Engine Pulsing/Surging

B

Bowtie Mafia

Member
Joined
Mar 29, 2011
Recently my car started to "pulse/surging" at around 2000 rpm under normal and less than normal acceleration. It felt like the engine was cutting out intermittently. I had my fuel pressure checked at 25 psi. I was pretty sure it was a fuel delivery problem so I replaced my fuel pump and the fuel pressure regulator (Red Armstrong XP and Accufab adjustable). I set the fuel pressure at 45 psi and went off for a test drive. The same problem occurred, right around 2000 rpm again. I'm at a loss and stuck on where to go or test from here. Any ideas? Thanks guys.
 
You set the fuel pressure w/the vac. line "off ", correct? You may have a bad maf or un-metered air getting past the maf, providing you are running a maf. With eng. running, lightly tap the maf (don't want to damage it by hitting it hard) and see if it stumbles. If it does, you will need to replace it or go to an SD style system to eliminate it.
Is this only in o.d. or will it act up in 3rd as well?
 
Ok, so here's the latest. Yes, my fuel psi is set to 45 psi with the vacuum off. I took the MAF off and cleaned it, put it back on tapped it a few times, nothing changed. I also unplugged the cam sensor after turning it on and it ran like it should. Is that the sign of my cam sensor going out?
 
Bowtie Mafia said:
Ok, so here's the latest. Yes, my fuel psi is set to 45 psi with the vacuum off. I took the MAF off and cleaned it, put it back on tapped it a few times, nothing changed. I also unplugged the cam sensor after turning it on and it ran like it should. Is that the sign of my cam sensor going out?
Click to expand...

Yes. The bushings are probably bad in the cam sensor. Replace it.
 
Thanks. I'm glad i now know what it is. If you don't mind me asking how did you diagnose that, everyone i asked had no idea.
 
I would say yes but both of them haven't been on here since 2020 and 2017. If you're having a similar problem just do the test he said and unplug the sensor and see if it goes away. If it doesn't start a new thread.
 
LANDAU LIMITED said:
I would say yes but both of them haven't been on here since 2020 and 2017. If you're having a similar problem just do the test he said and unplug the sensor and see if it goes away. If it doesn't start a new thread.
Click to expand...
So unplug the cam sensor, drive the car, if it goes away the sensor is bad? Will it drive with the sensor unplugged? I may not be having the same issue. I do have smooth acceleration except the rpms dip during acceleration going up then down a bit then up and down etc. I only notice it under hard acceleration.
 
Haloed said:
Did replacing the cam sensor fix your surging issue?
Click to expand...
This thread is 11 years old & the OP hasn’t been on in 6.

I second Landau’s advise. Again give all details including Scanmaster numbers.
 
'87 Turbo T said:
This thread is 11 years old & the OP hasn’t been on in 6.

I second Landau’s advise. Again give all details including Scanmaster numbers.
Click to expand...
It'll have to wait until spring, live in the north and don't drive the turbo Buick in winter with salt on the roads. I realize this thread is 11 years old, I was a member back then not sure why it shows me as a new member, maybe I too have not made comments in years. I've never experienced this issue before and been working on GNs since 1991.
 
Anybody have the cam sensor end play/ shim and bushing wear specs?
That seems to be the latest gremlin in mine. I never thought to check my cam sensor after rebuilding the engine, but I had it out checking things because it ran much better with it disconnected as was suggested as a test. The last fools that worked on it before I got it didn't install the pronged thrust washer between the gear and housing. I have no theory on that.... End play was excessive! So I installed one (seems to be the same as a chebbie distributor item) and it was still excessive, and doing a ton of distributor work thru the years, I also installed an endplay shim also from a chebbie dist. I set the endplay at .015 which is what normal distributors are set to. I also bought a Casper's adjustable cap with the LED but haven't run it yet. Bushings feel pretty good to me, but I haven't found a wear spec. so far.
Sooooo what is the desired shaft endplay spec and bushing tolerance spec?
TIA
TIMINATOR still chasing gremlins from the last fools that worked on my ride....
 
Any of you old guys ( like me), remember in the 60s and 70s when Chrysler had the high school mechanic contests? They took 50 cars and did a bunch of things to make them not run, and the team that fixed all 25 or so gremlins and drove a lap won a scholarship.
Did Buick ever do that? Have I gotten one of those cars? Do the Buick God's hate me? Tune in next week for the next exciting episode!
TIMINATOR
 
with the age of these cars they are all becoming gremlin infested. these were pretty early on in the all electric, all the time and most of there cousins have made it back as washing machines and refrigerators. even the newish stuff has little things that are specific to models and families that crop up. I was watching the questionable mechanic on the youtubes and he got a deal on an Escalade that had been to several shops but those scanner kids couldn't or wouldn't fix the rubbed harness. the mechanic got the meter out, chased down the fault and repaired it . so this Escalade got a bath and two big white dogs to ride around in it as a reward.
 
Were I to do the "cam sensor boogie" I'd opt for the new sensor with the pickup on the side of the body.
 
When I retired, I moved most of my machine and fab shop in a 2400 sq.ft. building in my back yard. It's my Inner Sanctum/ Mancave and I prefer doing everything myself. I'm an anal control freak, and want everything done my way, and at the track or lake when I smoke somebody and they ask; "who built yer engine?" I proudly reply; "I did, in my garage, in my back yard!"
I have a source for bushings and the ability to make or modify my own if required.
I just need the specs, or I will just handle it the way I always do. OVERKILL!
TIMINATOR
 
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