Another Mopar Off My Bucket List - Barracuda Fastback
My son took the Roadrunner out for a short test drive when he went to fill the tank up. It gave him a chance to get a feel for how the car was behaving prior to tearing into it. I felt guilty for not having spent more time troubleshooting before he got here but at least we've got room in the garage to work on it now.
Rather than try to figure out what was going on with the FAST timing control my son decided to pull the FAST distributor back out and replace it with the MSD that we'd run before and let the MSD equipment take over the duties.
Things get confusing when you're dealing with 3 sets of schematics. Of course there was the original wiring from the Roadrunner and it had been converted over to an electronic ignition instead of the points setup. Then there was the modifications made to wire in the MSD control box and distributor. Then we had further modified the wiring when we added the FAST fuel injection. And it got even more confusing when we switched to the FAST distributor and computer controlled timing. I need to document the way we've got the car wired now.
Pulling the FAST distributor out is a no-brainer. Wiring the MSD into a stock wired car is fairly simple too. But trying to reverse engineer this car away from the computer controls back to MSD had us scratching our heads. It's times like these that make me believe that a computer in the garage is essential.
We ran into problems when we removed the ignition signal from the MSD box that went to the FAST computer. Our first thought was that it was unnecessary if the FAST controller wasn't going to control ignition timing anymore. When we couldn't get the fuel pump to stay running or the injectors to fire we reread the manual and studied the schematics again. Without an ignition signal the FAST controller will not operate the pump or injectors. OK. We hooked a signal wire back to the ECU again. We were back in business.
After resetting the built in setup Wizard program for the fuel injection it was time to test drive again. Before dropping the billet distributor back in we had set it with what we'd hoped would be the correct springs and bushing to allow our advance to come in fully by 3200 RPM and give us an additional 28' from idle. We crossed our fingers and backed out of the garage.
Power sucked big time. - And it got worse the more we drove. Eventually it started popping and backfiring. After a few miles we limped it back home.
I was fairly confident that we had everything wired correctly. We decided to run a compression check. We did it dry and all of the cylinders read almost identical. 7 at 130ish and 1 at 125ish. Confident that our valve train was unlikely to have been the cause of our backfire and low power I re-installed the plugs and wires. That's when I noticed a badly burnt wire to #4 cylinder. My son had been working the passenger side and had not been careful enough when he routed the wiring when we made the distributor swap. I suspect that there may have been an issue with the order on that bank also.
After buttoning it back up we fired it up and I set the initial timing at 19' advanced. It purred like a kitten and there was no longer any sign of missing or backfiring. Throttle response seemed good in the garage but we didn't have a load on it yet. As much as I'd have liked to have taken it out for another test run it was getting late and we decided not to piss of the neighbors. (That's why I want to get moved back out to the farm. - The cattle never complain.)
Tomorrow's another day. We'll take it out then and find out if we were successful.
Our Lady of Speed, Pray for Us!
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My son took the Roadrunner out for a short test drive when he went to fill the tank up. It gave him a chance to get a feel for how the car was behaving prior to tearing into it. I felt guilty for not having spent more time troubleshooting before he got here but at least we've got room in the garage to work on it now.
Rather than try to figure out what was going on with the FAST timing control my son decided to pull the FAST distributor back out and replace it with the MSD that we'd run before and let the MSD equipment take over the duties.
Things get confusing when you're dealing with 3 sets of schematics. Of course there was the original wiring from the Roadrunner and it had been converted over to an electronic ignition instead of the points setup. Then there was the modifications made to wire in the MSD control box and distributor. Then we had further modified the wiring when we added the FAST fuel injection. And it got even more confusing when we switched to the FAST distributor and computer controlled timing. I need to document the way we've got the car wired now.
Pulling the FAST distributor out is a no-brainer. Wiring the MSD into a stock wired car is fairly simple too. But trying to reverse engineer this car away from the computer controls back to MSD had us scratching our heads. It's times like these that make me believe that a computer in the garage is essential.
We ran into problems when we removed the ignition signal from the MSD box that went to the FAST computer. Our first thought was that it was unnecessary if the FAST controller wasn't going to control ignition timing anymore. When we couldn't get the fuel pump to stay running or the injectors to fire we reread the manual and studied the schematics again. Without an ignition signal the FAST controller will not operate the pump or injectors. OK. We hooked a signal wire back to the ECU again. We were back in business.
After resetting the built in setup Wizard program for the fuel injection it was time to test drive again. Before dropping the billet distributor back in we had set it with what we'd hoped would be the correct springs and bushing to allow our advance to come in fully by 3200 RPM and give us an additional 28' from idle. We crossed our fingers and backed out of the garage.
Power sucked big time. - And it got worse the more we drove. Eventually it started popping and backfiring. After a few miles we limped it back home.
I was fairly confident that we had everything wired correctly. We decided to run a compression check. We did it dry and all of the cylinders read almost identical. 7 at 130ish and 1 at 125ish. Confident that our valve train was unlikely to have been the cause of our backfire and low power I re-installed the plugs and wires. That's when I noticed a badly burnt wire to #4 cylinder. My son had been working the passenger side and had not been careful enough when he routed the wiring when we made the distributor swap. I suspect that there may have been an issue with the order on that bank also.
After buttoning it back up we fired it up and I set the initial timing at 19' advanced. It purred like a kitten and there was no longer any sign of missing or backfiring. Throttle response seemed good in the garage but we didn't have a load on it yet. As much as I'd have liked to have taken it out for another test run it was getting late and we decided not to piss of the neighbors. (That's why I want to get moved back out to the farm. - The cattle never complain.)
Tomorrow's another day. We'll take it out then and find out if we were successful.
Our Lady of Speed, Pray for Us!
View attachment IMG_4889.jpg
View attachment IMG_4890.jpg
View attachment IMG_4891.jpg
View attachment IMG_4892.jpg
View attachment IMG_4893.jpg