Speedracer

One of the most fun things about tuning, unless it gets too frustrating, is working out the assorted quirks that inevitably occur in the process. Often, this leads to a much better understanding of one's vehicle.

When I finally got my HKS SC nicely working, I had noticed that the engine bay was a bit hotter. On recommendation from several members on this forum, I added Redline Water Wetter to my coolant to lower the circulating temperature of the coolant. Basically, Water Wetter is a coolant additive that changes the vapor properties of the coolant and lowers overall coolant operating temps by as much as 20 degrees.

Well...it worked....too well. For sure, the engine ran cooler. It was obvious....much less heat from the engine bay. However, after about 10 miles driving, my SES light illumniated. Now.... having put only 150 miles on the SC, I had to wonder what was going on. Could this simple liquid be causing a problem? It had to be the SC software, I thought. Some people on this board laughed at me for thinking that it could be the Water Wetter that set off my SES light. Confounding the issue was the fact that my car is a 2004.5 model. This is when Nissan made the change to wideband oxygen sensors to finely regulate the air:fuel ratio to make the car ULEV compliant. A quick trip to the dealer showed a fuel trim 25% richer than spec on both banks at all rpms. My exhaust tips were jet black and my I was getting about 10mpg. I also learned that any air:fuel reading that was more than 12.5% rich or lean over "spec"(whatever that unknown number is) would trigger an SES light. Now, the post cat sensors can help correct the A/F even if the pre-cat A/F is way out of range as long as you have stock cats.

So....what now....if I lean out the SC programming enough to not trigger the light, would I risk detonation? First, I changed and flushed the coolant to get rid of that Water Wetter poison. That night, I got a call from Adam at Z1 telling me his SES light went on. He is N/A running the Nismo low temp thermostat and an aftermarket radiator. It was a cold and rainy night.

Hmmmm...what's going on here????

Well, after changing the coolant back to normal, the SES light stayed off. Now after about 100 miles, 4x20 min idle tests and about 15 start-ups, there is no SES light. My mileage has improved and the exhaust tips, while still a bit rich, are no where near the jet black goo that was there before.

How sensitive this car is to coolant temps in terms of its air:fuel regulation. We all know that at start-up,when the coolant temps are way low the A/F ratio can be as low as 4:1. It appears that if a certain temp isn't reached by a certain time, the SES will illuminate and your car will continue to run super-rich as if in "start-up mode". This problem will be amplified even more if one's particular FI programming operates off coolant temp as one of its control parameters.

Anyway, I just wanted to share this story to help provide some more info to everyone that didn't already know.

MIAPLAYA

iTrader: (3)

Wow thats crazy. i've been running Watter Wetter in my car since day two of my ownership. I've had it for just over a year now and haven't had any probs. I dont have F/I yet but i will soon so I guess i better keep an eye on that.

Speedracer

You probably are running a little rich, but unless you have an '04.5 or later, and are more than 12.5% rich, your SES won't illuminate. I'm sure the SC programming factored into all of this as well. It is probably running on the edge of rich tolerances. The slightest change would put it over the edge.

MIAPLAYA

iTrader: (3)

My build date is Oct 2004 so I'm not sure if thats 04.5 or not.

Enron Exec

Thats odd. I want to say maybe your thermostat might be inaccurate or stuck open? The thermostat should keep coolant from flowing to the radiator until it reaches a certain temperture and close when dropped under another temp.

I ran water wetter with my ATI SC and didnt have this SES problem. But thanx for sharing!!!

Lawn Dart

iTrader: (4)

Thank you.

Do you think the SES trigger also could be caused by any other products, thermostats, radiators, etc...?

Z1 Performance

iTrader: (564)

he has stock thermo and stock radiator.

on my car, the ecu thought my thermo was stuck opened- it calculates how long it takes for the thermo to open. Since it was very very cold when my light popped on and I had been driving for about 10 mins, the ecu though something was up and threw the code for low thermostat threshold. I cleared it with my palm and have not had a problem since

adam

King Tut

iTrader: (1)

I think you mean October 2003. Since you have had it for over a year.

jpc350z

Interesting data. What do you suppose would happen if after a cold start and letting it idle for say 45sec's allowing the coolant to heat you were to shut it off and wait a few seconds before restarting it. Would the ECU restart the start up clock over and before it timed out the coolant would be at the proper temp..?If the redline wetter water is a significant consideration in FI engine reliability while this may seem retarted for the minor inconvience during the cold months it may be worth it..