My car was tuned by Sean Ivey around 15,000 miles (see signature) and it ran great; no knock. Now its at 30,000 miles and I frequently see knock, even at 23 psi. It used to be fine at 24 psi. Unless something is physically different, I don't see why the knock would increase. Does this indicate a problem?

Here are some additional notes:
- No new mods since tune
- Ran at 2 HPD events; engine/exhaust seemed louder after the second event
- At 2nd HPD event, engine ran lean (low fuel going around heel at Watkins)
- Ran a lot of poor fuel quality from 18,000 - 26,000 miles (saw knock then)
- Moved to TX from NY; a lot of knock during the summer (to be expected)
- Replaced spark plugs: went one step colder from stock
- Weather is cool now, but I'm still getting frequent knock (maybe bad fuel?)

 

Evo 8 or 9?

 

I'm guessing bad gas

 

^ Your sig says you moved to TX from NY... A good chance the gas from TX might not be as good as the gas you were originally tuned on causing knock. I would get a retune cant expect a tune to stay perfect forever. Possibly upgrade a few things to make the retune worth it??

 

Its an Evo 9.

Here are my notes on gas:

Had it tuned when I lived in PA. Gas was excellent there. Always used 93 octane Shell or Sunoco and never had knock.

Moved to western NY and the gas was terrible. Mobile was the worst; it would knock just putt-putting around. Sunoco was OK. Didn't have access to Shell, and the other stations were almost as bad as Mobile.

Moved to Houston and the gas has been inconsistent. The 2 Shell stations I tried were terrible: lots of knock. Valero is better, but I'm still knocking. Any other ideas?

My plan is to do some upgrades and do a conservative tune on E85. I'm hoping my problem is bad gas, but I don't want to be upgrading and tuning to cover up a mechanical problem.

 

Let me ask you a few questions:

- how many knock counts are your seeing at a given rpm?

- what kind of plugs are you running? (what size gap?)

 

I'm seeing over 3 counts of knock starting around 3,000 rpm going all the way up. On bad gas I'll see over 8 counts over 5,000 rpm. I haven't data logged though, thats based just on the Tephra Cel mod. I plan on logging soon.

Off the top of my head, I think they are Denso IKH24, 1 step colder than stock. I believe I gapped them at 0.022. They didn't seem to make much of a difference compared to stock plugs.

 

How old is your clutch, is it stock, aftermarket, recently replaced ,what style if replaced?

 

Stock clutch, never been replaced. It seems to hold just fine, but I anticipate needing a new clutch soon (especially if I do the E85 upgrades). I don't see a connection between the clutch and engine knock though...

 

^ I'm assuming the lean was towards a twin disk, ie - rattle from the clutch discs and/or assembly. Just a guess though

 

PM me we can help you out.

Sean

 

A stock clutch with broken spring cage (or one that has a spring rattling around) can and will do the same thing and get progressively worse. I doubt this is a tune issue, if it is Sean and his team will take care of it. I have personally had it happen in my car and seen it in others, thats why I was asking about the clutch.

 

Yeah, I'm sure its not a tune issue since the car ran great for awhile after being tuned. I'd reccomend Ivey Tuning to anyone.

I have noticed recently that the clutch doesn't feel smooth at the very bottom of the pedal travel. Could this be a sign of a broken spring cage?

 

Maybe try cleaning your intercooler;
"Over time the intercooler becomes less efficient because of various dirty things happening to it: bugs in radiator fins, oil film coming from turbo, dirt, etc. We will clean the intercooler to get us back to peak efficiency."
http://www.vfaq.com/mods/wayback/Bra...sc/cooler.html

 

engine oil recirculating into intake pipe gunking up intercooler and pipes. The intake manifold will be affected as well. Carbon build up in the head and piston tops. Worn out spark plugs, etc. etc.

Cars need to be tuned up, and ours need more attention more frequently.