cdaiscool

Got an oddball issue.

I'm trying to put an MTX-D boost gauge and MTX-L Wideband on my '97 Integra LS. It seems like it's working with the exception of when it's in some way incorporating the fuse box keyed hot. Let's start from the beginning.

The car was a small mess when I purchased it. JDM B18B engine, shift light under the dash, looped P/S. I have since done a LOT of work to it over the last 7 months - relevant details include dual fuel pumps and 1800 CFM SPAL fan running from this fuse holder, turbo'd GSR engine, jumper harness for ECU to go from OBD2A car to OBD1 ecu for Hondata. CPR setup.

Initially, I found the previous owner's shift light that was operating off this male spade on the under-dash fuse box. I removed the shift light, put a light tester there, saw it was indeed an ignition hot, and ran the MTX-L, boost sensor, and boost gauge off this spade. I put a 10a fuse inline to protect these.

Keep in mind, the wideband never has displayed any issues.

The gauges all fire up, but when I start the car, the boost gauge goes wonky. It almost seems like it's restarting quickly - 3 or 4 shift light LEDs (MTX-D is a dual gauge) but other times, its just sitting on the red LEDs and flashing 8s across where it shows the boost reading. During this time, if I turn the car off real quick it will continue to act up, but if I turn it off for ~10 - 30 seconds it starts working fine again - until I start the car.

I got hold of Innovate, they said sounds like corrupted firmware, resent me the firmware, put it on, no change. They recommended I run it off the battery with an inline fuse, use a relay. I ran it off the battery for a test, direct to the gauge, and it worked! I was able to see how much vacuum the engine grabs.

So then I ran a 10awg wire from the aftermarket fuse block I have (runs 2 fuel pumps and aftermarket fan), added a 10amp fuse there, ran that to a 30a relay, hooked all gauges off the relay, same ignition keyed hot to the trigger, and the gauge went haywire once more. Ran a wire direct from battery to the trigger for the relay, gauge works.

So that's where I am today. When I use the fuse box as an ignition source, even on a relay, the boost gauge messes up; the wideband is unaffected. Ideas as to what's going on? Troubleshooting tips to see if the under dash fuse box itself is having issues? Just find a different keyed hot (ideas where to go?)

cdaiscool

Innovate tech guy thinks I'm on a PWM circuit, I'll have to check tonight if I can get my hands on a multi-meter. I just hope we have an answer finally.

If so, time to find another keyed hot.

cdaiscool

Last night, checked the other male spades, found another ignition hot - last one was hot with accessories, this one was hot only when turned to 'on'.

Same exact symptoms.

Also, relay does NOT click on and off quickly, as if it's a PWM circuit. Clicks on, clicks off when key turned to 'start' then back on when key turned back to 'on'.

Gauge messes up at that time.

cdaiscool

So I realized today that the Mac solenoid, which requires 12v key hot, was on the same circuit. Moved it to its own circuit and no change.

Moved it to a relay setup with the Mac solenoid not wired up, same issue. It still seems like it's wanting to repeatedly restart. Just did another verification test and it definitely works with the battery running to the relay.

So the issue is not in the gauge. I think.