Bad starts, especially cold

[5ohdaddy]

Hey all, my first post here but it’s a problem post lol. I have a 2015 GT non PP Premium.

I’ve been having weak starts for a while now, but only until a few days ago my starts and especially cold starts, the RPM fluctuates and jumps around between 1-2.5k and eventually calms down, but it takes forever and engine also takes a lot longer than it used to to warm up.

Are plugs the main culprit here? I’m going to be cleaning my MAF and throttle body and changing the air filter. . But I think it’s the plugs.

And my last two cold starts the car has halted so bad it almost shuts off/stalls.

Thank you to anyone who replies. I’m a novice.

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[StangTime]

I would be interested in knowing what the problem could be as well. I don't have this problem on my Mustang, but my Fusion is doing this during the first cold start of the morning. Did it last winter and now again this winter.

When you start your car, does it act like it's going to stall? I would call it "chugging" at a low RPM and gradually the RPM's creep higher and the "chugging" becomes less pronounced and faster until the engine has had a few seconds to run then runs normally?

 

[lacanteen]

How many miles on the car? Could be the throttle body.

 

[5ohdaddy]

I would be interested in knowing what the problem could be as well. I don't have this problem on my Mustang, but my Fusion is doing this during the first cold start of the morning. Did it last winter and now again this winter.

When you start your car, does it act like it's going to stall? I would call it "chugging" at a low RPM and gradually the RPM's creep higher and the "chugging" becomes less pronounced and faster until the engine has had a few seconds to run then runs normally?

Yes, the engine does chug. It gets very loud to the point where it goes to 2.5k RPM (and with Roush axleback and H pipe this gets annoying) and then eventually calms down, but it takes FOREVER for the engine to get to running temps now.

 

[5ohdaddy]

How many miles on the car? Could be the throttle body.

How many miles on the car? Could be the throttle body.

Just hit 50k. Also, just did an oil change, and switched to 93 gas from using 87 all of its life so far.

 

[lacanteen]

Then I think you're on the right track with cleaning MAF and throttle body. Plugs are generally good for 100K unless you really drive hard and or use crap gas. Read up on top-tier fuel: https://www.toptiergas.com/licensed-brands/

 

[ChiTownStang26]

Maybe the battery is going out? Mine just died last week so that's where my heads at lol

 

[5ohdaddy]

Maybe the battery is going out? Mine just died last week so that's where my heads at lol

Maybe. I hope not though. Cause I changed it a little under a year ago. I was having bad cortisol issues with an old battery. I’ll see the status of the battery when I disconnect it later before cleaning the TB and MAF

 

[5ohdaddy]

Corrosion*** not cortisol lol

 

[Dfeeds]

Bad plugs would make for some drivability issues but unless you have a bad coil or plug that just won't ignite a spark then it shouldn't cause this.

I'd lean towards basic maintenance first. Clean the MAF, make sure the air filter isn't plugged, maybe change the fuel filter, and definitely check for any air leaks.

As a typical rule of thumb, if your issues happen upon cold start and get better when warm, then it's mechanical related (air leak, clogged filter, etc). If it's the other way around then it's sensor related.

 

[Fetlock]

Do you hear any hissing from the engine? Sometimes a vacuum leak can cause a lot of rpm fluctuations.

 

[ChiTownStang26]

Lmao your battery stressed out bruh?!?! Hope you figure it out!

P.S. maybe your having a fuel trim issue, disconnecting the battery for 5 mins resets LTFT and starts the relearn. Couldn't hurt! Also maybe a o2 sensor is fouled, if you have access to dataloging equipment I'd check o2 and fuel trims.

 

[5ohdaddy]

Do you hear any hissing from the engine? Sometimes a vacuum leak can cause a lot of rpm fluctuations.

No engine hissing. Only the good old normal tick after every oil change lol.

 

[5ohdaddy]

Lmao your battery stressed out bruh?!?! Hope you figure it out!

P.S. maybe your having a fuel trim issue, disconnecting the battery for 5 mins resets LTFT and starts the relearn. Couldn't hurt! Also maybe a o2 sensor is fouled, if you have access to dataloging equipment I'd check o2 and fuel trims.

Yeah I heard that from somewhere too. I think before I try anything I’ll just disconnect the battery for 5 or so mins then reconnect and see if that does anything.

 

[5ohdaddy]

Bad plugs would make for some drivability issues but unless you have a bad coil or plug that just won't ignite a spark then it shouldn't cause this.

I'd lean towards basic maintenance first. Clean the MAF, make sure the air filter isn't plugged, maybe change the fuel filter, and definitely check for any air leaks.

As a typical rule of thumb, if your issues happen upon cold start and get better when warm, then it's mechanical related (air leak, clogged filter, etc). If it's the other way around then it's sensor related.

Gonna do all of this. Getting the TB/ filter cleaner and MAF cleaner as well as a new air filter from AAP later on today. I sure hope it’s not a vacuum leak because I’m not too familiar with how to address that issue. :(

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