Can I manually manipulate my idle speed? (Page 8/10)
Kitskaboodle MAY 08, 09:41 PM
Hi gang. 😊
Wow, it’s taken a while to get to this point. I finally got my laptop / FieroStore scan tool set up.
Here is the first screenshot of the data. As a reminder and as you know, I had tried some tests per your suggestions (like abruptly choking the throttle body so the engine would die) so I had a check engine light before I hooked up the scantool this afternoon. So, the trouble codes at the bottom left of the screen may not be an accurate indicator of the real problem, ok?
So, before you look at the numbers in the screenshot below, I wanted to say that this first screenshot is 1 of 3 that I took with my phone that my pc was displaying. First pic represents what the program saw during the very first minute of the engine running since ice cold only. I will send pics 2 and 3 in separate replies so I don’t screw up the order. Ok, go ahead and read the parameters and let me know your thoughts. After I send you all 3 pics you’re going to see something quite wrong with the MAP voltage! It’s zero from start to finish. My understanding is that it should always read between 3.5 to 5.5 volts at all times. I heard you test MAP connector A & B with key on / engine off. But, the map has 3 prongs. Which ones are A and B? Pic would be great. 😊
Kit
Vintage-Nut MAY 08, 09:58 PM

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Which ones are A and B?



If you have a GM MAP, 'ABC' are on the top of the sensor...
If you have an aftermarket MAP, 'A' is frontwards {rear window} / 'C' is backwards {taillights}

PS - 'B' is in the middle....

[This message has been edited by Vintage-Nut (edited 05-08-2025).]

Kitskaboodle MAY 08, 10:26 PM
Ok, thanks for the connector pin info. If “B” is the middle one, that should be a no-brainer then to test it. 😌
Ok, here is pic #2. It represents the engine running after about 2 to 2.5 minutes from cold.
As an fyi, the engine by this point has already settled down to about 1500 rpm and stayed this way through the end of the test. (although with the scantool connected throughout the test this may not matter due to close and open looping during the test)

Kit
P.S. I forgot to point out (I noticed it) that the rpm indicated in the program says 1000 but my actual tach rpm clearly said about 1400-1500. It sure didn’t feel like it was idling at 1000. Hopefully this will not matter one way or the other.

[This message has been edited by Kitskaboodle (edited 05-08-2025).]

Patrick MAY 08, 10:32 PM

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Originally posted by Kitskaboodle:

As an fyi, the engine by this point has already settled down to about 1500 rpm and stayed this way through the end of the test.



1500 RPM? Not according to the scan tool.
Patrick MAY 08, 10:38 PM

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Originally posted by Kitskaboodle:

P.S. I forgot to point out (I noticed it) that the rpm indicated in the program says 1000 but my actual tach rpm clearly said about 1400-1500. It sure didn’t feel like it was idling at 1000. Hopefully this will not matter one way or the other.



I'd say it matters a great deal if you've been chasing a supposed high idle... and it's mostly because your tachometer is way off!

[This message has been edited by Patrick (edited 05-08-2025).]

Kitskaboodle MAY 08, 10:52 PM
Ok, pic #3. This represents the engine after it has been running for about 3.5 to 4 minutes or slightly more. As I said, by this point the engine pretty much stayed at about 1500 rpm. (as I mentioned above, my tach says 1500 rpm while the scantool program says it’s 1000)
Ok, last point: Just out of curiosity, I shut the engine off, disconnected the scantool, waited about a minute and a half, then re-started the car to see what it would do. Well, strangely enough it went right to about 1500 rpm and stayed there but this time there was nothing connected to the aldl port.
Oh, and I can confirm the engine wasn’t crazy about this test as I could swear the engine was missing here and there. (It’s rare for this engine to exhibit missing)
Kit
P.S. Tomorrow I am going to test the A&B prong voltage for the MAP and report back. (key on / engine off - should be between 3.5 to 5.5 volts unless I’m mistaken?)

[This message has been edited by Kitskaboodle (edited 05-08-2025).]

Vintage-Nut MAY 08, 11:02 PM
You're Really Close...

At Below 1,000 Feet / 3.8 to 5.5 Voltage Range
Kitskaboodle MAY 08, 11:07 PM
Patrick, ok I get your point about my tach being off. But 500 rpm off? 🙁 Oh my, that’s not acceptable. I supposed I just got used to it being off. Anyways, is there any way to adjust/re-calibrate it? I’ve never done this or heard of anyone adjusting / re-calibrating a Fiero V6 tach. Tach filter deaths I am definitely aware of and both my Fiero’s have Rodney’s filters.
Ok, i got an idea. I have a newer style timing light that has a built in digital rpm gauge. I think I will hook it up “to get a third party” opinion” on the actual engine rpm. I will report this tomorrow along with the MAP connector voltage readings.
Kit

[This message has been edited by Kitskaboodle (edited 05-08-2025).]

cartercarbaficionado MAY 08, 11:15 PM

quote
Originally posted by Kitskaboodle:

Patrick, ok I get your point about my tach being off. But 500 rpm off? 🙁 Oh my, that’s not acceptable. I supposed I just got used to it being off. Anyways, is there any way to adjust/re-calibrate it? I’ve never done this or heard of anyone adjusting / re-calibrating a Fiero V6 tach. Tach filter deaths I am definitely aware of and both my Fiero’s have Rodney’s filters.
Ok, i got an idea. I have a newer style timing light that has a built in digital rpm gauge. I think I will hook it up “to get a third party” opinion” on the actual engine rpm. I will report this tomorrow along with the MAP connector voltage readings.
Kit



hey kit? have you checked that your pickup in the dist and that the icm is reporting
Vintage-Nut MAY 08, 11:45 PM

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Anyways, is there any way to adjust/re-calibrate it {the tach}?



YES - connect member J Gunsett

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Are you talking about the tach / If you need the tach calibrated, I can do that for you...