I have been a member here for a while but this is my first thread. I wish it was coming to you under better circumstances. I have been reading thread after thread and have come up short handed, I hope someone on here will be able to shed some light on this for me. If any other information is needed please ask. I am by no means a professional so I will do my best to give you the information needed.

Here is a run down of the car, it may not be useful information but I want to provide you with all information possible because I have been fighting this issue for about 2 weeks and I’m at my whit’s end.

Car is a 1991 z28 camaro, originally a 305 TPI car with a 700r4. I have since made a lot of changes;
- 383 stroker motor with 4 bolt main
-AFR 195cc heads with 2.05 intake valve and 1.60 exhaust valve.
- Cam is 571/577 lift with 1.6 rockers. 230/236 duration @0.5 on a 114 LSA
-TPIS mini ram intake with twin 58mm throttle body.
-700r4 to t56 swap

The issue started (or that’s when I became aware of the issue) after I did the auto to manual swap. I have the 7730 ECM with a pcmforless prom and the original memcal.

Now to the issue, all indicators point to the ecm using the prom information for its data to run. When I say this I mean I have the required +5VDC source at pins B and M on the ALDL and the ECM ground on pinA has good continuity about 1-2 ohms. In addition the SES light passes the blink test with the key in the on position. The SES light blinks and then stays on with the key turned to battery on.

With all that being said when a laptop with TunerPro software is plugged into the ALDL connector it can see all of the engines operation and all sensors seem to be operating normally, but when the laptop commands a change to the prom in the ecm the command is ignored. Hence the issue I have this expensive set up and the tuner has no way of tuning the car.
In addition to this I have swapped out the ECM 2 times, both times car went into closed loop after about a minute or two of running and once shut off and restarted will stay locked into open loop.

I have found a wiring diagram and have checked all grounds for continuity and all checks out and have cleaned and checked the grounds on the back of the heads. When I did the auto to manual swap I bought pigtails for the t56 for reverse lights and used the factory blue and green wires at the gear selector switch so that I will have reverse lights. The thick purple and thick tan and white wire are connected together ( I know the correct way is to run the wires to the clutch switch on the pedal) and the black/white wire and orange/black wire I left open with butt connectors on the ends filled with glue so that they would not arch out on anything.

Am I missing something or have done something wrong? I don’t understand why the laptop will not communicate with the ECM and suggestions or direction would be a HUGE help.

Thanks in advance,

 

You can't program the EPROM through the ECM. You need an EPROM programmer to do that.

An alternative is to get an EPROM emulator, like the moates.net Ostrich 2.0.
Another alternative is the DynamicEFI EBL for the P4 ECM.

 

Thanks for the reply,
I don't know a whole lot about the tuning stuff. I'm having a very reputable tuner take care of it for me that has tuned a number of third Gen cars with great results. When I took the car to him the first time we swapped out the ecm for a new one and he was able to get everything to work as it should for about 5 min. He started to make changes and then everything stopped communicating/working just as it did before. He couldn't even adjust the desired rpm for the engine witch is locked at 800rpm. So I'm assuming get has all of the needed equipment. Any other ideas?

 

You can usually temporarily change the desired idle, clear the trouble codes and maybe 1 or 2 other commands through the ALDL connection but that's it. You cannot tune the car through it, there is simply no way to do that.

I've had a few '7730's crap out during tuning sessions on the dyno, all of them work fine however they won't communicate through the ALDL. I never found a fix, i just keep a spare '7730 with me and swap it into the customers car if needed.


We could use more info on your tuning guys setup.

 

I will give him a call tonight and get the details all that I know for sure is that he uses the latest version of tunerpro software.

 

Sounds like he was using an emulator such as an Ostrich or AutoProm.

RBob.

 

So if he was using an emulator then he can't tune thru the aldl? Sorry for my lack of knowledge on the subject. I just want this guy to be able to tune my car with no issues. Hes done third Gen cars of my friends with no issues using the same method but they where older than 1990. Does the 1990-1992 third gene have different methods of tuning? I would have thought he would have known this.

 

An emulator uses a separate cable/interface.

There is a device that can be used via the ALDL link. Can't recall the name. Guy here on TGO developed it. Can't recall his name either. Has RAM on board that holds the calibration portion of the PROM.

All of the stock 3rd gen ECMs use a PROM of some sort.

RBob.

 

the Ostrich emulator uses a regular USB cable, that's probably the most common tuning setup for the '7730.


He would have had a connection to the ALDL to log/view with tunerpro RT, then a USB cable to the emulator which takes the place of the stock Eprom to modify the tune. Typically people use this setup to completely tune the car, then they'll burn that file to an Eprom and put that in the car.


this is the Ostrich (2.0) http://www.moates.net/images/ostrich2/ost2_items.jpg

 

So here I was sitting in the dentist chair getting a tooth drilled, and I remembered. MonteCarSlow was the fellow that did the NVRAM board. Here are a couple of threads on it:

https://www.thirdgen.org/forums/diy-...ion-board.html
https://www.thirdgen.org/forums/diy-...730-727-a.html

Using ALDL mode 4 commands to update the RAM which holds the calibration.

RBob.

 

This is the exact method that the tuner used/uses. So what would cause the ecm to not make the changes that the tuner was commanding the ecm to do? Tunerpro RT software said aldl not connected. No changes could be made.

 

Please re-read what purple82ta posted. The changes to the calibration were not being done via the ALDL link.

RBob.

 

ok, so the changes are not thru the aldl connection, they go thru the emulator that is plug into the ecm where the prom goes. either way the ecm was not responding to the changes he was making on the laptop. what could cause this?

 

If he was indeed using an emulator, like the Ostrich 2.0, then he probably didn't disable checksum.

I've had a whole tuning session on a friend's car where I forgot about this until after and wondered why I had such a hard time. lol

 

What six said can cause these problems, That's an easy option to adjust. Also have him look at the "Upload full tables" option which i usually turn on. I'm assuming he knows his way around Tunerpro, there are other reasons this wouldn't work but those would be painfully obvious to someone who has done it a few times.



Think of it this way,

The Emulator makes the changes to the main program.

The ALDL (Assembly Line Diagnostic Link) gives you the feedback to see what those changes did in real time.



If the Emulator is running and the ALDL is linked then it's probably the most solid tuning setup out there. It blows away the stuff OBD2 guys deal with.