Engine idles eratically

nfljohnl · Mar 21, 2010

Hey evryone,
I just bought a 2g spyder. It is a 97 gs shell with a 6 bolt 4g63 turbo motor. Ok I am having a few problems the person I bought it from said that it needed a turbo and a battery to run. I bought the battery and it starts right up. After I start it up it idles good for a minute or so and then after that it starts to idle eratically, and shuts off. Ican turn it back on right away but the same thing continues to happen. When I press on the gas and put it in gear it does move but will not accelerate past 3,000 rpm's when in neutral or in gear. I have no leaks and only had some white smoke but hardly any after the first or second start up. The BOV is recirculated. For some reason whoever re organized the wiring left a few plugs not plugged in and I can't find where they are supposed to go. That might be the main cause of this problem. I am a newbie and would greatly appreciate any help I can get with this. I will post pictures later Thanks.

Lofty · Mar 22, 2010

1st plug;
Not too sure where that goes. could be a diagnostic plug. Something is definately up with your tps. Take more pictures of it so I can see what's going on.

is with the tape on it?

2nd plug. This is a diagnostic plug, ignore it.

The TPS wiring would explain why it wont go above 3,000 rpms.

snowborder714 · Mar 22, 2010

Lofty, are you referring to the oval plug? If so, how do you know it's a diagnostic plug, and what is it typically used for?

Learn to love this article.
http://www.dsmtuners.com/forums/art...047-2g-engine-bay-electrical-connections.html

The TPS looks ok to me, but it looks like he taped the knock sensor plug plug there, which needs to be plugged in.

My guess for the square gray plug is the main radiator fan motor. You can confirm by checking wiring colors with the tech article.

The oval plug might be for the N/T's ISC? What are the wire colors?

nfljohnl · Mar 23, 2010

I will find out the colors of each plug tomorrow and take some more pictures. I think the plug in the last picture might be for the idle air control motor, but I'm just guessing.

DSMified92 · Mar 23, 2010

2nd pic: looks like main fan plug which the fan isnt there

4th and 5th pic: looks like cas plug to me could be wrong tho

snowborder714 · Mar 23, 2010

IAC = ISC, so it sounds like we're both thinking the same thing nfljohnl.

Waylon, that isn't the CAS plug. The CAS plug looks like the TPS plug.

nfljohnl · Mar 23, 2010

Ok so I checked the car again and I found that there is nothing plugged into the cars idle air control motor. I tried to plug the square plug into it but the wire is not long enough. So I'm not sure if it goes there or not but that is probably the cause of my eratic idling but does it matter that the plug was for the non turbo's isc/iac. Also I found another plug that was not connected and I can't find where it goes but I'm pretty certain it's either for the EGR solenoid or the Fuel Pressure solenoid valve, I'm assuming this would also contribute to my eratic idling.

snowborder714 · Mar 23, 2010

Here's what the ISC plug should look like.

nfljohnl · Mar 23, 2010

Yeah that's the exact plug it's fot the iac. The only problem is that it is in the same wire looming as the mass airflow sensor so it doesn't reach the idle air control. What should I do? Does it matter if it is the n/t iac plug? Also what is that oval plug? Yhe only thing I can think of it matching up to is the MAS.

I don't know if you can see it but in the second batch of pictures, th first picture is where the iac plug should go and it's not there.The second picture was the plug with the tape on it in the first batch and yhe third picture could be the egr or fps plug but I'm not sure.

snowborder714 · Mar 23, 2010

The square one that's in the same loom as the mass airflow sensor is for the main radiator fan (4 pins). The ISC plug has 6 pins like in the link I posted.

I do not know what the N/T ISC plug looks like for sure, but I believe they are different.

As for that last plug, you'd have to check wire colors to verify which plug it is.

nfljohnl · Mar 23, 2010

Ok, thanks a lot. So what should I do about this iac plug? Also what about the possible knock sensor plug with the tape on it?

snowborder714 · Mar 23, 2010

Do you have an ISC plug that looks like the one I linked to?

Whoever did the 6 bolt swap into the GS chassis, I would guess they swapped in the wiring harness as well. Am I correct (if you know)?

That looks like it's the harness side of the knock sensor plug. You'll need to verify that it is indeed the knock sensor plug, and then start looking for the other part of it, which should be attached to the knock sensor (back of the block).

nfljohnl · Mar 24, 2010

I don't know where the isc plug is where would it be coming out of? Also that plug seems to be too short to be the knock sensor plug, I don't think it will reach that far to the back of the block. Should I be worrying about the other plugs such as the oval plug or the plug for the fan? Would they effect the idle or cause the check engine light to come on?

snowborder714 · Mar 24, 2010

The ISC will affect the idle (hence the name - Idle Speed Controller or Idle Air Controller). And it could possibly cause a CEL.

Just poke around in the area of the ISC and look for the plug. Same with the trying to get the knock sensor plugged in.

I wouldn't worry about the other two plugs. I'm still wondering what the oval plug is.

nfljohnl · Mar 24, 2010

What about the FPS plug? Would that cause a CEL? I can't find where that goes either.

snowborder714 · Mar 24, 2010

It could. I don't know all the CEL's off hand.

nfljohnl · Mar 25, 2010

Is it ok if I leave the isc unplugged? I heard that you can just adjust a screw on the throttle body to make the car run leaner or richer. He said he did it and had no problems. Is this possible?

snowborder714 · Mar 25, 2010

If you have the provisions to run an ISC, I would recommend doing so.

The BISS screw doesn't adjust if it runs lean or rich. It assists in adjusting the idle RPM.

Nicks2319 · Mar 25, 2010

First plug looks like the A/C fan, which you seem to be missing

wkmitsu · Mar 25, 2010

Nicks2319 said:
First plug looks like the A/C fan, which you seem to be missing

No that ones for the main fan, which is missing. The fan with the metal shroud on the drivers side is the condenser fan for the AC. Please promptly install a new main fan.

The plug for the ISC should be in the loom that goes up by the intake manifold, which also has the injector connections, MDP sensor, etc.

The one thats in the loom with the MAF plug is for the cruise control, which is removed.

The one thats taped to the TPS is most likely the knock sensor plug.

The six pinned narrow one I really don't know.

nfljohnl · Mar 26, 2010

Thanks everyone. There is this pipe that sort of looks like it is coming out of my turbo exhaust manifold or O2 housing and it's venting straight to the atmosphere. Does anyone have an idea of what this is?

snowborder714 · Mar 26, 2010

It might be an aftermarket o2 housing with the wastegate portion dumping to the atmosphere. Pictures would help.

burkgonzo · Mar 26, 2010

Does reek like fuel and make you sick, then its a vented o2 housing.

nfljohnl · Mar 26, 2010

It's that rusty bent pipe right below the dipstick. I that a vented o2 housing?

nfljohnl · Mar 29, 2010

Please someone help me and tell me what that pipe is!!!!!!!

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