Hey all. I'm having a few problems with my MSP that I'm hoping someone can help me out with. A little background: the motor was rebuilt this past summer while I was out of town on business. After I got the car back, I drove it about 1,000 miles before it seized, and it went back to the shop - they repaired it at their cost. Since I got it back the second time, about 500 miles ago, I've had these problems.
1. Idle dip: On cold starts, it fires up great! No idle issues and runs smoothly. It starts the same when the engine is at operating temp. If I drive long enough for the engine to reach normal operating temp, then let it sit for an hour or so, when I come back out and start it it's like it has a huge vacuum leak. It'll turn over like normal, drop to idle, and then start sputtering. The VAC/Boost gauge shows the vacuum drops from ~21inHg and moves anywhere between there and 0. Usually after 10 seconds or so it catches itself and acts like nothing ever happened. Last night, it did not catch itself and stalled. Thoughts...?
2. Consistently in 4th gear, and on occasion in 3rd, it feels/sounds like it misfires under moderate acceleration. It doesn't seem to correlate to a certain speed/rpm range, but more so how long I've been on the accelerator. Upon some experimentation, I was unable to recreate this in 2nd or 5th gear and didn't even try in 1st. Whenever this occurs, the boost gauge shows that it holds boost - no sign of anything out of the ordinary happened. I haven't gotten to checking plugs/wires yet, but is there anything I should check out? Is this related to #3 below?
3. This is something I've never experienced before. I can't get the car to do it everytime, but it still worries me. The first time it happened, I was accelerating out of town (~ 30mph) in 3rd gear. I've not sure exactly what rpm it happened at (probably around 4k), as it caught me off guard. There was a 'pop' sound and then all the power was gone. After pressing the clutch in, when I pressed on the accelerator, the vac would change but the rpms didn't budge, they just sat at idle. I slowly let the clutch back out and everything was normal. At the next stop sign, since I was ready for it, I tried to get it to do it again and this time it 'disconnected' in 4th. Exact same things happened, but in a different gear. I called into the local Mazda shop about this one and their pondering it. Today, while cruising down the freeway, it did the same thing again - this time I didn't touch the clutch and tried revving the engine. The rpms stay with the speed and gear (~ 3k @ 65mph) but the vacuum changes with the throttle. it also fixed itself without me ever touching the clutch. I'm also wondering if what feels like a misfire is really whatever this is, but it's resolving itself before the 'disconnect' sensation.
Mods currently include M-Tech rods, Wiseco Pistons with a 0.020 overbore, machined head, 0.051 MLS Head gasket, ARP head studs, Corksport Cams, 2.5in catless turbo back exhaust with an Apexi N1 muffler (changing tomorrow), Welded LSD, Canadian EGR, and some other things that i can't think of at the moment as I'm in a hurry to leave.
If anybody can give an idea of where to start looking to solve some of this stuff, I'd really appreciate it. Thanks!
1. Idle dip: On cold starts, it fires up great! No idle issues and runs smoothly. It starts the same when the engine is at operating temp. If I drive long enough for the engine to reach normal operating temp, then let it sit for an hour or so, when I come back out and start it it's like it has a huge vacuum leak. It'll turn over like normal, drop to idle, and then start sputtering. The VAC/Boost gauge shows the vacuum drops from ~21inHg and moves anywhere between there and 0. Usually after 10 seconds or so it catches itself and acts like nothing ever happened. Last night, it did not catch itself and stalled. Thoughts...?
2. Consistently in 4th gear, and on occasion in 3rd, it feels/sounds like it misfires under moderate acceleration. It doesn't seem to correlate to a certain speed/rpm range, but more so how long I've been on the accelerator. Upon some experimentation, I was unable to recreate this in 2nd or 5th gear and didn't even try in 1st. Whenever this occurs, the boost gauge shows that it holds boost - no sign of anything out of the ordinary happened. I haven't gotten to checking plugs/wires yet, but is there anything I should check out? Is this related to #3 below?
3. This is something I've never experienced before. I can't get the car to do it everytime, but it still worries me. The first time it happened, I was accelerating out of town (~ 30mph) in 3rd gear. I've not sure exactly what rpm it happened at (probably around 4k), as it caught me off guard. There was a 'pop' sound and then all the power was gone. After pressing the clutch in, when I pressed on the accelerator, the vac would change but the rpms didn't budge, they just sat at idle. I slowly let the clutch back out and everything was normal. At the next stop sign, since I was ready for it, I tried to get it to do it again and this time it 'disconnected' in 4th. Exact same things happened, but in a different gear. I called into the local Mazda shop about this one and their pondering it. Today, while cruising down the freeway, it did the same thing again - this time I didn't touch the clutch and tried revving the engine. The rpms stay with the speed and gear (~ 3k @ 65mph) but the vacuum changes with the throttle. it also fixed itself without me ever touching the clutch. I'm also wondering if what feels like a misfire is really whatever this is, but it's resolving itself before the 'disconnect' sensation.
Mods currently include M-Tech rods, Wiseco Pistons with a 0.020 overbore, machined head, 0.051 MLS Head gasket, ARP head studs, Corksport Cams, 2.5in catless turbo back exhaust with an Apexi N1 muffler (changing tomorrow), Welded LSD, Canadian EGR, and some other things that i can't think of at the moment as I'm in a hurry to leave.
If anybody can give an idea of where to start looking to solve some of this stuff, I'd really appreciate it. Thanks!
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