Some good points in there, Jim. One test I could also do is to run the car around the block then turn the AC on (for some reason, most of the failures I've noted were when the AC was on). If nothing else, let it idle and do a wiggle test.
I do know for certain that the ECU is right next to the steering wheel, and know exactly what wire going into it I'm looking for a signal on. However, once it gets away from the connector at the ECU, everything is wrapped up together. Would I have to take the whole thing apart to check it (I'm assuming if I have to, so would a Mazda tech). -Bryan --- On Wed, 6/11/08, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: From: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Subject: Re: [Miata] 2002 Bucking Without CEL - Fuel Filter to Blame? To: [EMAIL PROTECTED], "Miata Mailing List" <[EMAIL PROTECTED]>, "Miata Power List" <[email protected]> Date: Wednesday, June 11, 2008, 9:01 AM Greetings to Bryan and the list: Correct me if I am wrong, but didn't you report earlier that there was an error code for the crank angle sensor in the ECU? If memory serves, I seem to recall that you mentioned that you replaced the crank angle sensor and still had the bucking occur, combined with a repeat of the crank angle sensor error code? If this is the case, replacing the fuel filter is pure wishful thinking. While a blocked fuel filter can certainly contribute to poor running, especially at high throttle openings, it cannot generate a crank angle sensor error code. If you are indeed suffering from such errors being logged in the ECU, then there are three things that can cause the problem: 1. A defective crank angle sensor. It is possible to get two bad ones in a row, although not very likely. Therefore, if you have changed it out once, it falls to the bottom of the priority list. 2. A defective ECU. This is also possible, but not very likely either, as the car seems to run and the system is reporting errors; usually digital systems fail in less specific ways. 3. A defective connection between the crank angle sensor and the ECU. Since your problem seems to be intermittent, this is a likely culprit. I believe that I already mentioned that I have had connector difficulties on an early car. The location of the crank angle sensor on later cars (lower and on the front of the engine) means that its connector is more susceptable to water intrusion with resulting corrosion problems than one located high on the engine, as mine is. Start the engine, and grab this connector and wiggle it; pull on the wires (not too hard; we don't want to rip them out of the connector). Wiggle and flex the entire harness from the sensor back to where it goes through the firewall. See if you can cause the problem to occur. If you can, note where you were flexing and look for breaks or damage at that point. If near any connector, separate the connector and treat liberally with Cramoline, De-Ox-It D-5, or some similar product. Try unplugging the connector from the ECU (I believe it is behind the seat in the later cars) and treat its connector with a contact cleaner such as those mentioned above. If bending or pulling the wires at the connector causes the problem and it cannot be corrected by cleaning, you will have to replace the connector (as I did) or the entire engine wiring harness. Last but not least, most of these sensors like the engine block to be at ground potential. Check the condition of all of the engine ground straps for cleanliness of connections, tightness of bolts, and missing or frayed strands. Until you get rid of your crank angle sensor error code condition, you will not be successful in getting the engine to run right. Regards, Jim T. [EMAIL PROTECTED] '74 914 '90 Miata (x3) ----- Original Message ----- From: "Bryan Wyatt" <[EMAIL PROTECTED]> To: "Miata Mailing List" <[EMAIL PROTECTED]>; "Miata Power List" <[email protected]> Sent: Wednesday, June 11, 2008 3:43 Subject: [Miata] 2002 Bucking Without CEL - Fuel Filter to Blame? All, I replaced the plugs and wires last night have have driven to work and back twice on them so far.&nbsp; Thing still doesn't feel right but hasn't bucked yet. What I noticed this morning was small hesitations or misses and a general "flat" feeling from the engine. Not sure if it meant that the computer was dialing back timing or what. Definitely uncomfortable feeling--as if something worse was always about to happen. The lumps are subtle but definitely there. I should stress that I've been running VERY light throttle levels lately--I'm a bit scared of something happening if I were to try to punch it! Would a fuel filter be the cause of this stuff? I mean, the plugs and wires I installed are factory fresh.&nbsp; I should mention again that I'm just shy of 60k on the clock and none of the standard 60k items (aside from plugs and wires now) have been done. -Bryan
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