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So I went for an inspection today and failed all of my idle tests:
CO: limit 1.2, actual 8.88
HC (ppm): limit 220, actual 1059

2500RPM tests were good:
CO: limit 1.2, actual 0.01
HC (ppm): limit 220, actual 50

We poked around a little in the garage with the tailpipe still hooked up, cleaned the EGR, plugged the evap, pulled the PCV etc. with no change in the idle emissions.

Next step was to check timing, which was retarded by a long shot. We're talking like the timing mark is in the 3 o'clock position. At that point, I had to leave the shop.

Got the truck home, the distributor loosened, and the base timing wire unplugged with no change. Tried to advance the timing but it naturally won't even get close to the marks. Plugged the scan tool in to make sure all of my sensors were sending data, though I don't know what to look for on a lot of them at idle. Temp and everything was OK.

Any suggestions out there? I just can't fathom why that timing mark was so off unless the balancer ring slipped or something.

Truck runs fine, but is pretty rich at idle. I put a kit on the throttle body very recently, so it's all cleaned out.
 

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Discussion Starter #2
Following up to this since I hate dead end threads:

Changed the O2 sensor. That got me some action that I didn't have before on my scan tool.

Rotated the engine to TDC and marked the balancer. I guess it slipped. Got the motor timed to what I think is around 10 degrees. The 'ol screwdriver in the spark plug hole technique has a little room for error.

At this point I was running pretty good. I had reset the ECM and was out driving to relearn everything. Took it up to the inspection shop and hooked it to the tester, numbers were a lot better but still not where it needed to be. A bump to the throttle to keep the engine off idle, but still within the idle specs of the testing equipment brought it in to passing. Barely.

Only "problem" I have left is that the truck won't go into closed loop at idle. Which is why I think we had to bump the throttle during the test to get it to pass, it would go into closed loop at that point and clean up.

New vacuum hoses and a hot air riser should get me into a pretty reliable state for the winter.
 

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Only "problem" I have left is that the truck won't go into closed loop at idle.
What BIN is in the ECM?

I have the 1228062 ECM with ATKX BIN and it goes into open loop at idle.

It does this to keep the engine cooler by dropping the BLM value to whatever amount is programmed in the BIN.

What scan tool are you using?

If you can see these numbers with it, what is the IAC count, and, what is TPS voltage value?
 

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It has to get to certain coolant temp to go into closed loop so if you have scan data...if you don't see it go over I think it was 140 degrees farenheit...it won't go into closed loop which usually points to a lazy thermostat - if it needs a thermostat get the correct 195er from NAPA and get the Premium - it's made by Robertshaw and is warranted forever against defects including laziness or sticking closed
 

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I agree. It sounds like a lazy thermostat at this point.
 

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You've checked for vacuum leaks?

As stated, a lot of the BIN's for these ECM's go into open loop at idle and that is why you see the short term fuel trim locked at 128.

Has the maybe it's a cat problem?

What ECM are you using and do you know what the 4 letter code on is?

1000 rpm at idle after warm up seems high.
 

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That's REALLY fat at idle

Idle speed is too high however that's not going to cause you to be that fat

you might have weak spark and at idle that's gonna hurt ya

what's MAP voltage at wide open throttle?

Check MAP vacuum line for leaks
 

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what year is yours?

I remember back then they'd go into open loop at idle and that mostly because they have the oxygen sensor way down stream without it being a Heated oxygen sensor
 
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sparkybuoy
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