rough idle and need help asap

[etniesfaction]

starter took a poop on thursday night so friday i swapped the starter out...put everything together and as i put the battery cables back on the battery down by the starter sparked..took everything off and saw that the main power wire to the starter was exposed and touching side of starter so i electrical taped it and then put battery back in car and started the car up no problem..let warm up for 10 minutes idled normal at 750-900ish rpms..about to leave the shop and car starts to idle terribly from about to stall out to barely idling past 500 rpms...i adjusted my biss screw to raise the idle up and it surges from 500ish to 900ish rpms giving a really choppy idle and the car sounds cammed now...what is going on im stumped

 

[Bluefire16]

Idk if you have your cruise control on but mine can make my car act a little weird if the one bolt isnt other good. Just by moving it adjusts the idle .... its messed i no

 

[etniesfaction]

i have the none cruise control cable so thats out of the question

 

[1gDSM4g63]

Make sure the throttle body is clean and could be your throttle position sensor.

 

[etniesfaction]

from the starter sparking for that quick of a second could it have shorted something and if so why would it do it after 10 minutes of the car running fine

 

[BullseyeGSX]

Does your biss screw still have the little O-ring around it ? Also it could be a bad TB Gasket

 

[etniesfaction]

sure does and i did a boost leak test found no leaks i still have no idea what this can be

 

[greyspyder117]

It rarely happens but yes it could short out something. Some sensors use as little as 0.5v when you rubbed that positive wire to ground thats sending 12 volts right to the ecu

 

[dsmconvict]

We did a BLT, cleaned up the wiring a little, swapped MAS's, and the coolant temp sensor so far. His BISS screw is stripped out but I tried messing with that and after the wiring cleanup the car will stay running but idles like shit. I have a known working TB off my car that we can swap out if need be. I'm stumped too.

 

[dsmconvict]

It rarely happens but yes it could short out something. Some sensors use as little as 0.5v when you rubbed that positive wire to ground thats sending 12 volts right to the ecu

And the sucky thing is.... he's got a 97 and we both have 95 eproms laying around

 

[etniesfaction]

could the ecu have taken a crap if so can i swap out the ecu and if i put my other ecu in can it get damaged?

 

[dsmconvict]

95's have a different cas reading..... not sure if the 95 eprom will work in the 97. BUT unplugging the battery.... he's running an safc and 550's.... would unhooking the battery kick the safc settings out of line? im just trying to eliminate any possibilities here

Safc settings are good, also swapped out the plug wires, coil pack and power transistor today with no luck. Also pulled the ECU to check for board damage or leaking caps and we're good.... ANYONE know anything WTF

 

[etniesfaction]

turned out being a bad ecu popped in the eprom im good to go now

 

[LVcountryboy]

My 98 GST has a rough Idle. I just replaced the O2 Sensor and the MAF because my check engine light came on letting me know they had gone bad. My car still has a rough idle, going from feeling like it will shut off to up around 850-900rpm. But as soon as i barely touch the gas pedal, everything smooths out and runs perfect at 900 rpm plus. Any ideas of what causes this? The technician at the shop when reading my codes for the engine light said it's probably cause by the fact the my engine is burning a little bit of oil (i have a 123K on the car, and i just bought it last week). So any ideas on what to do without having to replace everything in the engine bay doing trial and error type maint?