I'm looking to get a tuner (sct, don't freak out) and I just installed the Hughes plate on a pretty much stock motor. I forgot to order the 180* tstat so I just installed a stock 190* from the local parts store.
My question is, can I run the tuner with 190*?
Anyone running a tuner on a stock motor?

 

The reason they say to put the 180 is so that the pcm thinks the engine is cold and will dump more fuel it so that it doesn't ping.
Or so that I'm told.
It also helps the engine deal with the extra spark advance, keeps it from running hot.

Then again, I don't think we'll have a warm winter here in Texas.

 

you won't be taking full advantage of that particular tune, but it's not going to do any damage either...

your PCM will adjust to what it adjusts to anyway... all that is really being changed is the baseline... But, again, you won't be taking full advantage of the tune as it was written/intended....but... your factory loaded Death Flash will be history, so you will see a huge gain from just that.

 

Well, thats good to know. I have intentions of changing it to a 180, Im just swamped at work and I dont see anytime in the near future to work on the truck. Especially witht the holidays comming up. I just wanted to know if I was going to be hurting anything installing the tuner and running it for a while on the 190* stat. I guess I will just do it and listen for pinging. Ill run the 87 tune for a while if I have to.

Im really looking to get rid of the deathflash and also to see if the engines newfound performance will help the tranny shift better.

 

Question. With changing to the 180* thermostat are you not making the catalytic converter less efficient because it is not up to temperature causing the PCM to think it is running too rich because of the O2 sensor reading and leaning out the fuel mixture causing the pinging? Just a quick thought.

 

honestly, I don't really know... but here is what I do know- the engine comes out of closed loop quicker, as the temperature to 180 opens the stat, as opposed to 195.. it stops dumping fuel at the rapid rate in effort to warm it up, and leans out.. what i'm having trouble wrapping my brain around is that the operating temperature isn't going to be that much different once you've been moving a while- even though it starts circulating sooner, your capacity for cooling is still going to be governed/limited by either your fan or your speed..

hypothetical- you are running in 90* weather, at highway dictated speeds of 70mph.. your radiators cooling surface = 5sq', and your coolant capacity is 7gallons... if your stat opened at 180, what is your average temp at a steady 2kRPM? How about if your stat opened at 195?...... see where I'm coming from? I'm having a hard time wrapping my brain around this, because the engines operating temperature is going to be dictated by the cooling system capacities and cooling surface more than when the stat opened..

I argued precisely the opposite with VW a few weeks ago, and the more I think about it- the more I agree with him now... A cooler opening stat is just fooling ourselves for the most part, even though it gets a head start cooling things off (which in turn provides a denser f/a mix), it doesn't take long to even things out..

I wouldn't worry about the 190* stat at all... your PCM will do what it wants to do anyway... for instance, I have the91 tune on mine right now, and have been running it for the past 2k miles or so... If I were to go out and 'reload' it, it would be a total different tune than what it's running now, even though they started the same, yet in a few weeks- given that the environmental variables don't change much- the tune now and the tune then would be close... get it?

I'd love to hear some ideas on this subject from some of the resident experts.. I may be way out to lunch, which is fine- but if I am I'd love to know why..

 

I may be wrong but isn't the vehicle running open loop when it's cold and goes closed loop once it heats up. In my opinion thermostat temperature is not going to have any bearing on when the system goes closed loop.

 

And you would be correct. PCM goes into closed loop when the CTS (coolant temp sensor) tells it the engine is up to some preset temp. (for GM, that was somewhere in the neighborhood of 106* F.... not sure what dodge uses.)

On some of the newer trucks (98+??), there is also a timer, and if the PCM doesn't see the engine getting up to what IT thinks the temp should be.... it will set a code for engine cold to long.... and constantly stay in open loop.

Under normal circumstances (unloaded), running the cooler stat WILL keep the engine cooler. By about 10 to 15 degrees. Does this produce any more power? Probably not directly..... but, cooler under hood temps means cooler intake air, and associated parts, which WILL translate to a horsepower or two. Does it reduce the tendency for pre-ignition? That one, I don't think so, (temp difference would be to small, and basically non-existent in the combustion chamber..... which is where it matters.) I have no facts to back that up though.

 

yah- not the first time I've made that mistake...

open 'stat, closed loop... check...

now as far as closing before the stat opens, I was unaware of that..

 

Well I called mr hemifever himself and ordered my sct.
I asked him about the tstat and he basically told me that I may experience spark knock on the 91 and 93 tunes. He said to just try it and see. If I do get knock I'll run the 91 tune and 93 gas. If it still knocks Ill need the 180 stat and run sea foam thru her. The tuner gets sent out tomorrow so I hope to have it middle of next week. I will try it out and report back.

Either way I'm stoked to get rid of the flash and gain a touch more performance.
I felt bad talking to him on a Friday afternoon while he was at home so I didn't get a good explanation of what/why you need the 180 stat.
Like I said, I'm going to try it with the 190, but it boils down to me being lazy and not installing the 180. If the man says it's better with the 180 then it's better with the 180. I will eventually install one anyhow. I was just looking to run the other until I make the swap.