To everyone on this forum, it is nice to be here in the hopes that maybe someone can help me with an issue on my new(to me) 99 ZR2. Here is what is going on....

I went and bought this vehicle and it was running great. Of course once I got it home I began to have issues of course. On the highway and even on residential roads the truck was missing, idleing rough and stalling out on me. May I also mention going through A TON of gas. I figured I was getting about 6-7mpg even highway. Finally it gave me a code.."Engine Coolant Temp Circuit high input". My next course of action was replacing the engine coolant temp censor, which I did. Immediately after doing this I noticed a big difference in how the truck was running and the missing and stalling stopped. I had everything figured out or so I thought...

At that point I began to notice that while although the sensor replacement solved some issues I am still having others. Mainly rough idle, especially at startup or while putting the truck into gear and still going through a ton of gas. With the sensor replaced I figured that now I am getting 10mpg and that is with very very easy driving. I am also getting a "system too rich" code for both banks 1 and 2. Apparently there is another issue going on here which is causing the truck to eat gas like its nothing. At this point I don't quite know which direction to go.

From what the last owner told me the spider injectors were replaced, tps and map sensors were replaced and it has a new catalytic converter. The EGR also appears to be newer although I can't quite confirm that. You can definently tell that the top of the engine is very clean and has been worked on recently. I don't want to just throw money at this truck trying to figure out whats wrong. Where should I go from here? This is a very nice truck and I love it and I am hell bent on figuring this out so I can actually enjoy it and not worry about constantly filling the fuel tank after every trip. I appreciate and welcome any help. Thanks!!

 

...tap..tap..tap....umm,is this one of those pesky 5.3 engines?

 

Highly doubtful as the only engine available in a '99 ZR2 was the 4.3.

Sure sounds like you have a vacuum leak somewhere. Possibly due to a bad job of replacing the intake manifold after the spider swap out. Get some starting fluid and spray around the entire manifold. You'll know if and where a leak is immediately if you have one.

 

There should be an internet fine for no follow up..!