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Like I say all six coil packs are brand new. The misfire was happening before I change all coil packs and now when I get all brand new coil packs. The misfire continues to happen. After upon inspecting all six spark plug. There is one foul dry plug. Meaning that cylinder is what causing the car to run on 5 cylinders I change the foul spark plug an it happen again. That dry foul plug smell like fuel

So why isn't it the wiring to the coil?

It's very hard to explain something to people that don't want to listen Ben, but good on you for giving it a go. :P

We have only wasted more of his money, somehow due to his mechanics incompetence.

Hey everybody I am new to this website. I need help on my vq25dd. I was trying to take out the injector but rite now all the the injector is in the engine block hard to remove an I have already remove the fuel rail an everything else. Only the injector hard to come out. Can some please give me some assitance. Thanks

  • 1 month later...

man, what a tedious job! and kinda scary to pull down a perfectly running motor past a point where i was worried i would cause a bigger issue...

i couldnt get a final result as good as others. left the bits soaking in unleaded petrol for hours, then scrubbed, then high pressure cleaned. all the intake parts seem to have been stained, but the worst is gone. even the secondary intake butterflies were caked badly in at least a couple millimetres of crap.

guessing it would only have looked perfect if i let them soak for 24 hours or more.... or had them acid dipped. didnt have enough time left to do that.

egr valve now blanked off, manifold coolant heating pipes bypassed, no ecu faults have come up.

plenum spacer installed

all learn procedures worked first time. had a big cough and misfire when it first started which scared the sh*t out of me, but the procedures sorted that out

car now accelerates with 3 people in it at the same rate as it did with just me. fuel consumption to be monitored. no change in sound as far as i can tell.

just need an oil catch can to stop crank case oil blow back to cylinder 1 and 2

thanks to all for tips and pics which were a big help

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Did you use the resistor method for blanking off your EGR? I had a Kinetix V+ plenum (that i'm now returning because when I ordered it I was unaware of the EGR valve built into the factory plenum), now I have the Motordyne 5/16" spacer coming and plan on blocking the EGR when installing the spacer. I cleaned the factory plenum (upper and lower) but still need to do the intake runners. How did you go about cleaning the butterfly valves? Scrapping and vacuum, or throttle/brake cleaner? I've also Seafoam'd the crankcase and fuel-system and have noticed significant performance increase but am looking forward to finishing this beast of a project and Seafoaming through vacuum lines to complete upper engine restore.

  • 11 months later...

Hi guys.

I know this is an old thread an not even sure if any of you are still around, however i wanted to thank you all for your input and comments, i brought a 2001 250gt with 130k on the clock and was surprised/ disappointed at the lack of performance and terrible fuel economy i was getting from it, i did some searching and came across this golden thread, i decided to tackle this project myself and started the tear down, scared myself shitless when i started it up the first time as i had left a vacuum hose off!, put it all back together and she is purring like new.

thanks again guys (and girls if any?!) you have all saves me much pissing around and money.

after a week i went back in and stripped the plenum again to see if any further buildup/ oil had collected (i like making my life hard) there was more oil in the bottom chamber and i decided i hadnt done it well enough the first time so decided to polish it all up and put in some iridiums while i was at it, got a great finish this time.

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  • Like 1
  • 1 month later...

Hi guys I'm a newbie here . I bought a 300gt a few months ago and it was a bit sluggish so decided to clean the intake manifold up . Have done this and all back together now but the car won't start . It turns over and has compression and fuel and spark but just doesn't want to start. Has anyone else had this problem?please need help .....

Hi guys I'm a newbie here . I bought a 300gt a few months ago and it was a bit sluggish so decided to clean the intake manifold up . Have done this and all back together now but the car won't start . It turns over and has compression and fuel and spark but just doesn't want to start. Has anyone else had this problem?please need help .....

Check the vacuum hose running from the swirl valve solenoid (in front of the plenum) to the swirl valves (under the lower plenum), mine had a kink in it when i first put it back together and i had the same issues, reconnected it and sorted out the kink and it fired away as if nothing had happened.

  • 1 month later...

Did you unplug the loom? A few pages before mentioned about the ecu forgetting where the throttle is or something to that effect.

Glad I found this post too, gives me one more thing to do on the new car. Might stop throwing codes and pulling timing

  • 1 month later...

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