Ok guys, I have been looking for help with my issue on another forum, but most of the guys there have the 94+ F-bodies with the reprogrammable computer. My 93 Z28 has a PROM chip so I think this is a better place to look for help. I recently did an auto to T56 swap, swapped in the CORRECT PROM for the 6-speed and now the ECM does not have an idle value set according to the Data Master log file. I bought this PROM from another member of that forum, and he said that he drove the car home the month before and had zero issues with it. Any chance that something could have happened to the PROM chip while he was removed it from the car or while it was shipped? The PROM was still in the ECM and the harness connected. Just looking for any help to figure out when this could have gotten damaged and if I need to throw the PROM out and get another.

Thanks!
Jordan

 

Does it with the auto PROM?

Are there drivability issues now?

 

what is the bcc of the memcal ?

 

jmd, there are no issues with the AUTO PROM. I also have the ECM from the 6-speed car and no matter the combination of ECM's and PROM's, the AUTO PROM works great, the 6-speed has the idle issue. I KNOW the problem is the 6-speed PROM. Now I am trying to determine if the PROM was bad before I got it, and/or if there is anything else that I can do with the PROM to make it work.

tunedperformanc, the bcc of the 6-speed PROM is BDLD. The bcc of the AUTO PROM is BDZL.

 

you can try BAFL, I will look and see if I have the BDLD to send to you for a compare.

http://www.gearhead-efi.com/Fuel-Inj...light=16159278

 

just looked I just have a bdzk and bdzl and a hypertech automatic.

 

tunedperformanc, thanks for checking on the PROM chips.

So at this point my question is should I be ditching this BDLD PROM chip that I have and getting another? Or is there any way to restore all of the data to this chip since the programming is incomplete?

 

You might be able to restore the eprom but you would need to do a read on the bdld and do a compare to a known good bdld .bin The other choice would be to get a piggyback adapter like the moates.net g1 and run a BafL. Do you have the means of burning ?

 

Are the BDLD and BAFL the same? I know the BAFL is the Corvette version. I also do not have any means of burning now, but have considered it so that I can make adjustments as I build the car.

 

I don't have the Bdld to do the compare on. I would assume the vette one might have a little more timing and slight changes to the Ve. If you wanting to save a little bit you can unsolder the bdld and solder in a moates d2 and then you would be able to install a sst flash eprom onto the memcal. The old eprom is more than likely a uv erasable one with can be reprogramed but not many people have the means to do so.

 

Let me ask you this. What is my CHEAPEST option for being able to modify/write my own chips, and then what is the BEST option for being able to reprogram chips assuming that I will need to occasionally make changes as I upgrade and tweak the motor, exhaust, gears, wheels/tires, etc?

 

the cheapest would be to modify the memcal with the moates.net d2 and use a sst 27sf512 flash eprom and a hdr1. you can purchase the moates.net burn 2 or put a ad in the classifieds here for a burn 1 or burn 2. You can use tuner pro software.

 

Is the car trying to die at idle?

 

Yes, the car is trying to die at idle. It is DEFINITELY not trying to idle properly without the idle parameter.

 

I'd like some clarification of this "idle parameter" that is missing. Target idle RPM, IAC position. what exactly?

Have you driven the car yet? Some SD systems need to be driven for the idle speed to actually set. I don't know why, I haven't figured out why, just know that some of my SD cars have needed to be driven, after disconnecting the battery.

 

Let me see if I can offer more clarification through a Data Master data log. I uploaded a data log from before the T56 swap and then after. Those logs can be found at:

https://docs.google.com/open?id=0B7x...2ZlaVJ6dGFPLXc
https://docs.google.com/open?id=0B7x...zYtTW4td3RSRjQ

Do you have Data Master or other program to be able to view that .uni file? I have very limited experience with data logs and what values to expect, so any help would be great!

 

No, I don't use datamaster, I use Tuner Pro.

I'm just trying to figure out what the missing "idle parameter" is.

 

One of the vets over on CamaroZ28.com, Injuneer, read the data log and responded on that forum with the following:

Since the swap, it's idling way too low. Are you sure you have the right PROM? There is no "target" idle speed shown in the data log. It is "0" so the ECM has closed down the IAC valve to "0" and I would assume the engine is idling (at 425 - 500 RPM) on whatever air can get past the closed throttle blades and the PCV system. The program appears to be incomplete. The spark advance is only 14*. I have never seen an LT1 idle that low, so I don't know if that is the normal advance pulled off the stock program table at such low RPM, or another programing problem. Stock T56 programming is 800 RPM fully warmed up.

The A4 log shows the correct 650RPM target idle speed, and the IAC valve is opening to 20 counts to hold the idle there. The spark advance is 25*, which would appear normal.

With the engine idling that low, and unable to adjust the idle speed using the IAC valve, it's going to feel a lot rougher, and RPM will be moving around a lot more.

 

Below is a screen shot of the log from Data Master. I circled the idle value on that image.

 

does the BDZL show this in a log ? should both be $DA3 definition's. no code 51 ?

 

Here is a screen shot from the BDZL PROM. The idle is fixed at 650 through the entire data log. I flipped through the BDLD PROM data log and did not see a code 51 DTC!

 

have you tried disconnecting the ecm [A21] Trans Position Switch O/B

 

The Orn/Blk wire needs to be grounded in "Park" and ungrounded in "Drive" for a automatic but disconnected for a manual transmission.

 

The wire at A21 is listed as "PNP SIGNAL" in my 93 Service Manual. I have not tired disconnecting that wire yet, but what exactly does that wire do on the automatic that is a problem for the manual??

 

Guys, just wanted to update that I pulled the A21 pin from the ECM and the car idles PERFECTLY!! Thanks for all of the help!!

 

Hey six shooter I see that you were posting on this thread and are online now. You seem to know a little bout ECM's was wondering if you could shoot me some info on how to troubleshoot my Ecm just bought a vats bypass module and its not working. want to check the ecm.

 

please start your own thread and do not hijack ! , depending on the ecm a would determine if you need a 30hz or 50Hz frequency sent to the ecm vats signal input. you can measure this with a good multimeter I use a fluke 78.