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I am working on my 1985 Corvette 4 plus 3. So the idle was a little rough and I disconnected the MAF and the car stalled out. I thought it could run without the MAF. We reconnected the MAF the car started. The MAF on this car is adjustable does anyone know how many grams per second the MAF should read. I'm using TunerPro RT. The O2 sensor is showing about 500 at idle 700 rpm the IAC is about 145 counts. Thank you for the help
I have 21 inches of vacuum at idle and the TPS is 0.55 at idle.
What is the secret to get TP to work with your 85? I have been trying for 3 weeks now to datalog mine on TP. I bought the Moates ALDU1 cable with 10k mode and an using the ADX file listed on TP website. Can't get my car connected. I've got to be missing something. Did you have to change any settings to make it work with your 85 (870 ecm)?
Around 7-8 gm/sec flow rate is normal for idle. With 145 IAC counts (except for initial startup), it is starved for air. You may need to readjust the tps and closed throttle opening for proper min-air flow. However idle can mean many things. Here'a an example with a desired idle of 800 rpm and 3000 rpm (it won't really get to 3,000 rpm):
Note the IAC position and mass airflow for both idle conditions and at every point in between.
At 1,000 rpm (in ALDL mode with 10 k resistor across A-B) ~10 gm/sec would be in the ballpark. 145 IAC counts may also be reasonable under these conditions. Sorry, I tend to forget about the 1,000 rpm target idle speed in ALDL mode. Once scanning with 10 k resistor at 160 baud in ALDL mode, you can try shorting pins A-B if allowed by your cable in order to enter field service mode (but not sure if this will work based on Viking info below). I don't have an 85 available to test/confirm.
Last edited by tequilaboy; Jun 15, 2020 at 07:23 PM.
Unfortunately, the 85 cannot be "scanned" without also being in "field service mode" which is to say that it forces the car to a 1000 rpm idle and does a few other things.
So, what this means, is that for an 85, and only and 85, you can use the scanning system (doesn't matter if it is a store bought scanner, or, tunerpro rt with a jumper, you CAN NOT VIEW THE 85 on a scanner at an unaltered state.
OK, what do i mean. Lets say you want to "set your 85's idle" using the IAC count method. You can't. Because the only way to look at the car on the scanner.....is when its being forced into field service mode which adjusts the IAC to create a 1000rpm idle target. Note that the 86 and later cars can also be forced into the fsm is you put the jumpers in a different spot on the scanner. But for 86 and later, you can also observe the ecm under normal operating conditions if you put the jumper in a different position.
Lets say you want to see what your 02 sensor is reading? Is it swinging like it should? from 200mv to 900mv? Yes, you can do that. But the car will be at 1000rpm at idle. Which is fine. Cause you can still verify that the o2 is function. Dido for the coolant temp sensor. Dido for egr being commanded on or off.
So, the 85 is not like 86+, but the scanning system is still very usefull for diagnosing different sensors on the car.
Here is how i get tprt to work for me, on my win10 surface:
- plug everything in. to car, and to my usb port.
- open device manager, go to com ports, figure which one is the aldl cable by watching for it to dissapear and reappear when i pull the cable in and out of my usb port. then i set that to com 2.
- now i open tunerpro rt. i start by opening the bin for an 85. then i open an adx file by converting from ads and i select the 85 ads file.
- then iin tprt i go to tools/preferences/dataaq|emulation and choose configure plug in component and ensure its set to match the com 2 from above.
then i press the two oppositely oriented blue arrow button, which is connect/disconnect.
if it doesn't connect its because i have my jumper in the wrong location.
ON MY USB CONNECTOR which is an aldl connector from aldlcable.com here is the orientation i need for the jumper.
1 2 > usb cable to the car (computer is left of the 1 and 3 in this little schematic i just don't know how to use tab here)
3 4
with the pins faceing towards me,
if i put the jumper on 1 and 2, it puts the car into field service mode and will connect on tprt. this is the only way to get an 85 to connect. You will see your IAC counts increasing and the car will run at 1000rpm idle.
jump 3 and 4 and the car communicates in "normal" mode (i am not sure what the name for that mode is) and i can observe and 86 + in "regular behavior" where.
TunerProRT isn't simple to use, but once you do get it, it works awesome.
If you guys want an 85 file, with a dash loaded, try the one attached in the post.
rename this to a .adx
and it appears this file is already an adx so you can skip the step above where you convert from an ads to an adx.
Last edited by VikingTrad3r; Jun 7, 2020 at 12:59 PM.
Unfortunately, the 85 cannot be "scanned" without also being in "field service mode" which is to say that it forces the car to a 1000 rpm idle and does a few other things.
So, what this means, is that for an 85, and only and 85, you can use the scanning system (doesn't matter if it is a store bought scanner, or, tunerpro rt with a jumper, you CAN NOT VIEW THE 85 on a scanner at an unaltered state.
OK, what do i mean. Lets say you want to "set your 85's idle" using the IAC count method. You can't. Because the only way to look at the car on the scanner.....is when its being forced into field service mode which adjusts the IAC to create a 1000rpm idle target. Note that the 86 and later cars can also be forced into the fsm is you put the jumpers in a different spot on the scanner. But for 86 and later, you can also observe the ecm under normal operating conditions if you put the jumper in a different position.
Lets say you want to see what your 02 sensor is reading? Is it swinging like it should? from 200mv to 900mv? Yes, you can do that. But the car will be at 1000rpm at idle. Which is fine. Cause you can still verify that the o2 is function. Dido for the coolant temp sensor. Dido for egr being commanded on or off.
So, the 85 is not like 86+, but the scanning system is still very usefull for diagnosing different sensors on the car.
Here is how i get tprt to work for me, on my win10 surface:
- plug everything in. to car, and to my usb port.
- open device manager, go to com ports, figure which one is the aldl cable by watching for it to dissapear and reappear when i pull the cable in and out of my usb port. then i set that to com 2.
- now i open tunerpro rt. i start by opening the bin for an 85. then i open an adx file by converting from ads and i select the 85 ads file.
- then iin tprt i go to tools/preferences/dataaq|emulation and choose configure plug in component and ensure its set to match the com 2 from above.
then i press the two oppositely oriented blue arrow button, which is connect/disconnect.
if it doesn't connect its because i have my jumper in the wrong location.
ON MY USB CONNECTOR which is an aldl connector from aldlcable.com here is the orientation i need for the jumper.
1 2 > usb cable to the car (computer is left of the 1 and 3 in this little schematic i just don't know how to use tab here)
3 4
with the pins faceing towards me,
if i put the jumper on 1 and 2, it puts the car into field service mode and will connect on tprt. this is the only way to get an 85 to connect. You will see your IAC counts increasing and the car will run at 1000rpm idle.
jump 3 and 4 and the car communicates in "normal" mode (i am not sure what the name for that mode is) and i can observe and 86 + in "regular behavior" where.
TunerProRT isn't simple to use, but once you do get it, it works awesome.
If you guys want an 85 file, with a dash loaded, try the one attached in the post.
rename this to a .adx
and it appears this file is already an adx so you can skip the step above where you convert from an ads to an adx.
Tuneportbeast,
I don't know why you car is not talking to TPRT. But I looked at all my settings in the preferences tab they are as follows:
Use Plug in
TP Data Acquisition I/O interface
Configure Plugin component
TP emulator Interface
Configure plug in component
All the boxes are checked
Vikingtrad3r Tuneportbeast, I don't know why you car is not talking to TPRT. But I looked at all my settings in the preferences tab they are as follows: Use Plug in TP Data Acquisition I/O interface Configure Plugin component TP emulator Interface Configure plug in component All the boxes are checked
Tuneportbeast is correct. Check device manager to find out what com port you are using. Then enter it in to the TPRT software and click on the check cable button. I hope this helps.
Last edited by jseremba; Jun 7, 2020 at 05:56 PM.
Reason: add information
Yup, the cable COM port is set and when I check, it does say "cable found and functional". Winaldl does work for me using the moates cable. 10k mode does bring the rpm up to 1,000. Do you have to have the adx file uploaded as well? I did try it with what I thought was the correct adx file uploaded as well as the adx definition file. I also tried it with the correct BIN in as well.
Last edited by tuneportbeast; Jun 7, 2020 at 06:24 PM.
Can you see all of the dials. Remember you need to expand the view so that all of the dashboard dials become visible. When I first ran the program I could not see any of the dials. Then I brought the cursor to the top of the white line. The cursor became and arrow. I held and lifted the line and the dials became visible.
All of the dials are stuck at these values and don't move, with the only adx I can get to even say connected. (It will connect on this adx without even being plugged into the car)
As you can see it does say connected at the bottom and I don't even remember where I got the "tunerproelm327" adx from but that's the only one I can even get it to say connected with. I just tried the adx file that vikingtrad3r posted (after converting it from txt to adx and it wouldn't even connect with that one. I did not, however, have an adx loaded with it. All my settings are the same as you mentioned, earlier in this thread, jseremba. I'll have to double check tomorrow that all the boxes are checked but I think they are.
Last edited by tuneportbeast; Jun 7, 2020 at 06:44 PM.
My TPRT does not look anything like that. I think you should uninstall it and then reinstall from the website.
I'm on windows XP and it is version 5 of TP. Are you on version 5? I actually have already uninstalled it and then reinstalled it from their site, in hope's that it would work. I even tried using version 4 TP. When I load an xdf file it brings up all these functions/values on the screen that it doesn't show without the xdf loaded. Do I need the xdf file uploaded as well?
Last edited by tuneportbeast; Jun 7, 2020 at 06:51 PM.
tequilaboy
If I have 12 grams per second. Then I am running rich correct? I have no error codes. Any ideas. Thank you Joe
Just having the MAF reading doesn't tell us much. Either it's correct, in which case it just means you're pulling 12 g/s of air through the MAF, or it's wrong, and then yes you would be running rich (if 8 g/s of air is entering the engine but the computer thinks you're pulling 12 g/s, it will inject 12 g/s worth of fuel, which is 4 g/s worth of overfueling).
When I had a MAF fail on my '94, there were no error codes either (the MAF still "connected," so the PCM was happy), but on a dyno run the MAF values were all over the place which caused the torque to also be all over the place.
So the MAF I have is adjustable. We believe it is working correctly. And the car is running rich. So should I be trying to adjust the MAF reading to 7 or 8 grams per second. And, I thought the car could run without the MAF being connected. But, when I disconnected the MAF the car shut off, immediately.
So the MAF I have is adjustable. We believe it is working correctly. And the car is running rich. So should I be trying to adjust the MAF reading to 7 or 8 grams per second. And, I thought the car could run without the MAF being connected. But, when I disconnected the MAF the car shut off, immediately.
Thank you for the help
Your 1985 L98 has no MAP like the 94-96 LT1 does. As a result, if you remove the MAF, the ECM has no way of measuring airflow whatsoever and will shut the engine off immediately.
If you believe your adjustable MAF is at fault due to the 12 g/s reading at idle, adjust it until you get 7 g/s and see if the rich idle condition improves. It can't hurt. If the rich condition does not change whatsoever, then it's generally safe to assume the MAF wasn't the cause.
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