Tweet
Symptoms: (1) Starts and runs perfectly up to 3,900 rpm. (2) At 3,900 rpm when throttle advanced, surges between 3,900 and 4,200-4,400 rpm at approximately 1-2 cycles per second. (3) At WOT surge stops but max rpm 3,900.
Change/Tested: (1) Plugs (twice). (2) Complete lp and hp fuel system (hp pressure exactly on spec and rock solid through entire rpm range).
(3). Beginning to suspect MAP sensor. Checked voltage per service manual. At 0 kPa right on the money @ 4v. At 40 kPa also correct @ 2.4 v. But cannot get to 80 kPa with hand pump. And MAP sensor alone will not hold vacuum. Takes 3-4 seconds to bleed off vacuum when pumping stops. Hose checks out fine - no leaks.
Question: Should MAP sensor hold vacuum? (Don't know the internal mechanics but acts like there could be a diaphram that has started to leak).
Any help would be greatly appreciated. Been screwing around with this off-and-on since last fall. Nice weather means screwing around time is over.
Change/Tested: (1) Plugs (twice). (2) Complete lp and hp fuel system (hp pressure exactly on spec and rock solid through entire rpm range).
(3). Beginning to suspect MAP sensor. Checked voltage per service manual. At 0 kPa right on the money @ 4v. At 40 kPa also correct @ 2.4 v. But cannot get to 80 kPa with hand pump. And MAP sensor alone will not hold vacuum. Takes 3-4 seconds to bleed off vacuum when pumping stops. Hose checks out fine - no leaks.
Question: Should MAP sensor hold vacuum? (Don't know the internal mechanics but acts like there could be a diaphram that has started to leak).
Any help would be greatly appreciated. Been screwing around with this off-and-on since last fall. Nice weather means screwing around time is over.
Comment