Trying to track down the cause of my partial throttle engine surge. Would love some help/ideas on what it could be. It happens with partial throttle application. Imagine an onramp to highway and you feed in the throttle and it accelerates but it fluctuates/hesitates until you reach speed. Very frustrating. I have done the following:
*smoked the EVAP system-all tight
*sprayed ether/carb cleaner all around intake/vacuum hose areas
*did a vacuum test at idle-15-20in vacuum
*have checked all hoses/intake plenum connections
*disconnected the MAF/no change
This just happened a couple of weeks ago after reassembly(again) of my VANOS repairs. No codes are being thrown either. Doesn't seem to be affected by engine temp. Blast away.
Thanks

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Dave S.
Northeast
2003 4.6is
2005 E53 4.4
2003 E39 Msport(a REAL ONE!)
1959 Fiat 600