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Rb20Det Startup Very Rich After Rebuild

jwest616

By jwest616,
in Engines & Forced Induction

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jwest616 Newbie

jwest616

Posted
Posted

Ok guys first off I wanted to say a big thank you to this forum. I have been building my project for the past few years and this forum has been gold. This is my first post because there is so much knowledge in hear that all I have needed is the search button. Alas I am at a point I could use some help.

My car is running but won't idle well at all. I have to give it some pedal to keep it going and it won't idle below 800 very well. It wants to die below that. Runs very rich. Here is my setup so you know what you are working with. I won't list everything but the stuff that should matter

1996 S14.5

RB20DET stroked to 2.2 fully rebuilt

RC650 injectors

Q45 Maf and TB

Power FC (injectors set to 37% with no latency correction and air to the 90mm option) other than that it is set to stock for now.

No AAC or IAC or any other smog options (I'm open to putting this one but would need some guidance)

Greedy knockoff intake but not crap one

Top mount GT3071R

Wiring Specialties Harness

Tomei Poncams or Procams (been a while haha and can't remember ATM)

Solid Tomei lifters and stiff springs

Adjustable Tomei Cam Gears

Supra fuel pump 2jz

3" Tanabe turbo back exhaust

Thanks for any help. I am hoping to have a wide band tomorrow

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AMR33 Mentor

AMR33

Posted
Posted

I'm no expert but I see running rich as one issue and the fact that it wants to die below 800 revs is another. Hard to diagnose these things online, maybe get her on the dyno and see what's really going on with the ARFs etc. All the best

Amir

GTSBoy Grand Master

GTSBoy

Posted
Posted

Cams. Big duration cams won't like to idle at normal revs unless everything else is really sweet. Raise your target to 1000rpm or so until you're sure that you don't have any other problems. And it doesn't matter which of the Tomeis you have - they're both pretty big when it comes to idle.

Latency. You will almost certainly need to adjust the latency. The new injectors could be not too far different to the originals, or they could be hideously different. What works at long pulse widths (ie, load and revs) will not work at idle pulsewidths if the latency is not right. This is because the latency does not scale with pulse length. The latency is fixed, and causes a much bigger delta to injection time at idle than it does when running on load.

Idle control valves (AAC and IAC) are not pollution gear. They are very helpful. If you can run them, then you should run them. It makes getting a nice smooth controlled idle a lot easier. AAC is more optional. It's a cold start thermostatic idle up that goes away once the engine has some temperature. But the IAC is closed loop speed control via stepper motor (or equivalent) that the ECU can use to stabilise idle. It's worth it. You'll get plenty of people on here telling you that they don't have it fitted and they have perfect idle......and good on them. But if this is intended to be a road car, driving in traffic etc, you'll likely be happier with it.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Have you had a tune at all? You really should get it tuned now even if you want to tune it yourself later. What do you know about the timing and is it rich everywhere or could it be leaning out under some circumstances?

Impressive build though!

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jwest616 Newbie

jwest616

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Thanks for the responses.

As for the cams, that makes tons of sense now, I will raise the idle. The reason I didn't was because everything said in order to use the timing light and adjust the CAS so I am at 15* I needed to be 650-700 rpms. Is there a way to do it at 1000 rpms? I think CAS adjustments are some of my issues but certainly not all. Currently the belt is spot on on mechanical timing and CAS is in the middle.

I figured I would need to adjust latency but wasn't sure if I could trust the sources I was finding on what stock injector latency was and what my RC650s are. I will be calling RC today to see what they say theirs are. As for the stock ones Webbers says they are 270cc with a .75 latency, is this correct? http://webbersrbguide.com/index.php?option=com_content&view=article&id=64:skline-rb-standard-injectors&catid=45:wiring-electrical-a-ecu&Itemid=23

As for the iacv and acc I know they aren't air pollutant control I was just saying that I didn't have those in addition to the others hooked up. I will see if I can find them and put them in. On the underneath of my plenum there is a spot for the iavc but I may need some help as to how to plumb it. If I run those I should remove the cold start from my Q45 correct? I think I would prefer to go this route anyway because I don't like the mechanical cold starts.

As for the tune, no it hasn't been tuned yet. I plan to soon but wanted to get some of these bugs out before I took it down so it is a more productive time. Also as it won't stay alive without holding the throttle a little it would be a pain to drive it to get tuned and don't really want to pay a tow. Thanks for the compliment, it has been a long process but happy with how it is turning out.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Have you checked the fuel pressure?

Adjusting the latency isn't too hard, it needs to be done first up in the tuning. If you don't know how to do it, best leave it and limp down there. Just raise the idle a little perhaps, so it doesn't stall.

Take a set of plugs with you, good chance you will foul the ones in there.

jwest616 Newbie

jwest616

Posted
  • Author
Posted (edited)

Here is what I got from RC on the latency. It is for the 750s but he said it should be close to the 650s. As for fuel pressure, I need to get a pressure gauge but I will soon to test. It is a supra fuel pump so it should be strong but I don't know how much.

post-137169-0-82307700-1413859150_thumb.jpg

Edited by jwest616

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