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    Thread: cold start / rough idle / misfire

    1. 12-22-2007 12:35 AM #26
      Quote, originally posted by rune3711 »
      If the cps is bad the car will not start. I'm not sure if this sensor can slowly die though and possibly cause a rough idle.

      not always the case. my CPS is bad, shoots a code every day. runs like a champ... just an example.

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      12-22-2007 12:36 AM #27
      When I had a MAF problem a little while ago, I swapped out a coil with 50K on it. Two longish hairline cracks had already begun to form.

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      12-28-2007 03:15 PM #28
      Quote, originally posted by RabbitsKin »
      I searched through a lot of posts on this topic. Almost everyone is describing an idle that hunts around and won't settle at the proper RPM.
      My problem is different. On some cold mornings, the car won't stay running at all without me giving it gas, and runs REALLY rough like it is only firing on two or three cylinders. It smooths out in less than a minute, but I have to rev it up and down several times to get the cylinders firing, if that makes any sense. It has a new T-belt, cap, rotor, plugs, and wires as of Spring time, and was running perfect all summer.
      Could the camshaft position sensor be causing this? Coil? Right now I am getting codes for the CPS, the MAF, and the 02 pre-cat sensor, kind of a chicken-and-egg scenario.
      Running update of parts that are new or recently changed, as of 12/21/07:
      Plugs, wires, cap, rotor from GAP in spring '07
      T-belt, tensioner, thermostat from GAP, spring '07
      PCV pipe
      cleaned PCV valve
      battery
      catalytic converter
      MAF sensor
      coil
      l

      Modified by RabbitsKin at 9:28 AM 12-22-2007

      I too have a very similar problem with my 2.0. It only seems to happen in the winter and I have replaced/cleaned almost all of the same parts as you too. It idles really rough and when I give it gas it misses a bit, like it isn't firing on all cylinders and it is clearly running rich when cold.
      I haven't been able to figure this one out either. I'm starting to think that oil may leaking and fouling up the plugs when the car sits for the night. But not enough to wreck the plugs? That would mean that it should run like $hit all year round though and not just in the winter, so that part doesn't make sense,
      Oh, and I have NEVER had a CEL come on in my car...EVER. It seems kind of strange to me considering how common it is.


      Modified by jeff323 at 8:19 PM 12-28-2007

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      12-28-2007 04:03 PM #29
      Just paid for an 02 sensor, so I'm keeping my fingers crossed. Current theory is that the bad sensor is throwing the mixture off, causing soot buildup on the plugs. This in turn causes rough running until it burns off (?). I don't know, it's just a theory.
      With mine, it always runs smooth after the first 30 sec. to a minute or so. I thought it was cold/wet weather related, but maybe that is a coincidence.

    5. 12-28-2007 04:23 PM #30
      Could be your TPS too. I was having similar problems that were driving me nuts and replaced/cleaned everything like you and still had problems. Scanned it again and had a code for TPS...replaced and been running fine since.

    6. 12-28-2007 05:10 PM #31
      i am now having the same problems but it seems to get worse..stalls, even when the car is warmed up it still does it..idles bad..engine shakes especially in gear and idling..i have had all these things fixed, anti freeze, coils, spark plugs, timing belt, alternator, battery , o2 sensor, vaccume hose...my boyfriend did the last 2 things...but still shaking and not running really good..especially in the cold..its been doing it for awhile but not its even worse..we have been trying to figure it out..because he can work on it if he knows what really is causing it...would like to get it fixed so i can sell it and get a newer one

    7. Member themagellan's Avatar
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      12-28-2007 07:12 PM #32
      Same thing here.

    8. 12-29-2007 01:47 AM #33
      mine does same thing.. idles like ish and stalls when i first start it.. i just thought it was the 268 deg. cam.. curious to see what you guys find

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      12-29-2007 10:59 AM #34
      A bad coil will foul plugs, too. Multiple cylinder misfires.

    10. Senior Member Dan J Reed's Avatar
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      12-29-2007 12:13 PM #35
      Could be people just keep guessing until things are fixed.
      Start with the basics. Which it sounds like you covered.
      But dont forget that internal engine parts like valve seals also wear and cause a rough start.
      I am very glad I swapped mine out last winter. Its seemed to have fixed my blue smoke/poor start/fuel rich smell at start up. The oil was leaking down onto a valve and causing the cylinder to foul on a cold start.
      The colder the weather the worse it was. The valve guide shrinks at a different rate than the valve stem. And the seals leak.

    11. 12-29-2007 01:06 PM #36
      I had this very same problem, it turned out to be quite a few things:
      MAF was really dirty
      ISV was shot
      Distributor timing was off (from what I've been told, this can happen pretty easily)
      Harness connectors for MAF/ISV/TPS were corroded
      Intake boot had a small tear
      this is a really hard problem to figure out/solve because it could be so many things, or all of them working against you at once.

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      01-02-2008 08:24 AM #37
      Just checking in to see if the OP has gotten any sort of solution found. I am having a similar problem on a 2.0 jetta. The car will crank and crank when it hasnt been run in a day or so. While its cranking and not starting it kind of starts to turn over then goes off. Do you ever see that happen?
      I too have spray tested everything and it had no effect cuz the problem only seems to be the first start after the engine really cools down.
      Not trying to hijack but htere is a ton of threads about things like this and im lookin to see if rabbit figured anyhting new out.

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      01-02-2008 09:22 AM #38
      Still waiting on my O2 sensor to arrive. Interestingly, I started the car yesterday after sitting for a week, and it ran fine. I'm not making anymore theories until the new sensor is installed and I clear the codes.

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      01-02-2008 03:00 PM #39
      My sister's '96 Mk3 Golf 2.0 tarted with this same behavior last week, too. A wet evening (fog, snow, rain, etc.), and the car won't start. It will crank and crank, but then takes forever to start. What's weird is that you do hear the engine "catch" every now and again...just not consistently enough to get the engine to start easy.
      Once it does get started (several frustrating minutes of trying later), then it runs fine.
      I replaced the plugs, wires, cap and rotor. That makes me think to change the ignition coil, next.
      But reading through this (and other) threads...that doesn't seem to be a 100% cureall.
      Is this the result of some other common weakness in the MK3 2.0? My sister's 1994 Golf did this same thing before, too. For reference, the 1996 has ~130k miles, and the 1994 had 143k miles when I sold it.

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      01-02-2008 03:18 PM #40
      I've had other non-VWs exhibit rough starting in cold/wet/foggy weather. Gotta be something to do with moisture, condensation, maybe grounding, IDK.

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      01-05-2008 01:15 PM #41
      Quote, originally posted by Dan J Reed »
      dont forget that internal engine parts like valve seals also wear and cause a rough start.
      I am very glad I swapped mine out last winter. Its seemed to have fixed my blue smoke/poor start/fuel rich smell at start up. The oil was leaking down onto a valve and causing the cylinder to foul on a cold start.
      The colder the weather the worse it was. The valve guide shrinks at a different rate than the valve stem. And the seals leak.

      That's what I have been thinking is going on with my car as my symptoms are exactly the same, I really don't feel like rebuilding the head though!

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      01-05-2008 05:19 PM #42
      Update:
      Replaced 02 sensor today finally. The weather wasn't too cold, and the car didn't have any rough idle or misfire symptoms on startup. BUT, I still have a CEL. I disconnected the battery, hoping that would clear them, which it didn't. Perhaps it needs some adjustment time, or perhaps this O2 sensor is bad (it was a low-mileage used one). Or, perhaps my new(ish) MAF is bad.
      Took it down to Autozone to see what the codes were:
      P0131, 02 sensor
      P1128, MAF sensor
      P0102, Mass or Volume Air Flow low voltage
      So apparently I haven't fixed anything. I'll know on the next cold/wet morning.

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      01-05-2008 05:22 PM #43
      Is there a way to have sensors tested, off the car?

    19. 01-05-2008 05:33 PM #44
      I had somewhat the same problem as rabbit but my car wouldn't stall. My codes were 2 for the downstream o2 (I ripped the wires out on a speedbump), 1 for the coolant temp sensor, 1 for an evap leak somewhere, and a pending code for MAF low voltage, I guess that means its bad?
      Anyway I replaced the coolant temp sensor because it was the cheapest. It fixed my cold start/high rough idle for about a week and it went back to normal again

    20. Member OneLowVento's Avatar
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      01-05-2008 05:54 PM #45
      im having the same trouble as most of you. rough cold start, and then runs perfect after about 30 seconds.
      i replaced everything that has been listed above except the 02 sensor. im gonna try to unplug it tomorrow when i start it up.
      keep us updated... im curious to know if that 02 sensor fixed your problem
      +3500 posts as VWDR1VER

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      01-05-2008 06:12 PM #46
      Me too, hafta wait until the 'right' weather to see if that was it .

    22. 01-14-2008 11:48 PM #47
      Same problem on my 95 ODB 1. Changed the valve stem seals in the last month and that improved the rough start somewhat - stopped the choking blue smoke. It still takes 30 seconds to get all 4 running, but only in the winter time (and for the last 5 winters; at least the machine is consistant.)
      I was wondering if there is any chance that it might be related to the fuel injectors? dripping/fouled?

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      01-15-2008 08:18 AM #48
      I dunno, it really is a strange problem. It is interesting that you are experiencing this on an OBDI car....tells me it may indeed be something other than a MAF or O2 sensor.
      Update on my situation:
      Had a friend clear my codes, since touching the battery cables together didn't work. I wanted to see if the codes were current, or just stored from before. Well I drove it around for a day with no CEL, but I could tell the problem was still lurking.....it will occasionally buck when I am shifting gears, and sometimes the idle dips way down and almost stalls before it stabilizes. But sure enough, the CEL came back on, so now I get to check the codes again to see which of the three has come back.
      It hasn't been running rough on startup for the last dozen or so starts, but I know I'm not out of the woods yet.



      Modified by RabbitsKin at 8:19 AM 1-15-2008

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      01-19-2008 01:09 PM #49
      01/19/08 Update:
      Took the car in for a code-reading just to confirm what I suspected: P0102 MAF sensor low input again. At least that was the only code. Pretty sure the used MAF I bought is the problem. But I think the CEL and erratic idle from the bad MAF are a different problem than the rough startup.

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      01-21-2008 12:33 PM #50
      1/21/08 Update:
      Using Dan J. Reed's excellent MAF diagnosis thread here, I was able to determine that both the old and the new MAFs are, in fact, bad.
      Pin 1 -- 1.1 Ohms
      Pin 2 -- 1.2 Ohms
      Pin 3 -- 14.4 Volts (awesome battery)
      Pin 4 -- .1 Volts, no change at any RPM
      Just for kicks I plugged the old MAF sensor in, it reads a low of 1.0 Volts and a high of 1.9 Volts, so it isn't reading the full range of .9-3.8 Volts DC either. Thank you Dan Reed! At least now I can purchase a new MAF with confidence that there isn't some wiring issue.
      borrowed pic from the other thread:



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