Hello fellas,

I have done a lot to my RS this summer, to include all of the mods in my sig, as well as rebuilding the TBI, replacing IAC, TPS, CTS, Spark Plugs, Open Element, and so on. After I put on the Edelbrock mainfold I messed up the timing by putting the distributor back in a little off and the thing was severely bogging down. I got a timing light and sure enough my timing (with ESC disconnected of course) was around 12* so I changed it back down to the recommended 0* and it was better. HOWEVER, it was not gone. PROBLEM: Whenever I go from an off-idle start, or from a cruising speed, the car takes a second or two to start reving up, and actually has a few hesitations while reving. I'm not talking bogging, ready to die hesitation, but enough to notice. I have changed the base timing from 2* to 4* and it will still do the same thing. What do you think the problem is?? ESC, ECM, or could my timing chain be the cause of this?? I'm clueless, help me out guys!

 

As a courtesy reply, check for absolute certain your vacuum circuit closed following the mods installed. Description fits IMHO. Good Luck

 

How do I do that?

 

First things first, visual inspection heat deteration and slightest of splits at every, repeat every connection. Should be a vacuum routing diagram underneath front of hood, I think. Mark ea line checked on both ends or you will be in circles. Your mods that replaced parts with Vhoses either must be plugged or spliced, depending on the continous routing. A vacuum gauge will be most helpful. Another problem area in the system is a small plastic tripod with at least 3 hoses attached near and to the left rear of the air cleaner that fails because of heat/carbon. Replacement is a small price to pay for piece of mind, especially if it has never been replaced. This pc alone contributes to a lot of emission failures. (Dealer only replacement part). A time consuming project well worth the effort, even tho it may not be the problem. Just a additional humble thought, are you spending enough time with your computor, is it properly operational? It might want to tell you something. Good Luck! Big Al

 

That tripod with three hoses attached...are you talking about that conical check valve that comes off the rear of the manifold right behind the TBI? I know that hose is pretty cracked, and I'm sure that valve has not been replaced. I am under the impression that this valve has something to do with the HVAC system, and my AC only blows out of the defrost and I have been trying to figure out why. Do you have a part number for that valve??? I'm pretty sure that this is going to turn out to be the problem.

 

Well, I replaced all the hoses and vac connections that run off the manifold vacuum. I bought a new check valve from GM and what do you know, my AC started blowing out of the correct vents again! As for the hesitation, I'll have to check and see if that solved the problem.