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    My 04 ENVOY 4.2 sounds like an old man getting up in the morning

    not sure but I think the system relies somewhat on knowing somewhat about atmospheric pressures which I think come "by" the MAP (calculated or otherwise). If it can't readily determine the manifold vacuum, then it may impact its "work" on other things besides engine running. Quote: "This...
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    My 04 ENVOY 4.2 sounds like an old man getting up in the morning

    you could be helped by getting some real time data at the start of the exercise and then again once things get "smooth". My initial guess is a "vacuum issue".... note necessarily a leak but a bad sensor or wiring. That would be my first data read along with fuel trims.
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    generator battery control module 2008 envoy

    you have to pull the negative cable back to the motor. The replacement is a cable with the module.
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    NEED HELP Starter only clicks

    since it appears that you have some sort of access to the starter connections, then you should do some electrical measurements at those connections to see what the state of the starter is. At the starter, check for voltage on the "b" connector... it should be seeing 12v all the time. Further...
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    04 trailblazer, brakes dragging after new pads, calipers, master cylinder

    You should check and / or replace the flex hose running from the solid line to the caliper. On other vehicles, I have seen issue with something causing the flex line to be "less than transmissive" resulting in new caliper "binding" and even not being able to compress when connected back to...
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    Headlights always on

    yes but... if the turn switch causes things to happen between bright and "normal" (ie. stalk position), then it follows that a possible faulty switch may impact how / when normal happens or doesn't happen depending on what the root cause is for a faulty switch...ie. bad connection, shorting...
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    Headlights always on

    I guess one question is: why the turn signal switch? maybe that's related to your issue with the lights??
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    NEED HELP P0171 Code causing high idle and poor fuel mileage!

    your upstream has "improved" (ie. better) but the downstream looks "funny". Of course, I don't believe the downstream has any impact on fueling (having said that, I have read in places that some system do have operational firmware that does have some "interest" in the downstream values...
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    2006 envoy 4.2L no crank no start!!

    :-) that is probably is his problem... broken connections and not the motor.
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    what causes hub bearings to fail so often ?

    Possibly incorrect torque of the hub nut (too tight) causing a slight compression force which during the bearing heat / cool cycle may cause run problems which then increases the temp further over time... just my guess with failures to date. I am currently running with a "re-used hub" that I...
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    NEED HELP P0171 Code causing high idle and poor fuel mileage!

    the first O2 voltage graph does not look right although it could be the time scale that makes that way. The "normal" graph should be a "wave" pattern oscillating about 4.5-5 v ish area. Of course, the FT confirm your "rich run" because they are set to dump more fuel because of a response of...
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    Intermittent starts, runs, then no starts no crank??

    glad you got further and have a working vehicle. Hopefully, it won't come back to haunt you again. Looking further at the C2, the other two pins that are more likely related to your problem (nothing on the dash) is the KS pins which I do believe deal with "key detection" meaning that the...
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    Intermittent starts, runs, then no starts no crank??

    what does the last part actually mean... NS,NG you need to describe what you are seeing at that point in terms of dash indicators, gages AND reactions to the key sequence for a "NOSTART" conditions. Although you indicate the C2 connector, it does not really appear that those pins / signals...
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    Frequency of 5V signal from EV fan clutch to the PCM

    I am not sure I understand "I did not command the fan here in any way". OK, so what was the current level asked for by the system? Since you aren't feeding any inputs other than engine rpm (assumed) then I would expect the system's "command" to be some "percentage" which of operating the...
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    Frequency of 5V signal from EV fan clutch to the PCM

    I think we aren't talking the same "words" ... I was questioning this statement that you made at the end of your post... "If so, the bandwidth of of this signal is withing the range of 40 - 200Hz (0 - 100% duty cycle command)" As I was pointing out, you could have a 100% command and the rpm...
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    Frequency of 5V signal from EV fan clutch to the PCM

    Perhaps I don't understand the EV clutch but I don't think it controls the speed of the fan "directly". It controls how much "clutching" is required which then is "computed" into fan rpms after the speed of the engine is taken into account. Hence, 100% percent at an engine rpm of 800 is...
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    4x4 Help?

    I guess every one is out 4wheelin in the new snow... :smile: did it ever work? how did you get to this state of "disrepair"... history? You can find the link to schematics here on the site or in one of the regular poster's signature (mooseman).
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    Persistent p0172 and p0175

    what??? it is so rich that your cylinders are "awash" with gas... equivalent to a "flooded, no start condition". Not overly surprising given the trims and the attempt by the system to overcome the richness. It is certainly not going to help your engine running oil with that much...
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    Truck died Need help asap

    you might want to ensure that they identify to you the specific fuse... why.... because it will likely happen again and you will have a place to look first.
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    Persistent p0172 and p0175

    don't buy any more... do the "free test" that suggested... graph your ltft and the absolute vacuum and see if anything shows correlation.
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    Persistent p0172 and p0175

    ok thanks... :-( still ugly. I see the ltft has a "plateau" of about -10ish which seems like some richness that the system is trying to take out most of the time.... BUT the spikes are disturbing and are likely causing the coding. During those "spike times", do you recall what is happening...
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    Persistent p0172 and p0175

    you need to post new graphs of your trims (especially LTFT) as there has been so much time and things done that I for one don't really understand what you are "chasing" at this point.
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    Transmission Line leak at the wheel well head clamp... temporary fix?

    I guess whether the retaining bracket is attached makes little difference as I wouldn't think that end section has any issues with the feeding of the line. Its the other end that problems likely occur... right? It would appear that the one with the "add on bracket" comes with a "cup seal" and...
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    Transmission Line leak at the wheel well head clamp... temporary fix?

    So I have started to do search for "proper lines" but am somewhat confused by the RA descriptions. Attached is the pictures of the two pressure lines (from the gear to the cooler). One description says: "Aftermarket Labor Saving Design (Removal of cup seal at port is required prior to...
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    Horrible Fuel Mileage

    the purpose of the "effort" is so that you can readily spin a wheel and determine if it is spinning somewhat "freely" or not. Going from the result as to be a "rolling" issue which is "eating your gas" or something else.
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    Horrible Fuel Mileage

    without looking at some of your running data, you don't know if you are chasing an "operation engine" issue or a vehicle mechanical issue. The "spin the wheels" suggestion is good for mechanical.
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    Persistent p0172 and p0175

    :-( I think your problem is still associated with the MAP and wiring there in. I would suggest that you do a vacuum test on the sensor (kept attached to the harness and reading its output with the app). Then compare this with what your vacuum pump / gage is telling you. They should...
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    Horrible Fuel Mileage

    I would get some running data on your fuel trims to see what the system is operating at. You have changed a lot of "stuff" without much impact so it is likely those things weren't a factor. Another likely culprit is an intake leak. Do some leak testing around intake areas with some carb...
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    Mystery Short circuit

    Now is the time to check what items work and don't work that should. IF as tjbaker57 speculates (a good one) that a chassis ground (likely) is broken then other circuits could be trying to get thru to the ground any way they can and went thru the obd adapter to get at the "other ground" which...

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