Just changed spark plugs.

[thahman]

I changed my spark plugs today and boy was it a pain in the a** with the wiring harness in the way. I put NGK R Platinum Laser Tipped (OEM) for the replacements. The car has 129,000 miles on it and I should've changed them earlier as they were pretty dull with most of the electrode gone.

After I got everything finished, I started the car and took it for a drive and it feels much more responsive than before. The only thing is now when engaging the clutch when the RPMs drop (idling), the RPMS drop below idle before it goes back to its normal 750ish.

I also started the car earlier today and when it started, the RPMS dropped and then went back up to the normal 750ish.

These plugs don't need gapped and I checked them mine and they all seemed fine.

Before I replaced these plugs the car's idle was just fine, what could cause this?
Modified by thahman at 12:36 AM 10/31/2009

[telcoman]

I changed my spark plugs today and boy was it a pain in the a** with the wiring harness in the way. I put NGK R Platinum Laser Tipped (OEM) for the replacements. The car has 129,000 miles on it and I should've changed them earlier as they were pretty dull with most of the electrode gone.

After I got everything finished, I started the car and took it for a drive and it feels much more responsive than before. The only thing is now when engaging the clutch when the RPMs drop (idling), the RPMS drop below idle before it goes back to its normal 750ish.

I also started the car earlier today and when it started, the RPMS dropped and then went back up to the normal 750ish.

These plugs don't need gapped and I checked them mine and they all seemed fine.

Before I replaced these plugs the car's idle was just fine, what could cause this?

Modified by thahman at 12:36 AM 10/31/2009

Wow 129k miles. I wonder if I can get 150k out of mine?

I would wait & see & give the ECU a little more time.When was the last time you replaced your air filter

Telcoman

[SVTCOBRA]

Telcoman,I replaced the plugs in my daughter's 00 Max recently (86K miles) and she reported last night that she got 27 MPG which is her best ever. And, included going up the mountains. Her old plugs looked OK too.Might want to consider. Plugs cost me about $57 from Nissan. I stick with OEM.

Like Thahman says, the G is a little more of a pain because you need to loosen the wiring harness, but still not too bad.

[telcoman]

Telcoman,I replaced the plugs in my daughter's 00 Max recently (86K miles) and she reported last night that she got 27 MPG which is her best ever. And, included going up the mountains. Her old plugs looked OK too.Might want to consider. Plugs cost me about $57 from Nissan. I stick with OEM.

Like Thahman says, the G is a little more of a pain because you need to loosen the wiring harness, but still not too bad.

So when did you say you were having the next B BQ?

[tollboothwilley]

Ya, don't worry. Thats normal. Your car is just trying to adjust the timing back to normal due to the better ignition. You can speed up that process by resetting the ECU but it will just take a little driving around for it to adjust.

[thahman]

Cool thanks. I was hoping that would be the reason. I'll keep y'all posted.

[Nazc0]

im going to be changing my spark plugs next week im getting horrendous mpg im barly past 15

[thahman]

Ya, don't worry. Thats normal. Your car is just trying to adjust the timing back to normal due to the better ignition. You can speed up that process by resetting the ECU but it will just take a little driving around for it to adjust.

I've driven the car for a few hours on Saturday, a few times yesterday and today and it's still acting up... maybe I'm being a little impatient but you'd think the ECU/timing would adjust by now. I tried resetting the ECU on Saturday just in case but that hasn't helped.
Modified by thahman at 3:46 PM 11/2/2009

[tollboothwilley]

what is it idling at?

You might have forgot to reconnect the vacuum line that connects to the z-tube/g-tube. That will throw off your idle pretty badly. Vacuum leak issues normally cause the idle to drop pretty good...kills the idle.

No CEL? Sometimes when people change spark plugs on our car they swap the #3 and #5 ignition coil wires.

cylinder order numberingFront of car <<< 2 - 4 - 6 (drivers side) 1 - 3 - 5

If this was the case though, you'd hear very very rough idle and CEL instantly with serious pre-ignition.

[thahman]

Yeah, everything is in the right order.

I gotta pull out each spark plug one by one and gap the darn things. It's my fault for believing the Kragen parts guy that they're pregapped. I'm surprised the car even started.

[SVTCOBRA]

all of the oem plugs that I've ever replaced were pretty darn close. Close enough in my opinion not to matter, but I still adjusted a couple of them.

[tollboothwilley]

Yeah, everything is in the right order.

I gotta pull out each spark plug one by one and gap the darn things. It's my fault for believing the Kragen parts guy that they're pregapped. I'm surprised the car even started.

they should be pre=gapped from NGK.. I tested mine before I installed them and they were spot on.

Idle should be at 700 rpms +/- 50. 650-750 is the normal operating range. If your idle drops below 650 it gets rough. normally that is due to vacuum leak condition or a very dirty throttle body.

Double check that the vacuum hose connected to the intake tube is on tight. If you have a plenum spacer make sure the bolts are all torqued appropriately (not tight, 90 INCH pounds I believe).