H2O sensor resistance alteration

[cbuzzetti]

I was reading a post earlier that quoted "many out there still using a varience in resistance from the water temp sensor to help control/correct their fuel mixture on ECU controlled cars..."
My questions are can this be used to lean out a 2nd Gen RX7?
Was this the common fix for 2nd gens before the ECU rule?
Was this mod done inline with the wiring? Or in the ECU box?
What was the gain if anything?
I have heard some about this, I just did not know what sensor to manipulate.
I am new to my ITS car and want to be competitive with the BMW.
Any help is appreciated. I know this may step on some of the tuner shops toes, but the closest one I have any confidence in is 7 hrs. away and cost about $1,000 for dyno tuning.
If this is the fix I could do this myself and pay my local dyno guy for a few hours of time.
Also is this not allowed by the current rules? It sounds as if this may have got left out.

Thanks,
Charles Buzzetti

[cbuzzetti]

Did I say something that offended every one?

Most posts get an immediate response, maybe I am the only one who can see it.

Hello is anyone out there? ;-)

Charles Buzzetti

[bldn10]

Well, I started to but it has been so long since I experimented w/ this that I thought I'd let some of the experts chime in first. It is the wire from the water thermosensor (WTS)to the ECU. I just found the wire in the loom inside the car and spliced in wires to/from a variable resistor from Radio Shack that I mounted in the cigarette lighter hole. You have to get the one w/ the right range but I don't remember what it was. I am probably wrong about this but as I recall the ECU monitors the WTS signal and when it detects the engine is getting too hot the ECU richens the mixture to lower the temp. As you probably know, a leaner mixture runs hotter. The resistor changes the signal and tricks the ECU into thinking (and here's where I am rusty) that the engine is either cooler (leaning out the mixture) or hotter (richening the mixture) than it actually is. Someone else will have to confirm which way it works but that is the basic idea. But note that, like a brake bias valve, the resistor only works in one direction - it can reduce whatever signal the WTS is sending but it cannot increase it. I used to have EGT gauges and was always fretting over the overall temp or variation from one rotor to the other. I used the resistor mostly to cool off the engine when it was running hot, but the tradeoff is a noticeable power loss. I now have a SpeedSource car w/o EGT gauges and am blissfully ignorant!

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Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[cbuzzetti]

Thank you Bill that info is very helpful.
Does your SS car use a Motec computer?
Are you faster in the SS car?
Being from California we don't see any SS cars here that I know of.
There are a couple of local shops (Sacramento and San Jose)that build ITS 7's but do not appear to be at the level of SS.
Hopefully my car will be ready in 2 weeks (getting new cage and fuel cell) and then I can see where it compares to the BMW.

Thanks again Bill.

Any additional info is appreciated.

Charles Buzzetti
04 STI
89 ITS RX7

[bldn10]

I am the 3rd owner of my SS car and it is an old warrior but has been taken good care of over the years. It does not have a MoTeC and I don't know what if anything Syl does w/ the ECU other than eliminate the rev limiter. Before I picked the car up not far from his shop I asked if there was anything else short of the MoTeC that could be done to my ECU and he said no. I have turned a personal best time here at Memphis in this car but failed to do so at St. Louis, the track at which I have the next most seat time. The car is easier to drive fast than my previous cars and I just need to push it more. An ex-Memphis ITS racer, Larry Cooper, races out there now in a yellow 240Z and was a front runner most of the time. Larry and I were always been pretty closely matched. You do have some good EP builders out there like Mariah so you might check in w/ them.

------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[cbuzzetti]

Thanks Bill, I will look around.

Cbuzz

[Marcus Miller]

Charlie,

Sorry, off-topic
Who is building ITS 7's from San Jose?

Marcus

[cbuzzetti]

Hoover Motorsports I believe. That is who my car came from, though I bought it second hand.
They are near Sacramento and seem to do a good job. I will try to post their tele # tomorrow.
The other company name escapes me for now I will post that if I remember.
We don't have alot of 2nd gens in So-Cal. Most have converted to EP. Currently we only have 6 or so ITS cars in our region running on a regular basis.
Nor-Cal has a larger field with many 2nd gens, not sure if they have any BMW's.
The track records for Laguna Seca, Sears and Thunder Hill were all reset last year by Randy Evens in a 2nd gen. At the West Regional Runoffs in Nov. the BMW of John Norris (So-Cal) wrestled away the track record for T-Hill but Evans won the race.
In our two regions at least the 2nd gen still has a chance.

Cbuzz

[Marcus Miller]

Ahh. Yep, Hoover is out of Sacto. Last I heard he was mostly doing SM stuff.

I'm thinking about a 2nd gen for ITS, but I'm having too much fun in my pro7!

Marcus

[cbuzzetti]

I thought I recognized your name then it came to me that you are a CalClub member.
Yes Hoover does mostly Miata's now. But still does ITS 2nd gens when somebody wants one. Got to go where the money is.
Randy Evans car is for sale at $12,000.
This car won the SFR Championship the last two years and set track records.
I have raced Pro7's many times at BRP, WSIR and Laguna with the 7's Only crew. It is a great group of racers and a ton of fun.
The big advantage of the 2nd gen is speed. These cars really handle well, have great brakes and decent HP.
Will you be at the BRP Dbl Reg in two weeks?