Low RPM hesitation/stutter on acceleration

AGGATX said:
I'm having a similar issue as OP and the last two posters. My car is a completely stock early 2007 car with 109k miles. I had P0192 and fixed it with a new FP sensor. When I got my car back from the mechanic, it had a weird noise. From the inside of the car (with the door closed) it sounds like either some high pressure air hitting a metal chamber or tube, or something rumbling. From the outside of the car it almost sounds like a slipping belt. It's worst when the car is cold, and I don't know if it only happens below 3k rpm or I just can't hear it above that. With the hood open, the sound seems to be coming from either the HPFP toward the back, or from the wastegate actuator area of the turbo.

I had brought the car in mostly to get oil consumption looked at. Roger Beasley had told me the turbo was leaking oil. This independent mechanic found that #3 cylinder had oil control issues. I know they took TMIC off and enough to look at the turbo (they said it looks fine other than the oil it accumulates from #3 cyl). They also took the spark plugs off to do compression testing and bore scoping.

The car's power is fine and driveability is fine...until you go make a turn. It's worst/easier on left turns, but I can make it happen on a right turn. It acts like a rev limiter (but at 3k rpm). I don't get a traction control light and it doesn't feel like the torque limiter function when turning. After finding this thread, it sure seems like it could be the HPFP.

The main point of all this is to ask if the HPFP is known to make strange noises when it's failing? It does also seem to tick very loudly when running.
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Hey did you ever figure out your issue? I have a very similar one currently. Got a P0192 after a weird misfire at like 5k. Car can barely rev above 3500 now without hitting what sounds like rev limiter. Replaced the pressure sensor on the fuel rail and still issue persists.

*EDIT* Buying the correct Bosch Fuel Rail Pressure Sensor - 0261545053 ended up resolving my issue. Don't bother buying the ones from Amazon, ended up ordering from Finland and waiting 3 weeks for shipping.
 
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My issue turned out to be #2 cylinder blow-by (45% leak down). People rebuild these engines right? They recommend a new engine. That seems drastic.
 
If you don't want to go with a higher power build it would be cheaper to get a motor from Mazda if they are still available or to buy a lower mileage motor from a wreck
 
The independent mechanic I first talked to found a used engine for $9k. Mazda wants $13k for a new one + turbo labor included. I'm not going to do that since I no longer need this car. I've rebuilt a Katrina flood engine in my NA Miata (disassemble, electrolysis dip, had shop re-sleeve the bores (was a stock build for racing so couldn't over bore) and deck it, then I put it all back together myself and back into my SM and raced a few years with it. Good power out of it. I gave away my engine hoist and don't have the patience and space for it anymore, otherwise I'd do the same with this engine. Hoping someone can do something good with this car maybe for a power build, since the rest of the car is in excellent shape.
 
The thing nobody has been able to explain to me is how the blow by on one cylinder causes severe hesitation after a left turn. They did mention the noise is indeed the HPFP. Oh well, I got a good and fun 15+ years out of this car. Hopefully someone can give it more life. Thanks all for the help!
 
AGGATX said:
The independent mechanic I first talked to found a used engine for $9k. Mazda wants $13k for a new one + turbo labor included. I'm not going to do that since I no longer need this car. I've rebuilt a Katrina flood engine in my NA Miata (disassemble, electrolysis dip, had shop re-sleeve the bores (was a stock build for racing so couldn't over bore) and deck it, then I put it all back together myself and back into my SM and raced a few years with it. Good power out of it. I gave away my engine hoist and don't have the patience and space for it anymore, otherwise I'd do the same with this engine. Hoping someone can do something good with this car maybe for a power build, since the rest of the car is in excellent shape.
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Sweet shit, the price for a brand new DISI just keeps going up and up. I remember when it used to be around $8k and that felt like way too much. $13k is 'fuck no' territory. Not when you can go 2.5 Duratec bottom end for a few grand.
 
MacheteJames said:
Sweet shit, the price for a brand new DISI just keeps going up and up. I remember when it used to be around $8k and that felt like way too much. $13k is 'fuck no' territory. Not when you can go 2.5 Duratec bottom end for a few grand.
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Damn...I got mine for $4,950 shipped in late 2021. Glad I purchased it when I did.
 
Brado said:
Damn...I got mine for $4,950 shipped in late 2021. Glad I purchased it when I did.
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You got a brand new DISI longblock from Mazda for that much? You made out real good. They've always been overpriced at shit as compared to the KBB value of the car.
 
I sold my car to a good friend for $2k. He is in the racing business and has the space knowledge and tools to further debug this problem. He also knows someone in the tuner industry that thinks the drivability issue is something was done wrong or maybe the Amazon fuel rail pressure sensor is bad. This person also mentioned crate motors are $4950. To clarify, the $13k was for the crate motor, turbo, and hpfp + R&R. The independent mechanic $9k for a used motor is definitely outrageous.
If my friend figures out the drivability issue I’ll post back up.
 
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