Bad Injectors, ECU, Grounds?
11-06-2014, 05:44 AM
#1
Safety Car
Thread Starter
Bad Injectors, ECU, Grounds?
From what I am reading on "batch" fire fuel injection, the TPI fires 4 injectors at a time. In our case its left bank, right bank. My car is running horribly and I am smelling intense fuel smells from the exhaust. Either the car is dumping too much fuel or it isnt burning it all up when its injected.
I just replaced the ignition coil because it ate up two pick up coils and finally bought a new distributor because I used up the only two pick up coils in town. The car ran a lot better but has been going down hill and now is barely running. You can feel that its skipping badly and shuddering, occasionally, like a half second, of running right.
I pulled the plugs out and I have ALL the plugs on the right bank are sooted up and wet with fuel. Left bank is the picture perfect light tan color of correct burn.
What the hell is making HALF my car run right and the other half screwed up??? Do I have bad injectors? Bad ground on one side? Bad ECU or ECU connections? I am at my wits end with this car.
HELP!!!
I just replaced the ignition coil because it ate up two pick up coils and finally bought a new distributor because I used up the only two pick up coils in town. The car ran a lot better but has been going down hill and now is barely running. You can feel that its skipping badly and shuddering, occasionally, like a half second, of running right.
I pulled the plugs out and I have ALL the plugs on the right bank are sooted up and wet with fuel. Left bank is the picture perfect light tan color of correct burn.
What the hell is making HALF my car run right and the other half screwed up??? Do I have bad injectors? Bad ground on one side? Bad ECU or ECU connections? I am at my wits end with this car.
HELP!!!
11-06-2014, 09:03 AM
#2
Team Owner
Check spark and fuel.
Check fuel pressure and see what it does after engine is shut off. Will it hold and for how long?
How are the plug wires? When run in a dark garage and a fine mist of water is sprayed around them, is there any leak? The side that is bad, is the spark quality good as in a blue flame? How is the cap and rotor?
Are there any vacuum leaks?
Check fuel pressure and see what it does after engine is shut off. Will it hold and for how long?
How are the plug wires? When run in a dark garage and a fine mist of water is sprayed around them, is there any leak? The side that is bad, is the spark quality good as in a blue flame? How is the cap and rotor?
Are there any vacuum leaks?
11-06-2014, 09:12 AM
#3
From what I am reading on "batch" fire fuel injection, the TPI fires 4 injectors at a time. In our case its left bank, right bank. My car is running horribly and I am smelling intense fuel smells from the exhaust. Either the car is dumping too much fuel or it isnt burning it all up when its injected.
I just replaced the ignition coil because it ate up two pick up coils and finally bought a new distributor because I used up the only two pick up coils in town. The car ran a lot better but has been going down hill and now is barely running. You can feel that its skipping badly and shuddering, occasionally, like a half second, of running right.
I pulled the plugs out and I have ALL the plugs on the right bank are sooted up and wet with fuel. Left bank is the picture perfect light tan color of correct burn.
What the hell is making HALF my car run right and the other half screwed up??? Do I have bad injectors? Bad ground on one side? Bad ECU or ECU connections? I am at my wits end with this car.
HELP!!!
I just replaced the ignition coil because it ate up two pick up coils and finally bought a new distributor because I used up the only two pick up coils in town. The car ran a lot better but has been going down hill and now is barely running. You can feel that its skipping badly and shuddering, occasionally, like a half second, of running right.
I pulled the plugs out and I have ALL the plugs on the right bank are sooted up and wet with fuel. Left bank is the picture perfect light tan color of correct burn.
What the hell is making HALF my car run right and the other half screwed up??? Do I have bad injectors? Bad ground on one side? Bad ECU or ECU connections? I am at my wits end with this car.
HELP!!!
11-06-2014, 10:11 AM
#4
as in it is shorted out, not functioning, and therefore not burning any fuel and therefore dumping it in unburned? possible cause for OP smelling fuel and rich condition?
(just trying to learn the cause/effects.)
cheers. VikingTrad3r
11-06-2014, 10:43 AM
#5
Melting Slicks
A shorted wire to any of the injectors or their ground lead wire will keep them open, (squirting) whenever power is applied via the fuse. That's why an early check of the system holding fuel pressure is important. In this case, I'd want to know the FP with key ON, with and without the affected side's injector fuse removed. There are Injector 1 and Inj. 2 fuses my car.
If the pressure falls or reads low with the key off, the injector(s) is(are) leaky; key on, one or more are triggered open. It trakes a while for the odor to dissipate, but confirms the leak you already know about.
I'd 'pinched' a wire between the manifold and rail when reinstalling my injector rails, causing a short; rather easy to do with the SuperRam and the tight spaces. However, I got to chase it some and learn before figuring it out. The system is rather simple but finding the problem is a painstaking process.
Not being expert on this, one injector's short is shorting the rest, I doubt it is the case, but unplugging one at a time, would surely tell. Likely, resistance or FP checks would tell w/o the engine running. The ECM grounds each bank to 'fire' (pulse, open) the injectors, so it really looks as if there is another, permanent ground overriding that ECM signal.
Is there a chance that the repeat coil failures are related; maybe another wire rounded in that circuit?
If the pressure falls or reads low with the key off, the injector(s) is(are) leaky; key on, one or more are triggered open. It trakes a while for the odor to dissipate, but confirms the leak you already know about.
I'd 'pinched' a wire between the manifold and rail when reinstalling my injector rails, causing a short; rather easy to do with the SuperRam and the tight spaces. However, I got to chase it some and learn before figuring it out. The system is rather simple but finding the problem is a painstaking process.
Not being expert on this, one injector's short is shorting the rest, I doubt it is the case, but unplugging one at a time, would surely tell. Likely, resistance or FP checks would tell w/o the engine running. The ECM grounds each bank to 'fire' (pulse, open) the injectors, so it really looks as if there is another, permanent ground overriding that ECM signal.
Is there a chance that the repeat coil failures are related; maybe another wire rounded in that circuit?
11-07-2014, 12:00 AM
#6
Race Director
What year is the car? Makes a big difference.
I'm not sure when it changed (sometime in the LT1 era), but all L98s that I know of fire all 8 injectors at the same time. I know for sure that all '86 to '89 Corvettes fire all 8 at the same time (same 1227165 ECM). If one bank is not firing then it's probably either a bad fuse (check INJ1 and INJ2) or a problem in the wiring.
One way to check for a bad fuse is to unplug one of the injector connectors on each bank and measure the voltage at the connector. It should be 12 volts on both pins. If you have that then the fuses are good.
You can check that the ECM is firing the injectors with a noid light:
I'm not sure when it changed (sometime in the LT1 era), but all L98s that I know of fire all 8 injectors at the same time. I know for sure that all '86 to '89 Corvettes fire all 8 at the same time (same 1227165 ECM). If one bank is not firing then it's probably either a bad fuse (check INJ1 and INJ2) or a problem in the wiring.
One way to check for a bad fuse is to unplug one of the injector connectors on each bank and measure the voltage at the connector. It should be 12 volts on both pins. If you have that then the fuses are good.
You can check that the ECM is firing the injectors with a noid light:
