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robertcope

1999 Lexus SC400 - I messed up good this time

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Harness looks good, other than the heavy use of white and green wires with no labels.  as a EE and currently dealing with a large telecom system installed by idiots, unidentifiable wires are the bane of my existence right now.

at least you can easily see both ends of those wires and *shouldn't* have to cut into anything or trace wires assuming the terminations are correct and it's truly plug & play...   

 

My dad bought a replacement engine harness for his 240SX, and every one of the important connectors was miswired from the place that made it.   it cost him 3 engines, 2 "shops", and a couple thousand in diagnostics at a good shop before he finally got everything sorted out.  I sincerely hope Panic's quality is vastly superior to Chase Bays!

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Chase Bays is the worst of the worst. I have no idea why their reputation isn't 100000% worse than it is (100% being max positive reputation on this scale). It's a bunch of uninformed kids half-assing stuff together and ripping people off as far as I can tell. With one of the guys kinda sorta teaching himself Solidworks at some point and making some parts that barely install most times. Ugh...

 

As a real engineer it gives me major heartburn to see people bumbling around and screwing people due to being so uninformed and their customers paying for their learning. 

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I spent some time this weekend trying to get the car fired up. Installation of the IAT and MAP sensor was easy enough. The ECU was "plug n play" so everything plugged in just fine. However, I couldn't get my TPS to calibrate. Long story short, the base map they sent had a sensor on AN5 but it was actually wired to AN11. That's one plug off, so I suspect it was a manufacturing error when the harness was made. Annoying, but not a deal.

 

Sadly, the car would not run. It would crank and run for a few seconds, but wouldn't idle, and any attempt at adding throttle would kill it. I haven't been able to figure out why it won't run, but I'm sure there is a good reason for it...

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First step when putting a standalone in is to put a timing light on it to try to determine the timing. If you can't get it to idle/crank long enough to get a steady reading, I would adjust that by maybe 5 deg at a time and try again. If it catches at all, you're "pretty close" (probably within 10-20 deg). 

 

If you can get your wideband to start giving a reading, that'll let you know if the AFR is way out as well. The car should idle anywhere between about 12-17:1 or so, outside of that very iffy.

 

The stalling with any throttle could be any number of things, but it's likely the tps dot (throttle enrichment) maps are a bit off, and when things are already just hanging on it's not hard to get to a total misfire in either lean or rich direction on transients. 

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Could also be much simpler-- how's your fuel pressure while running?

Lots of things to check!

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Could also be much simpler-- how's your fuel pressure while running?

Lots of things to check!

 

Yeah! I was actually wondering about fuel pressure, too. I believe these things have a two-stage fuel pump and it _sounds_ different than what I'm used to. Though, it sounds like it is stuck on "high pressure", but who knows? As you say, lots of things to check.

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My MR2 has a 2 stage setup with a resistor for low stage, and at idle the factory reg will still regulate even with a reasonably strong pump on high.

 

Look in the Big Green Book (BGB) for how the fuel pump circuit is laid out and you should be able to see if the ECU is activating that. I'd probably just say delete it for what you're doing with the car as long as fuel pressure doesn't rise at idle. Or if you have a fuel pressure sensor wired to the ECU it will probably compensate for the different differential fuel pressure automagically.

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It did end up being the fuel pump configuration. I had been noticing all the time that I was playing with the system that the pump was running anytime the key was "on", even if the car was not running, which seemed odd. I also thought that I heard it stop running when the car was on but I hadn't actually tested it. Well, I was right about those things. The tune was setup completely wrong for the fuel pump. It's all good now, though, and the car will idle and run. It is a two speed pump, though, so I may end up having to hotwire it into high speed mode, we'll see.

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sweeet

 

the run-sputter-die sounded like a poorly performing (or not performing) fuel pump..  glad you found the issue and got it running!

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That would explain it. On higher pressure fuel lines usually it won't do more than catch and die shortly after as the fuel pressure bleeds down very quick. If you have rubber hoses in there, it'd make sense it'd run for a bit longer. 

 

Work on getting the idle and idle target after startup maps dialed in, looks like she's idling at about 500-550 RPM!

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Work on getting the idle and idle target after startup maps dialed in, looks like she's idling at about 500-550 RPM!

 

Tach is misleading... needs to be calibrated. It's close but a little low, I think. Details, details.

 

Right now I'm sad because it doesn't look like the harness has any provision for AC on it. I want AC. I need AC. I can always put in a manual switch to trigger the relay that engages the AC clutch, but that seems pretty sad; I'd like the stock controls to work and I believe the Link ECU can make that happen.

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Some good news. It turns out that the harness does have the AC clutch control pin wired in, it's just not connected to the Link connectors. With that knowledge, I now have a plan:

 

- The current setup has an ACIS output set up; I don't have ACIS, so I can splice the AC clutch control wire into there. Now I have an output to control the AC.

 

- There's already a spare digital input. So there is an input for the AC on/off signal.

 

Should be pretty simple to wire it all together and set it up.

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I was able to execute to the plan this afternoon and the Lexus now has AC again via the OEM controls.

 

I'm still waiting on my wideband unit to ship. That's disappointing. That's really what I need next to make real progress on tuning this thing.

 

Also, I believe my passenger side header is cracked. Very lame. Looks like a major pain to pull off, too.

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I also want to say that the support given to my by Xcessive and PANIC have been amazing. I was getting emails at 9pm, 10pm, and even 1:45am in response to the issues I've had. Which were all rather minor, in the scheme of things, I should also point out. I'd definitely buy again and recommend them if you have the need.

 

It's also worth noting that this kit was NOT advertised as an SC400 specific kit, but rather a 1UZ VVTI kit. The 1UZ VVTI motor comes in a lot of different chassis and they're not all the same, so it's really incredible that it's possible to produce a kit very close to completely PNP for all those chassis.

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