'94 4.6L cat with a miss outta no where - TCCoA Forums
 
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post #1 of 26 (permalink) Old 09-07-2006, 04:13 PM Thread Starter
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'94 4.6L cat with a miss outta no where

Yesterday my cougar started having a miss that has progressivly gotten worse, its now to the point that at a light the car will dip to 500rpms (sometimes below) instead of the 750rpms it usually stays at. Its misses worse acceling with mid throttle and even some at full. The motor is a used one i put in last month, with 60k miles on it. The wires look fine, the plugs are brand new and when i checked the coil packs (before i put the motor in) they checked out ok. There are no vaccum leaks and the CAI has never caused problems before. Could part of the problem be the insane humidity we've had here in orlando the last couple of days? Im not counting out the wires or packs but since the CEL hasnt come on yet, im unsure and im looking for any possible reason.
Any help would be great thanks?

Last edited by mn12sskiller; 09-07-2006 at 04:56 PM.
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post #2 of 26 (permalink) Old 09-07-2006, 04:53 PM
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Do you use oil on the CAI filter, like a K&N? If so, clean your MAF.

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These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.
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post #3 of 26 (permalink) Old 09-07-2006, 07:51 PM
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Look at the MAF first and then double check you wires, preferably in the dark while spraying water on them to see if any are bad. Many times random misses are caused by plug wires that begin arcing, and often times it is horrible when the car is under load.

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post #4 of 26 (permalink) Old 09-07-2006, 11:05 PM
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Mine did that before the computer went completely outta wack

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post #5 of 26 (permalink) Old 09-08-2006, 01:05 PM Thread Starter
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Quote:
Originally Posted by 94mncougar
Mine did that before the computer went completely outta wack
ok I dont even wanna think about that one! Im gonna go ahead and clean the MAF and CAI and check the wire and coil packs (basiclly work through the system) today and Ill let you guys know
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post #6 of 26 (permalink) Old 09-08-2006, 01:34 PM
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ill bet on wires.
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post #7 of 26 (permalink) Old 09-08-2006, 01:39 PM
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ill bet on wires.
ME TOO! Wires fixed my miss!
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post #8 of 26 (permalink) Old 09-08-2006, 02:38 PM
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wires, and what kind of plugs did you put in it..

(awaiting response)
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post #9 of 26 (permalink) Old 09-08-2006, 04:04 PM
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wires, and what kind of plugs did you put in it..

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MSD wires and Motorcraft 12C's <~(chipped of course )

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post #10 of 26 (permalink) Old 09-08-2006, 08:40 PM Thread Starter
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well thanks to the ran i couldnt get anything done, Im personally betting on one of the packs because its acting like it did last time one went band (i was hopeing to get MSD packs before one gave out but oh well)
the plugs im running are the bosch dual plat. and the wires are supermax 8mm. like i said i'll let you know when i find out.
Thanks for all the info so im not going in blind
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post #11 of 26 (permalink) Old 09-08-2006, 08:54 PM
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Quote:
bosch


Quote:
supermax
super whats? is that who makes them?
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post #12 of 26 (permalink) Old 09-08-2006, 11:28 PM Thread Starter
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supermax- bosch if im not mistaken, both where a "I really need them whats autozone got in stock" deal
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post #13 of 26 (permalink) Old 09-09-2006, 01:10 AM
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Does the car do this when it warms up or is it all the time. Now that you guys mention wires, mine would miss, but only when it warmed up. Also, I have read that the coil packs can cause a miss after warming up when they are bad - not to say that they can't cause it when they are cold.

Winter mods included:
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- Saggy Suspension - fixed!
- Chipped paint
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post #14 of 26 (permalink) Old 09-09-2006, 08:10 PM Thread Starter
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well i switched out the packs from the ones i had on my old motor (they where brand new and checked out good) because I was getting weird readings from the packs that where on there. Didnt fix it. So since its dark out im going to check for a light show. Its almost acting like my 5.0 f-150 would when it got a tank of bad gas.
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post #15 of 26 (permalink) Old 09-10-2006, 01:15 AM
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Maybe you have a clogged fuel filter or a weak pump?

Jay

These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.
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post #16 of 26 (permalink) Old 09-10-2006, 01:21 AM
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maybe bad eec no firing injector???

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post #17 of 26 (permalink) Old 09-10-2006, 09:18 AM
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I would pull the plug wires and check for water/debris in the sparkplug tubes. I had this after it rained one day. If the plug wires don't seal against the engine and water gets in there you get an awful miss.
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post #18 of 26 (permalink) Old 09-12-2006, 12:18 AM Thread Starter
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well the only thing left is bad gas (which theyve been cutting like crazy down here) plugs are clean (in a good way) all the o2 sensors check out, new wires are on, its driving me nuts!!! It misses all the time, all the way up until WOT, and it has no power whatsoever, ive only got a 1/4 tank left so im going to add gas dry and fill it up again.
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post #19 of 26 (permalink) Old 09-12-2006, 07:30 AM
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does it run any better with the maf unplugged? you could have yourself a bad one.
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post #20 of 26 (permalink) Old 09-12-2006, 08:44 AM
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There are a few other items to check. Take a look at the serp belt tensioner, if the bearing is worn out it lets the tensioner hit the timing cover under load. The knock sensor is right under the tensioner. The last thing is the vacuum hose that goes from the pcv valve to the back of the engine. Follow the line and see if there are any holes in it.
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post #21 of 26 (permalink) Old 09-12-2006, 09:58 AM
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Hopefully it's not it, but I am starting to think that it is the EEC. I thought that SOHC tbirds didn't have knock sensors? Good luck with the miss, make sure to post what was the problem

Winter mods included:
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- Chipped paint
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post #22 of 26 (permalink) Old 09-12-2006, 11:37 AM
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Quote:
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I thought that SOHC tbirds didn't have knock sensors?
They don't.

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post #23 of 26 (permalink) Old 09-13-2006, 04:53 PM Thread Starter
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found and fixed it....just proves its the little things that get overlooked, that little foam rubber elbow that connects to the top of the pcv had a crack in it. replaced it and tada! its fixed.
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post #24 of 26 (permalink) Old 09-13-2006, 06:00 PM
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Well, ain't that a bite. Well, look at it this way, you just learned some more about your 'bird.

Jay

These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.
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post #25 of 26 (permalink) Old 09-13-2006, 09:56 PM
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I'm glad it wasn't the computer

Winter mods included:
- Developing Rocker Rust
- Saggy Suspension - fixed!
- Chipped paint
- I'm sure more to come... TOTALED
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post #26 of 26 (permalink) Old 09-13-2006, 11:26 PM Thread Starter
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its funny ive been working on cars my whole life (old ones and friends little cars). And to this day I still overlook the little things.
Thanks for all the ideas
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