gonna try to keep keep this short;

bought ram jet 350 crate motor, pulled the cam and heads, installed LT4 HOT Cam and fast burn aluminum heads. The car was originally a MAF car, but i switched it over to a SD 7730 setup.
Im using all the ram jet sensors with the 7730 wiring and ecm. Ed wright burned me a custom chip for this motor.

Now the problems; It acts like its running rich....black smoke, fouled spark plugs, etc. However after messing with it today with a friend (JMatlock88) we found that the car would idle better with the MAP sensor unplugged (WTF!!!).....also we setting the timing with the connector unplugged at 8* BTDC, when you plug the connector back in the timing doesnt jump up like it should. With the connector plugged in, it seems like the timing should be at least 30 something degrees, well it stays at 8. I dont think the calibration in the chip is too rich...i think its some kind of ignition problem linked to a short in the 91 harness....anyone have any ideas?

Im all out of ideas and i need some outside help....any help would be greatly appreciated.

BTW, for some reason, i cant retrieve codes from the ALDL port....the SES light is "steady on", no blinking.

 

Just a guess, but it sounds like the ECM is not getting the DRP (distrib ref pulse) from the ignition module. You should be using the 7-pin from a '91 AFAIK - you might check that, & make sure the pins are all making correct contact. HTH

 

I dunno. A code 12 means no ref pulses, so if that were the case, the injectors would never fire and you'd get at least the code 12. There may be something wrong with your harness, since I know you've been fighting that sumbitch for, what, a year now? If you started to get desperate you could try a good harness and ECM and plug it into your motor just for testing purposes. I see you're in Stillwater. I'm gonna be going through that area sometime in the near future. If you're still having problems by then, or even for craps and cackles I'll bring along a spare harness and ECM and we can give that a shot. I'd love to check out your and JMatlock's cars. My StealthRam is still on the living room floor where it's going to be for a while so there won't be much to see in the engine compartment as far as my car, but hey, it's still a hoot.

As far as the MAP sensor, have you tried pinching off the vac line to it, not just unplugging it?

It's gotta be something ECM or wiring related..

 

Just to let you know.....before JMatlock88 got his custom ed wright chip done, we took my 7730 and my ed wright chip and put it in his car and it ran way better than his stock chip....so we know my ECM is fine and my chip is probably fine too....at least good enough to run....we are question the harness i got from a local Fbody salvage yard while i was doing the 165/7730 swap.

 

oh yeah....by the way, i am not getting a code 12......when you try to run the codes, it doesnt even flash 12....it just stays steady, no blinking. Thats weird....thats one reasone we are questioning the harness....also the module in the distributor as mentioned above. I hope to have my hands on a scan tool this weekend, maybe that will shed some light on things, ill keep you posted and thanks for the help.

 

I just wanted to add that we did test the tan w/ white stripe wire for continuity from the distributor to the ECM. We also tested the SES light's ground at the ecm, and it does have a complete circuit as well. Was there a different module that came in the ramjet distributors? I have an extra working TPI distrib we can throw in there to find that out I guess. The distribs look the same externally and all the plugs match. Also we should measure the resistance on the reference pulse wire to see if it is causing a significant voltage drop in the signal to the ecm. Other than these couple things, I'm lost at what it could be.

 

I take that as a no....

 

Sorry, Jza... there is no vaccum hose on a ramjet map sensor. It bolts directly to the manifold and reads from an external passage that is cast into the manifold. It does; however, have the same voltage output specs as the TPI MAP. It is just spliced into Joey's '91 harness.

Edit: Jza, we could remove the map sensor from the manifold and plug the passage. This way it would read 0psig. Would this aid your diagnosis?

 

More guessing from me:

Ah, I've never seen the RamJet tech manual - but it uses a far different ECM (stock) than the 730. Could there be a mis-match on the EST line to the RJ module?

AFAIK, the 730 ECM & module use no EST signal below ~400 rpm; then the ECM starts to send a PWM(?) signal to the module to control timing & dwell. Maybe the RamJet module is looking for a different EST signal entirely?

Have you tried just plugging the '91 module in to see if it helps? (Also, some have reported the +/- reluctor pickups are reversed on some types of GM modules - that doesn't sound like it's an issue here, but it's something to remember for later.)

HTH