Detonation???

MN12 KID

Registered User
What sounds should I be listening for?

I'm getting a passengerside rattling sound under the engine bay, on throttle - intensity increases, as more throttle is given. The cats were checked at Meineke - all OK, there. Other than that, the car isn't all there with power. I can get full boost, but the actual power isn't there to back it up. Possibly leaning out?

I'm getting an occasional check engine light on and off, while coasting on the highway. Cylinder balance test shows a weak #1 cylinder - injectors? Idle sputters a little, holding a VAC between 20-22, and 750-900 RPM engine speed.

What needs to be replaced to resolve crap?

This car ran great, until the last couple of weeks - now, it's just average. Motor has about 155K on it, even though it used to run like a sub-100K car. I know I can get it back there, when I get the right help.

I have the tools, I just need the info. :)
 
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You're going to hear pinging. You will also lose power with bad detonation. Whatever you do, don't try to hear it. Detonation can destroy an engine quick. It has been hotter than norm out there too hasn't it? Heat will cause detonation to show up when it normally hasn't. I would check plugs, air filter, clean injectors and make sure you use good gas. I broke two ring lands on my last engine due to detonation. Great excuse to go crazy on the internals but quite costly.
 
Can detonation cause your emissions to skyrocket? I got a 524 of NOx, out of a legal 220 - yes, I failed emissions, bigtime.:(
 
You got a weak cylinder code on the cylinder balance test because you have a bad or dirty injector on that cylinder.
That would cause detonation on that cylinder.
Get it fixed fast or like Aaron said you'll destroy the engine.
High NOX would indicate that injector is making that cylinder run lean causing an elevated combustion chamber temp in that cylinder also causing the detonation that you hear.
High NOX readings are almost always caused by elevated combustion chamber temps. You already established that you have an injector acting up by the code you got from the cylinder balance test.
You have a bad injector.
 
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MIKE 38sc said:
You got a weak cylinder code on the cylinder balance test because you have a bad or dirty injector on that cylinder.
That would cause detonation on that cylinder.
Get it fixed fast or like Aaron said you'll destroy the engine.

If I lay off the boost, will that buy me some time to get the injector replaced? I kinda have a busy schedule, up until next Wednesday. Unfortunately, I don't have a spare car around, since my grandmother totaled her '97 Taurus.
 
Well youre gambling by doing that because you can still have detonation going on and not even hear it, boost has nothing to do with it, it only makes it worse FAST.

Detonation is equel to hitting your piston tops and valves with a very large hammer! It has the very same effect.

You will have to judge if you want to take that chance, if it was mine I'd park it until I could fix it. I dont like rebuilding motors and spending thousands of dollars fixing things that a $60.00 part or a couple hours time would fix, but thats just me.
You be the judge. Gotta hot date?
You have been warned.
 
MIKE 38sc said:
Well youre gambling by doing that because you can still have detonation going on and not even hear it, boost has nothing to do with it, it only makes it worse FAST....Gotta hot date?
You have been warned.

Not even. I work two jobs, all week along - time is very tight.:(
 
Sorry to hear that.
You could be like me right now and unemployed.:eek:
You know .....I've noticed that when I have a job I dont have time to do anything. Every job I get anymore is overtime.
On the other hand when I dont have a job I dont have any money.:confused:
Somewhere in between all that there has to be paradise, or at least as close as a working person can get.
But in the last 6 years I cant find paradise.
Its either feast or famine, there doesnt seem to be a happy middle anymore.:(
 
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