Severe Hesitation from Stop

RumDomRum · 04-21-2018, 01:39 AM

I changed all 6 fuel injectors in my 2007 335i today. It was actually pretty fun and only took a couple hours. My car has 130k on it and still had the factory, extremely problematic injectors. I decided to drop the coin to do the injectors because my car has developed an insane hesitation from a stop, and ONLY from a stop. Car falls lean and hesitates, then takes off. It run GREAT in all other conditions. I figured it was the injectors.

I was wrong.

Car has the hesitation just as bad, if not worse. It's horrid, honestly. The car runs better in every other situation than it ever has, however, the hesitation was not improved at all.

It does not misfire at all in boost.

The problem seemed to present itself after the last oil change. During the change I did the LPFP sensor because I got a code for it during some pulls.

After chaning the sensor, I logged the HPFP and LPFP actual and requested values. The HPFP oscillates around the target about 25psi or so, which doesn't seem bad considering the range of the pressure, but it does lag the request. I don't know how much lag is acceptable. LPFP matches req pressure very closely.

Things I've done to the car:
Injectors
LP Fuel Pressure Sensor
Valve Cover and gasket
PCV valve
PCV Flapper
Intercooler
Cleaned VANOS solenoids and swapped Intake and Exhaust (made no change or improvement)

I'm running out of ideas and open to suggestions.

Any help is greatly appreciated.

Thanks for your time!

BashShah · 04-22-2018, 04:08 AM

what about Intake port Cleaning?
like a Proper WALNUT Blasting.

also, if you have INPA, then i would do a Full adaptation reset.

PS: 2 points.
1) I had the same issue, hesitation and jerkyness at low speeds and slight up hills.
Walnut blasting fixed my issues.

2) Lag is not going to go away unless you replace your Turbos.
Lag is caused in the amount of time the Vacuum actuators are pulled to close the waste gate. This is normal for the car, but you might be able to reduce it with 2 things. 1) Replace all Vacuum lines. (use High Temp Silicone lines, and look up my DIY on the front turbo, will save you a hell of a lot of time) 2) tighten the rattle of the rear turbo actuator rod.

JFolt · 05-10-2018, 04:40 PM

I have a similar issue. Car runs fine at most engine speeds but I get a hesitation when starting from a dead stop. It doesn't happen when I first start the car, usually once it's all up to temperature it begins to slowly get worse and worse. Very hard to replicate and very annoying. I changed plugs and coils hoping that would solve it but no cigar.

I have an N55, RWD, manual.... not sure what tranny you have. I'm hoping it's not the injectors. For a while I thought the clutch was slipping but it never slips once I'm moving, even with WOT in 1st or 2nd gear.

04-21-2018, 01:39 AM	#1
RumDomRum New Member 14 Rep 9 Posts Drives: 2007 335i Join Date: Apr 2018 Location: Washington iTrader: (0)	Severe Hesitation from Stop I changed all 6 fuel injectors in my 2007 335i today. It was actually pretty fun and only took a couple hours. My car has 130k on it and still had the factory, extremely problematic injectors. I decided to drop the coin to do the injectors because my car has developed an insane hesitation from a stop, and ONLY from a stop. Car falls lean and hesitates, then takes off. It run GREAT in all other conditions. I figured it was the injectors. I was wrong. Car has the hesitation just as bad, if not worse. It's horrid, honestly. The car runs better in every other situation than it ever has, however, the hesitation was not improved at all. It does not misfire at all in boost. The problem seemed to present itself after the last oil change. During the change I did the LPFP sensor because I got a code for it during some pulls. After chaning the sensor, I logged the HPFP and LPFP actual and requested values. The HPFP oscillates around the target about 25psi or so, which doesn't seem bad considering the range of the pressure, but it does lag the request. I don't know how much lag is acceptable. LPFP matches req pressure very closely. Things I've done to the car: Injectors LP Fuel Pressure Sensor Valve Cover and gasket PCV valve PCV Flapper Intercooler Cleaned VANOS solenoids and swapped Intake and Exhaust (made no change or improvement) I'm running out of ideas and open to suggestions. Any help is greatly appreciated. Thanks for your time!
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04-22-2018, 04:08 AM	#2
BashShah Colonel 312 Rep 2,020 Posts Drives: 2012 335i Sedan Join Date: Oct 2012 Location: Vancouver, Canada iTrader: (0)	what about Intake port Cleaning? like a Proper WALNUT Blasting. also, if you have INPA, then i would do a Full adaptation reset. PS: 2 points. 1) I had the same issue, hesitation and jerkyness at low speeds and slight up hills. Walnut blasting fixed my issues. 2) Lag is not going to go away unless you replace your Turbos. Lag is caused in the amount of time the Vacuum actuators are pulled to close the waste gate. This is normal for the car, but you might be able to reduce it with 2 things. 1) Replace all Vacuum lines. (use High Temp Silicone lines, and look up my DIY on the front turbo, will save you a hell of a lot of time) 2) tighten the rattle of the rear turbo actuator rod.
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05-10-2018, 04:40 PM	#3
JFolt Enlisted Member 14 Rep 47 Posts Drives: 2011 335i Sedan Join Date: Aug 2014 Location: NNJ iTrader: (0)	I have a similar issue. Car runs fine at most engine speeds but I get a hesitation when starting from a dead stop. It doesn't happen when I first start the car, usually once it's all up to temperature it begins to slowly get worse and worse. Very hard to replicate and very annoying. I changed plugs and coils hoping that would solve it but no cigar. I have an N55, RWD, manual.... not sure what tranny you have. I'm hoping it's not the injectors. For a while I thought the clutch was slipping but it never slips once I'm moving, even with WOT in 1st or 2nd gear.
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