Bouncy Coolant Temp Sensor readings

[Brickster151]

Here's the problem- once the car is warmed up, either the coolant temp will read a steady 170 degrees, but occasionally it'll dip up to 215 right away and shoot back to 170 or the temp will stay at 215.

When it stays at 170 the car runs good, but when it jumps to 215 I'll get an uber rich AFR on the wideband.

Anyone know what the jumpy reading might be due to? Might I have messed up when using Easytherm to give MS the right #'s [I replaced the original thermfactor.inc file with one that has the right resistances/temps for my bosch sensor] ? Bad sensor? Any other guesses?

[The Aspirator]

Exactly which sensor are you using? Is it new or used? How's your wiring? Those are what sound like the problem areas here, either a dead sensor or interference in the wiring. Sometimes I get spikes in my coolant reading but they only last for a millisecond. 170* sounds a bit cold, Erik's car runs at 180* and mine at 190*, we're both using 180* thermostats.

[benflynn]

me too, and o2 and iat, and tps, i have to clean up some signals

[brucepick]

What car? Sig shows 2.

[Hank Scorpio]

bad grounds bud? I had a bad ground on the alternator that freaked out all kinds of sensors on MS.

[The Aspirator]

Lol doug you're probably right in my case...

[Brickster151]

Exactly which sensor are you using? Is it new or used? How's your wiring? Those are what sound like the problem areas here, either a dead sensor or interference in the wiring. Sometimes I get spikes in my coolant reading but they only last for a millisecond. 170* sounds a bit cold, Erik's car runs at 180* and mine at 190*, we're both using 180* thermostats.

I installed a brand new Volvo sensor in it back in late July last year, and it did just sit in there for a while. My connection to the sensor was a little ghetto, so last night I got a spare injector connector/pigtail [sensor uses same connection as an injector] and hooked it in with that, and than I changed all of my grounds for the CLT,IAT and TPS. Smoothed things out but it still has the random jump when it's warmed up. The jumps can sometimes be a millisecond or just a quick flash but like I mentioned sometimes it'll just stick at 215.

I'm using a 180 degree thermostat too [was using a 160 but changed it out a few weeks back], but right now I constantly have my electric fan running [probably going to install a switch for that soon] so that might have something to do with it sticking at 170.

What car? Sig shows 2.

The one most likly to be Megasquirted...... [the 240]

I'll try the alternator ground, hopefully that will fix it.

[ovlov760]

I have the exact same problem with the CLT sensor. I replaced the sensor, rewired, tried different ground locations but nothing has worked.

[benflynn]

i am going to rewire(i am hacked into oem harness) and run grounds back to the ms

[Brickster151]

Is there any way to supress the effects of the 215 degree spikes? Whenever mine starts spiking or stays at 215 the car runs uber rich. Might there be a setting that is on that enriches it after a certain CLT that I can disable so it won't run so damned rich?

[ovlov760]

I wish I knew one because mine spikes to 253* for split seconds.

[Lord_Athlon]

Mine spikes to 300 sometimes, it spikes whenever i tap the gas, and the car hangs for a second.

[Brickster151]

So you guys have the same problem with it going to 215 and running like ass for however long it stays there [my wideband pegs out at 10:1]? I can't stand it, the car is barely driveable when it hits 215.

[ovlov760]

So you guys have the same problem with it going to 215 and running like ass for however long it stays there?
Mine does not have any running problems when it spikes that I'm aware of. It has spiked as high as 280 IIRC and then the next second it's back at 197. Has anyone tried logging battery voltage to see if there is any connection to the CLT spike?

[The Aspirator]

I don't have any running problems with my car, and my datalogs show minor instant spikes here and there. Pat how ghetto is you wiring?

[Brickster151]

My wiring is definatly not clean, but I would'nt say it's that ghetto. It's mid-pack in terms of the MS wiring jobs I've seen

[Brickster151]

1 Month Update

I cleaned up some wiring, and some grounding points again [moved the CLT ground to the same location as the MS's].

Still having problems.

For a few days, the CLT would pretty much stay at 170 degrees and we tuned the car and it freaking hauled ass with no issues [aside from a slipping clutch and a weak M46]

Afterwards though, instead of spikes of 215 degrees, it'd just warm up gradually all the way to 215 and stay there. It'll still run uber-rich once it's there too.

I still have'nt changed out the ground strap. The current one is made of 10 gauge wire, and I built it when I was putting the car back together last summer so it's not that old or used. Perhaps that is too small? But I'm starting to think away from my current problem being an electrical/wiring issue.

My Autometer gauge, which is T'ed into the upper radiator hose, will read 150 degrees when the car is fully warmed up, while the CLT [in it's location on the head] will read 215. Should there really be a 65 degree difference between the head and the radiator hose?

Thermostat stuck closed?

[The Aspirator]

Well, maybe your thermostat is messed up. It's good to have the autometer gauge but I'd rather get it reading from the head just to be sure. Dunno what else to say, good luck with it!

[ovlov760]

Well, maybe your thermostat is messed up. It's good to have the autometer gauge but I'd rather get it reading from the head just to be sure. Dunno what else to say, good luck with it!
Changing the Thermostat, CLT sensor and grounds didn't solve the problem for me.

[jimjawz]

just tell ms to ignore the coolant temp.

P.s. I have pulled my hair out trying to get it to not spike. new sensor,new ground, new wiring, new coolant, new t-stat. All in all, who cares, if ms doesnt?

[benflynn]

my iat/clt/afr spike, i never tried to fix it, makes tuning a bitch. try and run it w/o the ac belt for a min and see if it still spikes

[Brickster151]

Sounds good. I'm just gonna disconnect it and move my autometer into the head.

[benflynn]

my iat/clt/afr spike, i never tried to fix it, makes tuning a bitch. try and run it w/o the ac belt for a min and see if it still spikes

i ment the alt belt

[Magnum TE]

I'm seeing all kinds of spikey fluxuation in my CLT lines check out my loggin thread

http://forums.turbobricks.com/showthread.php?t=74726

its the red line on the bottom pic, spikes to 311 under full boost WOT, but its definatly a noisy signal, it looks like AM modualtion on a carrier.


I'm pretty sure I've got the wrong values for megatherm, because I read ~190/200 with the Efan on, I think its even a 160deg thermo.

It does not affect my running quality, much

[Magnum TE]

just tell ms to ignore the coolant temp.

P.s. I have pulled my hair out trying to get it to not spike. new sensor,new ground, new wiring, new coolant, new t-stat. All in all, who cares, if ms doesnt?

where would I find that setting? can you detail that process to make a record of it in this thread.

[The Aspirator]

I'm not positive but I THINK MS only cares about coolant temp for warmup, so as long as you're above 160 you're golden. And Toby my car drives at 190* with the S80 fan blasting full speed, with a 180* thermo. Your coolant log is wicked spiky, mine is nice and smooth, don't know what you guys are smoking ;-). Interference somewhere I guess.

[Brickster151]

From the sound of it alot of us guys having spike problems are running the Bosch sensor.

I'm gonna switch to a GM sensor, since it won't fit in the head I'm going to T it into the upper radiator hose with the Autometer sensor, but I am going to adjust the values in Easytherm so that they are still the same except I'll drop the temps in easytherm 15-20 degrees lower to compensate for the difference in temp from the upper radiator hose and the head [so it will read right]

[The Aspirator]

I've used Napa Echlin sensors with no spiking problems at all, and they fit into the head. I'd be a bit weary of putting it in the upper rad hose since I'd think that doesn't really measure head temperature too well. Although you have had the autometer in there, so you're a better judge than me at how the temps are in that area.

Hope you figure something out.

[ovlov760]

My Bosch sensor spiked, so I put in the Wells version of the sensor and it spiked too. What do these NAPA sensors cost?

[The Aspirator]

About $20 bucks or so, TS5562 is the part number on the box.