2011 Tahoe random hard starts

[bsmith487]

2011 Tahoe with 220000 miles. Did new plugs coils wires and MAF on 09/26. Everything cranked and ran just fine. Went out to take for a drive a few hours later and it acted like it was starving for fuel. Finally cranked and Stabilitrack warning came on and extremely rough idle. Press accelerator and it rev then acted like it was stalling. Replaced new MAG with old on and it seemed to fix it. Few hours later same thing happened. Disconnected the battery for a few hours. Reconnected and it ran great last night and this morning. Came back this afternoon to drive it and the problem is back again. When it was driving it was great, smooth, no misfires no CEL or anything. I’m stuck on where to even begin looking.

 

[blondie70]

Try checking the fuel pressure.

 

[swathdiver]

Gotta get a scan tool on this and check for codes, view failure records and check fuel pressure and MAF/MAP readings against the manual for starters.

These vehicles do not take kindly to aftermarket parts.

Why did you replace the coils and MAF in the first place?

 

[bsmith487]

Started fee

Gotta get a scan tool on this and check for codes, view failure records and check fuel pressure and MAF/MAP readings against the manual for starters.

These vehicles do not take kindly to aftermarket parts.

Why did you replace the coils and MAF in the first place?

started having random low idle and random slow starts coupled with feeling what felt like misfire. Has 220000 miles and idk when the plugs coils wires were changed. Changed the MAF with OE parts as well

 

[swathdiver]

Coils often last the life of the vehicle. The plugs and wires ought to be changed every 100K miles for Iridiums. We don't normally change mass airflow sensors unless they fail.

In my own stable, we do clean the MAF and throttle body once a year on each truck.

Do you have an OBDII adapter to check codes and view live data?

 

[bsmith487]

Coils often last the life of the vehicle. The plugs and wires ought to be changed every 100K miles for Iridiums. We don't normally change mass airflow sensors unless they fail.

In my own stable, we do clean the MAF and throttle body once a year on each truck.

Do you have an OBDII adapter to check codes and view live data?

Ive got one of those topdon bluetooth
OBDII plugs on the way from amazon. Should show live data as well. I still have the old coils and everything in a box ready to go to the trash. Would you recommend putting the old ones back on and see if anything changes.

 

[swathdiver]

Ive got one of those topdon bluetooth
OBDII plugs on the way from amazon. Should show live data as well. I still have the old coils and everything in a box ready to go to the trash. Would you recommend putting the old ones back on and see if anything changes.

Keep the coils and use the TopDon first before swapping them back as part of diagnosing the problem.

 

[mikez71]

Might check your coolant temps as well.
Think I've heard of a bad ECT causing hard starts before..

 

[Fless]

Went out to take for a drive a few hours later and it acted like it was starving for fuel. Finally cranked and Stabilitrack warning came on and extremely rough idle. Press accelerator and it rev then acted like it was stalling.

What do you mean by "finally cranked?" Were you trying to start it after the engine died, and didn't the starter turn it over ("no crank")?

Or was the starter turning it over but it didn't fire? "Crank no-start."

 

[bsmith487]

What do you mean by "finally cranked?" Were you trying to start it after the engine died, and didn't the starter turn it over ("no crank")?

Or was the starter turning it over but it didn't fire? "Crank no-start."

Long crank and start. Always starts but when it does long crank and start I’ll also get the stabiltrack warning and rough idle as well as when you press accelerator it’ll rev then nearly stall out. All this seems to clear out if I disconnect the battery for 30 minutes to an hour. None of the issues have happened thus far today. Each time I’ve started the Tahoe it cranks and starts right away and runs smoothly.

 

[Fless]

You could have a leaky injector that is saturating one bank, or an intermittent purge valve on the engine. Next time it cranks but doesn't start (do a short crank to see if it's going to give you trouble) use clear flood mode by flooring the accelerator while cranking. If it starts right up, it's probably getting flooded. Clear flood mode turns off the injectors.

Also monitor the engine coolant temp to see if the sensor is giving false readings.

I don't think this is the cause but, to rule it out, do a CASE relearn with a capable scan tool to sync the cam and crank sensors. If they're out of sync it can cause long cranks.

 

[John H Daniel]

Before spending a bunch, check your engine bay fuse box. I got random poor running, shut off, weird light issues. Some fuse connections were corroded. There are Youtube vids on how to disassemble, not too hard. This is what mine looked like.
Its a 2011 Yukon w 210,000mi.