Bad fuel pump, sensor and assembly

[didjital|]

So I had a check engine light get thrown up at me over the weekend and I took the car into the dealership. Turns out a bad fuel pump, sensor and assembly was the cause. The PCM was reading the sensor incorrectly saying the tank had 3/4 tank in it when it only had just about a 1/4.

The car before this would sporadically idle a little rough but nothing too bad. Now that the problem is fixed the car is running great, no idling issues of any kind now. This leads me to what the service guy said next, and that is by cleaning the throttle body out and flashing the PCM it would make the car run even better.

Are there any tips/tricks on removing the throttle body? things to look out for, things that may break on removal, etc...? What would be the best agent to use too scrub the throttle body out with?

Secondly, how would just flashing the PCM actually make the car run better? I'm of course very familiar with the SCT xcal's but right now I don't run any custom tunes... I was just curious why flashing it back to stock like it already has been would benefit how the car runs?

I wasn't going to shoot myself in the foot and tell him that the Xcal2 is at home and has been used (but since went back to stock tune)... is he just poorly trying to upsell a service at that point? Just struck me as odd.

Thanks guys.

 

[Jim Henderson]

My car is still under warranty so I have not done any of this work on it so my comments are in general.

Depending on your miles, cleaning the Throttle Body might be worth while. The main difference you may feel is idle and off idle smoothness.

You can easily clean your TB at home if you have reasonable mechanical skill If you can do brakes, you can probably do a TB. Only gotcha I can think of is that the LS is a drive by wire throttle so the throttle position sensor might be finicky. I do NOT know if this is true but it is something I would wonder about and hope one of the guys who does know talks about it.

The key to cleaning modern TBs is that MANY have a plastic coating kind of like teflon to keep deposits from sticking. Some cleaners will eat this coating. Once the coating is gone, the TB gets dirty more often. So check that the cleaner is safe for plastic/polymer etc coatings. The can will usually state it is safe.

You need to remove the TB from the car, usually not difficult. Mostly have to remove plastic trim pieces and air intake ducting and sometimes water coolant hose from from the TB. You can spray the TB and use toothbrush to clean most of the TB. Spray into any small passages and if you have compressed air blow it out, watch your eyes. There is one passage often on a TB that is the main one you want to clean. I don't KNOW on the LS, but it is usually about 1/2 inch diameter or so and centered usually low between the two bores of the TB. It either has a small valve or flapper. This needs to be cleaned out since it is the Idle air control valve and affects slow idle and the transition from idle to part throttle. A dirty one can cause rough idle or a stumble off idle. The flapper or valve has to be able to move freely.

The LS had some issues with the transmission which sometimes was fixed thru a reflash. I don't know about engine issues that need flashing but usually they have to do with drivability and smoothness. Normally a reflash for drivability is a free or cheap service since it is really a fault with the original program. I have read that if they think you have reflashed it yourself with a tuner, a lot of dealers will wash their hands of any flash issues.

Good Luck,

Jim Henderson