Newbie, not able to connect

Discuss General Motors (GMC, Chevy, Pontiac, Hummer, Cadillac, etc) tuning topics here. Request definitions, discuss parameters, etc.

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No Quarter
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Newbie, not able to connect

Post by No Quarter »

Hi there, this is all new to me. I have two problems:
1. I can't connect. I have a USB ALDL cable, but the manual talks about COM ports only
2. I can't find a proper ADX file for my 1990 3.1 Beretta GT, only Buicks or 1991 and above

Any help will be appreciated
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Six_Shooter
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Post by Six_Shooter »

You have to solve #2 before #1 will be of concern...

The 1990 Beretta with a 3.1 should use $A1 for code and there are XDFs around for that. You have to load the correct XDF, set the com port in preferences and then you can connect.
No Quarter
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Post by No Quarter »

Found an $A1 on these pages, can't download it though...

When I right click, I don't get the Save As option

?
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Six_Shooter
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Post by Six_Shooter »

What browser are you using?
No Quarter
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Post by No Quarter »

Google Chrome

Just tried Explorer, yes Save as Option. It suggested .htm, I changed to .adx, seems to work, look forward to trying it on car. Thanks so far...
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Six_Shooter
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Post by Six_Shooter »

In Chrome:

Right click > Save link as...
No Quarter
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Post by No Quarter »

Finally I'm connected and can see a bit about how it behaves. :D Thanks for the help

Now the real problems start. I'm not sure what to look for, but I did notice that the O2 value was up and down in steady cycles, from 80 up to 1000, and further down it constantly switched between LEAN and RICH.

I've just changed the O2 sensor, so if that's the culprit, then the previous was also bad, because changing it had no influence on the rough idle.

Any ideas? Or what else to look for.
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Six_Shooter
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Post by Six_Shooter »

In closed loop, that's how the O2 sensor should act.
robertisaar
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Post by robertisaar »

a 1990 is MOST LIKELY to be $88, though there were still some $6D cars. would need to see what BCC is listed on the MEMCAL to be 100% certain.

i wouldn't think the A1 ADX would work with 88 code though.... send command is slightly different.
No Quarter
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Post by No Quarter »

Six_Shooter wrote:In closed loop, that's how the O2 sensor should act.
Yes, I've read that now, new to all this. But the article I read said it should cycle 5-7 times per second on a MFI engine. But mine cycles less than 1 time per second, and you can hear the engine going up and down with the change from RICH to LEAN to RICH.

:?:
No Quarter
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Post by No Quarter »

I now have a graph showing my O2 value running up and down between 80 and 800. It does that 10 times in 16 seconds from when it gets hot. When cold the O2 sensor reads very steady.

I'm not sure how to post the picture here...

What does it tell me?
robertisaar
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Post by robertisaar »

at idle, that would be expected....

if you were cruising at a steady speed(say 55MPH) and it were swinging that slowly, i would consider it a problem.
No Quarter
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Post by No Quarter »

How can that be expected when rpms go up and down with it and gives a very unstable idle?
robertisaar
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Post by robertisaar »

what kind of O2 sensor did you install? certain brands do not play well with GM ECMs/PCMs at all, Bosch seems to be a common one.

idle instability can be caused by a few different factors with these since idling is done via a hybrid alpha-n method. any kind of problem with the MAP sensor/vacuum line, IAC, TPS, IAT or a vacuum leak/throttlestop moved from it's factory set position will wreak havoc on the fueling calculation.

when the idle is upset and in closed loop, what do BLM and INT values look like?
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Six_Shooter
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Post by Six_Shooter »

Have you checked fuel pressure?
Have you performed a tune up?
Have you cleaned the IAC passage/throttle body?
Have you filled up at a different station than usual or different grade of fuel?

The O2 sensor is a reactive device, not a controlling device, so stop being so focused on it.

Yes, the feed back can have an effect on the fuel amount delivered to the engine, but it's not nearly that instant, it takes several seconds for sampling to occur, and then a change in the fueling delivered.
No Quarter
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Post by No Quarter »

robertisaar wrote:when the idle is upset and in closed loop, what do BLM and INT values look like?
BLM and INT showed around 128 both early on, later in drive BLM was a bit lower, and Red.

When I started it I had a 2200 rpm idle, and the IAC at a level of around 90, later the idle was less annoyingly high, but still 1400 rpm, and IAC was 55.
No Quarter
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Post by No Quarter »

Six_Shooter wrote:Have you checked fuel pressure?
Have you performed a tune up?
Have you cleaned the IAC passage/throttle body?
Have you filled up at a different station than usual or different grade of fuel?

The O2 sensor is a reactive device, not a controlling device, so stop being so focused on it.

Yes, the feed back can have an effect on the fuel amount delivered to the engine, but it's not nearly that instant, it takes several seconds for sampling to occur, and then a change in the fueling delivered.
Well, tried som basic stuff, put a vacuum gauge on it, nice and high, took out all the plugs, all looked fine. Wiggled wires and sprayed to find leaks, nothing. Put it all back together, and now I have a perfect idle! Has been so for an hour, but how long?
(TPS and IAC are new, no change when I replaced them)
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