idles rough but is fine under acceleration

[Drift247365]

Hope im not reposting any thread that someone has before, but I have a 97 eclipse gst and the problem im having is that when I start the car it ends up being a rough idle and almost sounds like one of the injector poppets is sticking. Sounds almost like a ball bearing being stuck and forced to move. Also with the a/c off it will idle between 600-850 rpms. At idle the afr reads around 13.2-15.6. But during acceleration it runs fine and doesn't bog or create any drag. It has a TD05h turbo with aftermarket 44mm wastegate, hallman mbc, not sure of injector size as the guy I bought it from had them done already, greddy type s bov, and injen intake with 2g maf. Bov is recirculated and has been tested for boost leak with no problems. Any info can help. Also I only run 93 Octane with VR1 oil.

 

[Drift247365]

Does anyone have any input or helpful advice? Any advice would be very helpful and I have searched the tech and previous threads and didn't find anything that matched this with these symptoms.

 

[jared98gst]

Plug gap, to small a gap bad idle conditions
Low alt output with bad plugs

 

[Drift247365]

Plug gap is set @.32 and it did this before changing the plugs(changed a week and a half ago). Also alternator is putting out between 13.5 and 13.95 volts

 

[Lou98GSX]

Did you try scanning the car for any codes .

 

[Drift247365]

Compression tested and all cylinders are in range of each other; timing is spot on; I just cant figure out what it is.

 

[Drift247365]

No CEL and there are no underlying codes. Also did an open line test for possibly a short in the wire and no wires are open or grounding out.

 

[Lou98GSX]

Does the idle smooth out once the engine warms up . If its always rough then you might want to check your valve timing .

 

[Drift247365]

Valve timing is correct, marks are true. Its almost like its an electrical issue.

 

[BlackDSMthingy]

What CAS are you running, the stock 2G or is it an adjustable 1G? Also, I would verify that the peripheral sensors are in spec such as the coolant temp, TPS, MAF, IAC, etc. Are you still running an EGR? I would see if that is carboned up. Just some possibilities...

 

[Drift247365]

Not sure which CAS im running. Have really changed anything since I bought it; the shop I bought it from the guy that originally had it is now in prison for some drug stuff I guess, but neither here nor there. Coolant temp is good; TPS is correct; MAF & IAT are both good. And as far as I know the egr valve is clean.

 

[jimsgsx]

I cant believe no one here has suggested adjusting the biss, your idle shouldnt drop that low. The ugly sound right when you start it is most likely your starter. Mine made that sound right before it started going out.

 

[BlackDSMthingy]

Double check to see if it's a 1G CAS or the stock one. If it's a 1G, you can turn them like a distributor to effect your base timing. That could be off. Also, are you running any kind of piggyback or stand alone engine management system like ECMLink or AEM? If it's a stock ECM, that's a lot of mods to be running with the factory tune.

 

[Drift247365]

I cant believe no one here has suggested adjusting the biss, your idle shouldnt drop that low. The ugly sound right when you start it is most likely your starter. Mine made that sound right before it started going out.

BISS? And my starter is new along with all the ground wiring on the car.

 

[Drift247365]

Double check to see if it's a 1G CAS or the stock one. If it's a 1G, you can turn them like a distributor to effect your base timing. That could be off. Also, are you running any kind of piggyback or stand alone engine management system like ECMLink or AEM? If it's a stock ECM, that's a lot of mods to be running with the factory tune.

Not sure if it is or not but I will check on Tuesday. Its my only day off. Ill try to get a pic of the CAS to see. Also should it have a track to adjust on like the adjustable cam gears do?

 

[Mauispyder]

Biss that plastic screw recessed in your throttle body housing, often covered with a plastic cap, often noted to have a boost leak from its oring.

 

[Drift247365]

Biss that plastic screw recessed in your throttle body housing, often covered with a plastic cap, often noted to have a boost leak from its oring.

So remove the cap and screw and check the o-ring and replace it?

 

[92AWDHX40]

Replace it's easy and a few bucks when in doubt also how's the idle speed control motor or isc.

 

[Drift247365]

Havent tested the voltage on that yet.....also whats the location on that so I know if its the right one?

 

[jimsgsx]

The biss is used to adjust your idle. Research it and try it out. I just adjusted mine. Idles like a dream.

 

[Drift247365]

Ok ill try it out but don't know if that's gonna work....almost idles like its got a heavy ass cam in it or missing a cylinder. But yet you drive down the road and it runs perfectly fine.

 

[BlackDSMthingy]

The 1G CAS has an adjustment track on both bolt holes holding the housing to the head. I would try replacing the BISS O-ring and adjust it before messing with anything else. Kinda kicking myself for not remembering that one...

 

[Drift247365]

Ok will see what I can do.....does anyone remember what size o-ring goes on the BISS?

 

[Drift247365]

Looks to be a 2g CAS and is tht the BISS screw setup?

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[Mauispyder]

Yes, yes it is.