1st Gen Haltech ECU Discussion

It's one of the hardest things to tune. If you don't have an IAT it's even harder

 

Just need some ballparks other than the base tables. I think I richened it too much (smoke plume when it does start) now I'm gonna go the other way if I don't get anything

 

Ok, I found the trick. There's fuel prime pulse, but there's also a 0 second idle control which will enable the IAC to open to whatever degree you want before starting the truck (you can audibly hear this under the hood with the key in the On position). Set this number to something huge, so that your IAC is 100% open when it's cranking and it'll start flawlessly on a cold crank (the 80% cell in my case), though the RPMs will fly (2k in my case). Then you can start to dial in the rate of decay.

 

@treyus30 and really any other haltech user. I found it. It isn't marked on any wiring diagram, but here is the splice tying cam and crank sensor negatives together. Only like 6" from the ECU connector.

 

Is that in the Toyota loom?

 

Yup, hiding under a bunch of tape and plastic.

 

Do you have reason to believe they are all like that?

 

Yeah I think it's likely to be this way for all of them. Unfortunately I don't know how to correct it on automatic trucks because the stock computer also bridges the sensors internally. So even if I remove the splice in the loom the stock computer is still tying them together... That said maybe the stock computer doesn't need cam and crank sensors for the automatic trans to work... But without an RPM signal I think it may be unhappy.

 

Define unhappy.

I was hoping there was something there for me but maybe not.

 

It's a strong maybe. What I really need is the wiring scheme for your pass through adapter from boomslang

 

Yes we do.

 

On the 1997? Auto?
Mine is running fantastic, 5 speed, (not a piggyback setup) no issues but have an occasional check engine light that pops only when the redline limiter is hit which is probably tied to one of the sensors.

 

I'm sure the 95-97 trucks all have this splice. Auto or not doesn't make a difference to the trucks engine wiring, it just makes a difference to how Haltech computers get wired in. The Haltech expects the cam and crank signals to be entirely separate to one another, so I can imagine this splice causes it headaches when it is trying to detect edges in an AC signal.

 

It's interesting that it still remains two wires after that. I wonder if they were inducing too much crosstalk on each other in the ECU sensing circuit so they just decided to bridge it beforehand.

Didn't we determine that the spliced one is grounded inside the ECU? In that case it would be G and NE+ doing the full AC pulse and you could therefore ground Home (-ve) and Trigger (-ve), and set the G and NE+ pins to be Trigger and Home (ve+)

 

I think they changed it slightly in '98. IIRC the other diagram he showed me for an older truck showed there was actually another negative terminal, and the two weren't meant to be bridged like that. It was probably an afterthought - an assembly line bodge. So then in 98 or so they removed the secondary negative terminal completely and bonded those two (three) wires permanently and updated the wiring diagram... that's my working theory anyway. The question would remain: are there still 2 wires downstream in 98-on, and does that now unused terminal (G-) still tie to the ground plane on the ECU PCB

'96:


'98-00:

 

The ground reference option is for if you connect the crank/cam sensor negative to the chassis ground. Not for tying their grounds together, that's just weird Toyota shit that Haltech doesn't account for

 

Right but factory is grounding them, so why not continue to do so? The Haltech obviously can account for it as seen there ^



It works great from the scope waveform I sent you a while back

You also lose two more pins if you want to decouple them..

 

Might work for you since the stock ecu is there to ground them for you, the wiring as it was from the factory with mine cause trigger errors. I'm opting for cleaner signal, keep them separate and off the vehicle ground plane.

 

None of the home/trigger pins can be repurposed anyway, nothing is lost.

 

@DrabT100 had the same trigger issues I had before separating his crank and cam sensors. And he has the same vintage wiring harness and no automatic trans so no pass through to the stock ECU, just the haltech. Although we have also had the same trigger issues with @Digiratus and he does have an auto so the stock computer is still hanging around, ground reference is turned on in his tune but even still after tweaking the voltages I still can't get it to rev over 4,000 RPM without throwing a trigger error and going into safety ignition cut. Do you mind posting your arming voltages I might just try them in his tune since you've had luck with yours @treyus30