Bad starts, especially cold

[Hack]

I was thinking O2 sensors as well, but I don't think the car usually looks at O2 sensors at startup. So O2 shouldn't cause a hard start. I like the O2 issue leads to fuel trims being off logic though. That could do it.

I think if too much air was getting into the engine there would be a check engine light.

The hard start I would lean toward ignition related. Since there's no check engine light, the plugs are probably firing, but the spark may be weak. If you've never replaced the spark plugs I would consider doing that.

Probably the best thing to do is to take the car to a good mechanic who can trouble shoot it rather than just throwing parts at it.

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[Hack]

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. :(

Vacuum leak you spray something combustible such as starting fluid around the engine compartment while the engine is idling. If there's a leak in a vacuum hose, the starting fluid will get sucked into the engine and make the RPMs increase.

 

[Dfeeds]

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. :(

It depends on the leak, to be honest. You test it by using a can of carb cleaner and spraying it around the hoses and gaskets. If your engine speed changes then it sucked in some of the carb cleaner and you found your leak. Best case it's a quick hose swap, middle ground is a gasket swap, worst case is a cracked intake manifold. I've actually had the latter on an older ride because I torqued the IM down too hard and it split open. So, being the intellectual I am, I bathed it in silicone as a bandaid until I got my new one LOL.

 

[Dfeeds]

I was thinking O2 sensors as well, but I don't think the car usually looks at O2 sensors at startup. So O2 shouldn't cause a hard start. I like the O2 issue leads to fuel trims being off logic though. That could do it.

I think if too much air was getting into the engine there would be a check engine light.

The hard start I would lean toward ignition related. Since there's no check engine light, the plugs are probably firing, but the spark may be weak. If you've never replaced the spark plugs I would consider doing that.

Probably the best thing to do is to take the car to a good mechanic who can trouble shoot it rather than just throwing parts at it.

Exactly. The car uses a preset trim on a cold start (called open loop) until the o2 sensors are heated up and the car enters a closed loop. So a bad o2 shouldn't cause a rough cold start. If it were ignition related I'd say it would have issues starting, but not hunting for an idle. It would have a, most likely, noticeable missfire and idle rough as a result.

 

[5ohdaddy]

Yeah another thing I forgot to note is my air/fuel ratio is fine all throughout everything; cold start, warm start, idle, accelerating, etc

 

[Hack]

Yeah another thing I forgot to note is my air/fuel ratio is fine all throughout everything; cold start, warm start, idle, accelerating, etc

You haven't noticed a change in fuel economy or power production? Just the hard starting?

 

[5ohdaddy]

Not really. Maybe a LITTLE power loss, and sometimes bitchy acceleration. My GF just got a 2017 Camaro 2SS so my car has felt very sluggish to me for a while now lol

You haven't noticed a change in fuel economy or power production? Just the hard starting?

 

[5ohdaddy]

Notchy acceleration*** lol my god

Not really. Maybe a LITTLE power loss, and sometimes bitchy acceleration. My GF just got a 2017 Camaro 2SS so my car has felt very sluggish to me for a while now lol

 

[13razorbackfan]

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/

Agree 100% when I bought both the Mustangs I recently bought was the first time in my life to search out top tier fuel stations. The 18 was giving me a check engine light and turned out to be a cold start misfire if the car had been sitting for a day or so in the cold. So I started the research and found switching to top tier 93 was the way to go. I then started doing research on top tier stations in my area. Found a few and they all have the green top tier sticker on the pumps. So that's what I've been using.

 

[ChiTownStang26]

Now has this issue been only happening with the same tank of gas or multiple fill ups. Sometimes it's just shit gas! If you've exhausted all options throw in some octane booster to at least rule out bad gas!

 

[5ohdaddy]

Now has this issue been only happening with the same tank of gas or multiple fill ups. Sometimes it's just shit gas! If you've exhausted all options throw in some octane booster to at least rule out bad gas!

*in response to this question and in general for this thread*

Yes, all tanks of gas. I recently changed my oil and then on the same day, filled up with 93 gas for the first time since I’ve owned it (32k-50k) and then the problems started happening like right after pretty much.

Few days later, I was going to clean my battery terminals, throttle body, and MAF sensor. Two seconds after disconnecting the negative it started to downpour so I had to quickly reconnect it and halt my progress. Haven’t done anything since. I have no garage (life in an apartment) so that’s why I can’t work on it while it rains. However the cold starts have been slightly better; doesn’t rev up quite as high, but still definitely does. And still takes significantly longer to warm up to running temps than it used to.

So I haven’t really gotten anywhere yet lol except for ruling out the bad gas question

 

[13razorbackfan]

*in response to this question and in general for this thread*

Yes, all tanks of gas. I recently changed my oil and then on the same day, filled up with 93 gas for the first time since I’ve owned it (32k-50k) and then the problems started happening like right after pretty much.

Few days later, I was going to clean my battery terminals, throttle body, and MAF sensor. Two seconds after disconnecting the negative it started to downpour so I had to quickly reconnect it and halt my progress. Haven’t done anything since. I have no garage (life in an apartment) so that’s why I can’t work on it while it rains. However the cold starts have been slightly better; doesn’t rev up quite as high, but still definitely does. And still takes significantly longer to warm up to running temps than it used to.

So I haven’t really gotten anywhere yet lol except for ruling out the bad gas question

Is it possible that bad gas already caused the "damage" so to speak?

 

[5ohdaddy]

Is it possible that bad gas already caused the "damage" so to speak?

I hope not. I don’t know what all I would need to replace if so

 

[5ohdaddy]

Update: my entire battery and surrounding area had an uncomfortable amount of corrosion around it, so I cleaned it all up best I could, as well as cleaned the MAF sensor. Was sort of visibly dirty, not sure if the CRC stuff I sprayed really did anything, BUT: when I put it back in, reconnected the battery, then fired up the car again. It was the strongest start I’ve had in a while and the RPM gauge did not move whatsoever. Waited 10 minutes on idle, drove around town for like 30 mins. Couldn’t really identify any performance gains, however the car/engine felt more stable and quieter.

 

[13razorbackfan]

Update: my entire battery and surrounding area had an uncomfortable amount of corrosion around it, so I cleaned it all up best I could, as well as cleaned the MAF sensor. Was sort of visibly dirty, not sure if the CRC stuff I sprayed really did anything, BUT: when I put it back in, reconnected the battery, then fired up the car again. It was the strongest start I’ve had in a while and the RPM gauge did not move whatsoever. Waited 10 minutes on idle, drove around town for like 30 mins. Couldn’t really identify any performance gains, however the car/engine felt more stable and quieter.

Good to hear! Bet you feel better huh? I know I would. Stuff like this would drive me crazy.

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