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Discussion Starter #1
I have an 89 Taurus 3.0L with about 82K miles on it. There is a terrible
knocking on acceleration as well as once the car is up to speed. Letting up on the accelerator will stop the knocking momentarilly, but once the car gets to a level speed again, the knocking comes back. It does not happen at idle. Higher octane gas makes no difference.

Any suggestions on where to look?

Thanks!

--

Shannon
 

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Someone will have to double check me on this, but I would guess that you need new spark plugs or wires or both, unless they have been changed recently. My car showed the same symptoms after I removed and replaced the plugs for an inspection.. I think that probably I didn't tight one of the plugs enough when I put them back. But after I got new plugs and wires (it was time after 40Kmiles :eek: ), it ran fine :banana:

Hope this helps.
DD
 

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Discussion Starter #3
I have also been ckecking for the other instances when it occurs, and it does not happen when the car is in park and I rev the engine, nor does it happen in reverse. Only in gear and upon acceleration.
 

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Sounds like spark knock to me. Could be one or more of a lot of things. Timing, carbon build-up, crappy fuel, blah, blah, blah.
 

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Well, engine knock is also known as pinging and sometimes detonation. But a knocking noise can be caused by connecting rods (rod knock), or piston slap (piston has enough clearance to make a slapping sound as it rocks a bit in the cylinder). It's hard to desribe the difference between these sounds in writing. But someone that has heard these sounds before can usually differentiate them easily, when you can hear it in person. Obviously, the fix is different for pinging than it is for rod knock. So, that's the first step for me, is to try to figure out which you are dealing with. Can you get a recording?
 

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I have to agree that it sounds like pinging. because you say it happens while under load also. Usually rod knock and piston slap will be evident when revving in nuetral also.
 

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I should consider reading the WHOLE post more often! :p

I saw that it said you used higher octane gas and still no worky. I still think it's spark knock because it only happens under load. My 89' Escort GT did this and let me tell you the story.

It knocked under acceleration, climbing hills, sometimes on flat roads. There was a notch on both the distributor and the head showing the stock setting. High octane didn't help. I checked the timing and it was WAY high (it's been years, but I think it was like 18* or 20* BTC). I cranked it down to like 14* of 15* and used 93 octane and it was fine. I started having other problems I couldn't figure out so I paid the dealer $50 to diagnose it. They said it was because the timing was wrong and they went and turned it back to the stock setting. It knocked as soon as I pulled out of the dealer, and all the time on flat roads. :rolleyes: Idiots, apparently they didn't drive it after they "fixed" my problem. As soon as I got home I turned it back and eventually found my other problem. I never could figure out why the stock setting caused the timing to be advanced so much, could have been the knock sensor but I don't remember if it had one or not. Could have been a lot of things.

Either way, the point is your distributor could have come loose enough to advance itself and octane isn't going to help. There could also be something else wrong. I think it's a timing thing because it sounds like spark knock, and octane doesn't make it go away. Even if it did, you shouldn't buy higher octane to fix a problem.
 

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I'm thinking that the engine has either a serious carbon problem or (more likely) the timing is waaay advanced.

I'd start with checking the timing, Shannon.

And since everyone else seems to have forgotten their manners... :p

Welcome to the :tcca: :chili:
 

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Oh crap, SORRY!! I didn't even notice his post count. Bad me!!! <pound my head on the screen> :punchbob:

Welcome to the TCCA!!! If you haven't noticed, we are full of useful and useless information. Enjoy youself and don't get addicted like I did.
 

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Discussion Starter #10
Thanks for the info everyone!

Hubby is going to change the plugs, wires, and everything (at my not so subtle "urging") as soon as he gets home from work today.

I have only had this car since February and it is really in good shape, and I would like to keep this one running good. You would think that having a mechanic for a husband that it would always be the case, but unfortunately, he dispises working on his own cars. :(

Anyway, I will let you know if this fixes the problem.

Thanks again for your help, and thanks for the warm welcome. :)

Shan
 

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Discussion Starter #11
Well that was a huge waste of $54.00!

Whatever the problem is on that car, is has nothing to do with the plugs, wires, cap or rotor. The clattering is still there. :angry:

Now hubby seems to think that it has something to do with a plugged catalytic converter. Does this sound right? I think he has a screw loose!
 

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I recommend calling around to the local muffler shops: For about $10 or $15 dollars (and a few will do it free), the shop will drill a tiny hole in the exhaust pipe ahead of the cat, and put a pressure probe in there to see what's going on.

Then they will weld it shut after they're done. That will let you know for SURE before you spend $600 or so on a new cat! :eek:

The other way to check this is with a vaccum gauge. 'T' the guage into the MAP sensor vaccum line, and start the car. At idle, there should be 17 inches of vaccum. Rev the motor a little, and the needle should drop a bit, but then return to 17" of vaccum OR VERY NEAR. Anything else indicates a plugged exhaust system.

Good luck!
 

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Discussion Starter #14
I will call around tomorrow and see if I can come up with a shop that will do that test for me.

If it makes any difference, I discovered today that the noise is constant when there is additional load on the engine, ie: using the air conditioner.
 

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Not up to speed on the older Taurus, But the first thing I would check is the EGR valve. second thing cooling system, water pump, thermostat, condition of radiator and so on.

good luck
 

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OMG!!1 WTF!1!! LOL!!1!one *cough*checkthetiming*cough*
:lol:

Seriously though... I would really check the timing... it sounds almost as if it's way too advanced from baseline.
 
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