Knocking coming from front of engine area
10-05-2018, 09:06 PM
#1
Rennlist Member
Thread Starter
Knocking coming from front of engine area
What the heck is this knocking noise?
When I went full boost car stumbled and cut in and out. Shut it off, restarted and then it boosted okay except WOT it was sputtering a little and losing a little power.
10 minutes later it ran normal. When I got to where I was going, I took this video of the knocking sound.
1989 951 Idle
10-05-2018, 10:20 PM
#3
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Thread Starter
10-05-2018, 10:39 PM
#4
Nordschleife Master
My bad, just saw it said idle in the link, I thought you were slightly on the gas in the video. You are obviously in a better place to hear the actual sound clearer than on that video, so if it sounds like balance belt slap to you then that’s what you should check first. How would you think that would cause your loss of power at WOT or don’t you think that’s related to the loose belt?
10-05-2018, 11:33 PM
#5
Rennlist Member
Thread Starter
I don’t know if they are related or not. I think I may have a boost or exhaust leak as I was seeing 10.9 AFR at WOT.
10-06-2018, 01:06 PM
#6
Rennlist Member
Thread Starter
2 mechanic friends came over and listened to it and said definitely not motor problem. I had the timing belt cover, off we checked everything out under there, and everything looks good. Sound seems to be coming from drivers side front area. Any other ideas?
10-06-2018, 02:33 PM
#7
Nordschleife Master
Long shot.... the bolt on the compressor belt adjuster link has been known to work loose and that may cause a knocking sound as that link bangs against the engine compressor mount.
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10-06-2018, 02:45 PM
#8
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Thread Starter
The mysterious knocking has left town��
I drove the car and now it is overboosting and hitting boost cut.
It runs perfect at 90% throttle and peaks at 20psi.
Prior to this weekend, I was seeing 17psi at WOT.
Can’t seem to locate any bad vac connections and can’t check the WG right now as I am at the lake with no lift.
I drove the car and now it is overboosting and hitting boost cut.
It runs perfect at 90% throttle and peaks at 20psi.
Prior to this weekend, I was seeing 17psi at WOT.
Can’t seem to locate any bad vac connections and can’t check the WG right now as I am at the lake with no lift.
10-06-2018, 05:19 PM
#9
The mysterious knocking has left town��
I drove the car and now it is overboosting and hitting boost cut.
It runs perfect at 90% throttle and peaks at 20psi.
Prior to this weekend, I was seeing 17psi at WOT.
Can’t seem to locate any bad vac connections and can’t check the WG right now as I am at the lake with no lift.
I drove the car and now it is overboosting and hitting boost cut.
It runs perfect at 90% throttle and peaks at 20psi.
Prior to this weekend, I was seeing 17psi at WOT.
Can’t seem to locate any bad vac connections and can’t check the WG right now as I am at the lake with no lift.
10-06-2018, 06:19 PM
#11
Rennlist Member
Thread Starter
10-06-2018, 06:20 PM
#12
Rennlist Member
Thread Starter
10-06-2018, 07:16 PM
#14
Rennlist Member
Thread Starter
[QUOTE=shortyboy;15342400]Do you have a billet fuel rail and aftermarket injectors? Mine makes a similar sound.[/
No.
I just figured out that the knocking noise is coming from the alternator as when I put my hand on the top of it I can feel it!
Also, Discovered that the vacuum line coming from my FPR was off.
Would that cause an over boost cut and a wonky AFR?
No.
I just figured out that the knocking noise is coming from the alternator as when I put my hand on the top of it I can feel it!
Also, Discovered that the vacuum line coming from my FPR was off.
Would that cause an over boost cut and a wonky AFR?
