OverEzzz

iTrader: (26)

So I've owned my FD for about 2 months now. I replaced the spark plugs today, and the car didn't run right afterwards. The idle is low, it hardly idles after pressing the gas, and the engine is running lean(white smoke out the exhaust). Here are the steps that I took and the results:

1. Removed and replaced the spark plugs 1 by 1 to ensure I didn't cross the wires. I have verified the wires are in the proper location (blue on the trailing side and black on the leading side). The correct spark plugs are in the proper place, I triple checked the correct part numbers to the correct spots. I used a torque wrench. Started the engine and it idled low, and white exhaust gas started to come out.

2. Removed the new spark plugs and replaced them 1 by 1 with the old spark plugs. Reassembling and cranking the engine after replacing each spark plug. After removing all of the new spark plugs and replacing them with the old ones the engine still had the low idle. This eliminates the possibility of faulty new spark plugs.

3. Removed all of the spark plug wires and checked for voltage via ohmmeter. This verified every plug was getting voltage. Put all of the new spark plugs back in and still the low idle remained.

I'm really stumped now. What could be the problem? I think it's pretty clear that one or more of the spark plugs is not firing correctly. Any help would be really appreciated.

Aaron Cake

iTrader: (1)

White smoke doesn't indicate a lean condition, it typically indicates moisture. From just regular old condensation, very humid air, or coolant being burned.

You must have a very impressive voltmeter that can measure the 50KV produced by the ignition coils!

Have you confirmed that there is spark from each coil? Connect a plug to the end of each coil wire and crank the car with the plug leaning on the shock tower so that you can see it from the windshield. Check each coil, one after the other.

Are these stock spark plugs, or some substitute? I ask because standard plugs may stick past the surface of the rotor housing, clipping an apex seal.

Sgtblue

iTrader: (16)

*Did you change plugs from above? If so, check the boost sensor on the firewall just aft of the throttle body. Make sure the single vacuum line is attached securely.
*I can't imaging it would make THAT much difference at idle, but check the ground wire on the plug side of the block...as well as the knock sensor lead.

OverEzzz

iTrader: (26)

I'm sorry for the confusion. When I said I removed the spark plug wires I didn't actually take them off. I did exactly what you described. Removed the end connected to the spark plug. Put one end of the voltage meter into the wire and the other grounded to the car, then cranked. All wires showed voltage.

As for the spark plugs, I did buy them from autozone, but they are NGK platinum and the part numbers match the ones I pulled from the engine. While troubleshooting I removed all of the new spark plugs and put in all of the old ones, but I still had the same problem. This removes any doubt of faulty spark plugs right?

The exhaust gas has a very 'gassy' smell to it, if that makes any sense. The never showed any signs of white exhaust gas prior to changing the plugs, and was there immediately after changing the spark plugs. If coolant was mixing into the combustion cycle would it produce the same results?

OverEzzz

iTrader: (26)

I did change the plugs from above. I removed the intake piping to gain access. It's very possible I could have knocked something loose. I didn't have very good sight on the front two plugs. Do you know of a diagram or a picture which shows some of the items you talked about?

Sgtblue

iTrader: (16)

I don't have a picture off-hand. It's labeled "sensor boost" or "boost sensor" IIRC. Sometimes referred to as the MAP sensor (Manifold Absolute Pressure). Probably a picture of it in the FSM, but again it's on the firewall just behind the throttlebody. It will have an electrical connector plugged into it and a single vacuum line running to it. Without the line connected, the car will run and idle like crap...similar to what you describe.
That's why asked how you changed plugs...from above or below. If you removed the intake elbow for access from above I was thinking you might have knocked it loose.

OverEzzz

iTrader: (26)

You sir, are a genius. Sure enough the vacuum line at the bottom of the map sensor had been knocked off. Took two seconds to reconnect. Now the car runs perfect. I really appreciate your help.

Sgtblue

iTrader: (16)

Genius?...hardly. Much bigger brains here then me. But your welcome. Glad it was simple. And those little zip-ties are your friend on that hose....at both ends.