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Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
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Author Topic: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??  (Read 246 times)
shorthorn
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Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« on: February 06, 2008, 02:40:18 AM »

So about a year ago my mechanic friend and I put a new timing belt and tensioner on my 96 2.5 venge.  It was way overdue and the tensioner was shot.  The belt was hanging loose when we took it off.  The crank was off three teeth too.  Don't really remember which way it was off(We quadruple checked it to the Haynes manual).  It didn't have a miss when we pulled it in to work on it, but it was running poorly and got awful gas mileage(10-12mpg).  So we got it all back together and now it has a miss under heavy throttle, but seems to idle fine.  Only prob at idle is that the lights dim considerably and it stalls sometimes when you let off the throttle to idle.  So I took it to a local mechanic's place yesterday and he won't be able to get it in for diagnosis for a few days.  He thinks 'bent valve'.  I know this is prolly what's wrong, but I was just trying to think of cheaper alternatives.  So here's another guess.  Hopin for any kind of input relevant to the saving money and not going to great lengths over something dumb.
I have had these expensive, junk, Directed Audio terminals on there for a while.  They've always been loose because they have the worst way of tightening I've ever seen.  A tiny little allen screw in each(3/32 or 1/8").  The negative now won't tighten at all and it basically just lays on the Red Top.  The positive is also kinda loose, as in, you can swivel it back and forth easily and even pull it off without too much trouble.
Never really considered this before, because I've had massive amounts of wattage running through the 0/2 guage power and into my 2000 watts of hungry Kicker amps and this thing barely used to dim the lights at full volume.
Anyway, sorry for the ridiculus length of this post.
Hopefully someone has some input.  I'm just tryin to save some money and get my baby back on the road. Cry
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96 Vengie 2.5L slushie wrapped in polo green

Sony CDX850MP(?) head unit
JL XR 6.5 comps, ground bolt, n twisted pair rca's
Kicker 1250.1 n 650.2
Memphis M3 MOJO 15
custom trunk that needs changed already
Optima Red Top n 0/2 power/ground
Darktengu
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #1 on: February 06, 2008, 02:59:58 AM »

Well I would start with the battery posts.  Get some better clamps on there, it's going to costs you all of 35 bucks to do yourself.  You can check your compression to give you a better idea, if your compression is good, it's not a valve issue.  There are plenty of sensors that could cause it to stall out.
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shorthorn
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #2 on: February 06, 2008, 03:11:22 AM »

10-4
I'm gonna call the mechanic and hopefully try some new terminals by the end of the week.  I'll have to get some fancy special audio ones of course, but I should have them in a few days.
What sensors could cause this?  Does the ECM need some sort of reset routine or I need to do something special after replacing the timing belt?  I have only driven this car like 2 miles since we changed the belt.  What numbers should I be looking for during a compression check?
I appreciate the fast response!   Grin
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96 Vengie 2.5L slushie wrapped in polo green

Sony CDX850MP(?) head unit
JL XR 6.5 comps, ground bolt, n twisted pair rca's
Kicker 1250.1 n 650.2
Memphis M3 MOJO 15
custom trunk that needs changed already
Optima Red Top n 0/2 power/ground
fixitfirstime
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #3 on: February 06, 2008, 03:43:38 AM »

compression check time,  your looking for one cylinder that lags more than 20% behind the others.
« Last Edit: February 06, 2008, 03:45:15 AM by fixitfirstime » Logged

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shorthorn
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #4 on: February 07, 2008, 04:35:01 PM »

Ok.  I put on the new terminals and no difference.  Didn't get it comp checked yet though.  He's gonna get it in the garage at the beginning of next week.  Here's some other ideas.  It has a horrible exhaust leak at both flex pipes in the downpipe.  Could the O2 sensors be causing a stutter or shudder like I'm getting.  Remember this is under heavy or WOT.  Also, I have a very poor open air filter on it.  I removed the stock box and put a cone on it.  Thought I read somewhere on here about a dirty throttle plate causing probs. 
I drove it after the new terminals today about a mile.  Still no check engine light.  It seems to kinda trip up unpredictably during heavy to WOT throttle. 
Any info would be great.  I'm just tryin to save a big repair bill.  The mechanic wants to go in and check my timing and such, and I'm sure that it's right.  I'd rather him not waste the time.  It's not like this is the first thing I've ever worked on or the first time I've worked on this car(6 trannys, 3 of which I put in).  Thank the lord, my foot is getting weaker as I get older.
Thanks for all the support so far!!
 Grin
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96 Vengie 2.5L slushie wrapped in polo green

Sony CDX850MP(?) head unit
JL XR 6.5 comps, ground bolt, n twisted pair rca's
Kicker 1250.1 n 650.2
Memphis M3 MOJO 15
custom trunk that needs changed already
Optima Red Top n 0/2 power/ground
Darktengu
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #5 on: February 07, 2008, 05:48:28 PM »

Get the compression test done.  Could be something as simple as your fuel filter.  It's also likely to be a sensor.  Sounds like your computer is cutting fuel when it reads too much air.  MAP sensor, O2 sensor those would be the first two I'd check.
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JusBringIt
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #6 on: February 07, 2008, 06:08:54 PM »

I would say fuel filter, worst case scenario fuel pump. (if u had gotten the oem replacement). however, u decide it would be cheaper to check ur sensor, wot is an open loop, so the computer has a set amt of fuel it will pump, if its heavy, but not WOT, then its closed loop, which would eliminate the sensor. another possibility would be clogged injectors. DEFINITELY one of the three:

fuel filter
fuel pump
clogged injectors

good luck
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JusBringIt
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #7 on: February 07, 2008, 06:30:47 PM »

open loop means its not reading from the sensor....so if it still has the issue while not reading the sensor then....
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Darktengu
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #8 on: February 07, 2008, 06:37:15 PM »

open loop means its not reading from the sensor....so if it still has the issue while not reading the sensor then....

Bah, I miss read your post.  I thought you said, it was open during acceleration.  Nevermind.
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #9 on: February 07, 2008, 08:04:36 PM »

Quote
Bah, I miss read your post.  I thought you said, it was open during acceleration.  Nevermind.

itz kool, i learned quite a bit from ya ne way Wink
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shorthorn
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Re: Misfire during heavy throttle. Loose battery terminal. Or bent valve.??
« Reply #10 on: February 16, 2008, 02:13:44 PM »

Well, I'm going to pick up my vengie this morning.  Mechanic says it's fixed.  It was out of time.  Don't I feel dumb Embarrassed
Thanks for all your input guys.  Now I just gotta get it painted and I'll be drivin my baby again.  Can't wait.  Maybe I can get some picks up of her then.
Thanks again guys!!
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96 Vengie 2.5L slushie wrapped in polo green

Sony CDX850MP(?) head unit
JL XR 6.5 comps, ground bolt, n twisted pair rca's
Kicker 1250.1 n 650.2
Memphis M3 MOJO 15
custom trunk that needs changed already
Optima Red Top n 0/2 power/ground
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