Real vs phantom knock?

[gijoe985]

So, I've got a new galant, rebuilt motor, all stock except an eBay 16g (not my doing), and mmcd shows high knock when I rev the engine. Like 40+. Now, I hear nothing and it drives fine other than I think I havbe a minor boost leak.

So how can you tell the difference between real and phantom knock? I've been reading around and still don't understand.

 

[LIV4PSI]

Are you talking about when you free rev? Than it is probably phantom knock. Have you replaced the knock sensor? Do you have a wideband?

Also, fix your boost leak. No such thing as a small one, that's no big deal . They all mess up the afr.

 

[manikbastrd]

Check your wideband...If you aren't running lean, and you aren't getting knock under loaded conditions it is probably phantom. Good luck!

 

[gijoe985]

Stock knock sensor, I don't have wide band it does happen on free rev, but also under load. It apappears to happen under many conditions...

 

[LIV4PSI]

I would replace your knock sensor and go from there

 

[Antilagged]

Check your knock sensor and ensure it isn't leaking the fluid. I remember trying to tune Manik'd old GVR4 and getting a lot of knock that ended up being phantom knock. Can kill your motor that way, ask Derek... lol Also check for any boost leaks, that could cause it as well. But it's never a good idea to free rev the motor, can hurt it eventually.

 

[gijoe985]

Plan for now is to retorque Ks, check for boost leaks, check for obvious rrattles, and then go from there. I'l keep you guys posted.

 

[gijoe985]

So, I do have a boost leak from my upper intercooler hose where the heat from the headers melted it.

I did torque my knock sensor again. I even put in one of those washers with the rubber ring. It still shows 45 knock count while revving (not high) in neutral. And while driving. I am trying to get the leak fixed asap. I have a wanted as out for the hose and I am looking at aftermarket options. Nothing fancy.

One symptom, probably from the leak, is that I'll get a major cut in power one I hot about 5k if I am pulling in 3rd. I assume that it is from the leak.

 

[gijoe985]

So, I have fixed my boost leak from my IC hose, and did not find any other leaks as of yet. I also replaced my knock sensor. I still have that engine cut out problem when accelerating while the engine is cold. I have MMCD and was watching my fuel trims. The long/short term trims have not changed, but the 02ft is at 100% under acceleration and it is 130-150% while cruising or revving in neutral.

Do I still have a boost leak? Kinda sounds like it. And the knock is still there after replacing my knock sensor. Just as much as ever, even with the washer with the rubber ring.

 

[AnotherNewb]

Stupid question but are you venting your blow off valve to atmosphere or back into the turbo intake?

 

[gijoe985]

Engine is all stock except for the 16g ebay turbo and headers.

So, recirculated.


Edit- just found leaks at the injector bases. Didn't show up until under higher pressure. New seals coming tomorrow.... still not certain if this will fix my knock problem.

I also just transported my car from my work home. 80miles. It registered a 43 knock count the whole way except under deceleration. Drove fine. Sounded fine. Temps were fine. Low on power, but otherwise good...

 

[theevozero]

Sound like excessive engine noise. How's that turbo holding up?

 

[gijoe985]

Seems fine. It was new when I bought the car. I had to do an engine swap when I got it.

Also- I just bought new injector seals from Oreilly's and they are too big. I just compared the to a blue top injector I had laying around and the seal isn't tight at all. Any ideas on where to get good ones?

 

[pot]

The blue top injector (provided your running stock injectors) part no both upper/lower from Autozone are cited below:

- ES 70600 (Felpro) *Upper
-158-0423 (Beck/Arnley)*Lower

You should be able to pick them up either from Autozone or cross referencing the part no at any over the counter auto parts store.

 

[gijoe985]

Ok, new injector seals are in. I cannot find any boost leaks at this point, though when I opened and closed the throttle body it seemed like something leaked out from the rod of the throttle body. But, by fuel trims still look lean and I still have my knock. Maybe dirty injectors? I just know that the guy blew the engine before me. I replaced long block, but have the same intake, injectors, etc. I thought I could hear some ticking fromt he top end, but I also have 3 gen lifters. So I hope I wasn't hearing actual detonation.

 

[EfiniX]

If you suspect your injectors, definitely have them checked out. My #3 injector fouled and was dumping fuel. It ran the cylinder hot, burned up a ring, and fused the plug to the head.

New motor going in this week...

 

[coyotes]

maybe run some sea foam or injector cleaner through your fuel system, see if it cleans out your injectors?

Throttle body shaft seals are a common thing to go bad on these cars, although I don't think that would cause knock. just a boost leak. Do you have the stock intercooler? Have you checked out the actual knock sensor? What's your timing set to?

 

[EfiniX]

Here's the knock sensor that Evan pulled out of my car when we yanked the old motor out. Usually the goop runs, but on mine, it ran out sufficiently to expose the sensor itself.

no good!

Tricky to get to, but if you are going to pull the TB off the intake mani to check for leaks, then you should be able to get to it without too much knuckle-bashing.