Stumbling, hesitation, numb gas peddle, Fuel trims crazy, Lean, P2187.

I had a similar issue with the LTFT going -20+ and throwing 2187 and or 2188. My issue was the MAF harness connection, specifically the black ground wire, 1st gen MS3, may be a different color on some models. I could wiggle the ground wire and idle would change and LTFT would jump. Just idle the car, wiggle the wires going into the MAF harness. Free to check.
 
VoodooJef said:
bunch of questions to help narrow it down:
Did it happen all of a sudden, slowly get worse, or after a particular mod?
How are you tuned, what fuel, has any of that changed?

Just an example; I recently got my car back after a lengthy engine build. Had evidence of a vac leak but could not find it for shit. Turns out it was the methanol solenoid fittings. They were still loose, and because they were on the opposite side of the throttle body it wasn`t getting enough pressure from the test to be visible. I ended up pressurizing it with the key on and a brick on the gas pedal and found the leak. Not to say you`d have the same issue (your sig says no meth yet), but it could be a similarly activated problem.
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I am having the same problem right now^
 
I have a 2008 Speed3 and I am having a similar issue. However, it is somewhat different ,the stumbling occurs only under load, does not have to be WOT in fact it happens during smooth acceleration, never when stationary. I can sit in my driveway/garage and rev the snot out of it and it never misses a beat, as soon as I get to the end of my street and turn onto the main rd, shift 1st to 2nd no issue up to 3rd and gently accelerate and then bang, major fuel cut, lasts for about 3 seconds and bang back to full power. This goes on continuously until I slow right down let it idle for a second or two and accelerate gently again and then it happens again. I have done the relief valve test and monitored the fuel rail pressures and they are normal. However I did notice that the injector pulse width goes to zero as soon as it happens which would explain the sudden fuel cut off. There are no fault codes, no pre-stumble misfires just complete fuel cut. I also monitored the TPS signals and they were normal. I am using a Foxwell NT530 scanner which I primarily use for my Beemer and am in the process of sell the Speed3 but need to fix this issue or no-one will buy it. I am not sure if I can grab a datalog with the foxwell so I am trying to go through potential causes one at a time but I was hoping that someone may have come across this problem and figured it out. Any help would be gratefully appreciated.
I forgot to mention that I have already cleaned the spill valve.
 
celticfc said:
I have a 2008 Speed3 and I am having a similar issue. However, it is somewhat different ,the stumbling occurs only under load, does not have to be WOT in fact it happens during smooth acceleration, never when stationary. I can sit in my driveway/garage and rev the snot out of it and it never misses a beat, as soon as I get to the end of my street and turn onto the main rd, shift 1st to 2nd no issue up to 3rd and gently accelerate and then bang, major fuel cut, lasts for about 3 seconds and bang back to full power. This goes on continuously until I slow right down let it idle for a second or two and accelerate gently again and then it happens again. I have done the relief valve test and monitored the fuel rail pressures and they are normal. However I did notice that the injector pulse width goes to zero as soon as it happens which would explain the sudden fuel cut off. There are no fault codes, no pre-stumble misfires just complete fuel cut. I also monitored the TPS signals and they were normal. I am using a Foxwell NT530 scanner which I primarily use for my Beemer and am in the process of sell the Speed3 but need to fix this issue or no-one will buy it. I am not sure if I can grab a datalog with the foxwell so I am trying to go through potential causes one at a time but I was hoping that someone may have come across this problem and figured it out. Any help would be gratefully appreciated.
I forgot to mention that I have already cleaned the spill valve.
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Did you try this? https://mazdaspeeds.org/index.php?t...-fuel-trims-crazy-lean-p2187.5535/#post-51029
 
celticfc said:
I did, the fuel rail pressures are good, getting in excess of 1650 KOEO when hot. Idle pressure is around 430 PSI. Cleaned the spill valve. Only significant thing I have noticed is the injector pulse width at zero when stumbling occurs. I'm trying to figure out what is causing it to shutdown.
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what was your fix? I’m having these exact same issues to a tee.
 
Awafrican said:
haven't seen that user since 17 Aug 2021 so I wouldn't expect a reply, but the koeo at 1650 indicates spill valve failure should hit 1850 psi with a hot engine
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yeah I didn’t realize the date until after I posted. That users issue is very similar to mine. Plus the car died on me 14 miles from my work to home last week, which is a 18 mile drive. Got a tow home, messed with the fuel pump & circuit relays. Thought I had it fixed as it started up and idled fine. Fast forward to yesterday. I mapped out a 14 mile drive to see if it’d happen again.
Did a 14 mile drive yesterday to get a datalog. At times my LTFT would go to +13.10 or even jump to +20 for a couple seconds. STFT would go from -25 to +24.80. It was all over the place. I’ve already serviced my injectors with a cleaning, new seals, etc. Still trying to get my gen1 to run properly after I installed a slew of parts. As I was cruising in 6th gear around 60mph at less than 15% throttle the car would buck a little. On datalog it looked like it was cutting fuel then coming back on. Then coming to my driveway I went to downshift from 6th to 5th and once I clutched in, RPMs went near idle then the engine turned off & I coasted into my driveway to a crank no start until a couple hours later after the car cooled down. P2178 code. Already have a purge valve coming (seems completely blocked off, no air in or out with a suction test) & an OEM MAF coming in (currently have Denso 604)
I’ve checked for boost leaks, all hoses to & from intake manifold, they’re tight. All DP & Turbo bolts are tight. My Spill valve was cleaned & new relief valve not even 1300 miles ago. Here’s the datalog:
 
cavsfan2 said:
yeah I didn’t realize the date until after I posted. That users issue is very similar to mine. Plus the car died on me 14 miles from my work to home last week, which is a 18 mile drive. Got a tow home, messed with the fuel pump & circuit relays. Thought I had it fixed as it started up and idled fine. Fast forward to yesterday. I mapped out a 14 mile drive to see if it’d happen again.
Did a 14 mile drive yesterday to get a datalog. At times my LTFT would go to +13.10 or even jump to +20 for a couple seconds. STFT would go from -25 to +24.80. It was all over the place. I’ve already serviced my injectors with a cleaning, new seals, etc. Still trying to get my gen1 to run properly after I installed a slew of parts. As I was cruising in 6th gear around 60mph at less than 15% throttle the car would buck a little. On datalog it looked like it was cutting fuel then coming back on. Then coming to my driveway I went to downshift from 6th to 5th and once I clutched in, RPMs went near idle then the engine turned off & I coasted into my driveway to a crank no start until a couple hours later after the car cooled down. P2178 code. Already have a purge valve coming (seems completely blocked off, no air in or out with a suction test) & an OEM MAF coming in (currently have Denso 604)
I’ve checked for boost leaks, all hoses to & from intake manifold, they’re tight. All DP & Turbo bolts are tight. My Spill valve was cleaned & new relief valve not even 1300 miles ago. Here’s the datalog:
Click to expand...
 

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