HKS Step 1 256 troubles... Nasty idle?

[driftin_sr20det]

I don't quite understand why the idles acting soo crappy. Install went perfect, took around an hour. But, its acting real lopey. At 1K rpm's its got 14 or less vacuum. Doesn't seem right. They work great through the band, but idle sucks. They are supposed to not affect the idle that much, I thought. I've had them lying in my closet for probably around 5 months and just decided to put them in since I had some time with the holiday weekend. I've tried adjusting the IACV and the idle screw, but the best I can get it is about 17 on the vacuum at a 1400 rpm idle. If anybody has some suggestions or idea's let me know. Timing is on by the way.

Oh by the way, I'm running a s13 redtop w/ gt28rs; FMIC, 255lph pump, topspeed intake manifold, SSAC exhaust manifold, divoced dump, 3" full exhaust, MBC @ 1 Bar

[Lroi]

Im a noob to this but could it be a ecu/management issue? maybe the increase in airflow is throwing something off.

[Onizuka]

There is also a idle timing adjustment screw on the ECU itself, you might be able to play with that to get things to smooth out.

[driftin_sr20det]

I had no idea that there was an idle adjustment screw on the ecu!... I'm running one of those Boost Up ecu right now anyways, and I don't think its set for a cam upgrade. But, they are supposed to be soo mild that it should matter is what I've been made to believe. But with a larger duration I guess you should expect a little trouble. I'll have to check that out screw out today. THANKS!

[driftin_sr20det]

Actually are you talking about the screw to check the codes? Thats the only screw I could see unless its inside the ecu or something. I'm not exactly a noob had my sr for about a year now, but I didn't know that adjusted idle also.

[highmilehatch]

There is also a idle timing adjustment screw on the ECU itself, you might be able to play with that to get things to smooth out.

You sure about that?

[VitaminT]

A buddy of mine installed a set of hks 256 step1 and he is having a slight issue at idle. The car seems to run fine but at idle has a slight miss. I don't know if he just needs to go ahead and get a rom tune for it or what. I have checked his cam timing to make sure it wasn't installed 1 tooth off and everything seems fine.

[driftin_sr20det]

Yeah sounds like the issues I have, mines more of a lope. Like a more aggressive cam should have. The whole reason I bought the HKS 256 step 1 was to not have that issue. Did his idle vacuum go way down after the install too? Mine likes to idle at 14 or 15, if not lower sometimes.

[BaliLover]

My step1 264s only pull 12 at idle and have a pretty damn lopey idle. So much so that I had to adjust the idle screw because with the new cams I was stalling out any time i came to a stop. I'm still not idling over 1000 though, I'm around 850-900.

[travisn]

with intake and 3" exhaust your vaccum is going to be less because there is less resistance to flow...

[BaliLover]

No, thats not correct, I was running a 3" turbo back and an alum. intake pipe with a K&N and was still pulling 18. It was only when I put the cams in that it dropped to 12. At idle, the throttle plate is closed so intake has almost nothing to do with it, vacuum is all about how long the valves stay open. The longer they stay open, the less vacuum you can pull. Vacumm is pulled when the valves are closed, so flow has very little to do with it.

[VitaminT]

On the vac issue. I think his dropped some buy haven't seen his car in a while so I don't remember what it idles warm at with the cams.

[driftin_sr20det]

Very interesting. It makes a more sense now that I think about the duration of valve lift. Thats what the cams are all about, so of course the vacuum will be down. I'm now not that worried about something being wrong, but whether I will be able to tolerate the lope with it being my daily driver. Thanks for everyone's replies and I appreciate the info.

[BaliLover]

Just keep the idle under 1000, mine likes to be around 800 in order not to stall between shifts. I'm sure the lope isn't that bad, its just much more noticible than stock. With the 264s I've got, if I drive hard and park somewhere, the turbo timer will keep it running for up to 3 minutes and I almost always have someone ask me if something is wrong with my car.

Do you have any way to record video of it running, or maybe just a sound clip of it running?

[highmilehatch]

Do you have any way to record video of it running, or maybe just a sound clip of it running?

Interested in this as well. I'm surprised your idle has been affected that much with the 256's. Could there possibly be air trapped in your hydraulic lash adjusters?
Modified by highmilehatch at 7:37 AM 5/30/2006

[driftin_sr20det]

It's actually been doing pretty good lately, idling at 800 with 15 vacuum. Just lopy. Everyone who's heard it has noticed the difference over the stock ones. Asking if I just put cams in and sh*t. I have an audio recorder so I will post some audio soon. I would post a video but my dad just backed into my car the other day and its looking pretty ugly right now. Have to replace about everything.

[D1 guy]

Yeah when i installed my hks step 1 cams which were 256 and 264, I went ahead and raised my idle about 300 rpms. It ran like crap for about 2 days and then everything smoothed out. It runs perfect now, so I think everything has to get broken in good and the ecu has to do a bit of learning. Over the next few days, it should smooth itself out.

[driftin_sr20det]

Got some audio I just can't seem to get it on my geocities site to put on here, so you guys can hear it. I'll still try to get it up.