Mechanics

ENGINE STARTS, RUNS 1 SEC, THEN INJECTOR

1990 Dodge Dynasty

Computer problem
1990 Dodge Dynasty 6 cyl Front Wheel Drive Automatic 48000 miles

When started, engine (3.3 V6) dies after running 1-2 seconds. If I use some starting fluid or pour some gas in the intake, the engine will run for 3 or 4 seconds. I don't get any useful codes from the check engine light, only a " 55", which is " end of message". When I use starting fluid or pour gas in the intake, I have monitored the injectors with a noid light and I can see the injectors quit firing after 1-2 seconds, but spark firing continues as the engine runs for 3 or 4 seconds as the engine burns off the starting fluid or poured-in gas. Therefore, it seems the loss of injector signal is causing the engine to die. What faulty sensors would cause the engine control module to terminate the injector signal but still allow the spark signal to continue? Fuel pressure at the rail is ok and engine vacuum appears ok during the short run period. I have bypassed the Auto Shutdown relay and the problem is the same. This LE model does not appear to have the Anti-theft system.
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Kenwld
July 24, 2009.




Sir-dunno if the crankshaft position sensor is being use to tell the computer to snchronize the injectors or an ignition reference signals-won't hurt to check. Further could be a problem with the injector drivers.

Fuel pressure at the rail is ok

When you checked the fuel pressure what was the pressure readings?

Tiny
Rasmataz
Jul 24, 2009.
1.) Re crankshaft position sensor: if this signal is absent, wouldn't I expect to get a fault code 11 (no crank sensor signal detected during cranking) from the SBEC (computer)?

2.) Are the injector drivers part of the SBEC? I inspected the factory manual wiring diagram and I don't see any external driver module between the SBEC injector output and the input to the injector.

3.) Fuel pressure readings were between 44-51 psi at the rail, but fuel pressure is not useful if the injectors quit firing.
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Tiny
Kenwld
Jul 25, 2009.
Don't always think just bcuz it didn't pop a code there's shoudn't be no problem with that particular sensor.

2.) Are the injector drivers part of the SBEC?

Yes its built into the SBEC, I've recheck it -it does have a camshaft and crankshaft sensor test this sensors- If these sensors are okay -and dark green and black wire at the injector harness connector has power that's coming from the ASD relay -You need to replace the SBEC

Tiny
Rasmataz
Jul 25, 2009.
The system is in anti-theft mode when it stalls after one to two seconds. A voltage spike confuses either the Body Controller or the Engine Computer into self-programming itself to think it's on a car with the factory anti-theft system. Either computer will then tell the other one (incorrectly) that it is on a car equipped with anti-theft. The second computer then does the same thing to itself. This programming can not be undone. You will have to replace both computers at the same time with units from a car that did not have anti-theft, or two rebuilt units from the dealer.

Most salvage yards don't inventory their computers according to manufacturer-installed features, only by part number. You must specify a Body Computer and Engine Computer from the same vehicle, and install both of them at the same time, before you turn on the ignition switch. If the engine runs, you're done. If it does the same thing, return them and try a pair from another car. Remember, if any one computer has anti-theft programming in it, it will teach it to the other one. From then on, those computers will only work in a car with anti-theft built in because it needs the disarm signal from the remote key fob or door switches to allow the injectors to fire.

This happened once to a Dynasty when I worked at the dealership in the 90s, and it happened to a '94 Intrepid donated to my community college by Chrysler. My stubborn tool room attendant refused to believe that both computers had to be replaced at the same time, and to save tax payer dollars, we wanted to find salvage yard parts. It took two years before we found a pair of modules without the anti-theft programming, (we weren't trying real hard), and could use the car again. We deserve part of the blame for that one because we make the students remove the battery every day after we use the car for experimentation. The sparking at the battery cables is believed to cause a lot of spikes that lead to this problem.

The advantage of this characteristic, if you can call it that, is that there don't need to be different part numbers for these computers depending on anti-theft vs. Non-anti-theft cars. You just stick it in and the self-programming will take care of itself from the other computer. Of course, if the new computer doesn't solve the problem you're working on and you take it off the car, that computer could be programmed now to the anti-theft system and could teach that to the computer on the next car it's installed on.

Caradiodoc

Caradiodoc
Aug 8, 2009.

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