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LQ1 CPS.


jiggity76

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As I said, the map may not be the primary issue, but the map may be the result of an issue, the ecm relies on ambient air temp & coolant temp to be able to properly calculate the needed fuel mixture. If the coolant temp sensor has either failed or the wiring circuit is questionable the ecm cannot calculate. The same goes for the IAT sensor, if the ecm isn't seeing the proper temp input from the sensor then it again cannot calculate the needed air/fuel ratio. The map relies on both of these signals functioning properly to adjust the proper air ambient pressure signal to the ecm.

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41 minutes ago, 55trucker said:

As I said, the map may not be the primary issue, but the map may be the result of an issue, the ecm relies on ambient air temp & coolant temp to be able to properly calculate the needed fuel mixture. If the coolant temp sensor has either failed or the wiring circuit is questionable the ecm cannot calculate. The same goes for the IAT sensor, if the ecm isn't seeing the proper temp input from the sensor then it again cannot calculate the needed air/fuel ratio. The map relies on both of these signals functioning properly to adjust the proper air ambient pressure signal to the ecm.

I've already put on a new IAT.  The only other sensors I haven't replaced are the oil pressure, coolant temp, CPS (I believe it is working), MAP, MAF, and even though it's not a sensor, the EGR valve.  I'll try the MAP first since it's the easiest to switch out and see what it does.

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You can test the MAP sensor before you replace it.  Make sure it has a 5V input and a ground.  The middle wire should change voltage based on vacuum, although I'm not exactly sure what is what.   Do you have a way to check what kPa the PCM is reading with key-on?  OBD-II has a table for the maximum kPa allowed and if it's above that, it won't start.  At least, that was what I determined with my GT.  I had two new MAP sensors that were faulty out of the box.  I have no idea, though, how OBD-I works with that.  You can also hook up a vacuum gauge to the MAP sensor and make sure the voltage varies with vacuum.

Edited by pwmin
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1 hour ago, pwmin said:

You can test the MAP sensor before you replace it.  Make sure it has a 5V input and a ground.  The middle wire should change voltage based on vacuum, although I'm not exactly sure what is what.   Do you have a way to check what kPa the PCM is reading with key-on?  OBD-II has a table for the maximum kPa allowed and if it's above that, it won't start.  At least, that was what I determined with my GT.  I had two new MAP sensors that were faulty out of the box.  I have no idea, though, how OBD-I works with that.  You can also hook up a vacuum gauge to the MAP sensor and make sure the voltage varies with vacuum.

Thanks for your help but I'm just not the skilled in the advice your giving me.  I also don't own a multi-meter yet but plan on getting one soon.  I just changed out the MAP sensor and it's no better or worse.  Still the same.  I made a quick video and I'll post it soon in the appropriate thread.

 

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4 hours ago, jiggity76 said:

Thanks for your help but I'm just not the skilled in the advice your giving me.  I also don't own a multi-meter yet but plan on getting one soon.  I just changed out the MAP sensor and it's no better or worse.  Still the same.  I made a quick video and I'll post it soon in the appropriate thread.

 

It simple the check the voltage, but without a multimeter...   Anyway, if it didn't change anything, probably wasn't it.

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17 hours ago, jiggity76 said:

Thanks for your help but I'm just not the skilled in the advice your giving me.  I also don't own a multi-meter yet but plan on getting one soon.  I just changed out the MAP sensor and it's no better or worse.  Still the same.  I made a quick video and I'll post it soon in the appropriate thread.

 

If I were you, I would buy a multimeter(or two...one standard one, and one with a current clamp capable of reading DC amps) and a scan tool at least capable of reading engine data on those LQ1's. Both will pay for themselves many times over if you do your own diagnostic work. There's tons of documentation online these days to help you get started using either tool. If you want some recommendations for either, let me know(buying all the stuff I recommended would be far cheaper than a single dealership visit by the way).

 

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14 hours ago, mfewtrail said:

If I were you, I would buy a multimeter(or two...one standard one, and one with a current clamp capable of reading DC amps) and a scan tool at least capable of reading engine data on those LQ1's. Both will pay for themselves many times over if you do your own diagnostic work. There's tons of documentation online these days to help you get started using either tool. If you want some recommendations for either, let me know(buying all the stuff I recommended would be far cheaper than a single dealership visit by the way).

 

What's a good multimeter to get?

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Realistically, you don't need anything expensive to work on automotive stuff. The majority of your testing will be low volts DC.  Something like this would be fine: https://www.amazon.com/AstroAI-Multimeter-Resistance-Transistors-Temperature/dp/B071JL6LLL/ref=sr_1_3_sspa?dchild=1&keywords=mastech+multimeter&qid=1616241193&sr=8-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzQzdVRjcyU05PVk4zJmVuY3J5cHRlZElkPUEwMTYyODk2M0JOWVc3T1FHWVhXOCZlbmNyeXB0ZWRBZElkPUEwNDk2ODEyOVdQUUYwQlUwWUY5JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==#productDetails

 

That will cover the majority of your needs on a car. 

 

As for the current clamp meter I also mentioned above, there are some starting around $40 that will read DC amps.

https://www.amazon.com/Meterk-Multimeter-Auto-ranging-Capacitance-Non-contact/dp/B0721MKXBC/ref=sr_1_7?dchild=1&keywords=dc%2Bcurrent%2Bclamp%2Bmeter&qid=1616242088&sr=8-7&th=1

I have a Tacklife version that looks identical to that one - the new tacklife model has changed a bit, but is still around that same price. All of them in that range are very likely rebadged copies of one another. I've only used my tacklife meter a few times, but it was accurate compared to other meters. This isn't something you absolutely "need," but it's nice to have to be able to clamp around a cable to check the output of an alternator with.

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Agreed,

one doesn't need to spend a fortune on a multi meter, you can find a decent meter at Home Depot, in the states they sell Klein, it's a decent device, they are practically all manufactured in China, even expensive Fluke meters are made there. Just pick up a manual range meter, you don't necessarily need an auto range device. Even Harbor Freight carry multi meters, but I believe that they stock one manufacturer that supplies for HB under the HB brand name.

We don't have HB up here, but when I go down to Buffalo I make a point of dropping into the HB to pick up simple items there.

Edited by 55trucker
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8 hours ago, 55trucker said:

Agreed,

one doesn't need to spend a fortune on a multi meter, you can find a decent meter at Home Depot, in the states they sell Klein, it's a decent device, they are practically all manufactured in China, even expensive Fluke meters are made there. Just pick up a manual range meter, you don't necessarily need an auto range device. Even Harbor Freight carry multi meters, but I believe that they stock one manufacturer that supplies for HB under the HB brand name.

We don't have HB up here, but when I go down to Buffalo I make a point of dropping into the HB to pick up simple items there.

Yeah, the maintenance guys at work use Fluke.  I recognize that name now.

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12 hours ago, mfewtrail said:

Realistically, you don't need anything expensive to work on automotive stuff. The majority of your testing will be low volts DC.  Something like this would be fine: https://www.amazon.com/AstroAI-Multimeter-Resistance-Transistors-Temperature/dp/B071JL6LLL/ref=sr_1_3_sspa?dchild=1&keywords=mastech+multimeter&qid=1616241193&sr=8-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzQzdVRjcyU05PVk4zJmVuY3J5cHRlZElkPUEwMTYyODk2M0JOWVc3T1FHWVhXOCZlbmNyeXB0ZWRBZElkPUEwNDk2ODEyOVdQUUYwQlUwWUY5JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==#productDetails

 

That will cover the majority of your needs on a car. 

 

As for the current clamp meter I also mentioned above, there are some starting around $40 that will read DC amps.

https://www.amazon.com/Meterk-Multimeter-Auto-ranging-Capacitance-Non-contact/dp/B0721MKXBC/ref=sr_1_7?dchild=1&keywords=dc%2Bcurrent%2Bclamp%2Bmeter&qid=1616242088&sr=8-7&th=1

I have a Tacklife version that looks identical to that one - the new tacklife model has changed a bit, but is still around that same price. All of them in that range are very likely rebadged copies of one another. I've only used my tacklife meter a few times, but it was accurate compared to other meters. This isn't something you absolutely "need," but it's nice to have to be able to clamp around a cable to check the output of an alternator with.

Thanks, I'll check those out.  What about this cheap guy for scanning?

Image 1 - Code-Reader-Innova-GM-Digital-OBD1-Scanner-Electronics-GM-Scan-Tool-1982-1995

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12 hours ago, jiggity76 said:

Thanks, I'll check those out.  What about this cheap guy for scanning?

Image 1 - Code-Reader-Innova-GM-Digital-OBD1-Scanner-Electronics-GM-Scan-Tool-1982-1995

That's just a glorified jumper wire that will allow you to flash out codes using the check engine light(pre-1994 cars). A paper clip or piece of wire will do the same thing and you likely have one or the other already laying around the house  See here for information on flashing codes and code definitions: https://www.w-body.com/oldsite/ecm-codes.html

 

 

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1 hour ago, mfewtrail said:

That's just a glorified jumper wire that will allow you to flash out codes using the check engine light(pre-1994 cars). A paper clip or piece of wire will do the same thing and you likely have one or the other already laying around the house  See here for information on flashing codes and code definitions: https://www.w-body.com/oldsite/ecm-codes.html

 

 

Yeah, I've seen a few other guys do that.  I think I'm gonna get it.  I want to use other money buying parts.

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22 hours ago, jiggity76 said:

Yeah, I've seen a few other guys do that.  I think I'm gonna get it.  I want to use other money buying parts.

Just use a piece of scrap wire off of something for $free. :wink:

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