Hey guys, I have a 91 z28 5.0 5 speed. It has a hypertech thermomaster chip that came with the car when i bought it. Other then underdrive pulleys, no cats, and a flowmaster muffler the car is pretty much stock. I was told that the hypertech chip plugs into the stock prom then into the ecm (or the other way around). Is this true? I was thinking about taking the hypertech out and seeing how the car runs. I was also told the car has a lower cooling fan switch. It has the stock temp thermostat in it, not the 160 that is recommended. I was having rough idle issues like many others on this forum were, and went crazy replacing many parts (tps, IAC, cts, recently new bosch 3 injectors and egr valve). Car def runs better especially bc i checked the base timing and it was at 0 degrees. Changed that to the stock 6. Should i just leave the hypertech in or should i try the stock one?? Thanx for the info!

 

Put the stock chip back in untill you get a 160 thermostat
the hypertech is looking for a 160 operating temp but is getting messed up because your car is running at 195.

 

so can i just take the hypertech out? or do i have to go out and buy another prom? and also can i put a 180 in instead of a 160?
thanx

 

First of all, you need atleast the stock chip in there to run at all. If you take one out you have to put another one in. If I am not mistaken, the Thermomaster is supposed to work in conjunction with a 160 degree thermostat. I also believe it is the Hypertech Street Runner chip that is supposed to work with a 180 degree thermostat. I have used all three, (stock, Street Runner, and Thermomaster) I have a 160 degree thermostat and a few other upgrades. Recently I ran all three of them at the drag strip (letting the computer relearn each time). I got my best time with the thermomaster. Coincidence.... maybe. See what works for you, I am looking into getting a custom chip burned for my particular application.

 

right i understand that you need some sort of chip to run, but is my stock chip still in the ecm? In other words do you still use the stock chip in conjunction with the hypertech? bc if it is still in there i will just take the hypertech out and see how it runs. thanx

 

Your engine's "computer" only has one chip. Either stock one or replacement one. You can't have both. Have you pulled your ecm out to look at it? It will help alot to understand.

 

My JET offroad chip plugs into the stock chip. Most aftermarket chips now work injunction with the stock chip. So you do have two chips in there.

In this pic, the chip with prongs plugs into the side of the blue calpak chip
http://img.sportruck.com/howto/chips.jpg

 

i pulled the ecm a couple of months ago and i do recall seeing the hypertech and something blue under it. im gonna have to pull it again and see what the deal is. i was under the impression that the hypertech plugged into the stock one but im not totally sure. if i do end up needing a stock one where is a good place to get one?

 

I could be wrong here,but I believe that the custom chip uses an adaptor to connect to the ecm, the stock chip does not need an adaptor. Either way you can only run one chip at a time.
As far as stock chips go, your local GM dealer may be able to get you a new one,
or look at the classifieds here someone may have a used one for sale.

 

just pulled the ecm and it turns out the stock chip plugs into the hypertech then plugs into the ecm, so i seperated the two and plugged the stock one in and it fired right up seems everything is ok.