Weird startup this afternoon

[bonz50]

started the car and it was shaking a little, not in a normal way, like it was missing a plug or somethin, no codes, nothing. eventually the rpm jumped up to about 1400 or so and it smoothed out and settled down to normal idle and it went away. That's a new one for me (granted I'm still fairly new to the coyote). it was a little disconcerting, motor has about 53k on it. manual trans, no mods except cat back exhaust.

any thought??

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[Darthy Jo]

Dirty MAF?

 

[bonz50]

Dirty MAF?

What’s the best way to clean that??

 

[Darthy Jo]

MAF cleaner spray, should be available at any auto parts store, probably even Walmart or Home Depot. DON'T use brake/parts cleaner or anything else. The sensor is on the intake tube; just remove it, spray it down, let it dry, re-install, and see if it worked. Youtube can give you a better visual procedure.

 

[coz0502]

While you're cleaning the MAF sensor, you mind as well wipe down the throttle body too. Something similar happened to me, the RPMs would flutter causing a little shaking at idle. I talked to my buddy/neighbor/personal mechanic and he suggested this. Pulled the air intake off, clean both and reinstalled. This resolved my issue.

 

[bonz50]

Figured it was something simple like this but wanted to check that there wasn't something special about it on the mustang.

 

[Cobra Jet]

If it's not the MAF, could be VCTs or IMRC.

 

[bonz50]

*secretly hopes for IMRC so I have an excuse to get an 18 manifold and lockout with a tune*

 

[sk47]

Hello; This is a very wild guess but a similar thing happens with one of my vehicles. It will run rough for a short while immediately after a startup, then clear up and be normal.
What i discovered is this odd start up occurs after a specific event. That being I would sometimes start the car to move it just a little and then shut it off after just a minute or even less. The engine would still be in fast idle mode of a start.
The next time i started the car it would do the odd stumble for a bit. My thinking is the engine is running on a rich mode from a cold start when shut off quickly. Then the next day when I start it again from cold some residue of fuel somehow is left or perhaps the plugs are a bit fouled from that short engine run before.
Anyway, what i now do if i need to say just start it up and pull it into the garage or something, is to let it run at least until the fast idle drops some RPM's. That has stopped the odd startup stumble from happening.

 

[ORRadtech]

Do you top up the gas tank after the handle shuts off? That can mess with the evap Purge Valve and cause similar symptoms.

 

[bonz50]

Hello; This is a very wild guess but a similar thing happens with one of my vehicles. It will run rough for a short while immediately after a startup, then clear up and be normal.
What i discovered is this odd start up occurs after a specific event. That being I would sometimes start the car to move it just a little and then shut it off after just a minute or even less. The engine would still be in fast idle mode of a start.
The next time i started the car it would do the odd stumble for a bit. My thinking is the engine is running on a rich mode from a cold start when shut off quickly. Then the next day when I start it again from cold some residue of fuel somehow is left or perhaps the plugs are a bit fouled from that short engine run before.
Anyway, what i now do if i need to say just start it up and pull it into the garage or something, is to let it run at least until the fast idle drops some RPM's. That has stopped the odd startup stumble from happening.

hey now.... quit giving me common sense solution to a problem when I can use this as an excuse to upgrade to the 18 manifold!!! LOL

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