It was a warm day today but not even that hot and I was boosting in 1st at 6psi then I heard a pop sound like a ballon popping and I quickly let off the gas. It didnt happen in 2nd gear only 1st. And it happened again not to long after. I was fixing my turboxs mbc, the boost never spiked and the a/f mixture was always rich. Was this detonation? If so how bad was it? Car still runs fine.

 

you might have an exhaust leaks, that's wwhere the popped sounds came from....

I have a bad exhaust leaks, and it popped many times...

do a compression test, it might sheds some light,...

 

maybe it was just backfire since you said you were running rich?

 

yeah chances are it was a backfire, might have even spit out a little flame if you're runnin a bit rich

 

What exactly does detonation sound like?

 

You cannot really hear it at WOT.

Dustin

 

backfire and since in ur case ur running really rich... when a flame for example comes out the exhaust... u hear it! its pretty damn loud... like a loud bang or pop

 

when you detonate, your engine sounds like it has a bunch of marbles in it.

 

Hmm i guess it was backfire then... i can give a sigh of relief then.

 

Is the engine making any funny noises now when driving? I had a similar thing happen the other day (maybe you saw my thread)....with a popping sound. Well, it looks like I'm okay after doing a compression test. You might want to perform one with a do-it-yourself kit just to double check. It's a good thing to have anyway.

 

Detonation or pinging sounds like ticking coming from the engine compartment. You'd probably know it if you heard it, but it's probably hard to tell with the valves clacking and the turbo whirring..

 

Yeah, it was a backfire. Since I went turbo, my car does the same every once in a while. I'm sure that I spit flames sometimes...especially when it's a really loud backfire.

 

Man, I hate to ask this... but how do you do a compression test? Is there a site that has a list of instructions, or is it in any Haynes or Helms manual? I know what a compression test is, but I just don't see how it's done with the engine still in the engine bay. How do you even crank it? what guage do you use?

I should probably ask this in tech section....

 

ok.. question for you guys..

i'm running NA, but i hear a pop also. i knowww it's from the exhaust.

but here's the thing.. i'm running a vafc at about 4-5% LEAN. so why would i still be hearing the POP sound?

this happens when i go from 1st -> 2nd at 7-8000 rpm

any help is appreciated.

 

Check http://www.c-speedracing.com They have a how-to section that explains the compression test procedure.

 

Is it 4-5% lean at 7-8k?

 

That could be an electrical problem. Don't you have af gauge? If not try richening it up and see if it goes away. Best way to know for sure is too look at the plugs.

 

Hey Anthony, thanks for the c-speed link. Yep, they had a compression test how-to. Looks pretty easy. Where do I get a compression tester (Pep Boys, places like that?)

and when the plug wires are out and that fuse it out, it says to floor the gas pedel and crank the car 5 times. Uh, do they mean turn the key and let the engine try to start -- so it'll make a noise, but won't actually start? Does it mean 5 rotations, or just try to crank it (start it) 5 times, but it'll actually rev a bunch of times?

 

No problem! That's the site that i'll be referencing when I do my tests You can get a tester at just about any auto store. They cost about 25-30 dollars. I'd probably try to get the best one you can afford since you want an accurate reading. I'm not exactly sure if there's that much difference between brands though as far as accuracy. The 5 cranks mean that the engine will try to turn over 5 times but not actually start. (like when you have a dead battery I think).

 

What you are doing is pulling the ECU fuse so their is no chance of your car starting. Then, with the compression test hose screwed into the spark plug hole, you are cranking the engine to cause pressure. If you have a hole in the top of your piston, you won't get any pressure, make sense? By 5 revs, they mean 5 revolutions of the engine. I just give it 5 seconds.

 

5 seconds or until the needle stops rising. Get a friend to help you do it.

 

from my experience, you should get the compression tester from sears because they cost less than the autoparts store e.g. kragen, autozone, etc and i believe they should a lot more accurate.

 

I got mine from the Mac Tools truck when they came by the shop I used to work at. You can order it online although it looks like it is a little more expensive than what I paid.
It was $80 but it had all kinds of adapters and is very well made. Here is a link to it - http://www.mactools.com/commerce_04/...mber=CTD300USN

 

So if the needle keeps rising for 12 seconds do you keep cranking it? Pretty much crank it until the pressure quits rising?

 

You shouldn't have to do that. If it takes 12 seconds for you to build up pressure, something ain't right. Either the batter and/or the starter is weak. Or, if your rings are worn, it might take a while for it to build. Taking 12 seconds to build up your compession isn't right.