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04-25-2013
just changed out my spark plugs on my 2000 gtp s/c and its running fine at idle and under vacuum but once it goes under boost it sputters, was running fine before I changed them. Could they be gapped to much I was told at the store they were supposed to be gapped to 60 and that they were already pre gapped, which I checked to be sure and they were. Also do they have to be Iridium plugs or Platinum?
04-25-2013
What plugs did you put in? IF you purchased Iridium or Platinum and tried to gap them, you might have bent the nipple sticking up.
If you got copper, gap them at 50 and good to go. I've never gone larger then a 55 gap on mine, others can comment on if 60 is to much.
Did you replace the wires? If not where they ok? seated good on the new plugs? create a short when pulling them off and reusing them?
04-25-2013
It had NGK's in it and I replaced them with A/C Delco and no I didnt gap them I just checked them to make sure they were gapped at what they had told me. Wires looked fine and went back on fine. Like I said car idles and runs fine until it goes under boost
04-25-2013
part number 41-601 on the new plugs
04-25-2013
Check your vac lines. The MAP is back there and I've seen several people snap vac lines and even the nipple off the MAP sensor wrestling with plug wires.
04-25-2013
ok will do thanks man. So the whole Iridium or Platinum wouldnt affect it tho?Originally Posted by dbextreme
04-25-2013
naaa. The part number you gave shows copper correct? I run the cheap copper Autolites in my car, I just change them every 3rd oil change. A buddy has a stock 97 GTP he runs the Iridium in his with no problems. I personally hate Platinum because they seam to hate high fuel, but I ran them in a muscle car thinking I'd get gains and was I wrong... But that's my opinion on them, I'm sure others love them so to each their own.
The reason I say vac lines is because your MAP is run off the nipple under the snout of your supercharger so it sees both vacuum and boost. If it's not reading boost it will mess with your fuel. Which reminds me also check your electrical connections. Once changing my plugs somehow I snagged the single wire going to my rear knock sensor and jerked it from the sensor. Another guy on here tugged on his harness hard enough to pull one of the pins out if his Output Speed Sensor. Both these issues arose from pulling on the plug wires then when they pop off there's that moment you don't really know what you hit.. LOL Neither of these issues would cause your problem, just giving examples of what can and has happened.
Good Luck!!
04-25-2013
ok thanks man this really pisses me off lol do you know of any website or link to a wiring diagram of these engines. Its my first rodeo with these things Im more of a LS guy, so I dont really know my way around these engines yet as far as location of sensors ect.
04-25-2013
I highly doubt it's an electrical connection to sensor issue, I just used them as examples. But Google can be your friend regarding sensor locations. There's not much running down the back of the motor: MAP, Rear Knock, O2's, Oil Pressure, Speed Sensor... Might be missing one or two. There should be a vacuum routing sticker under your hood somewhere showing you what all's back there. I know there's the EVAP and MAP above the valve cover, both have those brittle vacuum lines running to them.
Hope others chime in to, I'm by far smart when it comes to these cars.. LOL I understand the frustration, I spent 4 hours today tracking down an electrical gremlin in my car...
I'm more of a 4-5 wire hook up late 60's early 70's model car guy myself (I'm only 33 though LOL) but I'm learning more about the computer controled stuff. My LT1 car is fun and still pretty simple. if it blows I'll do an LS swap probably, might just build the LT1 to a 383 and be done with it but that's later down the road.
04-25-2013
The plugs you Bought are terrible. Take them out and note how the porcelain is all cracked on more than half of them. Replace with autolite copper cores (either 606 or 605) and enjoy a smooth ride again.
Thank me later.
04-25-2013
Stick with the stock delco Iridium plugs if you arent modded.
The waste spark ignition system eats platinum plugs and that why we don't use them.
04-25-2013
yea man LS is the way to go A LOT OF mods for it the possibilities are endless. But then again im sure its the same for older stuff. Its just what I've grown up on and own so yea but cant go wrong with it. Thanks for all the help.I highly doubt it's an electrical connection to sensor issue, I just used them as examples
Hope others chime in to, I'm by far smart when it comes to these cars.. LOL I understand the frustration, I spent 4 hours today tracking down an electrical gremlin in my car...
I'm more of a 4-5 wire hook up late 60's early 70's model car guy myself (I'm only 33 though LOL) but I'm learning more about the computer controled stuff. My LT1 car is fun and still pretty simple. if it blows I'll do an LS swap probably, might just build the LT1 to a 383 and be done with it but that's later down the road.
You think so I might just go ahead and swap em, have you had issues with these plugs?
04-25-2013
yea im not modded completely stock other than a K&N CAI but yea well the plugs arent platinum, I thought they were but it turns out they are copper. So is copper not good for these either?
04-25-2013
Copper is fine, they just don't last very long. Maybe 15,000 miles or so.
04-25-2013
Ok well I think im going to go change these plugs for autolites see if that helps if not ill do the iridiums and also check if I didnt unplug a wire or a vacuum line.
04-26-2013
That's why I change my plugs every third oil change. Rule of thumb for me to keep up with. And I've had good luck with Autolite's. I've never used Delco copper plugs so I don't know if they are good, bad, indifferent...
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