Knocking after oil change

[andysmee]

Since I am resigned to the fact that the car runs fine until I do any servicing on it, I need help with this week\'s problem...
 
I am getting significant knocking where I didn\'t last week. I have had an instance of 94% (%?) knock accompanied by the engine management light, then briefly something around 60% and since then it has calmed down to above-average 30% occasionally
 
Last week it was running fine with a peak of 23% every now and then on WOT.
 
This weekend I changed the oil, oil filter and tightened the negative terminal on the battery. The fuel was the same tank full before and after.
 
Any ideas?

[nikp]

Checked the level of oil? Also, what type was it? (Mineral, synthetic, semi-synthetic). Was it 10w-40? Suffice it to say, that if those high figures you\'re getting were really knock, you\'d have lost an apex seal by now. But a tuner with a wideband and datalogit software should be able to tell you for sure. Carl\'s not a million miles away.

As long as it\'s still holding oil, then you can\'t really go wrong!

[Red and Single]

I saw 149 the other day.... I was off throttle so that was cool :rollin

[rx7veilside]

on boost or off i have been told repeatedly that knock of boost is not a issue even though that flashing light can be unnerving but if on boost and flashing then u do have  a prob go see carl but dont disturb him if he building my engine:)

[andysmee]

these very high figures were on full boost, WOT :Thumbsup!
 
I usually get 17-19 on the motorway (off boost) and low 20\'s when WOT, so these two readings were unnerving.
 
...but I\'ve had nothing since, everything is back to normal.
 
I don\'t believe in blips so there must be some explanation. The intake temperatures were abnormally high as I had just been waiting in a lay-by and the engine bay was seriously heat soaked, water in the 90\'s, air in the high 70\'s, but the mapping should account for this, shouldn\'t it?

[rx7veilside]

you have had a lucky escape if u had those figures on boost..those intake and water temps are too high to start booting a car the mapping wldnt take into account those kind of extremes and u prob had a mild det..as a precaution these cars shd run water injection yo take the sting out of high intake temps or run pr injection(personal restraint)

[nikp]

Water temps are not an issue , but i was told not to welly mine if intake temps are higher than 50 as the mapping DOES NOT account for this.

[andysmee]

sound advice, thank you. I\'m working on the intake temperatures in any case, I hadn\'t read any advice on here before about high intake temperatures and the Apexi not being able to adjust (and hence, having to show restraint)
 
The heat soak effect on my car regularly gives me intake temperatures in the 60\'s after standing for a while, when driving hard it will be in the 50\'s and cruising it\'s in the 40\'s (and it\'s winter, folks :eek)
 
I am looking to get an air intake straight into the engine bay and a vented bonnet and bigger down pipe to help get heat out again. I would rather use water injection for safety than to solve this one - same goes for fan mods, would rather address the problem than just compensate elsewhere.
 
Having said that, a better I/C or water injection has got to be on my shopping list...but not until next year for money reasons

[nikp]

Think you\'re gonna need a better IC in that case. Even when i do get heat soak of 50+, all it takes is a few minutes driving and those temps start to drop. On a cruise i see about 29-30 in this weather.

[andysmee]

I don\'t really understand why induction kits on the FD are designed without an air intake.
 
You seem to have a choice of either forcing the air through the I/C (from the stock air scoop) and letting the induction kit suck air from the engine bay
 
...or venting the air into the engine bay (from the stock air scoop) for the induction kit and leaving the I/C with a poor air feed.
 
I have tried the latter which is crap, perhaps the former is better as the I/C will work properly. The ideal appears to be to have a specific air feed for the induction kit and force all the air from the stock air scoop through the I/C (and then up-rate the I/C, obviously)
 
...clearly I\'m talking about using what I\'ve got, not going with a FMIC, V-mount or water injection which would solve the cooling problem but it still wouldn\'t provide air to the induction kit.
 
I have plans to mimick the stock air scoop to provide a feed to the induction kit, has anyone tried to do this? Is there space side-by-side with the stock air scoop to build a simple ally vent? I figured this would be the most elegant and the least restrictive way of getting air in. I am not a fan of vented light covers or just knocking holes in front bumpers...

[nikp]

I don\'t think a cold air feed is the solution, unfortunately. The reason being is if you had a cold air feeding, feeding the intakes nice cool 20 degrees air, it then goes through the turbo, is compressed, and just heats back up again afterwards. Maybe there\'s an argument that says it\'s not heated up so much, but i\'m not convinced (and don\'t know the physics laws to prove either way). The intercooler is designed to cool this heated compressed air back down to some good temperatures, and that\'s therefore when the effort must be concentrated back onto.

[andysmee]

I\'m not convinced that going into the physics would necessarily solve that one...but there are plenty of people who build heat shields for their induction kits to help reduce intake temperatures and plenty of people using vented headlamp covers to get fresh air into the induction system.
 
I am inclined to run with the common sense view which is that the colder the air going into the induction kit, the colder the compressed air coming out of from the turbos. Whether the science would absolutely support this is not a discussion for here IMHO (perhaps in the members area LMAO!)
 
I shall track my intake temps and we shall see.

[rx7veilside]

most induction kits gains are pure waffle..the air will in most cases be warmer than a stock airbox and even with ducting run it through a turbo that has 800deg exhaust gas floating around it then u will appreciate how insignificant the air filter intake will be..water injection imho shld only be used for tuning by die hard power junkies but shld be used for all to ward of det if u have heat soak and still boot it..first step for me would be water as its cheaper than a new intercooler and then take it from there but booting it at 70deg and u risk going pop as standard i/cooler is gonna struggle to cool it

[Mave]

Definitely hotter intake air = hotter air coming out of the turbo, also works the turbos slightly harder, so higher back pressure. But... I\'d agree, the place to spend effort is on the intercooler side as it\'s the intercooler delivery temperatures which cause the most problems.