liquid_helix136

So basically long story short, I popped stock ECU in for state inspection, my speedo calibrator (Modifry yellow jacket) started bugging out after I installed an AEM Serial gauge, I replaced the yellow jacket but it's still having problems even after the serial gauge has been disconnected (still installed but all wires disconnected and flagged off).

Tonight I decide to put my AEM EMS 1052 back in the car to run my custom tune, no problem, I pop that bad boy in, install the modifry ECT driver, hook up the wideband signal to the o2 wire via T-tap and decide to go ahead and hook up the serial gauge again and fire it up.

First problem: ECT driver is blinking 5 times a second and reads full temp bars (overheating) the car has been sitting for over an hour, so I know this isn't possible.
Second problem: Speedo starts randomly cutting out again (it would still do it before, but rarely, and a power cycle of the ECU fixed it)
Third problem: o2 reading on the EMS and the actual o2 reading on the wideband gauge is WAYYY different, like 3 points different
Fourth problem: AemPro doesn't see the EMS as being connected to the computer half the time, I lost connection while driving, restarted AemPro and it's telling me the EMS is offline, the car is still running! wtf??
Fifth problem: I ended up disconnecting the power to the ECT driver and was just going to keep the temp gauge at 1 bar, well somehow while driving the temp gauge jumps to full hot, even with the ECT driver not getting any power. I've never seen this happen and didn't think it was possible, with no signal going to the dash, I've always thought it would just read 1 bar the whole time.

Anyways, I disconnect the computer, and the AFRs get right again (they were idling at like 17.0 because the o2 FB was thinking it was running super rich and was pulling 10% fuel) so I deem it okay to putt it home while keeping an eye on the AFRs the whole time, everything is fine and I make it home.

I get under the dash to take a look at my handywork and not a single connection looks bad, everything is tight, everything is properly grounded, every connection is insulated sufficiently, everything looks entirely okay, yet I'm having a slew of problems. I return all the electronics to stock minus my external wideband for now and everything is working fine again.

I'm ripping out the serial gauge entirely as everything was working hunky dory before I put that thing in, plus I don't have a clue how to work the software and the guide on this site that someone made a while back has no pictures anymore so it's VERY hard to follow if you don't already know what he's talking about.

I know it's a long shot but does anyone have any clue as to why everything is going nuts down there?
Past experiences / stories / suggestions and criticism always welcome

About a week before everything went to crap I replaced the battery, could this battery just not putting out the voltage needed to run all my extra instruments?

s2000ellier

first disconnect the ECT entirely so you can work on one problem at a time. the ECT is only for the dash gauge so you can run without it safely since you can read temp from the EMS with a laptop

next if i read your second paragraph right, you t-tapped your wideband to the EMS? Is that via pin C16? If so you cannot use a t-tap here you must cut the wire and have only the 0-5v wire from the wideband going into C16 (O2 #1)

i'd start with that.

get a volt meter on your wideband output and make sure its what the EMS is seeing. also make sure your Units in AEMpro is Gasoline, even if it is click off to something like Meth, click apply, then go back to gas and click apply.

Billman250

I have learned that any problem related to the speedometer can be a direct result of a loose ground wire on the back of the cylinder head. Cant hurt to check it.

Billman250

liquid_helix136

Thanks guys, good info for the wideband Ellier, I've had everything running fine for over a year on the ems so everything is set up right, but the t-tap is new, so I'm sure that's where my problem is with that.

Billman, thanks for the input, I know it's not a bad connection for the cars speedo system and it's something to do with the yellow jackets connections because when I disconnected the yellow jacket entirely and ran the speedometer uncorrected it had zero problems (except that it read 15% high due to my 4.77s lol). The problem only occurs when I hook up the calibrator

xviper

As the car gets older, the grounds may be getting bad. They may be getting too much build up of sulfates (that green powdery gunk that infiltrates the wire strands). Electricity doesn't flow as well as it used to. Electronic and electrical devices need a good electrical circuit to work well.
I had intermittent problems with my Yellow Box and then later, with my Yellow Jacket. I could never really get a handle on what exactly caused it. After I ran the YJ ground directly to a metal part of the engine, the problems greatly diminished but still occurred from time to time. I haven't had any problems for quite some time now. Looking back, it seems that it was after I installed a grounding kit that the problem has not resurfaced. I should have just replaced all the stock grounding cables but being lazy, I just installed an aftermarket grounding kit. It consisted of several very heavy gauge insulated wires from the negative terminal and going to various solid points on the engine and frame. Most people put on grounding kits because they think it will give them more HP. I did it to freshen up the grounds and check out a theory. Besides, they look so purdy.

liquid_helix136

Interesting viper. Bob from modifry was telling me he thinks my yellow jacket problem was from a bad ground, I've moved it to 3 different locations and the problem wasn't alleviated at all. My car does have 140k miles on it so what you said may be true, for whatever reason, somewhere some ground may be going bad. I was gonna check my battery today to make sure I don't have any build up of sulfates on any of the terminals or anything else weird.

I've also considered going crazy with the connections and soldering and heat shrinking all the connections but I'm scared its gonna be a complete waste of time as all my connections look super solid already.

I had speedo problems when I first installed my ems years ago and the problem ended up being just some things not being insulated enough, but as soon as I taped it all up, my problems went away. However I've made sure to either use insulated connectors or tape up anything like a t-tap or a butt splice so I think everything *should* be insulated enough to not have a rogue wire blowing things up down there

xviper

When I grounded my YJ to the frame of the car under the dash, the problem continued. When I ran the ground out to the engine, the problems diminished. I think all that did was to select a different ground - IE, from frame to battery then from engine to battery. The grounding kit freshened up the grounds all over. Remember that when you ground something to the frame or to the engine, the juice still has to complete the circuit back to the battery for most things. Sure, it may be possible for the engine and other associated systems to operate if you remove the battery after the engine has started but most things till need a reliable connection back to the battery.
Back in the day before computer controls, we used to fire up the engine, remove the battery to save weight before we ran down the drag strip. Eveything ran off the alternator and voltage reg. Today's cars may not be so forgiving.

liquid_helix136

So little update, I've done a few things and it *seems* to have gotten a little better, instead of it just cutting out to zero it will just have lower voltage and the speed will read lower, and jump back and forth. Still not a remedy by any stretch of the word and extremely annoying, but it is a little better than just seeing zero all the time.

Its so finicky, it works all day sometimes, and it wont work all day some days. Sometimes it cuts out every time I shift into 5th, and some days it immediately starts working again when I downshift into 4th. I've rewired and reinsulated it several times and still the same crap.

I just saw your last post xViper, I'm literally going out to the garage and gonna rewire the ground out to the engine and hope for the best.

liquid_helix136

So I went ahead and just grounded the YJ unit straight to the battery to see if it was a grounding problem or not. The engine ground is impossible to reach, so I'm not gonna mess with it if I dont need to.

Anyways, I have 2 YJ units, and after driving around for 2 seconds on one unit, the problem persisted, I swapped to the other (newer) unit and the problem was gone for about 10 minutes but when I stopped at a light, the unit quit flashing and the speedo stuck to zero.

So my conclusion to this test is that it definitely isn't a grounding issue considering it is literally hardwired to the negative terminal to the battery.

The YJ doesn't do the "proper" start up test when I turn the car on (5 second LED then 30 short blinks for 15% correction) it stays on for about a second and then just cuts off entirely.