Could a bad fuel pump ecu cause the engine to misfire?
05-28-12, 12:52 AM
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Could a bad fuel pump ecu cause the engine to misfire?
Can a bad fuel pump ecu cause the engine to misfire? I've searched, but could verify if it could actually cause the engine to miss.
05-31-12, 11:34 AM
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Its the sc400. Yes, i have checked the both ignition coils, replaced the plugs, caps & rotors, fuel pump, and fuel filter. I was just wondering if its possible if the ecu was faulty if it could cause the engine to run rough/misfire. Its really rough at idle and stalls out after a few minutes or if I put it in gear the rpms lower and it stalls right away.
I changed quite a few ignition parts and i have double checked everything and i'm just having trouble finding the source of the misfire(s). I have ohmed out the ignition coils and they test fine, the plug wires are only 3 years old and were within spec. Crankshaft and camshaft position sensors all were within spec. The primary coil was suppose to fall between .36 - .55 ohms and they both measured .5 ohms. The secondary coil also measured within spec.
I checked for fuel pressure by following the lexus shop manual and used a jumper wire for B+ and FP and the screw on the fuel pulsation damper raised and I felt the fuel line and it had pressure. Thats what the lexus shop manual said to do a basic check for fuel pressure. I havent yet checked for spark on all eight plug wires. So I need to do that yet. I don't have any codes stored and the cel light hasn't come on.
I checked and didnt find any vacuum leaks. I guess I need to check the injectors and test their resistance to make sure their within spec. But if the fuel pump ecu can cause the engine to idle rough and stall I'm starting to think thats a good possibilty. Like I said I used the jumper wire to bypass the fuel pump ecu to check for fuel pressure, but I haven't actually started the car while the fuel pump ecu was bypassed to see if there was any change.
I changed quite a few ignition parts and i have double checked everything and i'm just having trouble finding the source of the misfire(s). I have ohmed out the ignition coils and they test fine, the plug wires are only 3 years old and were within spec. Crankshaft and camshaft position sensors all were within spec. The primary coil was suppose to fall between .36 - .55 ohms and they both measured .5 ohms. The secondary coil also measured within spec.
I checked for fuel pressure by following the lexus shop manual and used a jumper wire for B+ and FP and the screw on the fuel pulsation damper raised and I felt the fuel line and it had pressure. Thats what the lexus shop manual said to do a basic check for fuel pressure. I havent yet checked for spark on all eight plug wires. So I need to do that yet. I don't have any codes stored and the cel light hasn't come on.
I checked and didnt find any vacuum leaks. I guess I need to check the injectors and test their resistance to make sure their within spec. But if the fuel pump ecu can cause the engine to idle rough and stall I'm starting to think thats a good possibilty. Like I said I used the jumper wire to bypass the fuel pump ecu to check for fuel pressure, but I haven't actually started the car while the fuel pump ecu was bypassed to see if there was any change.
Last edited by Lexus082; 05-31-12 at 12:54 PM.
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