2G Questions about idle (difficult cold start), Euro 4G63 N/T

[joanGS]

Hi guys,
first of all, I apologise for dumb questions and bad English, I’m a non-US based newbie. Aside from the Chilton manual, this forum has been my only source of info. I’ve tried my best searching, so please link me to threads if I’ve missed something. I have the Euro version of the 2G -98 Eclipse (manual, 4G63 N/T), and because it’s slightly different from the US ones it’s sometimes hard to figure things out. None of the mechanics where I live know anything about these cars, so I appreciate all help.

I bought the car on a whim, and the only thing wrong with it (that I know of) has been a bad idle. I’m not sure what the previous owner has done to it, but I’m pretty sure they had a different intake system installed to it while they were using it, and they changed it to something close to ”basic” when they sold it.

The car is difficult to start when cold. I need to keep my foot the gas pedal and nurse the TB until the car warms up. When it’s warm (aka quickly enough), it idles about 900-1000 rpms. The idle is pretty bad in the beginning, and it looks like it tries to ”search” it. I inspected vacuum leaks before and fixed them, and this is where I'm at. While warm and driving on gear, the car seems to start and run fine (but not idle at the 750+/-850 rpms that it should). It has only been driven during summer here up north, so I’m managing with the cold start, but it’s not nice. Also, if the air condition is put on, the idle rpms drop and it wants to stall.

Another problem is that I don’t have a datalogger. My two OBD scanners didn’t work on it, so I took it to my old mechanic who said it didn’t give any fault codes. I’ve read from here that this car should be OBD2, but I’ve tried two scanners that didn’t work, and I’m still confused if it's actually an OBD1.

There are no warning lights on the dash (— well, aside for the SRS light that just appeared yesterday out of nowhere after I literally just vacuumed inside the car. Never happened before in my time. But that’s another issue, I guess? Jeez.)

As for the idle —

I installed a new IAC motor, thinking it’s the issue. Took the battery out at first, put the new part in, adjusted the BISS about 1.5 turns out from fully closed, and tried to start it. It only made it run much, much worse. The idle surged like hell.

To adjust the BISS, I’ve read I should ground certain pins to keep the IAC on base position. Is anyone able to say if this advice is compatible with the Euro 2G?
http://www.vfaq.com/mods/BISS-1G.html

In any case, with the new IAC, the idle rushed up to 4k at once, and made the CEL come on. It scared the heck outta me, so I didn’t let it run any longer. It was so BAD I’m too scared to try again with BISS adjustment + proper grounding. I just put the old one back in like the wuss I am. It seems like something about the air/gas mix is messed up, and the ECU has no idea what to do.

I’m pretty sure the previous owner played with the BISS and maybe the throttle position sensor, too. Unfortunately I don’t have a link to help me with those. I’m pretty much still learning the most basic electric stuff here.

So far, I’ve also
- checked the throttle cable, which seems not too tight
- read about FIAV; but most threads only talk about bypassing it , so I’m still a little confused as to what to do if it’s wrecked. From reading this, I feel the only sane option would be to do that: http://www.dsm.org/how-tos/tttt/tttt3.html

Next, I’m considering these:
- does the throttle body have proper ground, and where is the ground located on the 2G TB? Is it a ”metal slab” similar to the one on the 1G TB, and could it affect the idle?
- could it be a bad coolant temperature sensor telling the computer wrong information, leading to incapability to start cold? Is there any sense in buying a new one?
- is the cheap new IAC I got from ebay just wrecked, or is the problem is the FIAV, or TPS?
- could the problem be a faulty ECU, as it (apparently) gives no fault codes for the idle?
- I’m also thinking of taking out the entire TB and cleaning it, if that would help.

Without a logger, it seems like I can only guess.

Would you guys have any ideas as to what to do next -- like, what's the most probable cause? Am I a totally lost case? Or is the answer to just.. get a logger

If anyone managed to read this entire thing, thanks a lot!

 

[ATF 2GTalon]

96 and up were fully obd2 compliant. Any obd2 scanner should have been able to read the ecu. Check your wiring harness at the ecu, make sure it has not been hacked up by previous owner. Make sure the wiring are connected and not loose.

It does sound like not enough air is bypassing the throttle body. Do you have a multimeter? You can check the resistance of the coils to make sure the iac is ok or not.

Do you still have the coolant lines connected to the throttle body?

Also check that your throttle stop is adjusted correctly. You need a feeler gauge to check the gap of the butterfly in the throttle body when closed.

And also check that your TPS is set correctly too. 2 of the TPS pins are supposed to have no continuity in the closed position and then have continuity when open.