2013 Yukon XL Denali idle and startup issues. SOLVED

[krekelly]

I’ve got a 2013 Yukon XL denali. It’s got a factory remanufactured engine installed in March. Original vehicle has 155k.

When I replaced the engine, I made sure to get a bunch of new incidentals outta the way. New flex plate, oil cooler hose, serpentine belt, water pump, plugs and wired.

Since May I’ve had an issue with startup and idle. Can’t quite put my finger on it so I’m here. No codes or check engine lights.

When trying to start it up, there are times it won’t crank over. It’ll time out before it stops trying. When it does that, I can pump the gas pedal to get it to fire up. I know it’s not carbureted. But it really is the difference between starting or not.

When that does happen I tend to smell gas as well as burned up fuel. I get a plume of black smoke out the exhaust pipe. That tells me the mix is fuel rich.

Also it takes a little while to let the engine settle. Sometimes the rpm’s will spike up to 3k. Sometimes it sputters and can barely stay running. Other times it straight up dies. If I don’t let the engine settle for a minute or so and I shift out of park, the engine will die.

I replaced the throttle body with a hitachi brand. I went through the idle relearn process, and still had the same issues. Replaced it again with the same brand. I did the relearn again, Gm has confirmed an updated pcm, and I had an idle sweep done.

I’ve had a local mechanic look at it for about an hour or two and he’s thinking a bleeding fuel injector. I haven’t pursued that yet but I’m not convinced. It should be throwing a code and misfiring after idle. But I don’t have any issues after I shift out of park.

What are your thoughts?

 

[OBSandaNNBS]

I’ve got a 2013 Yukon XL denali. It’s got a factory remanufactured engine installed in March. Original vehicle has 155k.

When I replaced the engine, I made sure to get a bunch of new incidentals outta the way. New flex plate, oil cooler hose, serpentine belt, water pump, plugs and wired.

Since May I’ve had an issue with startup and idle. Can’t quite put my finger on it so I’m here. No codes or check engine lights.

When trying to start it up, there are times it won’t crank over. It’ll time out before it stops trying. When it does that, I can pump the gas pedal to get it to fire up. I know it’s not carbureted. But it really is the difference between starting or not.

When that does happen I tend to smell gas as well as burned up fuel. I get a plume of black smoke out the exhaust pipe. That tells me the mix is fuel rich.

Also it takes a little while to let the engine settle. Sometimes the rpm’s will spike up to 3k. Sometimes it sputters and can barely stay running. Other times it straight up dies. If I don’t let the engine settle for a minute or so and I shift out of park, the engine will die.

I replaced the throttle body with a hitachi brand. I went through the idle relearn process, and still had the same issues. Replaced it again with the same brand. I did the relearn again, Gm has confirmed an updated pcm, and I had an idle sweep done.

I’ve had a local mechanic look at it for about an hour or two and he’s thinking a bleeding fuel injector. I haven’t pursued that yet but I’m not convinced. It should be throwing a code and misfiring after idle. But I don’t have any issues after I shift out of park.

What are your thoughts?

So there was some time after you put the new engine in that it ran well? (March to May?)

I'm wondering if your original ECM isn't quite recognizing the crankshaft position sensor on your new engine. Maybe just enough recognition to get by as you mentioned. Your mechanic should be able to relearn it. Or if you have a good bidirectional scanner you can yourself.
Alternatively, the CPS coulda gotten bumped/pinched/etc if you swapped it.

PS hate to be that guy but is Hitachi OEM? I don't remember from when I did mine. I caution again against using anything other than OEM for anything electronic to avoid problems. Also, the throttle body must be installed with the throttle body position sensor in the correct position. I think 1Aauto has a good YouTube video on it.

Not trying to state obvious but don't know your skill level, aptitude, etc.

 

[krekelly]

So there was some time after you put the new engine in that it ran well? (March to May?)

Correct.

I'm wondering if your original ECM isn't quite recognizing the crankshaft position sensor on your new engine. Maybe just enough recognition to get by as you mentioned. Your mechanic should be able to relearn it. Or if you have a good bidirectional scanner you can yourself.
Alternatively, the CPS coulda gotten bumped/pinched/etc if you swapped it.

I’ll check it out.

PS hate to be that guy but is Hitachi OEM? I don't remember from when I did mine. I caution again against using anything other than OEM for anything electronic to avoid problems. Also, the throttle body must be installed with the throttle body position sensor in the correct position. I think 1Aauto has a good YouTube video on it.

I know it’s not OEM. I’m in a pinch financially and OEM was double the cost. My dad, a former gm mechanic and 20 year service advisor was thinking hitachi was the same manufacturer as OEM. He’s getting up there in age and couldn’t quite remember.

I didn’t know about the throttle body position sensor needing to be in a specific position when I installed it.

Not trying to state obvious but don't know your skill level, aptitude, etc.

You’re good. I’m a decent YouTube mechanic. I can confidently do a lot of stuff but knowing the little details like that is where I lack.

 

[krekelly]

And thank you for your reply. I greatly appreciate it.

I’m so frustrated with this vehicle and am about ready to get rid of it but I’ve replaced so much on it that it has more new parts than not. Outside of brakes, ac, alternator, and transmission it’s all pretty much new.

 

[swathdiver]

When you get this sorted out, she'll serve you well and keep you safe.

 

[OBSandaNNBS]

Correct.


I’ll check it out.


I know it’s not OEM. I’m in a pinch financially and OEM was double the cost. My dad, a former gm mechanic and 20 year service advisor was thinking hitachi was the same manufacturer as OEM. He’s getting up there in age and couldn’t quite remember.

I didn’t know about the throttle body position sensor needing to be in a specific position when I installed it.


You’re good. I’m a decent YouTube mechanic. I can confidently do a lot of stuff but knowing the little details like that is where I lack.

The crankshaft PS is behind the starter. It also works in tandem with the camshaft position sensor. Location varies. Not 100% sure on this being the culprit, but worth checking out. If you do have a good bidirectional scanner with live data, you can determine if the signals from the sensors are good.

Financial pinch, I can certainly understand that!
My Throttle PS ended up being a wire... Here's a thread documenting my struggle.

I've owned this truck less than a year, and learned a ton thanks to this forum.

I agree with swathdiver, fix her up and she'll serve you well.

Throttle Sensors vs Wire Round 7 - SOLVED

Been a lurker here since I bought my lady a rather clean 2012 Tahoe LS three months ago. 156K miles. I'm above average mechanically inclined for being a [cough] mellenial, but untill now have always run older vehicles (IE a 263K 97 Burb) for ease of repairs and noted lack of sensor issues...

www.tahoeyukonforum.com

 

[OBSandaNNBS]

I’ve got a 2013 Yukon XL denali. It’s got a factory remanufactured engine installed in March. Original vehicle has 155k.

When I replaced the engine, I made sure to get a bunch of new incidentals outta the way. New flex plate, oil cooler hose, serpentine belt, water pump, plugs and wired.

Since May I’ve had an issue with startup and idle. Can’t quite put my finger on it so I’m here. No codes or check engine lights.

When trying to start it up, there are times it won’t crank over. It’ll time out before it stops trying. When it does that, I can pump the gas pedal to get it to fire up. I know it’s not carbureted. But it really is the difference between starting or not.

When that does happen I tend to smell gas as well as burned up fuel. I get a plume of black smoke out the exhaust pipe. That tells me the mix is fuel rich.

Also it takes a little while to let the engine settle. Sometimes the rpm’s will spike up to 3k. Sometimes it sputters and can barely stay running. Other times it straight up dies. If I don’t let the engine settle for a minute or so and I shift out of park, the engine will die.

I replaced the throttle body with a hitachi brand. I went through the idle relearn process, and still had the same issues. Replaced it again with the same brand. I did the relearn again, Gm has confirmed an updated pcm, and I had an idle sweep done.

I’ve had a local mechanic look at it for about an hour or two and he’s thinking a bleeding fuel injector. I haven’t pursued that yet but I’m not convinced. It should be throwing a code and misfiring after idle. But I don’t have any issues after I shift out of park.

What are your thoughts?

The more I'm thinking about this, I'm also suspecting a fuel/air issue like your mechanic.
The pumps are notoriously bad on these, how's your pressure at the fuel rail?
After you do your startup procedure, try listening to the injectors by using a mechanic stethoscope or the ratchet extension trick.

Also black smoke can mean a dirty or bad Mass Airflow sensor. Try cleaning it, use ONLY the cleaner designed for MAFs.

 

[OBSandaNNBS]

That's a lot of info, but start with easy and cheap.

Listen to injectors.
Should all sound the same, a nice click click click...

Clean MAF

TPS
Ensure the Throttle body position sensor is correctly oriented. Also inspect the wires leading to TPMS connector. And pedal sensor (check my thread)

Check crank and cam sensors
Viewing live data on scanner and wiggling wires, noting voltage change, and while running to see if it's "normal" (YT it)
Relearn crank if possible.

If everything checks out then move onto fuel pump

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving clarifying questions and sage advice from the knowledgeable folks on this Forum.

 

[krekelly]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving clarifying questions and sage advice from the knowledgeable folks on this Forum.

Thanks so much for the welcome. I can tell there’s knowledge, experience, and wisdom here. I appreciate yall walking me through this!

Attached are my two Denali’s. 2003 with 200k+ and my 2013 with 155k.

 

[OBSandaNNBS]

View attachment 463192

Thanks so much for the welcome. I can tell there’s knowledge, experience, and wisdom here. I appreciate yall walking me through this!

Attached are my two Denali’s. 2003 with 200k+ and my 2013 with 155k.

Nice trucks!
Okay, time to see what you're made of...which platform do you like more?
Not counting your current frustration, but also weighing in the fact you are having a problem.

 

[Doubeleive]

I’ve got a 2013 Yukon XL denali. It’s got a factory remanufactured engine installed in March. Original vehicle has 155k.

When I replaced the engine, I made sure to get a bunch of new incidentals outta the way. New flex plate, oil cooler hose, serpentine belt, water pump, plugs and wired.

Since May I’ve had an issue with startup and idle. Can’t quite put my finger on it so I’m here. No codes or check engine lights.

When trying to start it up, there are times it won’t crank over. It’ll time out before it stops trying. When it does that, I can pump the gas pedal to get it to fire up. I know it’s not carbureted. But it really is the difference between starting or not.

When that does happen I tend to smell gas as well as burned up fuel. I get a plume of black smoke out the exhaust pipe. That tells me the mix is fuel rich.

Also it takes a little while to let the engine settle. Sometimes the rpm’s will spike up to 3k. Sometimes it sputters and can barely stay running. Other times it straight up dies. If I don’t let the engine settle for a minute or so and I shift out of park, the engine will die.

I replaced the throttle body with a hitachi brand. I went through the idle relearn process, and still had the same issues. Replaced it again with the same brand. I did the relearn again, Gm has confirmed an updated pcm, and I had an idle sweep done.

I’ve had a local mechanic look at it for about an hour or two and he’s thinking a bleeding fuel injector. I haven’t pursued that yet but I’m not convinced. It should be throwing a code and misfiring after idle. But I don’t have any issues after I shift out of park.

What are your thoughts?

did said mechanic perform a leak down test? since he suspected a bleeding injector........

 

[krekelly]

Nice trucks!
Okay, time to see what you're made of...which platform do you like more?
Not counting your current frustration, but also weighing in the fact you are having a problem.

Thanks! I appreciate the design and features of the new one but the old one has been absolute champ. We’ve had it since 2014 and haven’t put more than $2k into it.

This 2013 we’ve had since March of 2024 and put a new engine in it plus about $4k on top of that.

 

[krekelly]

did said mechanic perform a leak down test? since he suspected a bleeding injector........

No but that’s in the cards. I’m gonna try to do do some of the easy and cheap fixes first and then put the injectors through some testing.

 

[krekelly]

The more I'm thinking about this, I'm also suspecting a fuel/air issue like your mechanic.
The pumps are notoriously bad on these, how's your pressure at the fuel rail?
After you do your startup procedure, try listening to the injectors by using a mechanic stethoscope or the ratchet extension trick.

Also black smoke can mean a dirty or bad Mass Airflow sensor. Try cleaning it, use ONLY the cleaner designed for MAFs.

I’m not sure about pressure at the fuel rail. If it’s a pump issue, would it be consistently throughout or only give me issues at startup?

I’m planning on cleaning the MAFs this weekend.

 

[Doubeleive]

I’m not sure about pressure at the fuel rail. If it’s a pump issue, would it be consistently throughout or only give me issues at startup?

I’m planning on cleaning the MAFs this weekend.

it depends on where the problem lies,,, a cold startup or whatever

 

[donjetman]

I’ve got a 2013 Yukon XL denali. It’s got a factory remanufactured engine installed in March. Original vehicle has 155k.

When I replaced the engine, I made sure to get a bunch of new incidentals outta the way. New flex plate, oil cooler hose, serpentine belt, water pump, plugs and wired.

Since May I’ve had an issue with startup and idle. Can’t quite put my finger on it so I’m here. No codes or check engine lights.

When trying to start it up, there are times it won’t crank over. It’ll time out before it stops trying. When it does that, I can pump the gas pedal to get it to fire up. I know it’s not carbureted. But it really is the difference between starting or not.

When that does happen I tend to smell gas as well as burned up fuel. I get a plume of black smoke out the exhaust pipe. That tells me the mix is fuel rich.

What are your thoughts?

If the purge solenoid is working properly it is closed with the key off (during fueling). If it's open (defective) with ign off it will let fuel vapors into the intake and flood the engine, causing hard starts.

 

[OBSandaNNBS]

Thanks! I appreciate the design and features of the new one but the old one has been absolute champ. We’ve had it since 2014 and haven’t put more than $2k into it.

This 2013 we’ve had since March of 2024 and put a new engine in it plus about $4k on top of that.

Aw man, sounds like a point for @OR VietVet!

Sounds like my story on my 97 vs my 2012. I think the 2010-14s are at the age where they start to develop big problems but will be happy for another decade if fixed up.

 

[OBSandaNNBS]

If the purge solenoid is working properly it is closed with the key off (during fueling). If it's open (defective) with ign off it will let fuel vapors into the intake and flood the engine, causing hard starts.

This! The evap system can cause all kinds of weird things. Purge solenoid is easy to replace.

 

[OR VietVet]

This! The evap system can cause all kinds of weird things. Purge solenoid is easy to replace.

Exactly why, when I did the fuel pump on my 05 Tahoe, I just replaced the entire evap system with new.