1984 Corvette CFI inj spray pattern problem
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1984 Corvette CFI inj spray pattern problem
Hi
I am new here but have been on many other forums throughout the years. A friend on the corvetteforum suggested I try here with some questions regarding my 1984 Corvette. Of course it has CFI and is a pain at times but I am close to getting on the road. After replacing all of the engine management sensors, rebuilding the TB's, balancing, renewed throttle shafts, stock ignition system but new parts, coil, wires, ignition control module, fuel pressure is 13 psi, new injectors, no vacuum leaks. I have it running pretty good. Except for one thing, idling.
When warm after the fan comes on, the idle gets rough, not terrible but like a mixture problem. I have replaced the temp sensor, twice, which seems to be the first thing asked about. Anyway, what I see is a nice cone spray from both injectors. Next I watch it with my timing light, freezing the image as it flashes. Mostly I get a nice view of the droplets suspended and it runs good. But at least 4 or 5 times in about a 10 second period, I see a, what I call a wave of fuel suspended in that light. It actually continues at idle continuously. 10 seconds is a reference point.
The wave seems to be about a 1/16 of an inch wide. I makes a complete circle in the cone of fuel and when it does, the engine stumbles. I would appear at that time to be getting an extra bit of fuel and the engine stumbles. Then it corrects smooth until that next wave of fuel comes out. Both injectors show the same thing.
I am trying to understand why this is happening. Someone suggested a Snap-on MT 2500 scanner to check this. I see some on ebay but they can be for several types of cars and years. What I am looking for it for something to show the pulse of the injectors. See if it is a ECM or PROM glitch that is causeing this. If the scanner can be used, I am not sure what type adapters I should be looking for and just where it plugs into! Has anyone had any experience with this type scanner? Would it show what I am looking for?
Anyone?
Thanks
Russ
I am new here but have been on many other forums throughout the years. A friend on the corvetteforum suggested I try here with some questions regarding my 1984 Corvette. Of course it has CFI and is a pain at times but I am close to getting on the road. After replacing all of the engine management sensors, rebuilding the TB's, balancing, renewed throttle shafts, stock ignition system but new parts, coil, wires, ignition control module, fuel pressure is 13 psi, new injectors, no vacuum leaks. I have it running pretty good. Except for one thing, idling.
When warm after the fan comes on, the idle gets rough, not terrible but like a mixture problem. I have replaced the temp sensor, twice, which seems to be the first thing asked about. Anyway, what I see is a nice cone spray from both injectors. Next I watch it with my timing light, freezing the image as it flashes. Mostly I get a nice view of the droplets suspended and it runs good. But at least 4 or 5 times in about a 10 second period, I see a, what I call a wave of fuel suspended in that light. It actually continues at idle continuously. 10 seconds is a reference point.
The wave seems to be about a 1/16 of an inch wide. I makes a complete circle in the cone of fuel and when it does, the engine stumbles. I would appear at that time to be getting an extra bit of fuel and the engine stumbles. Then it corrects smooth until that next wave of fuel comes out. Both injectors show the same thing.
I am trying to understand why this is happening. Someone suggested a Snap-on MT 2500 scanner to check this. I see some on ebay but they can be for several types of cars and years. What I am looking for it for something to show the pulse of the injectors. See if it is a ECM or PROM glitch that is causeing this. If the scanner can be used, I am not sure what type adapters I should be looking for and just where it plugs into! Has anyone had any experience with this type scanner? Would it show what I am looking for?
Anyone?
Thanks
Russ
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Re: 1984 Corvette CFI inj spray pattern problem
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