94 dodge stealth just puts new plugs in and it has a lot of knocking in motor. it ran fine prior to changing plugs. why would this happen

130

Asked by Apr 27, 2013 at 09:20 PM about the 1994 Dodge Stealth 2 Dr R/T Hatchback

Question type: Maintenance & Repair

what would cause knocking after changing plugs?

46 Answers

116,585

Did you use the proper length plug? And did you use platinum plugs?

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130

yes same length got plugs at orilleys platinum i believe yes

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116,585

It's an interference engine. If threaded end of plug is not the same as stock plugs they may come in contact with top of piston. Also did you replace the wires? If so are you positive that they are installed in correct order?

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116,585

Oh ok that's good. What else did you do other that the plugs?

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130

nothing just changed plugs

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could the computer have reset itself for the new load draw?...creating a slightly sooner spark?

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if there is a way to reset the ECU, would seriously consider doing this, could be as simple as un-doing the negative for 30 seconds, then re-doing it first introducing a load without the negative connected to "cleanse" the system of parasitic galvonic currents- these things are goddamn sensitive, and battery corrosion can make them get weird~

130

its a 3.0 rt no turbo with dual overhead cam

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116,585

Is knock on front or back head or both?

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130

i could try that. couldnt hurt i imagine. its my sons car and i no electronics r a pain. i hate these cars with all the electronics.

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130

both more so in front though

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your knocking is/probably a vacuum hose what's cracked (replace with silicone) as it's cheapo mopar, saw 6 foot length of Gates, in attractive fleshy-tone or amazon or ebay have them, BMW, MINI and other european brands have switched off butyl-rubber, but it's hella cheap to mass-produce....higher idle, less power and coughs out easily all indicators of a vacuum leak, which could have happened while you brushed up against the lines...could check for a leak by waving an unlit propane torch over each line and see if the idle mellows out~

116,585

Did the plug wire boots snap in good and tight down thru the head?

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130

thought about putting old plugs back in to see what it would do

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130

yes seem to snap on fine

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116,585

Torqued upper intake when re installed?

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your ECU continually adjusts itself based on the readings from the 02 sensor, the pressures at the evaporative unit, TPS, MAF, EGR, MAP and another 02 at the cat---makes performance decisions based on this info~ get your diagnostic readings rather than willy-nilly switchin' stuff out--- oK??

130

i dont think its vacuum all hoses r in good shape. it ran fine prior to changing plugs but the old plugs where running rich and needed to be replaced over 100,000 on them

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116,585

Judge might be on to something with the ecu. Disconnect battery for atleast ten minutes. This will reset everything.

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130

yes tighted back down, but didnt over tighten if u no what i mean.

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21,845

hope just carbon buildup till burned out clear ,otherwise piston pin or rod bearing knock not showing till firing as should .

1 of 1 people found this helpful.

SOHC=belt DOHC=chain for dodge this year~

116,585

Ok. Plugs running rich? Might be timing issue. When was timing belt last replaced?

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130

ok thanks guys i will try what u both said.. see what happens

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no way Jose, you got the tooths wrong?? nope....uh,uh~

21,845

tune-up thru intake will clean carbon !

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130

i dont know when timing was last done.

1 of 1 people found this helpful.

my buddy DavidH25 (bless his heart) suggested once to disconnect the negative, put the A/C on, pump the brakes five times, reconnect~ silly, ain't it?....sometimes the magic works...

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116,585

Also what fuel you running? Has to be 93 octane or more. 10:1 compression ratio. If running cheaper gas with new hot plugs could be predetinating the fuel prior to piston at top dead center. This would cause a knocking sound.

1 of 1 people found this helpful.

Think timing is the domain of the computer brain anymore...is like, don't mess with my decisions, now~

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130

anyway i got my boy disconnecting the battery. will see if it resets

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130

yes run premium fuel

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116,585

The non turbos are 10:1 but the turbos ones are 8:1

130

im not a mechanic. im a parts changer if u no what i mean. not a big motor head, but do have common sense. ive changed plugs in all my cars and trucks for years and never had a problem. thats why i like the old cars easier to work on. dont have all this electronic crap on it lol

116,585

If Davidh25 said it then I believe it. Will have to try that magic.

130

i really appreciate all ur feedback..ty

DavidH25 is our number 2 GURU...think cancer's got his wife...he's out for a while...just have to pick up the pieces, man...you guys have got to step up, we've lost DavidH25, Gary's nailed himself into his own coffin, the other heavy hitters haven't answered the need for over a year...so hate to say it, you gotta step up dandyoun and 7jimmy7, what's the worst that can happen, your solution causes a fatal crash?

1 of 1 people found this helpful.
116,585

Hate to hear that. Our prayers are with him and his family.

Tom, and Tenspeed pretty much at the helm, guys like smoothpapa, Racer_X, mmooney, LouB, are fantastically knowledgable guys, and it's always a pleasure to hear their responses to problems~

116,585

You forgot to mention the honorable judge_roy.

1 of 1 people found this helpful.
21,845

he has a vast knowledge, and an artist also, soft scenery peacefully depicted

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6,295

what did you set the gaps on the plugs at ? also just wanted to mention that all years and models stealth and 3000gts are belts and not chains

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105,495

I would take out the new plugs, disable spark and fuel supply and crank over the engine and see if anything blows out of the plug holes.

1 of 1 people found this helpful.

these are for a new corvette~

102,855

I would be checking the firing order. It could be a pair of wires are on the wrong plugs. If the plugs were hitting the pistons, the center electrodes would be pushed up, the plug wouldn't fire and the engine wouldn't run.

1 of 1 people found this helpful.
2,695

I've done this more then once, check the wires, I've rushed, and put the wrong plug wires on the wrong spark plug. If thats the only thing you've done, that could be it!. and then check the gap of the plugs, there not gaped,right out of the box.Dodge Stealth 1994, Spark Plug by Motorcraft®, 1 Piece. Gap: .044. If you need to replace your worn-out spark plugs, Motorcraft is the way to go. Engineered specifically for your vehicle, their high melting point provides...

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