I do not have a 7747 ecm here but I do have an 8746 which is a lot like a 7747 but uses an IAT sensor and is a different mask. I am now in the process of setting up a bench test for it using a FTDI usb cable. I will pick up a 7747 from a friend either tomorrow eve or Sunday morning and do further tests with it. I use TPv5 and I am going to try to reproduce the errors. I will let you know what I find tonight on the 8746.
Brian
Last edited by sturgillbd; 02-15-2015 at 03:33 AM.
Well, I just tested connecting to the ecm. It connected up instantly with no errors. I have no sensors connected. I just powered the ecm and hooked up the cable to serial data and ground. Screenshot was taken after about 3 minutes of being powered on. One thing that comes back to mind is you said your aldl A terminal wasn't connected to ground at one point. Where did you connect it to ground? If I were you, I would put a ring terminal on a length of wire and connect one end to the same ground on the engine block as your ecm ground and the other end back to your aldl A terminal.
I dont run the Windows OS natively. All of my PC's and even my firewall/router run Linux. I load windows in a Virtual machine to run Tunerpro. I set up a laptop with XP and Tunerpro for the same guy that I'm going to borrow the 7747 ECM from. I will grab his laptop also when I get the ECM. Will be tomorrow night or Sunday before I get to test the 7747. Try the ground idea first and let us know the results.
so you are saying i should run a length of wire and have pin a on one side and the other side will be connected to where the ecm ground is connected on the engine. Then i will use that new ground i ran as the ground for my aldl cable.
Yes.
when i did connect to my dads ecm a while ago i did get some errors but the data was consistent and i didn't get crazy almost constant errors like i am now. I dont know if i mentioned this but when the engine is stone cold it has really good throttle response and it does not pop through the intake. Its once it starts to warm up the engine gets worse and worse where i have to open the throttle slowly to not cause a bog or backfire through the intake. I still have the fuel pressure tester hooked up and i still have a constant 13 psi after the fuel filter. Also not sure if it matters but when i rebuilt my throttle body i shaved off the rings that went around the top of the venturis for the throttle blades and i think i might have 2 gaskets stacked to raise up the whole injector assembly but i might not. i will have to double check.
Last edited by joegreen; 02-14-2015 at 07:51 AM.
That sounds like it is lean in closed loop. You can unplug the coolant temp sensor and the ecm will think it is cold too and really richen up the mixture. Work on one issue at a time. Lets try to get clean data first. After you get clean data, then you can datalog and run the data through the spreadsheets.
Some good news. I ran a brand new ground wire to the same bolt everything else is grounded to and i only got 1 error in a minute of time while moving the throttle back and forth with the engine off. I also changed my latency to 1ms. When i start the engine i get a whole bunch of errors again. Im going to go move and secure some wires and see what happens.
Latency at 1ms and receive bytes set to 1024 and i haven't gotten one error in a couple minutes of playing around with the key on engine off and the data flows nicely. I tried moving all the wires i could away from the spark plug wires but i still get a bunch of errors when i start the truck.
That is still progress. Make sure you have the ground strap from the engine to the body connected and the connection is clean. Body, frame, and all electrical grounds need to be clean and actually installed. You may have to lower your buffer size on your port. I did some reading last night on problems people were having and they increased latency time and lowered buffer size. Also may try setting flow control to none on the usb serial port in windows. It is going to take some effort but you will get it figured out.
I have a ground from the battery to body, battery to motor and motor to body. I tried adjusting latency and buffer size all over the place and nothing made a difference while running. I have flow control set to none. I ran across something in my internet search but i dont know how to do this. http://www.thirdgen.org/forums/diy-p...pro-rt-da.html
I tested a WinXP laptop and a FTDI cable to a TBI conversion Jeep today, We put TBI on this Jeep in 1995. I put his original EPROM back in it and the BCC is ASDX. I started the jeep and connected the laptop to it and it ran for approximated 20 minutes. I had three errors during the time it was connected. It was 17 degrees here today and it took about 10 minutes for the engine to come up to operating temp. If you are getting clean data with key on and engine off but errors when it is running, you are getting noise induced into the harness from the ignition system or the charging system. The three errors I got were possibly because the jeep I tested on is getting really rusty and the grounds haven't been cleaned since we installed the TBI system on it. As for the thirdgen link you referenced, that is for a different type of ECM that uses two way communication for data. The 7747 ECM's just puke a packet of data out about every 1.2 seconds on the serial line and you don't have to send anything to it for it to start. See http://lukeskaff.com/?page_id=305 and look for the section on 160 baud. Do you have an inverter running your laptop when datalogging? Others have had issues with inverters creating noise causing data errors when connected to the ALDL. I'm attaching a couple of pictures I took with my phone. The pic of the cable end connected to the aldl connector will show the quick and dirty way I plugged in and how rough this old jeep is. I forgot my cable and we haven't soldered any pins onto the end of his. This could have been a couple of the errors :)
Brian
Edit: There is an error on the page of which I sent the link. He states serial data is on Pin A and it is actually on Pin E. Pin A is the ECM ground.
Last edited by sturgillbd; 02-16-2015 at 04:41 AM.
I have my aldl end basically missing and i just have my ftdi adapter soldered right to the harness so i wouldnt/shouldnt have a bad connection to the ecm. I haven't neatened up my harness yet. I was waiting until i got the truck running good so incase i have a problem i can get to the wires quickly. Right now its a somewhat orderly rats nest of wires. if i have tuner pro connected with the key on not getting errors i will get errors the split second i turn the key to start it. What wires in the harness matter as far as noise being introduced into them that would cause the ecm to display errors? As far as ignition noise do i just need to keep the harness wires away from the spark plug wires? How would the charging system introduce noise? I took apart my delco 10si alternator a couple months ago and cleaned it up nice. I was going to do a rebuild but it was in good shape. Could the capacitor in the alternator be bad? The laptop is not running off an inverter. Just its own battery. I am going to post up picks of my grounds and harness so you can see what i am working with. Hope things don't look to gnarly. The first pic is of the homemade aldl soldered to the harness, then the battery to body ground (looks rusty but its not), then battery to engine ground, then engine to body ground, the rest is of the harness. The yellow wire is the new ground i ran.
Last edited by joegreen; 02-16-2015 at 05:55 AM.
It looks as though your whole harness is basically laying on your plug wires. You need to bundle the wires up at least with some zip ties and get them a few inches away from the plug wires. When the harness wires lay parallel with the plug wires, a voltage is induced into the harness. Your ecm is seeing a spike each time a plug fires. If you get them away from the plug wires, you have a good chance of cleaning up your data you see on TunerPro. I would also take all of the grounds loose and take a wire wheel on a drill and clean the steel until it is shiny metal. I would put dielectric grease or NOALOX on the terminals and the steel before putting the bolts back in to secure them. This will slow the corrosion down and you will have a much better electrical connection. I believe your main issue is the harness is too close to the plug wires. Normally the harness is bundled in loom and comes from firewall area down the passenger side of the intake. I'll post a pic of how my harness is routed.
Brian
Last edited by sturgillbd; 02-16-2015 at 07:24 AM.
the pictures dont do it justice but the harness wires are a good 2 inches from the plug wires. But tomorrow i am going to zip tie all the wires and get everything as far away from the plug wires as i can. thanks
This was taken last Sept when I was cleaning up the engine harness. Picture isn't the greatest and I didn't have any wire management on my plug wires either. You will get the idea of how I routed the harness though.
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