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.


Y
ou 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.
Added freon, cold on driver side, blows warm on pass side, now all warm
2001 trans has code P0753, no 1st gear, starts in 2nd. 1-2 shift solenoid
A few other Chevy questions.
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Chevrolet Tahoe 2003 Hard To Start