magnuman

I have a 1989 4x4 Chevy Silverado 2500 HD truck(extended cab, full bed) with a 350 Engine.
The transmission does not have overdrive.
When I bought the truck last year it had already had a Hypertech chip in it with a K&N Filter. It towed my boat fine, but I have always had some concern with the engine temps running high.

Since buying it I have also added Doug Thorley headers.

Recently, I had a tune-up performed and the truck has not had the same power. It also seems as if it's shift points are not the same.
The engine temps have even beeen running higher too.
After doing some of my own research, it seems that when you tune your truck, the Hypertech chip needs to be taken out and re-installed after the tuning. This was not done and I don't have the original chip. Also I saw on the Hypertech web site that they have a low temp thermostat which I know I don't have in my truck. I also noted that modifications like headers can affect the chips performance also.

What needs to be done to get the chip working properly again?
Or do I need to use a different chip with the header modifications?
I believe the chip model is a G7.
Is this the right chip to be using and should I add the Hypertech low temp powerstat?
Or, should I abandon this chip and use another manufacturer that performs better?

The truck and engine are in perfect shape. It has always been used as a third car/truck and has hardly any miles on it.

I would appreciate any help from the board.

Thanks.
Magnuman

magnuman

Thanks,

The truck does have the throttle body fuel injection and I also have a large tranny cooler.

The actual chip product number from Hypertech is 129152.
When I called Hypertech this morning they said that that chip should work fine with the headers. Although they did say to tune the engine, the original Chevy chip needs to be in to set the timing correctly. After that is done, the Hypertech chip needs to be reinstalled.

Do you know if this is the same procedure for the Jet Performance chip?

I also really appreciate those service bulletins. The recall work has all been done and I'll have to check the maintenance records for any of the other problems.

You would not believe the maintenance records that I got with the truck. The former owner was an major airline pilot and he kept records as if it were a jumbo jet!

ragtop409

magnuman

Did that fix the problem with your truck? My buddy is having a simular problem with his 1987 4x4 Chevy Silverado 2500 HD truck(crew cab, full bed) with a 454 Engine. Anything else you find out would be appreciated. Thanks Charlie

magnuman

I will know utimately on Thursday and will post, but here is what I found out today.

Unfortunately, I didn't have the original GM chip for my truck. So, I had to order one which will come tomorrow.

You need to remove the high performance chip and reinstall the original factory chip to set the timing. You cannot set the correct timing with the performance chip in the truck. After that all you need to do is plug the performance chip back in.

I was told by Hypertech that my headers won't affect the performance of the chip that I have.

I also called Jet Performance and ultimately ordered a new stage two chip from them. You still must set your timing with the stock GM chip with Jet.

The Hypertech chip needs to be used in conjunction with their low temp Powerstat (thermostat). I believe this is a 130 degree thermostat. I did not have this in my truck.

I was also told the Hypertech chip operates at the top end of the power band. This is great if your driving is mostly high speed, whereas the Jet Performance chip operates at all levels of the power band.

It is also recommended that you use a lower temp thermostat with the Jet chip. It is either a 150 or 160 degree thermostat.