Home page
SPONSOR AD

Support our Vendors!  |  Advertise Here

Topic: scanning question for 85 owners

in Forum: C4 Engines


Already a Member?
Login
Not yet a Member?
Register for Free!

scanning question for 85 owners (1/12)
 8/17/13 5:09pm
laurieb
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1995 Coupe, Automatic, Dark Red Metallic, 1G1YY22P6S5100376 1985 Coupe, Automatic, Gold Metallic, 1G1YY0783F5114974


Joined: 4/11/2013
Posts: 109

I have an ALDL cable with the 10k resistor for use with scanning software (WinALDL) on my stock 85 with the 870 ecm.  I took it for a drive and noticed that the idle is high with the cable in place.  I've now read that the cable causes other changes, as well.  I'm wondering how to use this cable/software in such a way as to get good readings.  I'm also a bit concerned about using it again because I've now read that the cable retards knock sensor, so you could end up getting lots of knock while driving.  A little "light" pinging was heard during the drive (about 20 minutes) when getting on it a bit.  That's concerning, as the car doesn't ping normally.  Thanks!

|UPDATED|8/17/2013 2:09:57 PM (AZT)|/UPDATED|


______________
~Laurie~

1985 and 1995 coupes:
1985 and 1995 coupes
Our Sponsors help support C4VR
Re: scanning question for 85 owners (2/12)
 8/17/13 8:34pm
Adams' Apple
Standard Member
Moderator
Send Private Message

Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2230

Sounds like you are driving with it in "Diagnostic" mode, which will change some of the operating and data parameters. Does your "Service Engine" light come on while this cable is plugged in? If it does, then the cable/software is putting the system into diagnostics mode....and that's gunna make it run funny....

If anyone is planning on doing much in the way of diagnostics, or other work on these cars, I would highly recommend the purchase of a capable "Scanner". They are so cheap these days it just don't make sense to not have one. I've got two different ones, and I've spent a ton of money keeping them updated over the years. 
Here's just one I found on fleabay....has everything you wound need for a '81-'95  car....dirt cheap! 


If you want to have something that will work in the '95 & later cars, just be sure it is OBDII capable. The above scammer I posted IS OBDII, but that particular one does NOT have the OBDII adapter, or keys. With the correct adapter and keys, the scanner will do OBDII vehicles.


|UPDATED|8/17/2013 5:34:34 PM (AZT)|/UPDATED|


______________

Joel Adams  
My Link

 
   
(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: scanning question for 85 owners (3/12)
 8/17/13 9:00pm
laurieb
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1995 Coupe, Automatic, Dark Red Metallic, 1G1YY22P6S5100376 1985 Coupe, Automatic, Gold Metallic, 1G1YY0783F5114974


Joined: 4/11/2013
Posts: 109

Adams' Apple said: Sounds like you are driving with it in "Diagnostic" mode, which will change some of the operating and data parameters. Does your "Service Engine" light come on while this cable is plugged in? If it does, then the cable/software is putting the system into diagnostics mode....and that's gunna make it run funny....

If anyone is planning on doing much in the way of diagnostics, or other work on these cars, I would highly recommend the purchase of a capable "Scanner". They are so cheap these days it just don't make sense to not have one. I've got two different ones, and I've spent a ton of money keeping them updated over the years. 
Here's just one I found on fleabay....has everything you wound need for a '81-'95  car....dirt cheap! 


If you want to have something that will work in the '95 & later cars, just be sure it is OBDII capable. The above scammer I posted IS OBDII, but that particular one does NOT have the OBDII adapter, or keys. With the correct adapter and keys, the scanner will do OBDII vehicles.







Hi Joel,

Nope - no SES light.  In WinALDL, it was noted that it was in "ALDL Mode (10k ohms)" mode as opposed to "Diagnosic Mode (0k ohms)".  I'll look into more robust scanners, too.  

Thanks!


______________
~Laurie~

1985 and 1995 coupes:
1985 and 1995 coupes
Re: scanning question for 85 owners (4/12)
 8/18/13 12:29am
davep85c4
Former Member

Send Private Message

Joined: 4/4/2009
Posts: 254

Yes you're in ALDL Mode. I'm not familiar with WinALDL, so can't help you with that program.

There's a very cool old school data program called Diacom. It is an old DOS-based program that you actually run in DOS mode, not a DOS-window in Windows.  It has been obsolete compared to more recent data collection programs for years. I still have my Diacom Cable, and a copy of the program. The problem is finding a dinosaur of a laptop that can run Diacom. I've tried a bunch of different old laptops, and none of them successfully link. If you have a functional old Window 3.1 or Win 95 machine, I'll let you try my Diacom cable and program.

I've been using DataMaster and more recently TunerPro for my Syclones, Typhoons and the ZR-1's I work on. Neither of these programs support the 85.

When you find a solution, I'd be curious as to what it is.
Re: scanning question for 85 owners (5/12)
 8/18/13 12:43pm
laurieb
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1995 Coupe, Automatic, Dark Red Metallic, 1G1YY22P6S5100376 1985 Coupe, Automatic, Gold Metallic, 1G1YY0783F5114974


Joined: 4/11/2013
Posts: 109

Hi Dave, I may very well take you up on the offer to use the Diacom.  I'm a computer person, so I have plenty of operating systems lying around my upstairs office.  I have, however, gotten rid of most of my hardware that would work with an older application such as Diacom.  But, I can likely scrounge one up fairly easily and get it in working condition without much issue.  Too bad I'm not nearly as good with cars as I am with computers Confused  Maybe someday that will change, if I keep at it.

Anyway, what prompted my desire to scan, aside from raw curiosity, is that I recently experienced a few unusual incidents with my 85.  At start up, it immediately went to low idle.  It did this intermittently and even stalled once at start.  Sometimes, though, it would start up normally (very little crank and at the higher idle, then dropping down.)  It didn't throw any codes, so I wanted to scan and see what's going on in there that would lead to that.  Suddenly, though, the car isn't doing it at all anymore, and is starting normally every time.  Before these incidents, as a matter of maintenance, my husband cleaned the throttle body, changing the gaskets, as well, and cleaned up the IAC a bit, too.  I'm wondering if the IAC was sticking a bit at start up sometimes after that.  


______________
~Laurie~

1985 and 1995 coupes:
1985 and 1995 coupes
Re: scanning question for 85 owners (6/12)
 8/18/13 6:59pm
CaledoniaBrian
Former Member

Send Private Message

, - Canada

Vette(s):
1988 Convertable


Joined: 11/3/2011
Posts: 150

Some start problems; last week it was an idle thing..... I am wondering if you maybe didn't get a tank of bad gas. Sometimes this does happen.  Just a thought. 

______________

Re: scanning question for 85 owners (7/12)
 8/18/13 8:18pm
laurieb
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1995 Coupe, Automatic, Dark Red Metallic, 1G1YY22P6S5100376 1985 Coupe, Automatic, Gold Metallic, 1G1YY0783F5114974


Joined: 4/11/2013
Posts: 109

Hi Brian,  It's a good thought, but I don't think so in this case.  This car gets driven quite a bit.  I go through a tank a week.  The weird start thing was new, but not the rough-ish idle.  I'm not so concerned about the idle anymore.  And, while the start issue seems to have cleared up (I think,) I can't help but be curious, especially since it occurred right after the TB clean-out/gasket change.  

______________
~Laurie~

1985 and 1995 coupes:
1985 and 1995 coupes
Re: scanning question for 85 owners (8/12)
 8/18/13 10:12pm
birdman11
Standard Member
Send Private Message


Vette(s):
91


Joined: 7/10/2013
Posts: 12

 How is it running now?  

|UPDATED|8/18/2013 7:12:28 PM (AZT)|/UPDATED|


______________
Re: scanning question for 85 owners (9/12)
 8/20/13 4:59pm
laurieb
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1995 Coupe, Automatic, Dark Red Metallic, 1G1YY22P6S5100376 1985 Coupe, Automatic, Gold Metallic, 1G1YY0783F5114974


Joined: 4/11/2013
Posts: 109

birdman11 said:  How is it running now?  


It's actually running pretty well at this point.  I haven't had any more of the intermittent low-idle start issue.  I'm still driving the car frequently, as I really enjoy driving this car quite a bit :-)  So, at least I'm able to keep good track of unusual occurrences.  I will continue to keep an eye, and am still going to see about the whole scanning thing.  If nothing else, I'm just interested in learning more by using this tool, and being able to diagnose in the future.  

______________
~Laurie~

1985 and 1995 coupes:
1985 and 1995 coupes
Re: scanning question for 85 owners (10/12)
 8/20/13 8:38pm
eddie20890
Standard Member
Moderator
Send Private Message

lanoka harbor, NJ - USA

Vette(s):
1990 L-98 white/ red/black leather interior targa top auto 1975 L48 blue/black leather interior t tops auto


Joined: 3/22/2009
Posts: 1363

it may have been as you say something sticking after all the cleaning. remember an older car use to clean the linkages and stuff every now and then and the choke rod would stick. had to spray some lube on it to keep it free.

if it cleared up it may not show on a scanner.


______________


















the dynamic duo


c3vr life member #97
Re: scanning question for 85 owners (11/12)
 8/21/13 9:47pm
laurieb
Standard Member
Send Private Message

Sacramento, CA - USA

Vette(s):
1995 Coupe, Automatic, Dark Red Metallic, 1G1YY22P6S5100376 1985 Coupe, Automatic, Gold Metallic, 1G1YY0783F5114974


Joined: 4/11/2013
Posts: 109

Well, intermittent it is.  This afternoon the car started at low idle again, after not doing it for about a week.  I thought it was all cleared up.  I just gave it a little gas and everything was fine, but it's a very odd thing to have happen.  Otherwise, the car is running great.  Just the intermittent starting up at a low idle thing.

______________
~Laurie~

1985 and 1995 coupes:
1985 and 1995 coupes
Re: scanning question for 85 owners (12/12)
 8/22/13 1:33pm
davep85c4
Former Member

Send Private Message

Joined: 4/4/2009
Posts: 254

laurieb said: Well, intermittent it is.

Check the P/N switch output to the ECM for intermittent connection. (This is separate set of contacts NOT associated with the starter contacts. Even if it cranks reliably, the ECM contacts may not be 'set'). If the ECM doesn't know the shifter is in Park, it may not properly 'set' the IAC for start-up.

It is an orn/blk wire on pin B10 at Connector 2 of the ECM.  Back-probe this connection with a VOM connected to ground. (A12 blk/wht, C2 is an ECM ground. It's difficult to establish a good ground in a Corvette for test meters).

With key on, engine off, in P or N you should read 0-volt. In any other shifter position you should read nominal 5.0-vot. Wiggle the shifter in Park and watch the meter. If the voltage isn't a constant 0-volt throughut the "wiggle-range", move the shifter to where you get voltage in Park, and try to start it. If it cranks, you have a worn P/N switch assembly that allows the starter to operate, but not send the 0-volt signal to the ECM.

As a further diagnostic, note where this occurs. It will be either at the forward, or aft end of the shifter position. Note which one is "wrong". When starting the car, make sure the shifter is pushed to the "correct" position. If the intermittent low-idle is gone when doing this, you figured it out.




Our Sponsors help support C4VR