MakkMarci

iTrader: (1)

Hi,

I have a close to stock LS1 firebird (year:2000, 180.000 miles).
My car has a rough idle in the last 6-7 years.
We made generic repairs in this year, but these fixes not modified and/or repaired the idle
When i open the door wide, its shaking.
The idle is rougher in N, but i feel it in D too.
I feel it at cold start, but its rougher when the engine warm.

We already exchanged the followings:
- new PCV hose, PCV valve
- new EGR valve
- new front O2 sensors
- Headers are rebuilt with new factory GM springs, compression are equals in all cylinders now.
- Trunion rocker arm bearings installed
- new lifters
- new water pump
- new motor mounts
- injectors are cleaned and tested
- new spark plugs
- new spark plug wires
- new quality oil pump
- new dual chain with gears
- new muffler
- new IAT sensor
- new oil pressure sensor
- new AIR valves
- new CATS
- rebuilt alternator
- rebuilt steering pump

I have a diablo sport programmer, so i can check some basic values.
I have about 2% difference between left and ride side long and short fuel trims (i don't know is it means something)
I already tried plugged the AIR and EGR, I had same rough idle .
My idle moves between 635-675.

I already checked TPS sensor, its looks OK
I checked MAF sensor, its move fast with RPM

If you have any idea what I have to check, please share it.

thanks for your help

Exeodus

iTrader: (1)

Any codes in the PCM or is the SES light on?

MakkMarci

iTrader: (1)

Now i have AIR system BANK 2 problem, its appeared only in the last 2 weeks when i reinstalled the AIR.
I used the car with plugged AIR in the last 3 years(and i delete it with diablo sport).
My mechanic said, we have to put everything back (AIR, EGR), but no difference.
Of course we search and fix the AIR problem soon, but I have rough idle with and without it

Exeodus

iTrader: (1)

Do you have a difficult time starting the car? Does your tuner device show live data while it is running? If so, check the water temp reading and see if seems accurate. If the reading is way off, it can throw the fuel tables out if whack.

MakkMarci

iTrader: (1)

The car starts well always, no problems with it.
Today I deleted the error codes, i drove 2x10 miles, and i read all datas what i can.
The trans was in P. No SES light. (after the 3rd trip, i get AIR error P410)

engine load 1.57%
engine coolant 204F and its went to 214F slowly

short term ft bank 1 0-3.14%
long term ft bank 1 -3.91%
short term bank 2 0-3.13%
long term bank 2 -1.2%

MAP 4.6psi
RPM 628-665
IAT 113F
MAF 0.631-0.674 lb/m
vehicle speed 0
spark 17.8-18.3
knock retard 0
TP angle 0%

ho2s bank 1 sensor 1 40-850mv
ho2s bank 1 sensor 2 160-700mv
ho2s bank 2 sensor 1 70- 840mv
ho2s bank 2 sensor 2 110- 700mv


Intervals means these values are moving. the long fuel terms slowly moved to ~-5%.
I see, the sport cats lots their efficiency, but i don't know these values are OK or not.

thanks for your help

HappySalesman

iTrader: (3)

usually most tuners can also tell you misfire data. what does it show for that? is it isolated to one cylinder?

I think about the only thing left to investigate would be your coils. they don't commonly go bad but it's possible.

JakeFusion

iTrader: (7)

MAP pressure seems low. It should be closer to 6-7psi with stock cam. What's it reading in kPa?

You have a leak somewhere or, worse-case, you need to perform a compression and leakdown test. I fear worn rings...

MakkMarci

iTrader: (1)

HappySalesman: thanks for the idea, now, i try to search a guy with a useful programmer, but its not easy in east EU. but, I measured the coil's resistances. (only the front 6, i don't have time to mine the last 2.
Lots of coils has the following values on pins(+- 1k ohm):

AB - 118k ohm
AC - 118k ohm
AD - 75k ohm
BC - 12.3k ohm
CD - 42k ohm

but on passanger side, the values has more different:
AB - 121k ohm
AC - 121k ohm
AD - 77k ohm
BC - 12.3k ohm
CD - 43.7k ohm

and the worst:
AB - 108k ohm
AC - 108k ohm
AD - 70k ohm
BC - 12.3k ohm
CD - 37.6k ohm

is it possible, the last has partial shorting?

MakkMarci

iTrader: (1)

JakeFusion: thanks for help. I have rebuilt headers, all compressions are very good(~230 psi +-2%), better than factory requirements.

Before the rebuilt, one was around 140 psi, and all other between 160-190 psi.

4.6 psi =~ 31.7 kPa (i converted with google).

I checked it in GM service manual, it says, I have a problem if the voltage is under 0.1V (they don't give any exact pressure value). The document says, it's depends on altitude and some other conditions, but i recheck all air/vacuum pipes for leaks, thanks.