2004 xc90 t6 chugs when starter engaged

[jjaapro]

recent issue with 147K mile '04 xc90 2.9L T6 when starter is engaged... sounds like car is chugging/struggling to start but once it does start it runs just fine. Can minimize the 'chug' by holding the key forward for quick short bursts but always rough starts until vehicle actually 'starts'. Only time rough start symptoms occur is when key engaged for starting, vehicle starts immediately once key is released. I thought maybe the starter was staying 'engaged' with flywheel so i replaced with new starter motor but unfortunately issue still occurs. No warning lights appear during the startup. Wondering if this sounds like an obvious item to anyone - thank you

[joejoethedogfaceboy]

By "chug" do you mean misfire? Like maybe only catching on a few cylinders? Is it temperature dependent? (meaning only when engine is cold or only when engine is hot)

I have a long lingering issue on my '04 T5 when the engine is cold (on cold days), it will crank over for 5-6 seconds, then eventually catch and start, but will idle rough for a second or two. Then it idles smooth and doesn't misfire for the rest of the drive. I've tried all sorts of repairs/parts replacement. I can avoid the issue (for the most part) by turning the key to position II (2) - without cranking - until the check engine light goes out, then turn key off, then turn key to start car. After this issue started, the stealer allegedly replaced the fuel pump when I brought it in for a recall, but I'm skeptical that they actually did, since my issue points to a possible leak back situation with the pump. Hopefully this info helps you out.

Is the check engine light on after this happens? Are you able to check for any stored codes? Can you try the key "trick"?

-Joe

[jjaapro]

yes, misfire accurately describes my starting issue. engine or outside temperature does not seem to make a difference in my situation. my misfire symptoms are only when cranking, goes away and runs smooth once it starts. does seem to take a second or two longer to start than before the issue began. my check engine light has not come on at any point during this issue. i did try the key trick exactly as you described, but in my case the same symptoms continued to show themselves. thank you for your suggestions joe.

[joejoethedogfaceboy]

Sorry it didn't help. Unfortunately, that's the best I can offer. I'll be watching the thread, though, since you've piqued my curiosity.

[jimmy57]

Were there any repairs made involving engine removal or transmission removal?
Watch the tachometer while you are cranking engine over to start. Does tach bounce? Does tach move off zero while cranking?

[precopster]

My 2001 T5 did this for the first time last week one morning and did this only once on a Monday after sitting over the weekend. It was as rough as guts even for the first 15 seconds until it cleared so I revved it up a little so it wouldn't stall. For the rest of the week it's been fine.

My engine/trans was separated recently for engine replacement. Are you pointing to a damaged or badly aligned crank sensor jimmy?

[FLXC90]

Or perhaps a faulty ground. Does your fan run if you turn the key to II but don't start it? Does your fan run longer than normal after shutdown ? Those could indicate a bad Engine Coolant Temp Sensor, which would be like a bad choke (If you remember those) Those are symptoms my 04 T6 has displayed.

[jimmy57]

No, The surfaces of engine and trans where they meet HAS to be clean in order to give the barely adequate EMF shielding. The starter plays hell with magnetic field in the flywheel and can affect signal from RPM sensor (CKP sensor). A faulty starter that has a bit high current draw can make more EMF than the suppressive features can shield. Starter replacement was listed so I discounted that.
The starts immediately when key released from pos III is a hallmark symptom of the suppression issue. The EMF goes away when current stops in starter.

[jjaapro]

thanks all for the commentary; in the case of my misfiring while cranking my tach stays fixed on zero while cranking - no bouncing. This vehicle has not had any repairs where engine or trans where ever removed or separated. Fan does not run at key position II when engine is cold. this may not mean anything but i removed CKP sensor and unplugged it and same issue with and without it. i was thinking of replacing CKP sensor since cheap and easy unless advise is that is highly likely not the issue. recall that starter was just recently replaced.

[jjaapro]

quick question for anyone... does my 04' T6 have a CAM position sensor or a CRANK position sensor or are they one in the same? the only sensor like that i located on my engine was not located on the transmission ?