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-   -   PAS (power steering) causing engine knock (http://www.subaru-impreza.org/forum/engine-bay/108474-pas-power-steering-causing-engine-knock.html)

alunian 04 Apr 2020 03:35 PM

PAS (power steering) causing engine knock
 
Car is a UK Turbo 2000, mods are :
MAC 3 port boost solenoid
TD05 Turbo
Samco Intercooler hoses
Remap 303bhp by Bob Rawle

Just wanting to know if anyone has had this issue with power steering?

This is a weird issue, I've heard of exhaust shields rattling causing engine knock which makes sense, but I have just discovered that something relating to the power steering is causing engine knock.


When I first got the car the metal cover that goes from the power steering reservoir to the alternator wasn't bolted to the reservoir. It had no issues even when it was remapped and it didn't cause any problems with tuning as Bob Rawle said he was able to add a lot of timing to the map.

The only problem I found was that the PAS belt would squeal in freezing cold weather, turned out that the belt was 15mm longer than it should and it was brand new. When I had the time belt done I also got the correct size PAS belt supplied and fitted by Alyn he stated it was the same brand and product code as what was already fitted he showed me before fitting it.

This is when the issue started. Again the cover for the belt wasn't bolted down as the bolt was missing. However it was hitting the bonnet when corning and hard acceleration as it had worked itself loose (I could hear and feel it through the steering wheel) this was showing in the logs as a very small amount of engine knock of -1.5 degrees of timing for less than a second at 4300rpm and then it would add the timing back. I then bolted it down and ended up with engine knock of -8 degrees of timing for just under 1 second again at 4300rpm and I felt it, it felt like no boost and then it would add the timing and the car would take off again.

I have now removed the cover and cable tied the throttle cable to the PAS reservoir, I still get engine knock of -8 degrees of timing but its only for approximately 271ms each time on the data log and I can barely feel it.




I have noticed that my exhaust shields near the radiator is broken loose so Im going to try and remove it to see if that makes a difference.

bugeye_bob 05 Apr 2020 12:50 PM

Re: PAS (power steering) causing engine knock
 
Is the knock sensor torqued correctly and no cracks?

alunian 05 Apr 2020 08:42 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by bugeye_bob (Post 424905)
Is the knock sensor torqued correctly and no cracks?


I'll have to get back to you on that one, I remember replacing the knock sensor just before it was mapped because the old one was setting off the check engine light as it was rusty and cracked, I installed it with out a torque wrench and just kept doing quarter turns when it bottom out until it felt tight enough.

bugeye_bob 06 Apr 2020 08:31 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by alunian (Post 424906)
I'll have to get back to you on that one, I remember replacing the knock sensor just before it was mapped because the old one was setting off the check engine light as it was rusty and cracked, I installed it with out a torque wrench and just kept doing quarter turns when it bottom out until it felt tight enough.

I have happen across some too tight being a little too sensitive, which may , only may, be whats happening here,
Free check lol

alunian 07 Apr 2020 09:36 AM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by bugeye_bob (Post 424907)
I have happen across some too tight being a little too sensitive, which may , only may, be whats happening here,
Free check lol


It turned out it wasn't tight enough it had came loose, I cant seem to torque it down enough using a multi point socket as it keeps jumping off the bolt as it bottoms out. I've ordered a 6 point/sided socket.

bugeye_bob 08 Apr 2020 12:43 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by alunian (Post 424908)
It turned out it wasn't tight enough it had came loose, I cant seem to torque it down enough using a multi point socket as it keeps jumping off the bolt as it bottoms out. I've ordered a 6 point/sided socket.

Nice cheap fix, love those lol

alunian 11 Apr 2020 05:11 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by bugeye_bob (Post 424909)
Nice cheap fix, love those lol

So do I if it works, but I still dont get how the power steering cover/bracket was making it worse ?

bugeye_bob 12 Apr 2020 07:49 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by alunian (Post 424910)
So do I if it works, but I still dont get how the power steering cover/bracket was making it worse ?

Harmonics, over what it would normally hear is my guess.

alunian 14 Apr 2020 03:41 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by bugeye_bob (Post 424911)
Harmonics, over what it would normally hear is my guess.




ok


I've managed to torque the bolt down, but my battery is dead.
Unbelievable I only drove it last week. I hope it is the battery, I checked the voltage after 4 attempts and its at 5v and with each attempt I noticed the fuel pump would prime slowly and sometimes not at all.

bugeye_bob 14 Apr 2020 08:30 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by alunian (Post 424912)
ok


I've managed to torque the bolt down, but my battery is dead.
Unbelievable I only drove it last week. I hope it is the battery, I checked the voltage after 4 attempts and its at 5v and with each attempt I noticed the fuel pump would prime slowly and sometimes not at all.

Just to rub it in(joking), Id forgotten to connect mine back up to the conditioner and wondered if it would be flat, but it started straight away, id left that a few weeks tbh,
We had a flood warning over the bank holiday, so I stick mine up in the air out the way.

alunian 16 Apr 2020 03:34 PM

Re: PAS (power steering) causing engine knock
 
Fixed, it was the knock sensor bolt.
:tr_thanky

bugeye_bob 17 Apr 2020 03:28 PM

Re: PAS (power steering) causing engine knock
 
Quote:

Originally Posted by alunian (Post 424914)
Fixed, it was the knock sensor bolt.
:tr_thanky

Brilliant, Glad a daft suggestion helped.


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