I took my Z28 to the mechanic to figure out why it was hesitating off idle, and after a week or so he said that it was the computer not matching up, and that we would have to either have a blank computer bought and reprogrammed by Chevrolet, or try to wipe my current one(if that was possible). This is all because I swapped a 96 LT1 into a 94's body.

Does this make sense? Has anyone had this problem before? Is wiping the current computer instead of buying a new one possible? Is my mechanic full of crap?

Thanks for any help.

 

When you put in the 96 motor did you use your knock sensor from your 94?

That is the only place you would have any trouble with the computer. Any extra sensors the 96 has will simply be ignored. I am running a computer from a 95 car in my 97, basically the same thing you are doing. onlything to worry about is the knock sensor.

 

It might still be using the 94 knock sensor, since that is the code it's throwing from the SES light. Could the old knock sensor be causing the hesitation? A new computer and reprogramming it by the chevy dealership was quoted around $1000~.

Thanks for the help, btw.

 

You are using the computer from a 94?

If you are then then you want to be using the knock sensor from the 94.
94 knock sensor is a different resistance than the 96 knock sensor, so the the different computers look for different signals depending on which yeah it is.


What ever you do dont pay $1000 for a new flash. All they will do is put the stock program in it. You can buy a computer for about $100 online, or you can send the one you have to Ion (www.madz28.com).

 

I wonder if the knock sensor not matching up is causing automatic retarding? Do you think this could be causing the hesitation?

 

If you have the code for the knock sensor, the PCM is defaulting to a programmed calculation that figures retard based on other sensor parameters. You will see knock retard almost all the time, and up to 15-deg at peak. You would definitely feel that.

You need to answer the question people are asking.... WHAT YEAR PCM ARE YOU USING? Its just making it harder for people to help you when you don't give all the info up front, and don't answer the questions.

 

Sorry. I figured people would take the '94 body to mean 94 computer, too. But, yes. It is still a 94 computer, I believe (Not 99.9% sure). Also, the SES is returning code 43 for the knock sensor, but the first mechanic I took it to said the knock sensor was working . Do you suggest updating the knock sensor first?

Sorry again, I can be braindead at times, but thanks for any help.

 

If you are still using the 1994 computer, you need the knock sensor for a pre-1996. The sensors changed in 1996 to be compatible with OBD-II (you have OBD-I with the 1994 computer). Get the compatible knock sensor.

 

eeg3,
The knock sensor in question is not part of the computer (PCM) it is mounted into the block. If you pulled the motor from a 96 and didn't replace the knock sensor on the block of the 96 motor, then you have a 96 knock sensor and need to replace it with a 94 type knock sensor. You will have to drain the coolant to do this, but it can be done in your driveway with jackstands or ramps.
Read the information and questions provided by Shoebox and injuneer very carefully. They are both VERY knowledgeable and VERY detailed.
good luck,
Steve

 

The knock sensor is GOING to work, but it's not going to work PROPERLY.

 

The mechanic I took it to said "the wire coming from the 94 computer could not connect to the knock sensor in the engine, and that there was no way to change the knock sensor," and that he was going to take it to the Chevy dealership to see if they think swapping computers will help...

Listening to you guys, he's full of crap, I guess? He's had my car for 2 weeks jerking me around. I guess I should take it somewhere else. Is it harder/more expensive to swap computers to match the knock sensor or to swap knock sensors to match computers? Moreover, will this knock sensor mess-up cause the car to take it a second or two to get power and start moving (hesitation), because that is originally why I took my car to the mechanic to get it fixed.

Everyone here is helpful and knowledgable, and I thank everyone very much for their help.

 

So you are using the knock sensor that came with the 96 engine???

 

Yes. The knock sensor was not replaced in the 96 engine when it was swapped in. Computer = 94; KS = 96; Engine = 96

 

ok, you need to either pull the old Knock sensor from your old engine, or go buy one from the dealer.

If you have to go buy one, just tell them you need a knock sensor for a 94 z28, dont say anything about it being a 96 engine taht will probably confuse the hell out of the parts guy.


The knock sensor is located on the passenger side of the block. The sensor doubles as a plug for the coolant, so when you remove it coolant will come out so be ready with the new one and thread it in there as quick as you can so you dont lose much coolant.

Replace the knock sensor before you mess with anything else, it may not be the only thing contributing to your problem. but it for sure is needs to be changed.

 

If you need a little help finding it here it is. This is looking at the passenge side of the block from underneath the car behind the front tire.

http://shbox.com/1/ks.jpg