Low/Rough Idle after upgrades

[crazykid]

Ah where to start I just recently finished installing my urethane motor mounts. Since I had the UICP pipe off, I went ahead and took off the throttle body and changed both the TB gaskets, I also tried to clean up the TB a bit with some degreaser I had, didnt do a perfect cleaning job, but looked better than before. I put everything back together, cleaned some things up, started the car, and have been having some rough/low idle. I found a couple vac lines that were disconnected, reconnected those, did a boost leak test and found no major leaks (although im going to do it again later with a buddy as it will be easier to watch the gauge, adjust pressure, and check for smaller leaks). I started playing with my MAFT and found that if I changed my base from 750cc injectors to a lower setting like 730cc, this made everything run a WHOLE lot smoother (I find this funny as I will explain later on), but my idle is still way to low (~like 500,600rpm). Would taking off the TB and putting it back on require me to readjust my idle? Or Am I looking at something else?

When I originally installed the new turbo blowthru setup with the MAFT, I had it runny very smooth at a 750cc setting, and an idle of +2, and I believe mid at +1. Now after what I have done listed above, it seems like everything is different and im having to really lean things out instead of making them slightly richer? I dont have a logger available right now, and DSMLINK is on my list of things to get, I just find it funny that I had things running smoothly at 15psi before, and now I can hardly get the car to idle right, rough accel, stalls.

Ive heard that the MAF/MAFT is not always accurate, and removing/reinstall can change things, is that what this could be?
Im sure I installed the gaskets correctly, it really does not take a brain surgeon to do. Why would my idle be off?
Is it possible I have a dead O2 sensor?
Maybe changing the old gaskets with the new ones or reinstalling piping fixed old leaks and threw everything off?

Remember, I had things running smoothly before changing the gaskets and doing the motor mounts, but now it seems like im having to lean things out. I really know I need some EM, im going to be getting dsmlink and a wideband as soon as I have the extra money. I just want to get this car running smoothly again at low boost for the time being.

Damn, just noticed how long this is sorry. Any help is really appreciated. If you need any more info just ask. Thanks so much.

 

[andymoraitis]

When fixing leaks, especially on the throttle body, your idle will change and you'll need to compensate for it accordingly. If the car isn't throwing any CEL's I'd move straight to the simple things. Adjust the BISS and see if your idle improves. I'll bet it does.

Keep us posted,

Andy

P.S. Nice informative novel, err I mean post, by the way (really).

 

[crazykid]

When fixing leaks, especially on the throttle body, your idle will change and you'll need to compensate for it accordingly. If the car isn't throwing any CEL's I'd move straight to the simple things. Adjust the BISS and see if your idle improves. I'll bet it does.

Keep us posted,

Andy

P.S. Nice informative novel, err I mean post, by the way (really).

Thanks, I was really considering doing that first step, just wanted to make sure I was doing the right thing. I set all my settings back to what should be base and decided to stop messing with the MAFT for now and take it 1 step at a time. Actually speaking of CELs, ever since I did my turbo swap, I have been throwing a CEL, got it checked at autozone before my most recent 'teardown', and it said it was the Catalytic Converter. Well I dont have a CAT (never did before the new turbo setup either), so why would it start complaining after the new turbo setup?

 

[andymoraitis]

Sometimes the CEL for secondary O2 sensor won't kick on for ages but if the ECU is re-set from the battery being disconnected, it'll crop up. We have a tech article on how to build a simulator for the rear O2 here if it starts to get annoying:

http://www.dsmtuners.com/forums/showthread.php?t=221951&highlight=O2+simulator

Since your CEL isn't related to your idle, I'm still thinking you're good to go with a simple BISS adjustment.

 

[crazykid]

Wow, an idiot I am. So I go ahead and ground my connections and start trying to adjust the idle, but its giving me issues? First I couldn't the car to stay running in the first place, finally after I gave it some gas and let off slowly I got it to stay running. But it seemed like I couldn't turn the idle up very much at all, and it was very rough. At this point im like WTF. Then just for kicks I double check all connections and lines on the thorottle body. DAMMIT the ISC? connector (one right next to BISS screw, correct me if im wrong) wasn't plugged back in all the way. Snapped that back in and boy did it make all the difference in the world, was probably most of the reason of all the problems from the beginning. I had to mess around with the idle still though since I had already started messing with it before I noticed the connector was loose. I had to go by the tach, and set it to around 800-850rpm let it sit for awhile. All seemed well. Started it normally and it seems to be working great. Still a bit "bouncy" but probably since the ECU has to relearn crap as normal from the batt being out. Nothing new there. After awhile it was pretty even at where I had it set.

On a side note, my biss screw didn't have any cap over it. Also, when turning the screw (was pretty easy to turn to, thought it would be a bit tougher/stiffer?), I could hear a "hissing" and it would change slightly as I turned. Putting my finger over it, I could feel a slight suction. Bad biss o-rings? Are these a certain type or can I use any kind of new oring? Or do I just need that cap that is supposed to go over it. I can definnently hear some kind of hissing around the TB area or where all the vac lines are around there, when the car is idling, but I cant directly pin point it.

Im going to attempt to do another boost leak test later on and use some soapy ass water and see if I can find anything. Earlier I didnt hear any hissing when doing the test. So I dont know whats up totally. Also had trouble with my leak tester wanting to blow off the turbo intake at ~15psi (ouch is that loud and scary). Any suggestions to fix that would be nice.. maybe ill have to socket that ring clamp down to get a tigher hold. Really dont feel like jacking up the car to remove the LICP plus I dont think I got the right size coupler for that.

 

[zippyshoe]

You should not feel suction at the BISS screw even without the cap. This does sound like a leaky BISS screw o-ring. Here is one source for this part: http://www.extremepsi.com/store/customer/product.php?productid=19021&cat=865&page=1. They also carry the replacement cap: http://www.extremepsi.com/store/customer/product.php?productid=19020&cat=865&page=1. Hope this helps.

 

[andymoraitis]

Definitely get a new O-ring as mentioned above. In hindsight, I'm glad it was something simple. You wouldn't believe the stuff I forget to hook up when I pull things apart so don't feel bad.

 

[crazykid]

Definitely get a new O-ring as mentioned above. In hindsight, I'm glad it was something simple. You wouldn't believe the stuff I forget to hook up when I pull things apart so don't feel bad.

Yeah I know it happens. Just makes me mad that I had it "connected" just not fully snapped into place, and it really wasn't obvious that it wasn't plugged in. I dont know how many times I had looked to double check just making sure I plugged everything back in and re-connected things.. grrr damn dsm