My 2003 Chevy Tahoe truck has rough idle at idle speed. What causes that and what is the best way to take care of it? And what is the best way to get more horse power without putting a lot of pressure in the engine. In other words I don't want to kill my engine prematurely. Thank you.
Answer: There are several common things. It depends on when the problem happens. Does it run rough cold or is the engine hot? This makes a big difference in helping diagnose your problems.
1. Upper intake manifold gaskets could be leaking vacuum. This rough idle on your Tahoe happens when the engine is cold only. The intake manifold gaskets shrink when cold and expand when hot. So, when the engine warms up the rough idle will go away and the engine will run just fine. GM redesigned the gaskets to prevent this from happening. So replacing them will fix your problem. The old style have green rubber in the ports and the new ones are orange.
2.Throttle body may need to be cleaned. Carbon buildup in the throttle will cause a rough idle as well. This can happen hot or cold, but will be worse when warmed up. Cleaning the throttle with a rag and some carb cleaner will usually take care of this problem. That is as long as there are no codes for the throttle stored in the computer. If there are, it may need to be replaced. There was a recall on these, so if you call your local Chevrolet dealer and give them the VIN number of the truck they will be able to tell you if the recall applies.
3. Possible injector problem, or leaking fuel pressure regulator-leaks gas into the vacuum line. When the fuel pressure regulator (FPR) leaks gas into it's vacuum line this causes a very rich condition and a rough idle. You may also have a check engine light on. Replacement of the regulator is very simple. Just relieve the fuel pressure by pressing in the pressure tap pin, then remove the snap ring that holds the fuel pressure regulator into the fuel rail.
4. Also, if it has not been to the dealer in a while, there may be a PCM (powertrain control module) update available. Module programming updates are released often and may take care of the idle on your Tahoe. This would not be a free service since it is not a recall, it is just a service bulletin that the mechanic can perform to possibly fix your conditions.
You may have many different concerns with many different systems. Need to have the system scanned to check for trouble codes and view all the different parameters by a mechanic to get to the bottom of the problem, but checking the things above should take care of it.
For getting more power out of the engine, there are many things that can be done. First do a complete tune-up with quality parts. Use a good fuel system cleaner and always use name brand gasoline. There are many performance kits that you can buy such as a larger MAF sensor, PCM repgramming, etc. Just search online and you will many different options. Dont worry about putting too much pressure or whatever you mean in the engine, that Chevy engine can take it. It is a very durable engine and should last you a long time assuming you take care of it properly.