Real beginner with a Ramjet 502 in a 69 SS Chevelle

Discuss General Motors (GMC, Chevy, Pontiac, Hummer, Cadillac, etc) tuning topics here. Request definitions, discuss parameters, etc.

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NOT2SLO
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Real beginner with a Ramjet 502 in a 69 SS Chevelle

Post by NOT2SLO » Thu Dec 19, 2013 1:54 pm

I'm really over my head here. I dropped in a 502 crate and am trying to DIY troubleshoot this beast on the cheap. I'm hoping someone here could point me in the right direction. I have the Codemate, but am looking to try this very cool TunerPro.

Where do I go to get the least expensive cable (10 pin to USB). According to the GM parts list I have a MEFI-3. Could I make my own? If so, where do I get the parts and schematic.

Thanks in advance

Bill

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Mangus
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Post by Mangus » Thu Dec 19, 2013 9:30 pm

Hi Bill,

Check out obd2allinone.com for the MEFI cable and definitions that you'll need. They're good people.

M
Last edited by Mangus on Fri Dec 20, 2013 9:31 am, edited 1 time in total.
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cbernhardt
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Joined: Fri Apr 18, 2008 5:19 am

Re: Real beginner with a Ramjet 502 in a 69 SS Chevelle

Post by cbernhardt » Fri Dec 20, 2013 5:26 am

NOT2SLO wrote:I'm really over my head here. I dropped in a 502 crate and am trying to DIY troubleshoot this beast on the cheap. I'm hoping someone here could point me in the right direction. I have the Codemate, but am looking to try this very cool TunerPro.

Where do I go to get the least expensive cable (10 pin to USB). According to the GM parts list I have a MEFI-3. Could I make my own? If so, where do I get the parts and schematic.

Thanks in advance

Bill
I believe the website is obd2allinone.com.

I have the MEFI Scan and Tune package from this company (OBD Diagnostics) and it works great. Unless they have changed things their software uses the (older) ScannerPro and TunerPro individual programs, not TunerPro 4 or 5. To actually modify the tune in your RamJet MEFI3 computer, you will also need their MEFI Burn program. The MEFI Burn program will not work without their USB cable (software security device).
If all you want is to scan the engine, they do offer a relatively inexpensive scan program which includes definition files for ScannerPro and a USB cable.

Charles

NOT2SLO
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Post by NOT2SLO » Fri Dec 20, 2013 12:36 pm

Thank you all for your suggestions

NOT2SLO
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Joined: Thu Dec 19, 2013 1:28 pm

Post by NOT2SLO » Sun Jul 26, 2015 1:42 pm

OK I purchased the ScannerPro software and cable from the very nice OBD Diagnostics folks. When I tried to connect, I get SEND COMMAND FAILURE (0x00000006) error. Per OBD tech support, I checked my preferences and port connections using the Hyperterminal on their disk... (very nice to supply that).... All OK. It seems that there is simply no data being generated by my MEFI4a (originally I thought I had the 502 ramjet with a MEFI3)

So I can't connect... any suggestions?

Again thanks in advance

Bill

cbernhardt
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Post by cbernhardt » Mon Jul 27, 2015 1:56 am

NOT2SLO wrote:OK I purchased the ScannerPro software and cable from the very nice OBD Diagnostics folks. When I tried to connect, I get SEND COMMAND FAILURE (0x00000006) error. Per OBD tech support, I checked my preferences and port connections using the Hyperterminal on their disk... (very nice to supply that).... All OK. It seems that there is simply no data being generated by my MEFI4a (originally I thought I had the 502 ramjet with a MEFI3)
So I can't connect... any suggestions?
Again thanks in advance
Bill
The older RamJets had the MEFI3 controller, but there was an upgrade kit that had the MEFI4a. Does your engine have an O2 sensor? If so it is most likely an MEFI4a. If you recently purchased your RamJet 502 it should be the MEFI4a unless it has been sitting in a warehouse for a few years.

Check the serial number on the MEFI controller and compare it to the numbers listed on the MEFIBurn website (mefiburn.com). The serial number is on a paper tag on the underside of the controller.

Charles

NOT2SLO
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Post by NOT2SLO » Mon Jul 27, 2015 5:00 am

JEGS sold me the 12499121 engine back in '08 which has the O2 sensors and TPC. The model number of the MEFI is on its bottom and taking that off is something I wish to avoid. And yes its been sitting around for many years.

cbernhardt
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Post by cbernhardt » Wed Jul 29, 2015 2:36 am

NOT2SLO wrote:JEGS sold me the 12499121 engine back in '08 which has the O2 sensors and TPC. The model number of the MEFI is on its bottom and taking that off is something I wish to avoid. And yes its been sitting around for many years.
What is "TPC"?

The MEFI3 and MEFI4a controllers look identical, so there is no way to tell for certain which one you have just by looking at the top.

You should have received a manual with your engine. The manual is a thick paperback book, about 100 pages.

You should have also received a DTC (Diagnostic Trouble Code) tool that you can plug into the harness connector and read trouble codes. That will tell you if the MEFI controller is communicating.

Are you using the OBD USB cable?
What operating system are you running on the computer that you have connected to the RamJet? If you are running Windows 7 or 8, try running the program in compatibility mode. Might also try a Windows XP computer if you can find one.

That's all I can think of. If Bob at OBD Diagnostics can't figure out your problem, you might be in serious trouble.

Where are you located?

Charles

NOT2SLO
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Post by NOT2SLO » Wed Jul 29, 2015 4:45 am

OOPS... I should have said TP; throttle position sensor instead of TPC.

Anyway, all documentation I have points to a mefi4a. My 250 page manual is overwhelming. :shock:

The Rinda Tech Codereader works fine. Per a discussion I had with the nice folks at Rinda, the Codereader LED is driven directly by the mefi. The Codereader is NOT connected to the mefi serial data port (J2-10 per page 66 of the manual).

All the folks at OBD tried to help, but no luck. I'm running W7-64. I will just have to take it down to a local marine shop who has the super Rinda Diacom setup.

Thanks again

Bill

cbernhardt
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Post by cbernhardt » Wed Jul 29, 2015 9:03 am

NOT2SLO wrote:OOPS... I should have said TP; throttle position sensor instead of TPC.

Anyway, all documentation I have points to a mefi4a. My 250 page manual is overwhelming. :shock:

The Rinda Tech Codereader works fine. Per a discussion I had with the nice folks at Rinda, the Codereader LED is driven directly by the mefi. The Codereader is NOT connected to the mefi serial data port (J2-10 per page 66 of the manual).

All the folks at OBD tried to help, but no luck. I'm running W7-64. I will just have to take it down to a local marine shop who has the super Rinda Diacom setup.
Thanks again
Bill
The Rhinda Codemate MEFI Codereader does connect to the MEFI data port, at least the one I used several years ago did. The Codemate is basically the same as the GM DTC tool which should have been furnished with your engine.

The Rhinda scan tool also connects to the same port, but it is not nearly as easy to use as ScannerPro.

Anyway, good luck.
Charles

NOT2SLO
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Post by NOT2SLO » Wed Jul 29, 2015 9:33 am

There are several wires from the mefi to the DLC. According to the folks at Rinda, the codereader LED is driven directly by the mefi through pin E. The Serial Data Port goes through pin G.

cbernhardt
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Post by cbernhardt » Sat Aug 01, 2015 2:36 am

NOT2SLO wrote:There are several wires from the mefi to the DLC. According to the folks at Rinda, the codereader LED is driven directly by the mefi through pin E. The Serial Data Port goes through pin G.
You are correct. The GM DTC code reader (and probably also the Rhinda code reader) has 4 pins in the connector while the MEFIBurn cable has only 2. They all use the same physical connector.

If you are going to be tuning your engine, and you probably will since almost all RamJets run very rich, my suggestion is that you find yourself a laptop with Windows XP.

Charles

NOT2SLO
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Post by NOT2SLO » Sat Aug 01, 2015 12:08 pm

Hi Charles,

I found an old XP laptop (Dell Inspiron 8100) and gave it a try... no go... still same SEND COMMAND FAILURE (0x00000006) error notice. I tried 2400, 9600 and 19200 bauds... all on port 4.

Thanks again,

Bill

cbernhardt
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Post by cbernhardt » Sat Aug 01, 2015 3:17 pm

NOT2SLO wrote:Hi Charles,

I found an old XP laptop (Dell Inspiron 8100) and gave it a try... no go... still same SEND COMMAND FAILURE (0x00000006) error notice. I tried 2400, 9600 and 19200 bauds... all on port 4.
Thanks again,
Bill
Well, I have a Dell Inspiron 8000 with XP that I use with the OBD software package – TunerPro, ScannerPro, and MEFIBurn.

You may have gone through his with OBD, but try this:
1. With the OBD cable unplugged (I am assuming that you have the USB cable) open Device Manager.
2. Plug in the USB cable.
3. In Device Manager under Ports (COM & LPT) you should see an additional COM port added , should be something like USB Serial Port (COM4).
4. Also in Device Manager under Universal Serial Bus Controllers you should see an additional USB port added , should be something like USB Serial Converter.
5. Unplugging the USB cable should remove both and plugging in back in should add them again
In ScannerPro, under File, Preferences, COM setup make sure that the COM port is the same as that shown in Device Manager.

On my computer under Device Manager I have the COM4 setup as follows:
9600 baud, 8 data bits, Parity-None, Stop Bits- 1, Flow control-None.

Under the USB Serial Converter Properties I have:
General Tab – Location=0 (OBD Diagnostics MEFI)
Advanced Tab – Load VCP is checked

I can reproduce the SEND COMMAND FAILURE (0x00000006) error by not having the cable connected to the MEFI harness connector. Check the pins in the MEFI connector on the RamJet harness, perhaps one of them is bent.

Charles

NOT2SLO
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Post by NOT2SLO » Sat Aug 01, 2015 5:06 pm

Thanks Charles,

I did a continuity test on everything, but the GM Performance people did suggest an additional test of doing a voltage drop test on the wires to verify a good connection. I'll do that then I'll get back to you.

Bill

NOT2SLO
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Post by NOT2SLO » Thu Aug 06, 2015 11:57 am

!!!!! Problem Solved !!!!!

It turns out that the USB plug has some "issues". Bob at OBD Diagnostics was again very helpful and after all of his remote checks to make sure I installed everything OK, he asked me to squeeze the USB plug where it plugs into my computer... and Ta-Daaa, I was able to read my engine.... with a whopping 5.042 hours of total run time. Now I have way more engine info than I will ever understand. :wink:

Since everything is still under warranty, I returned the cable for a new one.

Thanks for all your help here on this forum.

Bill

cbernhardt
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Joined: Fri Apr 18, 2008 5:19 am

Post by cbernhardt » Fri Aug 07, 2015 2:18 am

NOT2SLO wrote:!!!!! Problem Solved !!!!!

It turns out that the USB plug has some "issues". Bob at OBD Diagnostics was again very helpful and after all of his remote checks to make sure I installed everything OK, he asked me to squeeze the USB plug where it plugs into my computer... and Ta-Daaa, I was able to read my engine.... with a whopping 5.042 hours of total run time. Now I have way more engine info than I will ever understand. :wink:

Since everything is still under warranty, I returned the cable for a new one.

Thanks for all your help here on this forum.

Bill
Glad to hear you got things working. Always look for the simple stuff first.
Charles

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