Cold start problems

[kordy]

Hello FiST owners

The other day I started to have some problems with my car on cold start. The car is working really poorly and even turns on the check engine light.
The error codes indicate that there are random misfires detected on cylinder 4.

The thing is that the car works normally after it warms up a bit (20-30 seconds after I turn it on). It drives normally and there are no problems.

I have reset the DTCs, mixed the sparkplugs and hoped to get the error codes again but now they don't want to show up even though the car still doesn't "work" properly when it's cold started.

Please take a look at the short video I made:

View: https://www.youtube.com/watch?v=HtteHeV6vDI


Any ideas where to start to diagnose the problem? Thank you for reading and have a nice day.

 

[kivnul]

All the plugs looked identical and looked good? (color, gap, porcelain intact?) How does the exhaust look right at startup? Does it smell sweet? (like burning coolant?)

If the code does come back and it is still cylinder 4, try swapping the coil packs and see if it stays that cylinder.

 

[WannabeST]

Are you running pump gas or a pump & ethanol mix? I get a misfire code on my mustang but it is from the ethanol.
I would get a clean rag and throw it over the exhaust pipe and hold it there for a little bit after startup, maybe even give it a little rev. Once you do that check for any potential oil or coolant. You may have a potential leak for oil or coolant.
If it is not, I would just replace all the spark plugs, cheap and easy. If that does not fix it, I would move the coil packs around, if the misfire switches location then it is time to buy one or all replacement coil packs.

 

[Sam4]

OE Heat range spark plugs?

 

[kordy]

Thank you for your replies.

All 4 spark plugs look identical, they were replaced 5k miles ago. The car is running rich so they are a little bit "black" but other than that they are still good.
I forgot to check which model they were and if there is cracked porcelain. I will check that today.
There is no sweet smell from the exhaust and the coolant level is exactly the same as it was.

I have swapped the coil packs and ofc it still has the same problem but as I said in the first post, car just don't want to give error code as it did before so I can't check if different cylinder now missfires.
It's running just pump gas, revo stage 2

I will try that rag over the exhaust pipe trick.

 

[WannabeST]

Does this issue happen on all cold starts or just cold starts after the car sits over night?
(asking for potential moisture/ condensation purposes) In my grandmas part of mexico during a certain time of year the moisture in the air is disgusting and it makes everyone's car idle rough for a bit and even feel slower when we go to visit.

 

[kordy]

Only when car sits over night or cools down... If the temperature gauge shows 4 bars (right in the middle, perfect temperature) it starts normally.

 

[WannabeST]

If the car passes all the other test mentioned. I would give the car a full seafoam treatment (Oil, intake and gas) My guess is that something is either gunked up, staying open or staying closed more than it should. After the car gets a solid treatment you should notice a difference by the next 1-2 fill ups. If this helps, I would recommend you give the car a seafoam treatment on a regular basis of some sort. ( I personally do this on all my cars every oil change). In your situation, I would do it 2-3 more times to try and get it all cleaned up good then go on some sort of schedule for it.

 

[kordy]

Hello guys, I hope you are all doing well...

I have found and fixed 50% of the problem.

Turns out, this hose was completely disconnected.



The car now has a normal cold start.

The other 50% of the problem is that I can still sometimes hear a small misfire when the car idles (no error codes though).
I have found out that my battery is really old. I have charged it but it goes to 11.5-11.8V after a day or two of car not being driven.
I will replace the battery in next few days and see if it does anything.

Take care.

 

[dhminer]

Hello guys, I hope you are all doing well...

I have found and fixed 50% of the problem.

Turns out, this hose was completely disconnected.

View attachment 54027

The car now has a normal cold start.

The other 50% of the problem is that I can still sometimes hear a small misfire when the car idles (no error codes though).
I have found out that my battery is really old. I have charged it but it goes to 11.5-11.8V after a day or two of car not being driven.
I will replace the battery in next few days and see if it does anything.

Take care.

Let us know if the battery fixes it. This car HATES having a marginal battery and does all sorts of weird stuff as a result.

 

[kordy]

Unfortunately I can still hear it sometimes, it's like a really small choke while car being idle (more noticeable when the car is cold).
I can't get any error codes, even when pushing car hard.
Also I still can't see any change in oil or coolant levels, they are the same and I did around 100 miles with the new battery installed.
I'm currently busy so I can't really work on it, but I will try to do compression test when I can.

One thing that I did notice is that when the car gets really warm (after 30 minutes of driving), these small chokes are barely noticeable.

 

[Sonnyst225]

Unfortunately I can still hear it sometimes, it's like a really small choke while car being idle (more noticeable when the car is cold).
I can't get any error codes, even when pushing car hard.
Also I still can't see any change in oil or coolant levels, they are the same and I did around 100 miles with the new battery installed.
I'm currently busy so I can't really work on it, but I will try to do compression test when I can.

One thing that I did notice is that when the car gets really warm (after 30 minutes of driving), these small chokes are barely noticeable.

What actually was the hose that came loose? I’ve a similar issue with regards to noise in cold starts.

 

[gtx3076]

If the car passes all the other test mentioned. I would give the car a full seafoam treatment (Oil, intake and gas) My guess is that something is either gunked up, staying open or staying closed more than it should. After the car gets a solid treatment you should notice a difference by the next 1-2 fill ups. If this helps, I would recommend you give the car a seafoam treatment on a regular basis of some sort. ( I personally do this on all my cars every oil change). In your situation, I would do it 2-3 more times to try and get it all cleaned up good then go on some sort of schedule for it.

I would never seafoam this car.

 

[FiestaSTdude]

I would never seafoam this car.

Why?
I’ve heard others say this as well and I’m curious because normally people like seafoam. Does it have to do with the turbo?

 

[Capri to ST]

Why?
I’ve heard others say this as well and I’m curious because normally people like seafoam. Does it have to do with the turbo?

Yes, the concern I've heard is that it could knock loose debris which could damage the turbo.

 

[WannabeST]

Yes, the concern I've heard is that it could knock loose debris which could damage the turbo.

Most of the debris would be extremely small. I really doubt any of it would damage the turbo. I used sea foam on every oil change on my old integra track car. 5 years on the same engine and never had a single drivetrain failure. I’ve used it on friends and families cars and seen noticeable results.

 

[kordy]

What actually was the hose that came loose? I’ve a similar issue with regards to noise in cold starts.

Check the attached image, it was the smaller hose that connects to induction hose.

 

[Sonnyst225]

Check the attached image, it was the smaller hose that connects to induction hose.

Ahh im
Not running the revo system I’ve got an itg fitted

 

[Capri to ST]

Most of the debris would be extremely small. I really doubt any of it would damage the turbo. I used sea foam on every oil change on my old integra track car. 5 years on the same engine and never had a single drivetrain failure. I’ve used it on friends and families cars and seen noticeable results.

Thanks for the information. I'm not saying I've seen that kind of damage happen myself because I haven't used it, just that I have heard other people express that concern.
Because of that, if I was going to use Seafoam, I would want to get a comfort level first that it's safe. Knowing your good experience with it would help to do that, so that's good to know.

 

[M-Sport fan]

^^^It should be a 'no-brainer', but just in case; the oil MUST be changed out with a LONG drain time after doing that procedure to get out ALL of the severely diluted/contaminated oil as a result of the Seafoam.