Idle problems

[1G9S9T7]

I am having an idle problem in my gst. First it is a 6 bolt swap. When it is warmed up, it idles at 1200 rpm and it will rise to 1700 rpm then drop back down to 1200 rpm and continues to follow that pattern. At times if I barely tap the gas, it feels like it might stick and the rpm goes up to 2500 and maintains that, if I tap it again, it comes back down and continues to follow the above pattern. I have tried the following:

Boost leak test
soapy water to find vacuum leaks
tested and changed the isc motor w/ good o ring inside
cleaned a FIAV off my 7 bolt tb and installed
egr blockoff plate installed

It seems like I did more than that, I just can't think of it offhand. I intend to do another boost leak test in the morning to double check. I have ran out of ideas for what to do. The car runs fine and idle has improved a lot throughout the alterations I made above but it still has issues I can't seem to solve. I started by changing the ISC motor, then the whole FIAV, idle improved slightly, I ran a boost leak test and used soapy water to find leaks, I had bubbling from the tb elbow gasket, the BISS screw, the caps on the nipples on top of the tb and somewhere near where the intake mani bolts to head. I used red silicone my friend had to put on the tb elbow gasket, tightened the biss screw, changed the caps on the top of tb and upon removing fuel rail to investigate the leak near there, I found that two of the o rings that go in the head to seat the injectors were bad so I replaced them with two good ones from my 7 bolt head. I did a boost leak test after that and everything checked out. It's current idle has been the best it's been since I got it running. The biss screw was adjusted by someone else and I found out from research it was a bad idea to touch before checking everything else... I can try to answer any questions to help anyone help me. I also read on adjusting the tps and biss screw but I need advice for it. On the tps do I use the 1g or 2g guide? I have a 1g tb with a 2g tps and on the biss screw, same question, do I use the 1g or 2g guide? I wasn't sure if it would differ since I had a 1g engine in a 2g car...

 

[The1G_Guy]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)
A friend of mine had this problem with his car.

Let me know if that helps please, I don't want to give false info, and would like to know if thats the case so i can help another later on

 

[1G9S9T7]

This diagnostic mentions removing a connector on the idle switch... Is this a reference to the TPS? Judging by what I read, it sounds like it. There are a couple pieces of info I haven't heard yet in this so I will give them a try and see what happens.

 

[miguelmcv]

Check your ISC, Test all coils to see if they are good, also, check if you have any exhaust leak, it will give some headaches.

 

[007jimmy]

Is your throttle cable too tight?

 

[apocalypsio]

I was about to ask the same question my throttle body cable was to tight and my idle surged alot as soon as a put my foot under the pedal and pulled towards me it stopped. Check the tension on the throttle cable and also clean up the tb if it seems to be sticking.

 

[1G9S9T7]

On the ISC motor, I tested that originally following a youtube video by jafromobile. I had a bad one so I tested the one on my 7 bolt tb and it checked out good, 32-34 ohms on each coil.

On the tb cable, it may be on too tight, I don't exactly know how to adjust it or what the spec is for it (This is the first car I ever fully worked on in my life. Only prior experience was a 5 speed swap)

Now I had the tb off when I changed the FIAV and I cleaned all of it with carb cleaner. During the boost leak test I first did, I detected leaks from the gasket that goes between the tb elbow and the tb. My dad used Indian head shellac gasket compound on that gasket before putting it back on and it stopped the leak at that instant. I took the elbow off tonight and found that some of the gasket compound has hardened on the bottom of the tb on both sides of the throttle plate. Is that a possibility that it might be allowing air past my throttle plate by not allowing it to close completely? I intended to clean it in the morning btw.

Where are some common places I can check for exhaust leaks? Sorry if this is a stupid question. It doesn't seem to sound like it has one but it won't hurt to check. I thought about checking the o2 sensors. I was told there were 4 of them but I read somewhere that there was 2 of them so I don't know which is right. If an o2 sensor was bad though, wouldn't it throw a code? I had it hooked up to a scan tool and the only code was p1105 (fuel pressure solenoid), the guy said he was actually impressed that it only threw one code especially with the egr gone.

EGR delete question. I used a picture of blockoffs on here for the delete. These are what I blocked off, just making sure I did it all right and didn't miss something that might be causing me grief. I removed the evap can under the battery and got a blockoff plate for egr. I put caps on all the nipples on top of the tb and one on the intake where the hose runs to the evap can. I seen others to block according to the diagram but found no reason to block them (I intend to put the egr back in when I get the time to figure out how)

 

[miguelmcv]

A hard peace of compound inside of the Throttle Body will be extremely risky, which it will come off with the vibration and will get into the valves and cause to brake them of to bend them.
Remove that peace to be save, I always put grease on the throttle gaskets, the grease will make the gasket to expand a little and make a good seal, next time just use grease and you will be OK.

Throttle Cable.
Just loose the 2 bolts holding the cable at the intake, some times the cable is to tight that it keeps the throttle open, loose the cable and make sure that it doesn't open the throttle when you tight the bolts.

 

[007jimmy]

Yea, I would try to remove the gunk buildup on the bore of the TB. Be careful not to nick or scrape the TB bore or it would have to be replaced. Especially near the throttle plate. You shouldn't have to ever RTV TB gaskets. Were you re-using gaskets?
Exhaust leaks could be found at:
Head to exhaust manifold
Exhaust manifold to turbo (or cracks in the exhaust manifold)
Turbo to o2 housing
O2 to downpipe
These are the most common leaks. We also only have 2 o2 sensors. The one near the turbo is for your fuel trims and the one under the car is for your cat converter. If they are dead or dying most likely it would throw a CEL.

 

[1G9S9T7]

I was gonna see if carb cleaner will take that crap off of the tb. I will adjust the cable tomorrow. I didn't get time today to do it. I have a few issues besides idle that I gotta do some research on as well.

This question is a little off topic but I figured I would ask it. I was removing some excess wires under my dash from past electronics and I found a thing in a vent that said "Auto trans only" on it. It's under the dash on the left in the vent right next to the hood release. My car is a manual and I have a 95 GSX that didn't have this and it's also manual. I didn't take my lower dash apart to see it better but does anyone know what this is? If my car has been swapped from auto, I am highly impressed by it. I had AT to MT swapped Hondas before and they were by far a shame to the automotive world.

 

[miguelmcv]

Be careful not to let that peace go into the intake manifold, other wise, you have to remove the intake to take the peace out.

 

[The1G_Guy]

How did the carb. cleaner and ajusting the cable go?

 

[1G9S9T7]

My apologies for taking so long to reply. I had some internet issues. I cleaned out the tb and adjusted the throttle cable upon installing the tb. Idle improved drastically but opened up a couple more problems. I am about to start doing some searches on it but I figure I might mention it here too. First off it idles at 1k approximately now. It still fluctuates but this is like very minor ones like not even a full 100 rpms drop. Every so often, it cuts out like almost enough to shut the car off. My dad said you can hear it in either cylinder 3 or 4 like it's misfiring. The plugs and wires are brand new. My factory boost gauge quit working since the tb install and now when I give it gas, it hesitates to respond. Neither of these occurred before the tb removal and clean. I was considering the fact it may have jumped time because I noticed that the timing belt has this bad habit of loosening up bad on top of cam gears (not just the play that the exhaust cam gear normally gives) but if you take a wrench and turn it slowly, it tightens back up. I'm not entirely sure. Any imput?

 

[Roberti 2G]

Good old dsm think you fix one thing then another comes up. Im working on my idle problem as well.

 

[angelito2g]

I had that same problem in mine. When I remove my cruise control cable it stop doin it.

 

[rhtwng2]

Check your ISC, Test all coils to see if they are good, also, check if you have any exhaust leak, it will give some headaches.

I had this same problem and I bought a ISC motor and it cured the problem although I will need to re-tune the motor since I added a larger turbo and wastegate at the same time.

https://www.partstrain.com/store/?N=0&VN=4294967143+4294960711+4294960689+4294965973+4294967066&Ntt=Idle+Control&Nr=AND%28universal:0%29&ref=partfinder&sv=0

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[1G9S9T7]

Well scratch that last post. I posted assuming my directions were followed. My in dash boost gauge wasn't working and it was dark so I didn't check it but the maf was unplugged. So my basically the idiot helping me failed to plug the stupid thing up. Guess I need to start double checking the work. As for idle, you can rev it up and it will go to like 1500 rpm and hold that steady. When it idles regularly, it is a rough idle between 900 and 1100. It stays close to 1k so changes on the gauge aren't drastic but the idle is just rough.

*I tested the ISC motor twice already. It's good. I also went through the troubleshooting guide. I pretty much combed over the tb aside from biss screw and tps which I need to verify which instructions to follow. I have a 1g tb with 2g sensor and 1g engine in 2g car so I not sure which instructions to follow.

 

[1G9S9T7]

I haven't set base timing yet since I finished the timing belt job and installed the cas. The cas is set at mid range of adjustment. Will that have anything to do with rough idle? I would have set it earlier but I couldn't keep it running then once it stayed running, we entered the idle issues.

 

[G-STowner]

I just had a rough idle. It turned out my BOV diaphram was shot. I pulled the line on the BOV that connects to the intake manifold and just covered up the nipple with my thumb. when I did that it idled just fine.

 

[1G9S9T7]

Bringing this back, didn't want to start a new post but i have a question on tps and biss. I have a 2g 97 car with a 1g swap, the tb is also 1g but the tps is 2g. My question is this, on adjusting the biss and tps, which set of instructions do I use? My guess is following 2g for tps but the biss, do I use the 1g or 2g instructions for adjusting biss on my car? I never really got a clear answer and wanted to make sure it's all right. I don't have link yet