Figured I'd Share My Frustrations

CoffeyLover · January 6, 2012

So I have a 2003 Silverado 1500 with a 6.0 swap (originally a 4.8) and have had one problem lately that has been making me crazy.

I experience a bit of a hesitation in the motor when cruising at 45 or 65 mph, mostly around 1800rpm in 4th. It happens when I am not gaining speed, but just maintaining an even speed. The motor is brand new as well as the trans and the rear end, so I am pretty positive these are not the culprits. I have pulled the codes and returned nothing. I was told it could be bad plugs or wires, so I replaced both (plugs were new with the motor swap, but I put new ones in again). I opted for MSD wires over OEM, due to price and reviews I read about the MSD ones. Plugs are AC Delco, as I have heard not to touch aftermarket plugs. My next thought was the fuel pump, so I bought a brand new AC Delco pump and pressure regulator. I have yet to install these due to bad timing. It seems whenever I finally have the time to do it I have a full tank and my bed is NOT easy to remove. So this could theoretically still be the issue. I just read tonight that a bad TPS can also cause this, and I just ordered one from Amazon (only 30 bucks so why not). Does anyone have any other ideas? It isn't a big problem but enough of one to annoy the h*** out of me.

Some more info: Although I do have a built trans (shift kit and the works), the 1-2 shift does seem to be a little bit harder than it should. I have heard a bad TPS can cause this as well. Most of the truck has 150k on it, besides motor (along with knock sensors, wiring harness, and some other acc), trans, and rear-end. One of my catalytic converters decided to fail (sounds like a tin can flopping around inside it, no cutting cats out due to CA smog) but I don't think that would cause a problem. I just put 2 new O2 sensors in (before cars). Let me know if you need more information.

Thanks guys! Love the forum and look forward to some advice or thoughts!

jro909 · January 6, 2012

torque management

not trying to be a dick but why did you spend the money to do all the swapping instead of just getting a truck already equiped with the 6.0?

CoffeyLover · January 6, 2012

What about torque management?

And because the quantity and quality of everything on this truck is so amazing. It would take at least 20k into a new truck before it would even begin to compare to what I can do with this one. Hard to understand if you're not an off-road guy like I am. Being able to blaze 60mph + down a dirt road with two-foot whoops all while blasting the A/C and stereo is my joy and passion. In the end everything comes down to money, and I'd rather spend 7k in a motor than 20+k in suspension and framework. So no offence taken

Daryl LBZ · January 6, 2012

torque management

not trying to be a dick but why did you spend the money to do all the swapping instead of just getting a truck already equiped with the 6.0?

Some people like what they already have maybe?

Gurrzt · January 6, 2012

Some more info: Although I do have a built trans (shift kit and the works), the 1-2 shift does seem to be a little bit harder than it should.

If you have an aftermarket shift kit and use the number 2 or 3 washer (I am speaking of what I have read) you will get a firmer shift, also a common upgrade to a built transmission is performance 2-4 servo (located on the transmission housing), this will also increase the 1 to 2 shift.

Torque management "pulls" or retards timing just before the transmission shifts to not damage the transmission (or so GM says). The most common thing to do is to have it deleted.

music · January 6, 2012

I experience a bit of a hesitation in the motor when cruising at 45 or 65 mph, mostly around 1800rpm in 4th. It happens when I am not gaining speed, but just maintaining an even speed.

Smooth/rough driving surface?

When you say "45 or 65", do you mean "45 to 65"?

Describe "hesitation" a bit more. How long does it last, how much power is lost, etc.

redjewel2ss · January 6, 2012

is the tune stock?

i would guess TPS also seeing as its not during acceleration.

CoffeyLover · January 6, 2012

I guess I'll have to call the guys that built the trans for that.

I don't think torque management is present in tthe 03 models??? I could be wrong.

I mean 45 or 65. Basically juat cruising, not accelerating. By hesitation I mean as youre going it feels like a misfire. Or as if someone taps the brakes for a split second.

The tune is not stock, it was done by Justin are Blackbear Performance.

Stevens03 · January 6, 2012

I'm not much help, but the 03's did have torque management controls

CoffeyLover · January 8, 2012

Hmm well I'll have to send an email off to BlackBear to see if mine is still there.

I'll keep everyone posted when I change the TPS and fuel pump.

silverado_lover · January 8, 2012

Definitely sounds like a fuel issue

Badass truck man, my next truck will be getting LT suspension hopefully

not trying to be a dick but why did you spend the money to do all the swapping instead of just getting a truck already equiped with the 6.0?

Most trucks equipped with a 6.0 are 2500s which are a good bit heavier and if you look at the OP's sig he has done some pricey suspension work so I doubt he would want to do that all over again.

grampadirt · January 8, 2012

Just thinking out loud here....have you cleaned your MAF sensor?Have you checked for vacuum leaks?A vacuum gauge(and someone who can read it)can tell a lot about how an engine is running.Ask one of the older guys at Bohan's..

BTW,I live in Santa Clarita too and have seen your truck around...very cool.I drive around our valley delivering auto parts,maybe you've seen our shirts & sweatshirts on most of the area's mechanics...does Fast Undercar ring a bell with a pretty cool graphic pic of old hot rods?Both Bohan's & Reeves use our parts.

CoffeyLover · January 8, 2012

Just thinking out loud here....have you cleaned your MAF sensor?Have you checked for vacuum leaks?A vacuum gauge(and someone who can read it)can tell a lot about how an engine is running.Ask one of the older guys at Bohan's..

BTW,I live in Santa Clarita too and have seen your truck around...very cool.I drive around our valley delivering auto parts,maybe you've seen our shirts & sweatshirts on most of the area's mechanics...does Fast Undercar ring a bell with a pretty cool graphic pic of old hot rods?Both Bohan's & Reeves use our parts.

I put a new MAF sensor on it before I had the motor done, but I'll have to check it. Maybe I'll have Kenny at Bohan's do a vacuum test on it.

Thanks man it's the love of my life And yeah I have purchased quite a few parts from Fast Undercar, very cool. Glad to see another person from SCV on here!

gmtech4 · January 8, 2012

put a exh back pressure gauge after the messed up cat and see what the pressure is ,maybe the outlet is plugged and the engine cant breathe causing bad things to happen,no power etc

yukon_denali_05 · January 8, 2012

I would also venture to say that you have a fuel related problem. When was the last time you did a tb clean? Try throwing a bottle of b-12 too. It does wonders. Had similar issue with mine. It's hesitating at 4th and 1800rpm because you are most likely under powered at that speed so it's starving for fuel.