Low Idle issues

[z_tune]

Hey guys I need some help diagnosing an annoying problem I've been having. I'll just list every little symptom I have.
So here's whats happening:
-The car will always idle around 500 rpm and seems to get worse as it warms up.
-Idle dips to 200 maybe even to 100 when I shift into reverse then comes back up to 500 ish.
-surges occasionally maybe 100-200 rpm.
-almost stalls itself either while slowing down or at a stop (rarely happens but has happened)
-car seems very stinky and the exhaust tip is very black
-Loud ticking sometimes from engine, I always thought lifter tick but could be exhaust leak.
-at 3k rpm cruising the car the rpms will go down then back up but only when cruising at those rpm.

What I do know:
-battery, plugs, wires have been replaced
-small leak where cat connects to catback.
-no CEL
-runs fine ironically

let me know what you guys think might be going on. Currently it sits in my driveway but will be back on the road in a month so I want it running perfect

 

[drzdude]

Sounds like your idle speed controller is not functioning or dirty.

 

[pos4g63]

Do you have the stock BOV, and is the BOV recirculated?

 

[92AWDHX40]

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

read this for idle issues it may help lots of information there, start with one thing and go on another.

 

[z_tune]

Do you have the stock BOV, and is the BOV recirculated?

I have a rs bov and it is recirculated

 

[wraithGSX]

There is a screw in the throttle body,it is on the side of it,facing you near the top.It's like at an angle,and it's recessed,so you have to look for it.Try pulling it out and changing the O ring on it,then put it back,and adjust your idle with it.
That O ring gets dried out,and it creates a vacuum leak,and some annoying idle problems.

 

[jorgea]

I would advice you to have your idle speed controller checked for defects.

 

[dsmlover07]

Seven bolt im assuming you can test the isc, tps, adjust the biss screw lots of things in the post above on dsm idle.

 

[Tiki2777]

You could have a boost leak. Mine ran like sh^* and i didn't believe it and when i finally checked the lower intercooler pipes they were hardly connected. I would check you lower intercooler pipes and jpipe if you have one.

 

[dsmlover07]

Ok how about a video, loud ticking? A video would really help.

 

[z_tune]

Here's a video:
99 eclipse gst idle problem - YouTube

You can hear how the idle dips real low after I rev it in the video

There is a loud hissing when I rev it which I always thought was the turbo but I've been researching and it sounds like it could be an intake manifold leak?
I dunno tell me what you guys think

 

[feardafish]

Dunno, that ticking sounds like it may just be your injectors. Check your ISC for proper functionality, and do your boost leak test. Also check your ECU for busted or leaky capacitors, those tend to go if the ISC isnt functioning properly.

 

[z_tune]

Thanks for the help guys I will be testing my isc soon. Hopefully thats the problem

 

[z_tune]

Alright guys so I finally got around to testing my isc and just to make sure I did it correctly I tested 1-2 2-3 then 4-5 5-6. All of them were at about 42 ohms. Is this within acceptable range? I read it should be around 40 on dsmisc.com

FYI I have the black plastice isc motor

 

[21_Eclipse]

Where is the isc located? And how do i check it?

 

[tcbikerguy6]

Where is the isc located? And how do i check it?

main page

 

[The Great White]

I'll be interested to hear what you find z-tune. I literally have all those same exact problems. Be sure to post what fixes the problem if you come across what is causing it.

 

[z_tune]

Definitely will let you know. I was going to clean my throttle body this weekend but the Colorado weather says otherwise

 

[Abe'sGST]

whenever you get a chance do clean out the throttle body, that may help you out some, but also check and fix any leaks (exhaust, intake, vacuum and boost)

 

[The Great White]

Definitely will let you know. I was going to clean my throttle body this weekend but the Colorado weather says otherwise

Yeah I'm in the same boat, gonna clean the throttle body and probably my MAF this weekend. I peaked under my car the other day tho when it was cold out, so I can see any noticeable leaks, using the cold weather to my advantage. Sure enough, I have a nasty exhaust leak and could see a bunch of air dumping out before the muffler, pretty much all the way down my exhaust. So like the other guy said maybe check that too.

 

[z_tune]

Alright I had some free time today so I decided to throw in the isc I got from dsmisc despite what I think getting good readings from my old isc. I put the new one in (which read a bit over 38 ohms) with a new o-ring and so far it seems to have fixed the idle. I'm so freakin happy this has been bugging me for so long! Idle is solid a bit over 500 and never dips below that. Now from my understanding if this isc goes bad my ecu is bad so we'll see.

 

[theoutlaw82]

Sounds like your catalytic convertor is going bad. Thats why you have the bad smell and also low idle and stalling. When a cat starts to plug the enine isn't pushing enough air at idle to breath through it so it starts to stall at low rpms.

 

[WES_393]

Alright I had some free time today so I decided to throw in the isc I got from dsmisc despite what I think getting good readings from my old isc. I put the new one in (which read a bit over 38 ohms) with a new o-ring and so far it seems to have fixed the idle. I'm so freakin happy this has been bugging me for so long! Idle is solid a bit over 500 and never dips below that. Now from my understanding if this isc goes bad my ecu is bad so we'll see.

Yes, a bad ISC can burn up a daughter board in the ECU. I would pull the ECU and check for any burns or corrosion. 500ish is still low for idle. The ISC should be able to keep it around 900 warmed up.

 

[jb2zero0six5]

Doesn't anyone BLT anymore?

 

[brownie956]

Before assuming your ISC is at fault, be sure you have no major wiring/harnesses unplugged. My radio deck all of the sudden crapped out on me, so I took it out to have it tested where I bought it. After they had tested it, I left it aside without plugging the harness or power cable back in. That night and the following day I had low idling around the 350-500rpm neighborhood. The day after, I plugged it back in and got everything back together. I no longer have a low idle issue. Not entirely sure if the battery is excessively stressed because of this or what the deal is, but it fixed it. This is the first time I've ever had an issue with idle, and the first time I've left my deck unplugged, so it's highly unlikely it is coincidence.
Also, be sure to troubleshoot your low idle issues when the car is thoroughly warmed up, as it will obviously idle higher than normally when in warm up mode. AC off, defrost off, and your wheels turned straight in a manner that won't cause the ECU to increase engine speed.
The service manual calls for a normal idle operation of 750rpm, +/-100rpm.