Cxracer

iTrader: (6)

Need some help / advice on newly mounted gauges (AFR, Boost / Vac, Water Temp)

The back story: I finally got my Greddy kit installed into my 91 along with a bank of 3 digital gauges on the A pillar.

At the bottom I’ve got a digital AFR gauge getting readings from a LC-1. I did the free air calibration.

In the middle I have a digital Cyberdyne Boost / Vacuum gauge getting readings from a remote sensor mounted on the firewall with a boost signal coming from a Y in the vac line going from the front of the intake manual to the charcoal canister.

On the top I’ve got a digital Cyberdyne water temp gauge connected to a one wire Cyberdyne temp sender at the back of the head (with no Teflon tape) in the BEGI thermostat mount for the coolant reroute.
This Sunday I’ll be driving at Laguna Seca for the Miata event that Mazda is throwing so I’m trying to get everything finished and ready to go before I head out the track with a turbo for the first time.

Problem:
The water temp gauge turns on and goes through the normal start up routine and reads temp over 70F. However at idle with the car fully heated up and fans kicking on and off the gauge only reads 115F. Driving it stays at about 90F. If I stop the car and for a few min after driving and then start up again I see an initial temp of anything as high as 222F followed by a quick drop down to 90F in the span of about 30sec. If I stop and back into my driveway (slight hill towards the street) the temp will rise up to about 180F then go back down and sit at about 120F.

I called Cyberdyne first when I saw the low temp at idle and fully heated up but before I saw all of the other symptoms. They said probably bad ground but now that I have seen all this other weird behavior I’m wondering if it could be that. Does anyone know the most likely grounding point that I should be looking at?

I’m really kind of bummed about the water temp gauge problem because it was going to be my fail safe at the track given that I’m running the turbo set up for the first time and it doesn’t have a intercooler and only the rising rate fuel regulator.

Question:
My AFR gauge seems to bounce around constantly. I’m assuming this standard. Most of the time its flicking between 14.3 and 15. When I get on the gas or into boost it will drop down to about 11 or 12 for a few seconds and rise as I back off on the throttle (I have the Vortec rising rate fuel regulator installed that came with the kit). All this seems normal.
However, when I am engine braking or sometimes even braking with the clutch in and vac is upwards of 20psi the AFR will peg at 22.2 and stay there until a second after I am back on the gas. Is this right / OK?

So far the highest boost I’ve seen is 3.1psi right before the stock intake tube slid a little off the intake manifold causing the AFRs to go off the chart and the engine to die when I stopped at the light. I have since changed the clamp from the original pipe clamp to a T style clamp in hopes of avoiding this at the track.

Seefo

iTrader: (5)

you mean vac of 20 in?

Its normal to be at 22.2+ when off throttle as you have fuel cut at that time. As for how quickly it should get back to a normal AFR, well I am not turbo'd but I would imagine it should be when you touch the throttle pedal.

Cxracer

iTrader: (6)

Yes, sorry 24 inch of mercury in vac (which is the limit of the gauge). AFRs drop as soon as I am on throttle. Glad to cross that off the list.

Any advice about the wacky temp gauge? It's grounded to the same spot as the ECU on the engine (also same as the wide band and other gauges.

psreynol

Lc-1 can be very particular about ground, and calibration. I had issues with mine and changed the wiring several times and then set it back to them. they sent me a new one and the reading did not make sense. so something was not right, I ended up selling the car so I never got it dialed in. if you car not confident on the readings I would put the car on a dyno and do some runs, including cruse, and part throttle just to compare the numbers.

my car has a greddy jdm( in c) water temp gauge and I 'm going to get rid of it. the gauge moves all over the place. just get a vdo gauge and a sender for 50 bucks. I just dont trust a water gauge with 10 wires going to it, and for the road track you ust need a reliable gauge ,


have you been to a track before? if you've done it a bunch I would be cautious about do it before you get the issues worked out.

psreynol

really even if you have not been to the a track still get this stuff worked out. add a real oil temp gauge as well.

skidude

iTrader: (3)

Is the water temp gauge reading the temperature of coolant coming out of the radiator? I'm not sure if you have a reroute, or where exactly you're getting your temperature, but those temps seem reasonable for what could be coming out the bottom of the radiator in those circumstances if the coolant hasn't been through the motor yet.

Seefo

iTrader: (5)

It does sound like a bad ground, but I am not exactly sure. Temperature wise, I just modified the stock gauge to be linear.

As for you, I would certainly try to recheck the wiring setup for the sensor (so check the ground, power, and the signal back to the gauge, also check any power wiring for the sensor too). Check the wiring to make sure its not broken somewhere.

Cxracer

iTrader: (6)

Cyberdyne gave me a few things to check. I can disconnect the sender and add a 100 ohm resister and ground it to the block. If the Gauge is correct it should read about 170 deg. I can also read the resistance of the signal line from the sender once the engine is fully warmed up and that should be about 100 ohms.

If I have a chance I'll check this tomorrow.

I've done a number of track days before I added the turbo. Since this is not my ultimate setup I'm going to take it pretty easy and just treat it as a fun event and not try for any personal best lap times.

Mobius

iTrader: (2)

It is.
This is normal. Under the conditions you describe, the ECU actually shuts down the injectors completely, so the gauge will read max lean 22.2.

11.5 ish is where you want the gauge to be when you're WOT or under load in boost.


When you start the car completely cold, is the water temp gauge showing ambient? It should. Possibly you have air in the system. Check it cold; add coolant as necessary. When refilling the system after having been drained, the Service Manual recommends a fill rate of no more than 1L/minute, which is a pain, but helps prevent air from getting trapped.