Cold Start Issue - Possible Injector Replacement

[Nitrousbird]

56 minutes ago, midwestdenaliguy said:

Thanks for sharing. Did you have the programmer or did you take it in for coding? I'd have to take mine in and have it done, so wondering if that drive to the dealer without them programmed would hurt anything. 

It's a $30 cable and free software, so I did it in the driveway with my laptop.  You just code this with INPA; pretty simple process (hardest part is getting all the software setup on the laptop, which I did years ago for various other coding tasks). 

[midwestdenaliguy]

1 hour ago, Nitrousbird said:

It's a $30 cable and free software, so I did it in the driveway with my laptop.  You just code this with INPA; pretty simple process (hardest part is getting all the software setup on the laptop, which I did years ago for various other coding tasks). 

Looks like INPA is exclusive to BMW. I get what you're saying though, I'll have to do some research to find the software I need for my L86 engine (6.2L).

[tbarn]

GM injectors are install and go. No programming or matching required.

[Nitrousbird]

41 minutes ago, midwestdenaliguy said:

Looks like INPA is exclusive to BMW. I get what you're saying though, I'll have to do some research to find the software I need for my L86 engine (6.2L).

Oh yeah, INPA, Tool32 and NCS Expert are all BMW-only (and free) coding tools.  I was only mentioning my direct experience with DI injectors.

 

I do find it funny that GM doesn't make you code for the injectors.  The reason is to get the exact flow rate for each injector into the ECU.

[tbarn]

Maybe they have a better system.?

[midwestdenaliguy]

After quite a bit of research on this tonight, it appears GM took the stance of making 3 different types of injectors for this platform as opposed to using an injector that can be programmed for flow rate. GM offers 'nominal' flow, 'high' flow, and 'low' flow injectors. The L86 for my Sierra Denali came with the nominal flow injector installed from the factory (now part # 12668393). I'll be ordering a set of those to swap them all out (if 1 has gone bad I'm assuming others will follow in a short period of time).

[SS502]

7 hours ago, midwestdenaliguy said:

After quite a bit of research on this tonight, it appears GM took the stance of making 3 different types of injectors for this platform as opposed to using an injector that can be programmed for flow rate. GM offers 'nominal' flow, 'high' flow, and 'low' flow injectors. The L86 for my Sierra Denali came with the nominal flow injector installed from the factory (now part # 12668393). I'll be ordering a set of those to swap them all out (if 1 has gone bad I'm assuming others will follow in a short period of time).

Curious why they would put "nominal" flow in the 6.2?

[tbarn]

Just curious, did you pull the intake to check the part numbers? I know the GM parts catalog cannot discern which of the 3 available injectors is used in any given 6.2 engine. 5.3 L83's all use the same injectors.

[midwestdenaliguy]

1 hour ago, SS502 said:

Curious why they would put "nominal" flow in the 6.2?

I haven't found an exact answer on that yet, I got that info from an online source. I'm going to confirm the flow rate with another contact I just made that knows quite a bit about the L86. I'll let you know what I find out.

2 minutes ago, tbarn said:

Just curious, did you pull the intake to check the part numbers? I know the GM parts catalog cannot discern which of the 3 available injectors is used in any given 6.2 engine. 5.3 L83's all use the same injectors.

No I got in touch with an injector wholesaler who uses your vin to confirm the part # you need. I recently sold my Wrangler so the truck is my only vehicle at the moment and weekend's are busy, so I don't have time to pull the intake to confirm part #'s. Here's a graphic that the wholesaler sent me that matches against injector part # 12668393 (the injector I need):

 

[midwestdenaliguy]

So "what is the difference between all 3 flow rates" is being asked in many GM forums - corvette and camaro talk about it the most (which makes sense because they're most likely tracking/racing them). It's being asked for both the 5.3 and 6.2 GDI engines. The only real answer I could get searching many forums, google, and talking with a couple guys is that there is very little difference between low, nominal, and high flow rates in these injectors. HP/performance is *slightly* gained across these GM injectors. If you really want the most performance out of your engine you'll have to go aftermarket and do more than just swap out your injectors (performance throttle body, headers, etc.). Interesting enough, us L86 guys have no choice but to install GM injectors. There is no aftermarket option out there. I tried multiple racing sites, the bosch site, and spoke to one tech who said he's not aware of any for the L86.

 

The most important factor to keep in mind if you decide to change them out is to make sure they are flow tested and matched to be within 1% of each other. No one seems to have the definitive answer as to why GM made 3 different flow rates for the 6.2L GDI engine. 

Edited January 7, 2019 by midwestdenaliguy

[SS502]

21 hours ago, midwestdenaliguy said:

 Interesting enough, us L86 guys have no choice but to install GM injectors. There is no aftermarket option out there. I tried multiple racing sites, the bosch site, and spoke to one tech who said he's not aware of any for the L86.

That is odd since the L86 was used a lot in development of aftermarket parts for the LT1 crowd. I believe you just seems weird but with different intake and exhaust manifolds and of course the tune guess it makes some sense.

[midwestdenaliguy]

4 minutes ago, SS502 said:

That is odd since the L86 was used a lot in development of aftermarket parts for the LT1 crowd. I believe you just seems weird but with different intake and exhaust manifolds and of course the tune guess it makes some sense.

I agree, I was just as surprised. We just need someone to get aftermarket injectors for an LT1 and try them in their L86, maybe you SS502???  ;-)

[SS502]

1 minute ago, midwestdenaliguy said:

I agree, I was just as surprised. We just need someone to get aftermarket injectors for an LT1 and try them in their L86, maybe you SS502???  ;-)

?

[cpttimerestraint]

I would check with your dealer. BG includes a warranty on your injectors with the service. I think it is either $1k or $2k towards the replacement of injectors.

Sent from my Moto G (5) Plus using Tapatalk

[midwestdenaliguy]

1 minute ago, cpttimerestraint said:

I would check with your dealer. BG includes a warranty on your injectors with the service. I think it is either $1k or $2k towards the replacement of injectors.

Sent from my Moto G (5) Plus using Tapatalk
 

BG didn't foul them up, they were already going bad. All the tech would have to do is check my code history and see they started before the BG service. BG has actually helped, the cold start issue doesnt happen as often, my mpg's have gone up, and the throttle response is better. I've got a bad injector or two so I'm just replacing them all before they get worse. Also, this is a good chance to see how much (or little) the BG service actually cleaned the back of my valves since I'll have the intake pulled off.