idle surge / high problem

[1fast97gsx]

I just built my motor and installed it and finally got it starting after learning I had to switch around my firing order. So now the car starts right up and doesn't throw any check engine lights or anything, but it idles at about 1500 rpm and once in a while it will drop down to about 900 and then it jumps back up to 1500. If I step on the gas for a second and just let the revs drop the car will die out. The vacuum guage says I'm at 17, and whenever the rpms drop my vaccum drops to about 14 or so and then the idle goes back up to about 1500.

1) how do I change the idle? I tried adjusting the idle screw ... I think backing it out raises the idle and screwing it in lowers. The problem is the screw is all the way in and it's still at 1500 rpm. Maybe the tps need adjustment? The safc says I'm at 0% throttle and if I floor it it says 100%.

2) do I have a vaccum leak and that's causing the surging?

I'd really appreciate any help or any ideas. Thanks.

 

[dets]

the chitlins has a procedure that they have using a pair of alligator clips and resetting the idle by grounding out a fuse. You should go buy one if you don't already have one.

i'd explain it more thoroughly but i don't have the manual on me.

good luck.

 

[TSIfreek]

I woud double check all your vacume lines before changing the Idle setting. It Idled fine before the work was done right? I bet you have a vacume line off some were you forgot about.

 

[1fast97gsx]

it had no idle problems about 7 months ago. I then put the car away for the winter and pulled the motor and rebuilt it. I did a boost leak test and it was leaking out of one of the silicone connectors I used so I fixed that. Now If I blow air into the leak tester I don't hear any hissing like a cracked vaccum line or anything, but a slow silent leak coming from somewhere underneath the intake manifold. ( kinda where the head meets the block ... headgasket? ) Really it doesn't even sound like a leak it sounds more like air going into the block ... but shouldn't it still remain in there and continue to build boost on my boost guage if there are no leaks? If I keep adding air the guage will go up, but as soon as I stop adding air it slowly drops down wit the only sound I hear is what sounds like the air traveling into the head. I'm thinking maybe since some of the intake valves might be opening I'm just hearing it go into the head??? I'm not sure, but I couldn't find anymore leaks. I will do a compression test tomorrow.

I looped the coolant lines that go to the throttle body and capped the nipples off on the throttle body. Could this be causing it as well? I'm going to change that back to the right way tomorrow. How is idle actually controlled in our car? I know there's an adjustment screw on the throttle body but is that the only way to adjust it?

 

[awd4g63]

If it's hardly making any noise while you're doing an intake leak test, it's probably nothing uncommon among engines. Here's a problem I had with mine: When I first got my GReddy Type-S BOV, it was adjusted way too loosley, so when I idled, the car wouldn't be able to hold a straight RPM for more than, say, a few seconds. Most of the time I would idle really high, roughly around 16-1700 RPMS. I didn't see any MAF upgrades in your mod list, so I'm assuming you still have your stock MAF (point is, it's before the BOV). I'd check that, see if it's leaking a lot under idle. I adjusted mine until it didn't leak until I revved it up around 1000 RPMS.

Hope that may help a little

 

[dreamdemon]

The BISS being all the way in is what is most likely causing the dying. Did you block off the FAIV or just loop the lines? This could be a major contribution to your problem if you didnt block it off.

 

[1fast97gsx]

I just blocked off the lines. I'm going to hook them back up today and see what happens.

 

[APEXiD33a]

its ur throttle body causing the problem if u didnt block the faiv valve while looping the coolant lines. The same happened to me. Just block the valve holes using steel weld in the right places and youll be running fine again.

 

[1fast97gsx]

ok I just reconnected the coolant lines and it's all good again. now I ran into another problem , but I will start a new post on that one.