still have MAF?

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Quote: . Hi,Thanks for input, It is not coils and plugs..If that were the case it would do it all the time and show on Data Log..Car pulls 1.4 bar and hauls,,no problems. Also I think you met one step colder instead of hotter..

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Quote: Yes.. MAF is working fine.

do you have a Durametric? Shut-off the SAI when you fire it up to see if anything improves. Also capture a datalog of the fire-up

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Quote: yes, of course was walking and typing lol thx for correcting me. I meant by way of example using the Bosch FR-6-LDC ( gt2 ) instead of the 5 ( stock 996t ) series. but I see youre using those fancy denso's? about which I know nothing of their heat range numbers.

My Audi tt does the same thing and so far its always been the MAF, runs rough at start up and then better when warm new MAF I'm good.

I didn't ask if the plugs were new, plugs that are too cold can misfire even if brand new and then warm up to run better. It might be worth swapping in plugs closer to stock, even if used, to see if the problem goes away. When did the problem begin - was something changed just prior or did it simply begin? Weather change?

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Quote: My first impression is it reads like either the coolant temp sensor is reporting too high a temp or the intake air temp sensor -- part the MAF -- is reporting too high a temp. The result is the engine is not fueled properly for its actual temperature, in this case it is fueled too lean. If you tell me the engine spits back in the intake that's a sign the engine is running lean. Upon a cold start you can look at the coolant and intake air temp readings and confirm they are close to ambient and that they behave, do not suddenly jump (or drop). Continue to watch these and if one of these sensors is the problem I think'll you see enough to make the diagnosis.

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Quote: Thanks,,I think that is a step in the right direction...And it makes sense to look at those.. Because the dealer after all there diagnostics believes its lean fueling problem also..But the cause at only cold start up in the cold with no other codes is the problem... Markski did the data log back after it first happened but it was warmed up and it showed everything was right on..As I said it has to be real cold out and sitting for a few days to happen. He thinks it maybe a vacuum leak in the hoses that work with the secondary air pump so the next thing is he is going to do a pressure test and we shall see..I hope it is that simple.. Besides what you mentioned,, Maybe a bad secondary pump rely or a crank sensor might cause a lean condition or misfire at that initial start up from what I researched ? But I was told there would be codes showing,as for the pump also? If its in the upper 30s or driven daily with normal cool downs after the intial start up problem in colder weather it doesn't happen... All in all my car has been great in reliability and now to get something out of the norm isnt that bad because after those several minutes it runs great..

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Bump... If you don't that's fine, but would be good to know... Another way to test your coolant temp. sensor if you have a basic OBD2 reader is to start the car with MAF disconnected(or similar to replicate fault code) and read the freeze frame data, it will tell you the coolant temp readout... Quote:

My car had the same exact issue when I bought it, then I found that the vacuum hose from plenum to fpr was disconnected at the plenum side. Could be a possibility!

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Quote: Hi, Thanks, spot on..Markski found that mine came off from FPR when he did his pressure test on it , plus a few other little leaks..I hope that was it also. . He is going over everything now.. He does know his stuff ,as he said at the beginning it was most likely a leek .

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Quote: Quote: Maybe I'm missing something here, but how exactly do you know it's not misfiring? Just because you replaced the plugs and coils doesn't mean it's not misfiring since there are a lot of possible causes for misfiring. A new battery isn't going to make any difference in whether it misfires either. And just because it logs fine when it's warmed up doesn't mean it's not misfiring when it's cold. As a matter of fact, data logging it when it's warm doesn't help you prove anything since the problem only happens when it's cold... If it walks like a duck and quacks like a duck and misfires like a duck then I bet it's a <misfiring> duck.

Thanks for your input,,But a lean condition from what ever source will cause misfires,,basic 101 fueling. Also no signs or clue off Any coil or plug problems after a few minutes of cold start are over or no signs of missing under load on data log at 1.4 bars or any areas ,runs strong and awesome. When any engine is cold it needs more fuel and if it it is not given it it will produce these type of signs. Any vacuum leaks will worsen that because the ECU will only compensate for so much fuel delivery. We will see when I pick it up from Mark.

^ i bet when you get over to markskii it will have been sorted. only reason i can think of to be near chi town LOL! good luck john..!

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Quote: Hi,Thanks..Yes, read one of my above posts.

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Quote: HI,Thanks for you input.. A weak battery can cause a misfire as the techs at the Porsche dealer have seen it happen,they told me to get the new battery.. On a cold start up the motor doesn't turn over fast enough for the crank sensor to read at first ,thus a misfire until voltage goes up...Also a bad crank sensor or to big of a gap can cause a cold misfire ..Its not as simple as a coils and plugs sometimes. As a lean condition can also,,like when cold and or a bad vacuum leak that the computer can not compensate the fueling. Just sharing info now since I have been gone through this . So far it seemed Marski found several vacuum leaks ,the main one was the FPR line. Since fixed it has not done it but it is still it is not a silky smooth cold idle for the first 2 minutes or so like I would like.But I don't think it ever was that smooth since my build.

Glad she is improving for you John. I wonder if it's just the cold adding to it?

i have never in all of my cars seen the vast number of issues a low or dying battery can mimic that this car can/does. it's confounding in its peculiarity. on the rare occasions i see a cel, or even when seeing an obd code, i often check or mess with the battery first. i can see it happening. cold? i wouldn't think so. it snows in deutschland. but hey, ya never know.

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Quote: Yup same thing on my car the hose from plenum to FPR was completely off.

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Quote: HI,, The Porsche Tech at Loeber Motors,Rich H.,who has been a master tech for 30 years told me to buy a battery the first time I brought it in to them for the problem ..My battery was about 5 yrs old and the car sat for a few weeks in the coldest of the winter in Chicago...I posted a thread on Battery purchase. Well the car sat in the dealer and it was replaced,,the problem didn't happen again but the weather temps went from 0/teens back to 40s after that..NO PROBLEM after that..THOUGHT it was fixed. But when it went back down to the 20s it happened again on ice cold start ups..Back to square one after that and then all of the above posts for info. So far no cells or dash board messages after Markski vacuum hose repair. Hopefully he fixed it. If it happens again,,I hope it gets that cold again to be sure,, I was told it could also be the secondary air pump module . But the above advice about the temp sensor could also do it.. And of course the crank sensor..

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Quote: well it sucks you haven't fully isolated the issue, but that battery thread may be timely for you? a 770 bosch c/a aint bad @ 125$! but i'll share last months battery issue to illustrate our mutual point about batteries. i regularly trickle charge with a ctek and yet am notoriously lazy, so consequently didn't for a month or two. i drive the car most every day whether i need to or not, and never thought about my 1.5 yr old battery even being near to low on amps. began to get "cam position sensor low imput" cels!? ordered a new cam position sensor from pelican parts for 50 bucks, put the car on the ctek again, and now am again doing so weekly.. and guess what!? i STILL have a brand new 50$ cam position sensor sitting in a box lol. was the battery being low is all. good luck tho john speed.i hope you sort it.

John had a similar problem turned out to be a hair size crack on one of the welds on my 3" y pipe. If u still have the stock y-pipe maybe check ur cooler welds etc.

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Quote: Hi,Thanks ..But Markski did a pressure test and came with other leaks which we thought was the problem..

OK,,Has not had any lights come back on since Markski fixed the vacuum leaks and the temp has been warmer out,,,BUT NOW The temps went back to the 20s yeaterday and at night ,, When I went to start it up this morning it happened again ,,lights went on and very rough idle for the first 2 minutes only ,, Then after that is everything fine, idle and drivabilty and no start up problems after that intial overnight cold start up.. Thanks everyone for your input,,time to take a look at the other causes of a misfire condition other then coils or plugs.

OK this is one for the books,after the above post, I put about 100 miles on the car last night going to events including a few stops,, After one of the stops I noticed the cell light went off and the dash memo didn't appear ...Is that strange or what? Now to go out this morning and start it and see what transpires.