Gain extra benefits by becoming a Supporting Member Click here find out how!

Classic Performance Products Classic Parts
American Auto Wire Classic Industries
Danchuk Catalog
Hellwig Products IncPerformance Rod & CustomNu-Relics Power Windows



Username Post: OBD1 Live Data        (Topic#359044)
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-05-19 07:45 PM - Post#2781564    

1990 5.7 C1500. I am interested in reading live data, not just reading codes. On ebay, I see some old used OTC scan tools, but get confused by which cartridges to look for. So I looked around and saw that there are live data scanners of some sort to use on an Android phone. Anyone know about these? The little looking I did got confusing because it looks like someone sells the cable adapter, someone else the interface, and someone else the files for the particular vehicle. Figured someone here could explain it to me. Thanks.



 
junkman104 
Frequent Contributor
Posts: 1465
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
12-06-19 04:18 AM - Post#2781571    
    In response to go_hercules

I found this explanation on another site why OBD1 is not available for android. "OBDI protocols and hardware connections are proprietary to each vehicle manufacturer, unlike OBDII which is a universal standard as federally mandated. So there isn't an "OBDI app" and there isn't likely to be one as you'd need specific interface hardware and software for every vehicle manufacturer (GM, Ford, Chrysler and each of the foreign mfrs)."

You can look for a Snap On MT2500 they are getting reasonable in price compared to what I paid for mine back in 1996. I will admit I use it in my shop pretty often on older vehicles.



 
Sabino 
Member
Posts: 109

Reg: 07-16-05
12-06-19 06:51 AM - Post#2781580    
    In response to go_hercules

I’d recommend TunerPro, a laptop, and a cable from Moates.
TunerPro is freeware/donate & you can find cables from many sources but Moates made it easy with tutorial to get going.

There is also a freeware “EEHack” which I haven’t messed with but people like.

gearhead-efi.com has info on data logging for OBDI / ALDL

65 Belair 350
68 Camaro 327
93 Suburban 5.7L TBI


 
65_Impala 
Very Senior Member
Posts: 4368

Reg: 12-29-02
12-06-19 06:54 AM - Post#2781581    
    In response to Sabino

I second using Tunerpro.

EEHack won't work on a truck. It's only for 94-95 LT1 engines using a '8051 PCM.





 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-06-19 08:32 AM - Post#2781587    
    In response to 65_Impala

Will TunerPro work on a phone, or laptop only? I do not have a laptop.



 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-06-19 09:21 AM - Post#2781592    
    In response to go_hercules

Just looked at all the GM files that TunerPro lists and lo and behold my truck is not listed. Just about everything but mine. The closest was a 5.0 for that year.



 
Sabino 
Member
Posts: 109

Reg: 07-16-05
12-07-19 07:49 AM - Post#2781645    
    In response to go_hercules

You need a laptop as far as I know. You can search on gearhead-efi for other options perhaps. gearhead-efi also has huge archive of files for TunerPro.

It’s likely something will work for your truck. The most sure way is to look inside your ECM and get the bin and ECU num. post your truck and that info on their web and someone will tell you what you can use.

I looked around for a while trying to find something to datalog & troubleshoot the ALDL for my 93 and choices were either a old tool, no longer supported- usually expensive, sometimes needing different cartridges for different things, etc. - or something like TunerPro which is active and has a large community of users to help with questions.
Good luck!

65 Belair 350
68 Camaro 327
93 Suburban 5.7L TBI


 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-08-19 10:12 PM - Post#2781761    
    In response to Sabino

I saw some OTC4000E scanners on ebay. I have used these long ago and think they would do the trick on my 1990. The thing I don't understand or remember about these OTC scanners is what cartridges to look for. The cartridges seem to have a year listed on them, and then some say domestic, 3 in 1, pathfinder, etc. What is the difference in these, and what do I need to do scanning on my 1990 truck? And one other thing I see listed for the OTC scanners is a "smart insert" - what the heck is that? Thanks.



 
junkman104 
Frequent Contributor
Posts: 1465
junkman104
Age: 60
Loc: Murphy N.C.
Reg: 01-25-14
12-09-19 04:43 PM - Post#2781820    
    In response to go_hercules

Did you even read my post, just wondering. SnapOn MT2500 is half the price and has live data.



 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-09-19 10:01 PM - Post#2781850    
    In response to junkman104

Yes, I read it. And I have been looking on ebay at the MT2500 and OTC4000. There are several of each of the two types, and in roughly the same price range. I was leaning towards the OTC simply because I had used one long ago. It's hard to buy stuff like this on ebay because the descriptions are so vague you don't know if they even work most of the time. I think a lot of people sell these from estates and what not and don't know much about what they are selling. And the cheapest ones are $100 plus, many with no returns accepted. So yes I did take your advice and am working on it. Thanks a lot.



 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-10-19 08:41 AM - Post#2781871    
    In response to go_hercules

For anyone interested, I actually found that Bosch/OTC/Actron (same company) currently makes an OBD1 scan tool. OTC 3211, Actron 9690, Bosch OBD1300. I bought one last night and plugged it in to my 1990 C1500. Got good live data, so was surprised and happy. Paid $217 for it at Pep Boys Auto Parts. Also does OBD2. Now the bad part. I started driving home and was watching live data. All was reading fine. But the truck started idling higher and higher and pinging. So I stopped and unhooked the scanner and truck went back to normal. Tried a few times and same thing. Seemed like the timing was advancing. Took the scanner back for a refund. The only thing I can figure is that since the ALDL can be jumpered for codes, fuel pump operation, field service mode, etc., that the scanner must somehow triggered something by virtue of being connected there. This scanner should not have been able to change, or drive, anything in my PCM. At least I tried it, was just surprised that you could still even buy a brand new OBD1 scanner.



 
CowboyTrukr 
"8th Year" Silver Supporting Member
Posts: 4325
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
12-10-19 09:16 AM - Post#2781872    
    In response to go_hercules

My truck does that with the OBD1 cable and TunerPro running. Takes the default idle up to 1K.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD
‘87 GMC S15 SCLB 4.3 Auto - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-10-19 09:44 AM - Post#2781876    
    In response to CowboyTrukr

Weird. Kind of hard to troubleshoot when the scanner is changing things on it's own.



 
someotherguy 
Senior Moderator
Posts: 29050
someotherguy
Age: 49
Loc: Texas
Reg: 08-01-03
12-10-19 03:01 PM - Post#2781892    
    In response to go_hercules

  • go_hercules Said:
Weird. Kind of hard to troubleshoot when the scanner is changing things on it's own.


Agreed but I want to say I've seen similar behavior, although it's been years since I've had an OBD-I vehicle on a scanner. It seemed like when my buddy would put his MT2500 on my OBD-I stuff it would enter some kind of diag mode that raised the idle and the engine would behave differently. We were trying to figure out at one point why a '91 Caprice 9C1 was running a little strange; when we put the MT2500 on and test drove the car, it pinged a lot and temperature would rise rapidly when even gently power-braking the car - telling me timing was way off. Been forever but I don't think we ever quite figured it out.

Richard

06 Silverado ISS / 06 Silverado SS / 06 300C SRT8


 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-10-19 04:30 PM - Post#2781904    
    In response to someotherguy

Yeah Richard, unfortunately it was hard to really figure out the logic programmed into the PCM's or scanners back then, and even tougher now. I'll keep looking around for the OTC4000 or the MT2500. I think they will be my best bet overall.



 
Sabino 
Member
Posts: 109

Reg: 07-16-05
12-11-19 07:13 AM - Post#2781935    
    In response to go_hercules

This is due to the ECM going into data streaming mode when the diag cable is plugged in to connector. Whether it changes something depends on the specific bin and ECM. As I understand it, which is very little - when the ECM is only managing the engine it has enough time to do what it needs to do. In some ECMs, bins, situations when in data streaming mode it can’t stream diag data and manage everything as it would normally - or something like that.

My 93 C1500 suburban runs normally, idles normally while datalogging with TunerPro and the Moates cable. What you see is not uncommon. Google and you‘ll see - https://www.thirdgen.org/forums/diy-prom/24713 5-id... I’m sure the guys at gearhead-efi know all about the details too.

As I understand it, and again-that’s not much so you need to do you’re own verification, if you start the engine in ALDL diag mode (ie. a 10k resistor across A-B) the timing and other stuff can get reset and the ECM has to relearn. Perhaps this expains the knocking, etc. I’ve read that you should plug in the tool without the 10k switched in then start engine. Then switch in the 10k to put in diag mode and start datalogging. But as mine doesn’t seem to have problems datalogging I’ve never tried anything different.

This is why I think you are better off using something with a community for support on old stuff like this. There’s a ton or people using TunerPro and you can find people you’ve already run into your problem. The TunerPro forum, gearhead-efi, and thirdgen are good resources.
Also Moates has a cable which allows you to switch in/out the 10k resistor http://www.moates.net/aldu1-and-cabl1-p-127 .html?c...
Good luck - this stuff on old ECMs is not just turn-key


65 Belair 350
68 Camaro 327
93 Suburban 5.7L TBI


 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-11-19 10:53 AM - Post#2781941    
    In response to Sabino

That was some interesting info on that link. Sounds like something to do with putting a 10K resistor in the ALDL then taking it out or something so it doesn't go into the bizarro mode. I am going to read up on that more. Maybe the old proprietary scanners had that 10K resistance built in or something. Who knows. But it's an interesting lead that I will read up on. Thanks.



 
65_Impala 
Very Senior Member
Posts: 4368

Reg: 12-29-02
12-11-19 06:06 PM - Post#2781984    
    In response to go_hercules

You don't need the 10k resistor on the '7747 ECM. It transmits the data stream all the time. The resistor just screws up the operation as you saw. The scanner you bought likely had the resistor build in. You could remove pin B from the ALDL connector so the resistor doesn't get connected.



 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-11-19 07:10 PM - Post#2781988    
    In response to 65_Impala

That makes sense, and would be interesting to try. Only problem is I already returned it.



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3842
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-12-19 06:18 PM - Post#2782034    
    In response to go_hercules

Some of the scan tools will let you select the data mode you want.

Open Mode – Normal Mode
Limited parameters can be observed without changing the engine operating characteristics.

Data link (also called 10K or special) In this mode all obtainable data is readable.
Closed loop timers are bypassed
Distributor ignition (DI) is advanced
PNP restrictive functions are disabled
IAC controls engine idle to 1000 RPM + or – 50 RPM (if applicable)
On some engines the canister purge solenoid is enabled

A 3.9K ohms resistor installed between ALDL terminals 'A' and 'B' forces the ECM into Backup Fuel mode. This mode forces the ECM to use predetermined fuel calculations in the ECM PROM instead of the learned inputs in active RAM. This is more commonly referred to as the "Limp Home" mode of operation. Backup fuel is usually around 12:1 or richer from the factory.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-18-19 06:15 PM - Post#2782445    
    In response to Chevytech

Okay, just got my hands on an OTC4000E scanner. It works great on this truck, with none of the oddities of the other one I tried. I was watching the IAC counts today and had a question: I realize that the IAC takes commands from the PCM and gives no feedback in return. So, when looking at scan data and watching IAC counts, is there any way to really know what position the IAC is in? I know you can check the resistance of the two coils in the IAC stepper, etc. but you still don't know if it's really where it's commanded to be, do you??



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3842
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-18-19 08:03 PM - Post#2782453    
    In response to go_hercules

  • go_hercules Said:
... I was watching the IAC counts today and had a question: I realize that the IAC takes commands from the PCM and gives no feedback in return. So, when looking at scan data and watching IAC counts, is there any way to really know what position the IAC is in? I know you can check the resistance of the two coils in the IAC stepper, etc. but you still don't know if it's really where it's commanded to be, do you??


You're correct. The computer does not know the IAC position. The computer just keeps sending commands to the IAC until it gets the RPM signal it wants.

With the engine fully warmed up and all accessories off with the truck at idle in park look at the Idle Air Count. If everything is working well you should see an IAC count between 15 and 20.

Note that the count can be off if you have been working on it and it has not hit the criteria to do a relearn yet.


For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-18-19 08:16 PM - Post#2782454    
    In response to Chevytech

Yes, I did that today and the IAC count at idle and warmed up was just below 20, where I would expect. Reading into what you said, can I assume that if the IAC were NOT following commands, then the count would be different because the PCM was "chasing" it?



 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3842
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-19-19 09:26 AM - Post#2782494    
    In response to go_hercules

  • go_hercules Said:
... Reading into what you said, can I assume that if the IAC were NOT following commands, then the count would be different because the PCM was "chasing" it?


Correct.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
65_Impala 
Very Senior Member
Posts: 4368

Reg: 12-29-02
12-19-19 04:40 PM - Post#2782519    
    In response to go_hercules

The IAC has a throttle follower function that opens the IAC proportionally with the throttle opening. You can use that function to test the IAC is moving. Give the throttle a big fast blip. The rpm should jump up with the blip, but it should kind of hang for a split second and then come back to the proper idle rpm without going under the idle rpm or stumbling. It does this because the IAC will open to catch or hold that approximate rpm and then the IAC recloses again to bring the engine back to the idle rpm. If it's an auto do this in gear with a foot firmly on the brake.



 
go_hercules 
Contributor
Posts: 122

Reg: 10-27-16
12-19-19 08:35 PM - Post#2782533    
    In response to 65_Impala

I will try that. Your explanation makes sense along with some other stuff I read. An awful lot of explanations are pretty wrong I think, when they say that the IAC closes at higher throttle settings. At first glance that makes sense, but along with what you described I also read in some GM driveability manual that the IAC "hovers" around where it is anticipated to be next. So at cruise, it expects to be at idle next, etc. I'm learning, but it's tough when you can't actually see the dang thing in action. I was thinking about taking an IAC apart, cutting a hole in the side so I could see the pintle, then attaching another complete IAC so that it drove the dummy pintle. A little machine work, shouldn't be too hard. Or maybe I can think of a way to get position feedback from the IAC. I know they make feedback solenoids, so maybe I'll look into that. "I got's to know"



 
Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

511 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.315 seconds.   Total Queries: 16   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 03:14 PM
Top