Extremely rich idle

[carbon]

we have a planet to save here, gentlemen!

Really?

[86FieroSEv6]

Good info is never after the fact, we have a planet to save here, gentlemen!

[robertisaar]

this is a bit "after the fact" but here it is for anyone that could need it in future reference:

Too much timing causes high NOX and high HC
Too lean causes high NOX and high HC
Too rich causes low NOX, high HC and high CO

that's from RBob of TGO.

[weba]

Yes i swapped another o2 in, with about the same miles on it.

Same spark plugs passed last year. I thought that too.. weird.

And yes off course the cat was all warmed up for the test.

[IsaacHayes]

Did you ever swap O2s?
The spark plugs possibly could have been to blame if they were a range too cold. Did you let the car get really warm before bringing it there? I could see that helping.

[weba]

Okay I'm just back from another emission test and it passed! I guess I'm lucky, didn't except it to pass, but decided to take it anyway, since ordering new fuel system parts would had easily been weeks, and my time to get the car inspected was almost over.

Here are the numbers for emission tests:

First test (failed), Maintained car with BFUZ binary, drill-modified cat.
idle 2000
HC 163 44
CO 0.42 0.28
O2 0.6 0.58
CO2 14.67 14.54
L 1.01

Second test (also failed) Brand new cat converted, else same
idle 2000
HC 550 57
CO 0,30 0.14
O2 0.63 0.34
CO2 14.54 14.73
L 1.01

Todays test (passed!) New plugs+wires+PCV, AZKX binary
idle 2000
HC 67 30
CO 0,14 0.10
O2 0.30 0.50
CO2 14.7 14.6
L 1.02

Btw, the emission guy told that my readings looks like the car would be cammed

I think only thing originally wrong was that i was using the J-body binary, since the car feels and seems to be running lot better with the L-body one, how ever ECM seems to tune down the fuel on all rpm's, reason for that i can only guess.

Thanks for everyone who helped!

[86FieroSEv6]

What were the CO and O2 numbers?

[robertisaar]

changing the idle table won't do anything since the ECM is likely still running on the IAC tables instead of the VE tables.

being a 92, it should be an $A1 car.

what are you using for datalogging and tuning?

[weba]

HC was around 550 for idle and 53 for 2000rpm.. that was with brand new cat, with the stock one i got 163/44... 100 is allowed for idle to car this age here.

[86FieroSEv6]

Is there a shop nearby that has four gas analyzer to give you an idle and a no load 2,000rpm reading?

[weba]

Hmmph, adjusting the mentioned table gave no results at all. 115BLM this time, didn't change any even if i vent from VE of 10.16 to 7.5.

I did like 10min driving datalog and it seemed to run in BLM of 112-118 pretty much all the time.

[weba]

I think I'm getting few datalogs of the idle today and try to make the changes on the binary itself so the values would be closer to 128.
Table called Idle volumetric efficiency Vs RPM Vs MAP seems like it's the one i need to lean out. Getting the emission tests ain't free and I'm going to get punished if it's not running good soon.

Tho i can't think a reason why stock engine would need anything else than stock chip, unless something is wrong!

[86FieroSEv6]

Good reading on the coolant residual voltage. 110/124 indicates a mild leaning, although I'd rather see them both averaging 120.....I guess the exhaust gas analyzer will tell the tale.

[weba]

86FieroSEv6, thanks for the tip, i measured the voltage and it's about 0.015V.

I have only taken emission test when the car is fully warm so in closed loop mode.

I ended up using AZKX binary for my car, and it seems to run smoother.

@850rpm idle speed (warm) BLM is 110 and INT is 124~ Maybe i should do a datalog to see does it actually run rich most of the time or what.

[86FieroSEv6]

By the way, what were your long term and short term trims in closed loop idle? Is it "rich" at idle while still in open loop? If it becomes worse in closed loop you have a control fault, if it is the same in open loop as it is in closed loop, then you are looking for a basic fault. Just for shits and grins, have you checked for stray voltage from the engine cooling system. Warm up the car, place your voltmeter positive lead into the radiator coolant without touching the radiator itself and your negative test lead on the batt. neg. term. any reading that is more than .10 volts will cover up part of the O2 signal voltage. For instance, if the coolant is reading .3 volts, when the O2 is sending a .5 volt signal, the ECM will only see .5 - .3 = .2, so the ECM will see lean and go rich. I have been flim flammed by this before. Make sure all grounds are in place and clean and tight. Including batt. to body and eng. to body. Other than that, make sure you have the correct baro. values relative to your locations altitude. That's about all I can think of that hasn't been mentioned yet.