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Discussion Starter #1
Ok, 2003 3.8 118k miles. I noticed that she starting having issues. I used to be able to get great acceleration from a stop. that had disappeared and the milage was horrible. I am the 2nd owner, bought it with 108k, so I decided to do a tune up. I replaced the plugs with platinum and new Taylor 8mm wires, The plugs were called to be gapped at 052. The old ones were so disintegrated that the gaps ranged from 065 - 089. They were pitiful! After this was done, it idles perfect accels smoothly until 4 grand. than it sounds like a miss. When I drive it, there is the same miss under a load. No codes are thrown double checked the vac lines, i pulled each wire from the coil one at a time and it idled like crap after each individual wire was pulled. I cleaned the MAF sensor with electrical cleaner. I am out of ideas, maybe the coil pack?

I need help
 

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Did you check to make sure all the wires are properly seated on plugs and coils?
 

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Loss/lack of power could also be:

Excessive EGR flow (some what less likely because higher RPM's).
Low fuel pressure. Start by changing the fuel filter.
Exhaust blockage

This could also be an ignition problem. Did you follow the factory spark plug wire routing? Did you use the factory stand offs and looms? Are the spark plug wires touching any metal parts?

Consider if the wires are touching a metal part, because you have a preimum wire, this may not misfire at low RPM's.
 

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Discussion Starter #4
Factory routing was followed, I do not see any arc'ing at night(dark) Fuel Pressure is 38psi @ the rail, steady. again it started when I replaced the plugs, first, I didnt change the wires until after the issue (they were 2 days after the plugs) I noticed it when just the plugs were changed, but I figured it was the wires that was causing it.
 

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Regarding the fuel pressure. I'm assuming that it was verified under load and it's OK. Further, going to assume that the fuel pressure sensor intake vacuum reference line is connected and leak free.

I'm also assuming that you have ruled out the other possible causes. Now the stakes get higher.

Clogged fuel injectors. Consider an injector cleaning/flow test service such as injectorrx.com. Once cleaned, the injectors are as good as new. Cheaper than new.

Others have reported good results with Seafoam.
 

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Discussion Starter #6
Thanks for the responses. I am going to remove the Bosh plugs that I put in and replace them with the NGK GP's.
The 38PSI was at WOT. I cant stop thinking that it is related to the new plugs. If this dosent work, I will replace the Coil pac. I figure with 120 K on her, it would be preventitive if nothing else.

I will explore other issues if that doesnt work.
 

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which bosch plugs are you using? the ones with 4 electrodes?
 

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which bosch plugs are you using? the ones with 4 electrodes?
I used to have those!! LOL :shigrin Bosch +4s... Totally overrated, although it may have helped them last longer:?:

Either way, I'm running NGKs now (G-power, I think). :yelwacko:
 

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what i was getting at is the +4s or any other multi electrode plugs can behave really terribly and cause all sorts of problems
 

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Discussion Starter #10
Update.... Changed the plugs to NGK G and it still has issues, but now it's a differant issue. It now runs decent. I seems to have an issue if you rev past 4k with no load on the engine, could this be a rev limit? anyway when driving it will go to Red line no issues. Still seems a little sluggish though. I will buy a new coil pac just to make sure its new..... The saga continues:?:
 

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I'd have the O2 sensors checked...at that milage they may be "sluggish" or not working properly...also the mass air meter may need adjusting, the other thing is the throttle body may need adjusting/cleaning...
You might just try running some premium fuel and fuel system cleaner for awhile and see if that improves your situation by cleaning the internals
 
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