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Discussion Starter · #1 ·
Hey guys this is my first post besides the intro so feel free to redirect me if this thread doesn't belong here.

So I just brought my 2015 Forte5 SX six speed home from the dealership tonight. Car has 50k on it. When I test drove it a few weeks ago I did a fourth gear pull with the salesman in the car and I was greeted by a serious oscillating stumble and a blinking check engine light. The first owner of the car did some bolt ons listed below:

Cold air intake
Blow off valve
Turbo back exhaust (both cats deleted)
Oil catch can
Intercooler resonater pipe delete

Obviously I told the dealer to address the stumble issue. They ended up putting two new cats on the car but keeping the rest of the stuff where it was including the cat back exhaust and everything else under the hood. So imagine my surprise tonight when I drive the thing home and again I get a blinking CEL and jerking acceleration throughout the RPM range.

I will be heading back to the dealer tomorrow to get this taken care of, but I have somewhat low expectations for successful results. This isn't my first turbo car, and no I have not had a chance to check and see if the ECU set a code. Only does this when car is warmed up and under >75% load. Any advice or ideas? Thanks guys.
 

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Two things come to my mind.

Tune and fuel lines.

Let's address the fuel lines - some, including I, experienced fuel line restriction/kink/collapse under WOT in higher RPM range. Higher means about 5000 rpm for me. But not every time... so go figure.

Tune - what I suspect is it might be tuned (properly or not), but due to lack of this knowledge, a regular petrol was added resulting in predetonation. How to check for tune - well, only a tuner can or a dealer can. You will not know unless you can measure boost. If it bumps higher than 18 psi - it is clear indication it was touched.

And additional thought - spark plugs. Maintenance asks to replace them at 45k mile mark, so it might be them as well.

Other than that - the mods (although not called bolt on as bolt on would be a new exhaust, turbo, and such) should not really make a problem. Except Oil Catch Can. If the OCC does not have a check valve, it will get all content back into the engine what will cause a Christmas tree problems.


What's your location, though?
 

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Discussion Starter · #3 ·
Thanks for the response. I live in Northeast CT.

I did have a suspicion about the plugs, so I am planning on trying those today. I have an appointment on Friday with Kia service tech to see if he can do a live scan during a road test and watch the boost and hopefully see what the blinking CEL is indicating.

After that or before I'm going to have him reflash the ECU or at least just check to see if it has a tune on it. The dealer said he put 93 octane in it but who knows for sure. I'll run the tank down and fill it after I do the plugs. How would I know if the occ has a check valve or not? Thanks again
 

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Hmmm. I am not sure how to respond.

On one hand I would say - do not reflash yet and rather test the boost yourself. Get one of those cheap 10 USD BT OBD adapters, get a free Android Torque app and see boost yourself.

Spark plugs - that depends on what your plan is. If to keep car completely stock - stay stock. If you find the tune or planning on tune, or adding some power - you may consider HKS M45XL or M40XL.


As for the OCC - there should be a check valve between the can and the throttle body. It may also be full...
I would revert everything to normal and start there.

I am actually quite happy that the dealer is working with you.
 

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Discussion Starter · #6 ·
Thanks again. I want to keep it safely stock for now as this is our family car and I already have an rx7 to smack my head against if I feel like building something. I wanted a stock unmolested forte sx but this was all the dealer could find near me that was stick shift.

Catch can is almost completely empty but unless there is a check valve inside the intake manifold, I don't think it has one. One hose connects to the pcv valse and the other to the large port right next to the throttle on the manifold, so maybe that's the valve it needs.

As far as if there is a tune, I don't care if there is or not as long as it runs and can be driven to full throttle, so I wouldn't mind them reflashing the ECU and getting rid of the tune. Are the aftermarket tunes for these just a flash or would it be a chip where I would need a whole new ecu to revert back from?
 

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ECU reprogram. Some sell or rent out a reflashing through OBD, but I am not sure how good they are.
I shipped mine (original and spare) to get reflashed.
Dealer will clear and put a stock one on.

I am surprised they did not do all of this before the sale... but again - it is very nice of them to work with you on all of this.
 

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Discussion Starter · #8 ·
Well apparently nobody has driven it hard enough to notice the issues. I picked up the plugs just now and will put them in when it cools down. A full tank of 93 seemed like it made it a little smoother maybe. I was however able to finally set a constant code and now the CEL is solid on so it should have set a code. I'm sure it will just be a generic too lean or misfire code though. I'll just hope the Kia tech knows his stuff on Friday. Yes it is good they are working with me as well.

Will let you know how it goes.
 

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Discussion Starter · #9 ·
Also does the vacuum solenoid that is in line with the bov need to be bypassed or left how it is now? I noticed the bov is held open slightly when you first start the car for a few seconds. I can also hear it open when driving gently. As soon as you floor it I can hear it shut and the engine bay gets much quieter except for the sound of the turbo.

This normal on these cars? Last couple turbo setups I had didn't do that...
 

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The intake definitely adds noise.

But your description makes me thinking if the previous owner didn't do a BOV hack, when you bypass some vacuum lines. Sorry, I do not remember, it was explained on Velociraptor forum (Veloster Turbo).

Also, depending on the intake, it may or may not have the BOV recirculating hose connected. That may explain why you hear the BOV venting.
And yes, on start it always vents and then gets quiet. I am not sure if it vents slightly under partial throttle.

Take a picture of the setup and we might be able to get things back to normal.


You see, I also mod my car, but for sale, I revert everything back to OEM state. No mod in my car is non-reversible.
I have when things are left this way...
 

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Discussion Starter · #11 ·
Ok so yes the BOV is atmospheric as the intake does not have a recirc port on it. You will see there is a breather port that I believe should go to the valve cover that is capped off on the intake with a breather filter on the corresponding hose from the valve cover. I assume this is because the OCC is installed? I have two more pictures I will post as well that might help.
 

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Discussion Starter · #12 ·
Sorry I uploaded the wrong picture. That one of the throttle just shows where the other end of the catch can hose goes to. This is the intake picture.
 

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Discussion Starter · #13 ·
Finally I couldn't get a clear shot of all the hoses that link to the BOV so this was the best I could do. There is a vacuum line from the intake manifold to this switch or solenoid that sits under the radiator hose. Then there is a small hose directly from the intercooler to said switch, and then the hose from the switch to the BOV. The valve hose has tight zip ties on it and a nice silicone hose while the other hose from the intercooler to the switch just has factory spring clamps on a factory cloth-wrapped hose. I take it that vacuum switch tells the BOV how to operate based on manifold pressure?
 

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Finally I couldn't get a clear shot of all the hoses that link to the BOV so this was the best I could do. There is a vacuum line from the intake manifold to this switch or solenoid that sits under the radiator hose. Then there is a small hose directly from the intercooler to said switch, and then the hose from the switch to the BOV. The valve hose has tight zip ties on it and a nice silicone hose while the other hose from the intercooler to the switch just has factory spring clamps on a factory cloth-wrapped hose. I take it that vacuum switch tells the BOV how to operate based on manifold pressure?
So I think you are missing some parts... and there is the BOV hack done.
The vacuum line from TB should be connected to a valve (or sensor?) and then it is split I think to wastegate.

The OCC - seems to be OK. The breather is atmosphere vent. The PCV side should have the check valve, something like in the picture below.

As for the other vacuum lines - I think there is a part missing there. I would have to look closely how it is on mine. I am not 100% sure the diagram is correct that I found for the turbo hack, but seems quite right.
Link to VT forum for more info on the modification.

check valve.jpg

https://www.forteturbo.org/forum/19-kia-forte-turbo-performance/167-turbosocks-hack.html

20181024_202142.jpg

20181024_202122.jpg

boost hax.jpg
 

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Discussion Starter · #15 ·
Very interesting. My hoses are indeed setup like the stock diagram you posted, but the vac line coming out of my throttle has a tee in it which as you can see is capped off with a screw (not a good way to do it). Looks like the previous owner had done the turbosocks hack then reverted for some reason.

The valve I have is a turboxs sml hybrid. I'm going to try redoing the hack tomorrow and see if it changes anything. I also might take the valve off and check it out because it seems like the spring is super light I mean I barely let off the throttle cruising around and it hisses out. Looks like fun to pull the bumper off anyway...

Other than that I was wondering if maybe I'm overthinking the whole damn car and maybe it has a faulty map sensor or something stupid. I feel like even if it had a tune it would behave especially getting on it. As of now anything over half throttle is blinking CEL and a surging lag in power.

Again my service app is Friday morning so one way or another I'll get to the issue and let everyone know. Thanks
 

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Very interesting. My hoses are indeed setup like the stock diagram you posted, but the vac line coming out of my throttle has a tee in it which as you can see is capped off with a screw (not a good way to do it). Looks like the previous owner had done the turbosocks hack then reverted for some reason.

The valve I have is a turboxs sml hybrid. I'm going to try redoing the hack tomorrow and see if it changes anything. I also might take the valve off and check it out because it seems like the spring is super light I mean I barely let off the throttle cruising around and it hisses out. Looks like fun to pull the bumper off anyway...

Other than that I was wondering if maybe I'm overthinking the whole damn car and maybe it has a faulty map sensor or something stupid. I feel like even if it had a tune it would behave especially getting on it. As of now anything over half throttle is blinking CEL and a surging lag in power.

Again my service app is Friday morning so one way or another I'll get to the issue and let everyone know. Thanks
Looks like your bov solenoid have all connections in place.
If your hose from TB is connected to that small black canister what PLP showed you're also good there (T is capped and probably was used for boost gauge or so).
Just get dongle and torque app, and check values on WOT, if its holding boost, fuel pressure, afr...

Sent from my SM-G950W using Tapatalk
 

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Would be good to know what the code is...

The tee could be for a boost gauge.

As per the little throttle - yes, that is correct. It will hiss at almost any throttle unless you slowly let it off.


I just realized - you said the car did not have cats, right? So what did the dealer do? I mean, to put cats in you basically need to put a new exhaust as the mid pipe has the second cat.
 

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Discussion Starter · #18 ·
Thanks everyone. I have a dongle on order as of this morning. Good to know that the BOV seems like it is doing it's job.

As far as the exhaust goes the dealer told me they put both cats on it. I told them to give me the old exhaust parts and all that made it into my trunk was the 845 Motorsports downpipe they took off so I'll have to get it on a lift and see what actually was replaced. I thought I saw a stainless mid pipe when I looked under there a few days ago but it was probably just the stock mid pipe.

With any luck tomorrow morning the dealer will have it figured out. I don't mind wrenching my own vehicles, but I waited almost a month in a loaner car for the dealer to "get the car all set" after I noticed this issue during the first test drive. I just wanted a stock daily driver lol but I'll get it figured out through service or that dongle when it comes in.
 

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Discussion Starter · #19 ·
So the verdict according to the tech is two bad coils. Under heavy load cylinder 1 and 3 could we're dropping out when they did a live scan test drive. Also they put denso plugs in to replace the autolites it had in it. They said these motors don't like autolites at all.

Turns out I was overthinking the issue, and I hope I didn't waste too much of anyone's time with all the questions. I appreciate everyone's advice and I did learn a lot about my new car so it was worth it for me. Thanks all
 

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Turns out I was overthinking the issue
Happens all the time :)

They said these motors don't like autolites at all
Actually, not so true.
Autolites have 3 heat levels. The best is the XP5702 as it improves power delivery limiting spark plug overheating under low boost. However, they have mechanical problems, such as cracked ceramic insulator, or core drops...

Glad they solved it.

I wonder how they could tell the coils were failing... what exactly they measured. I doubt there is any way to tell what was the spark voltage/power.
 
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