I just found out the EGR valves are different from a 305 TPI and a 350 TPI? I've been running the 305 TPI EGR valve on the 350 TPI for about 8,000 miles. What makes them different?? The car came with a 305 TPI with 5-spd from the factory and I installed a 350 TPI with the 5-spd, Should I change the EGR valve to the 350 TPI?

 

Jas,

Sorry for the slow reply, but I was trying to find an answer to your question (and it's a good one). Apparently, the oriface in the EGR valve for the 350 was slightly larger and the backpressure pilot valve was slightly stiffer. Since you have the 305 valve on your 350, I can only guess what would happen, but I'll take a stab.

The smaller oriface will admit a slightly lower volume of exhaust gas through the system, which shouldn't hurt performance at all, but might raise emissions and chamber temperature slightly. On the other hand, the weaker backpressure valve will tend to allow the valve to open sooner on the larger engine, allowing exhaust gas to flow at a little less load than was originally intended. Put both together, and you still shouldn't experience any real problems from the slightly different valve. Also, the EGR system will probably be very tolerant and never fault or set a DTC since the temperature sensor should be satisfied very quickly when the EGR solenoid applies vacuum to the valve.

All said, I wouldn't even bother giving it a second thought, but it was a very intriguing question.

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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."
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Thanks for finding out for me Vader

Jason

[This message has been edited by Jas87T/A (edited March 09, 2001).]