Hello everyone!
Sorry to just have registered on this nice forum and be posting here about my problems straight away) But I'm (and my mechanic too) already kinda desperate.
The story so far. I have a 05 JDM 6-port HP rx8. It's previous engine was blown, most probably due to an oil shortage, though I was rather well informed about how important was to keep oil level high. That was a very sad story, occured right in my birthday, and I could tell much things which would try to excuse me, but this post is not about this at all. It's about that a couple of months ago I've bought a new factory engine (not even rebuild) to resurrect my car. It wasn't bought from the dealer or directly Mazda itself. There was an intemediary seller. But the engine came in the box, with all theese Mazda logo stickers, serial number etc. Along with it, I bought: new coils (seller listed them as last revision C OEM), new Desno plugs, new OEM plug wires, new OEM oil injectors, and a bunch of irrelevant stuff (clutch disk with bearing, polybushings etc.). What was left old - MAF sensor, throttle body, intake manifolds, fuel injectors - were thoroughly cleaned by mechanics. When they were installing the engine, they noticed that the rear O2 sensor was broken (bent) and I've bought a new one.
After all the work was done and we started the car, it ran normally for some time, but then THE problem appeared - unstable idle and stall. No CEL with any codes. First we thought that we should just reset the memory. What we did, including famous 20 pedal stomp voodoo magic to make it forget about old engine's e-shaft. That wouldn't help. I've driven a car for almost 500 km (sorry for my metric numbers, it's something about 300 ml) and I beleive that was more than enough for ECU to get used to new engine, but the problem persisted. Then it came time for first oil and plugs replacement, along with wich we tried to install different used MAF. Finally I've bought entirely new MAF and used throttle body (and ofcourse it was cleaned) - no effect. ECU was again reset, I've came driving and had a feeling that the problem got even worse. Oh yes, did I mention that mechanic convinced me that he checked every square cantimeter of intake system to detect leaks? He filled with glue every place that were suspected. As I already said it's like the problem worsened, after we installed new MAF. Before that, the car would never stall not being warmed up enough for the temp indicator start travelling up from leftmost position. And even then, it would first start to hunt for idle for some time and then stall. Now it may stall significantly earlier during warm up and without any idle hunting. Mechanics say that they checked fuel pump, air pump, all theese air valves (SSV, etc), and all works. They activated them through the diagnostics device and saw them switching. I've read somewhere about the following procedure to check proper ECU idling behaviour: rev the engine to something about 5000 and then drop the pedal rapidly, the rpm should drop fast but should noticeably slow passing 1250. This was the perfectly what I saw beforce MAF and throttle replacement, though problem still existed. After MAF and throttle replacement I don't even see this! RPM drops like a rocket-hit aircraft all the way down to stall without even trying to slow down near 1250.
I guess I've told everything or so. I have no idea what to do next, as well as my mechanics. I think it's unlikely fuel injectors failure, though in one moment I was almost getting myselft (and my pocket) ready to buying a new pack. As far as I know injectors would cause problems in all rpm range, which is something that I don't observe. Compeletely new throttle body? Well since it's also not very much probable I'd like to be more certain that it is the real cause, before throwing out some 300$ on it.
Any help, suggestions, tips. I would appreciate that very much. This seems to be a hard problem, and even harder to diagnose remotely, but if *anyone* can tell *anything* useful I would be happy and grateful.
Sorry to just have registered on this nice forum and be posting here about my problems straight away) But I'm (and my mechanic too) already kinda desperate.
The story so far. I have a 05 JDM 6-port HP rx8. It's previous engine was blown, most probably due to an oil shortage, though I was rather well informed about how important was to keep oil level high. That was a very sad story, occured right in my birthday, and I could tell much things which would try to excuse me, but this post is not about this at all. It's about that a couple of months ago I've bought a new factory engine (not even rebuild) to resurrect my car. It wasn't bought from the dealer or directly Mazda itself. There was an intemediary seller. But the engine came in the box, with all theese Mazda logo stickers, serial number etc. Along with it, I bought: new coils (seller listed them as last revision C OEM), new Desno plugs, new OEM plug wires, new OEM oil injectors, and a bunch of irrelevant stuff (clutch disk with bearing, polybushings etc.). What was left old - MAF sensor, throttle body, intake manifolds, fuel injectors - were thoroughly cleaned by mechanics. When they were installing the engine, they noticed that the rear O2 sensor was broken (bent) and I've bought a new one.
After all the work was done and we started the car, it ran normally for some time, but then THE problem appeared - unstable idle and stall. No CEL with any codes. First we thought that we should just reset the memory. What we did, including famous 20 pedal stomp voodoo magic to make it forget about old engine's e-shaft. That wouldn't help. I've driven a car for almost 500 km (sorry for my metric numbers, it's something about 300 ml) and I beleive that was more than enough for ECU to get used to new engine, but the problem persisted. Then it came time for first oil and plugs replacement, along with wich we tried to install different used MAF. Finally I've bought entirely new MAF and used throttle body (and ofcourse it was cleaned) - no effect. ECU was again reset, I've came driving and had a feeling that the problem got even worse. Oh yes, did I mention that mechanic convinced me that he checked every square cantimeter of intake system to detect leaks? He filled with glue every place that were suspected. As I already said it's like the problem worsened, after we installed new MAF. Before that, the car would never stall not being warmed up enough for the temp indicator start travelling up from leftmost position. And even then, it would first start to hunt for idle for some time and then stall. Now it may stall significantly earlier during warm up and without any idle hunting. Mechanics say that they checked fuel pump, air pump, all theese air valves (SSV, etc), and all works. They activated them through the diagnostics device and saw them switching. I've read somewhere about the following procedure to check proper ECU idling behaviour: rev the engine to something about 5000 and then drop the pedal rapidly, the rpm should drop fast but should noticeably slow passing 1250. This was the perfectly what I saw beforce MAF and throttle replacement, though problem still existed. After MAF and throttle replacement I don't even see this! RPM drops like a rocket-hit aircraft all the way down to stall without even trying to slow down near 1250.
I guess I've told everything or so. I have no idea what to do next, as well as my mechanics. I think it's unlikely fuel injectors failure, though in one moment I was almost getting myselft (and my pocket) ready to buying a new pack. As far as I know injectors would cause problems in all rpm range, which is something that I don't observe. Compeletely new throttle body? Well since it's also not very much probable I'd like to be more certain that it is the real cause, before throwing out some 300$ on it.
Any help, suggestions, tips. I would appreciate that very much. This seems to be a hard problem, and even harder to diagnose remotely, but if *anyone* can tell *anything* useful I would be happy and grateful.
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