Engine performance chip

I have a 2004 GMC Envoy with a 6 cyl. 4.2 liter engine. Although its 3.42 ratio rear & towing package, is said to be capable of towing 5,300 lbs, I can not quite maintain 55 mph on level ground in 4th gear while towing my 23 ft house trailer with a loaded weight of about 4,000 lbs.

I am thinking of instaling a variable engine performance chip from: http://www…hip-x2-p-8

They claim the replacement chip can increase HP, then be adjusted down for more efficiency when extra HP is not needed, do no harm to my engine and not void my warranty.

Are their claims accurate and can the addition of this chip give me the extra hp I need to cruise at 55 in 4th gear with my trailer in tow?


You need a V8 truck or a 3.90-4.10 rear axle…That trailer just catches too much wind. It’s aerodynamic drag, not the weight…A computer chip would be a waste of time and money…

What tire pressure is in the trailer tires? You may have to go higher. The trailer has a lot of wind resistance. If you had a smaller trailer with 4,000 pounds in it, the car would pull it a lot easier. You need a more capable vehicle. The performance chip will not help. Consumer Reports says that your vehicle is helpless. They didn’t use those exact words.

I agree; you need a V-8 engine to tow this much. A diesel might not be a bad idea.

As to the link you provided, I got a pretty good chuckle out of the claims and based on some of what they state I would not trust them any further than I could throw them.

Note the horsepower phrase “is UP to…” with the key word being “up”.

I would love to tear one of those widgets apart to see what makes it tick and my feeling is that once torn apart, one would find nothing more than a variable resistor. In a nutshell, it’s a gimmick to try and fool the ECM into providing more fuel to the engine by tricking it into thinking the engine is colder than what it actually is. (done through the ECT or ACT sensor, etc.)
You can do the same thing with a 50 cent resistor from Radio Shack. The problem is that it will not make any noticeable difference in spite of any claims.

You got to love the part about “voiding the warranty”.
Note it says that it will “not void MOST warranties…” and (not a direct quote) “you can remove it for a warranty repair and reinstall it after the warranty repair is completed”.
Very ethical of them.

A little further digging on that site just reinforces my opinion it’s all a scam.
They provide a number of known worthless “miracle fixes” and this adjustable resistor is just one of them.

These chips and the companies that make them get very little respect on CarTalk and they and their products don’t deserve much more than they get.

I can believe that being told your truck and trailer are not compatible is a bitter pill to swallow, but that’s about it. Mind you I am not saying your combination is unsafe,just not prefered.

Wow…that chip looks cheesy! I’m not a big fan of the performance chips in vehicles. From my experience, the systems cost $300 and above. They all screw with the vehicle’s computer. That may mess up your warranty, put more strain on your engine than it should be subject to, and mess with your tailpipe emissions. Not to mention you have to remove the modifications if you bring your vehicle to the dealer for anything. Often dealers reflash the computer with updates when your vehicle is in for any service. If you’ve modified the programming, bad things can happen during the reflash. Even after you remove the programmer, I believe some vehicle computers record that its program was modified. My advice…leave it stock.

You might want to check the Owner’s manual. My 2000 Blazer has a similar towing capacity (5500 lbs) with a 3.42 rear and the manual is pretty clear about towing in 3rd gear. I believe the Blazer and the Envoy both have the 4L60e 4 spd automatic. From the owners manual:

If you have an automatic transmission, you can use
THIRD (3) (or, as you need to, a lower gear) when
towing a trailer. Operating your vehicle in THIRD (3)
when towing a trailer will minimize heat buildup and
extend the life of your transmission. If you have a
manual transmission and you are towing a trailer, it?s
better not to use FIFTH (5) gear. Just drive in
FOURTH (4) gear (or, as you need to, a lower gear).
See ?Tow/Haul Mode? in the Index.

Ed B.

In other words, stay out of overdrive…You can tow all day in third (direct) at 60mph…

Great link to a $5 collection of parts…not worth it in any way. I agree with others, try 3rd, if unsuccessful, you need a bigger truck!

As OK4450, Texases, and others have noted, that site is full of slick-talking smooth selling miracle cures. Save your money.

Not all chips are scams. See: Cobb Accessport for Subarus, and whatever the thing was that the VW TDI people were all excited over. Some cars just respond really well to stuff like that.

That’s the exception, though.