I just read a tech article by William Weissman in regards to the cooling system. I put a 160 degree thermostat by Stant to supposedly make the car run cooler and at the same time had a problem with the egr solenoid and the catalytic converters. I got the egr solenoid and converters replaced. The car ran fine for 3-4 weeks, now it is starting to miss creating a steady spitting sound at idle and at low speeds also making the car shake inside. Do you think its the thermostat? If so, what temp. thermostat should I buy for the California region and will it cure the engine miss condition ?

 

The miss is something other than the stat temp. That being said and although I think ******* article is well written I do not agree with many conclusions about what temp the engine is happy. Prior to replacing my block in my 89 5.7 TPI I experimented with all different operating temps. In every case fuel economy suffered which translates into efficiency. While the ECM has some range to correct for variations in engine temp a 160 is just too cold. I found a 3-5 mpg loss with a 160. Also, I have a pipe sniffer and it always ran on the rich side with a 160 or 170 stat. A 180 would be a good choice if you want to go lower and would still keep you in the approximate range that results in best engine operation. Almost every gas engine out there runs at 195, a few have stock 180 stats and get well over a 100k miles and run well. I personally think engine oil temp is more critical than coolant which is why I run synthetic oil in all my cars. I run a zz-4 block with everything else stock with a 195. It meets emissions and gets 24-25 mpg on the highway in OD.

 

So installing a 180 degree thermostat won't cause the ECM to malfunction? The reason I ask is because plan to install either a 180 or a 195 degree thermostat. Anyone's response is appreciated. The engine in the car is a stock 350 tuned port motor.

 

Not at all. The ECM can compensate for a 180, no stat temp will cause a failure of the ECM-the most that happens is gas mileage suffers a little.

 

In a computer controlled fuel injected car the ECM will command a much richer A/F ratio when it sees cooler temperature because it thinks you're still in warm-up. It does this by increasing injector pulse width. The extra fuel will lower your MPG, contaminate your oil with fuel much quicker than normal, and can cause more wear in the engine because it's spraying way too much fuel into the chambers.

A very simple way to solve this problem is with aTricker Box so you can tell the ECM that it is normal operating temperature even if you're running 160*F or cooler.
This is very useful in cold climates when you are running a low temp thermostat for performance. The tricker box effectively leans out your A/F ratio to normal giving many benefits.