LS surging idle throttle blade hole

[K5Rob]

Hey guys I have a 5.3 LS in my K5 Blazer with a mild cam and a 3200 stall converter. This motor was in my 04 2wd that I had for years and it worked great but would surge at times, during idling or shifting into reverse in some cases and kind of almost stall but maybe very very rarely actually stall out. I did have it sort of base tuned by a local guy with a good reputation but it was expensive and Im not sure he even did a whole lot as it was driveable on the stock tune as it was. Fast forward to now and I have everything from the 04 in my K5 and it surges, and stalls, bad. I drove around the block a few times and it kind of seems to be learning itself out (same PCM as before) so IDK if it will be a self correcting problem but I have read, and maybe this is with more aggressive cams, but people are drilling a small hole in the throttle blade and claiming it completely rectifies their surging problem. Does anyone have more detail on this as I am willing to try it rather than pay a tuner. Also I dont know how much drive time is appropriate for the computer to learn these auto correcting behaviors so if anyone could chime in on that angle that would be awesome as well.

 

[TotalyHucked]

Those Gen3 computers will learn a little bit, but it's not "self learning" like aftermarket computers do (they also only do so much, they also benefit from a good tune from someone that knows what they're doing). The actual fix is to get a good tune put in it. My '05 is doing exactly that right now but I'm just on the initial base tune that my tuner loaded to get the engine broken in. Surges, stalls out, tries to die alot. But he literally just uploaded a basic file so I could put some break in miles on it.

For a good, full tune, some street miles need to be done. Part throttle, idle, AC on and off, full throttle, steady state cruise, all of that needs to be covered while tuning. Plain and simple, you need a better tuner that knows what he's doing. The hole in the throttle blade is a bandaid, not a fix.

Get in touch with my buddy Eric, he can work with you to get a remote tune done. It's not cheap, but it's the right way to do it. If you want to actually enjoy your truck, this is what's needed. He'll need to know full engine and cam specs, transmission, tire size, gear ratio, injector size, etc. But he's the best guy we've got around here, has a full machine shop/builds engines, flies all over the country tuning all kinds of stuff. He's the man.

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[Chevy 88]

Would the previous tuner guy do a free checkup on his work? I would call and see what he will do for free.

 

[K5Rob]

Would the previous tuner guy do a free checkup on his work? I would call and see what he will do for free.

Probably not at this point. This was prob 6+ years ago.

 

[Zelph]

What are the cam specs?

 

[K5Rob]

What are the cam specs?

209/[email protected]
261/270 advertised
.550/.550 lift
112 lsa

 

[Hunter79764]

That doesn't seem like a big enough cam to cause that many issues, looks like the Summit Stage 1 truck cam? I'd make sure your IAC and passage is clean, maybe run some SeaFoam through the intake, and general tune up stuff. Any chance you have a bad cam lobe or a burned valve etc?

 

[K5Rob]

That doesn't seem like a big enough cam to cause that many issues, looks like the Summit Stage 1 truck cam? I'd make sure your IAC and passage is clean, maybe run some SeaFoam through the intake, and general tune up stuff. Any chance you have a bad cam lobe or a burned valve etc?

Yes summit stage 1 cam, very mild cam. Iac could be dirty but everything else checks out, i do have a 3200 stall converter as well. I did have sort of a surge with the old truck but very rarely would it stall. And with this truck within 15 minutes of driving around the block It got way better but would still stall. I dont know if more driving is the ticket. If i could just drill a hole i would prefer to do that than revisit the tuner, i know its not correct, i am just very frugal.

 

[TotalyHucked]

I'm tellin ya, that's not the fix. It has a garbage tune in it. These computers don't "learn". They'll adjust a bit, but they don't learn enough to go from what you're describing to drivable.

 

[K5Rob]

I'm tellin ya, that's not the fix. It has a garbage tune in it. These computers don't "learn". They'll adjust a bit, but they don't learn enough to go from what you're describing to drivable.

Okay Hucked, thank you. I will explore the tune option

 

[Hunter79764]

I'd talk to the tuner, he should be willing to drop a stock tune in there and see what it does. A bone stock tune and that cam should be more driveable than you are describing, unless you just have the idle RPM set way too low? Tuner's often are willing to revisit old tunes for minor stuff. I'd start there for sure.

 

[Zelph]

In addition to the above I would look at the fuel supply.
From your description it sounds like a starvation could be the cause.

 

[Chevy 88]

Probably not at this point. This was prob 6+ years ago.

Might be worth a phone call. Someplace offer a lifetime warranty on stuff.

 

[Honest Bob]

Have you checked for vaccum leaks?

 

[K5Rob]

Have you checked for vaccum leaks?

I have not, Would anyone know where the port on an LM7 is that I can hook a vacuum gauge to?