83TAinprogress

Hi, I'm having issues with my 83 Trans Am 305 TBI. My EGR valve and solenoid were bad and my engine was stalling under a load. I couldn't find replacements so I did the delete plate. The vacuum line that was attached to the valve is now just hanging there sucking air. It's still stalling under a load, much like if it had a vacuum leak. What's confusing me is that it runs worse when I cap the open vacuum line. There's also another vacuum line that broke off what I think is the EGR solenoid (might not be) that is also just sucking air. Again, car runs worse when I cap it. Even worse when both are capped. Any ideas? I'm wondering if maybe the stalling on acceleration isn't related to the vacuum lines and is actually a TBI problem, but I would think that I still need to do something with those lines.

n1ffer

If by TBI you mean crossfire injection, then there is a lot of areas where you can be getting vacuum leaks.

Is it crossfire? Are you just getting this back up and running or did it just start happening?

83TAinprogress

Yes, it's crossfire. I know there could be several possible vacuum leaks, just don't understand why plugging an open vacuum line would make the car run worse.

I recently got it running after 9 years of sitting without being started. I do remember it having the same problem before I parked it, though.

n1ffer

IIRC I had the same issues with the EGR when I unplugged it and tried to cap the line. I never did understand it. I know that the correct EGR is hard to find, but I did end up special ordering the correct one through one of the parts stores. Don't remember if it was a carquest or a NAPA or an O'Reilly. but digging deep enough I did finally find one.

The other thing you are probably going to want to do is replace most or all of your sensors. I replaced the EGR valve, coolant temperature sensor, O2 sensor, map sensor, thermo vac switch and the ECU in mine before it started running right. Even though they all tested ok, after every replacement it ran a little better each time.

I didn't replace the throttle position sensor, either idle air control valves, or the air injection valve, but you might want to make sure they are set correctly and operating ok.

It may seem like a lot of unnecessary work and expense, but if you think about it all of these valves and sensors are now 30 years old and the self diagnostic functions of ODB I leave a lot to be desired.

The other critical fix was vacuum lines. Most of the lines near the cruise control unit were rotted and leaking. I replaced almost all of them. Check as many as you can find - thermo vac line, brake power booster, etc.

There is also some debate on whether the bushings in each of the TBI units can wear causing an out of balance condition that can cause a stumble under acceleration. I don't know if mine are ok, but I haven't done anything to them and believe they are original.

The other thing is fuel pressure. Fuel pressure should optimally be measured at 12 psi or more at idle and should be measured between the throttle bodies. The pumps are weak to begin with and over time they get very weak. Upgrading to a 1985-1992 TPI fuel pump is a good idea to get some better pressure.

There is a vendor called DCS that has some crossfire specific parts and has some good tech info. www.crossfireinjection.net is their url.

Hope this helps and don't give up on finding the correct EGR valve. They are out there.

Todd