Misfiring while cruising

[jalexquijano]

I guess i will need to hire one of you to come to Panama and solve this problem. How come i cant drive my car on traffic as i have to struggle to avoid spark plug fouling on cyl 3 and 4 which eventually leads to misfiring and lumpy idle.

[Mark Maras]

 I didn't give up on #5. That plug looked pretty darned good, imho, having idled for a long time. I was just glad to see that all the plugs weren't black. It doesn't matter to me if the other five were black. The fact that at least one plug looked good narrows the problem down. Also, the original problem was always isolated to #4 until the dist was removed and reinstalled. Then #5 started doing the same thing as #4 did previously. Seems to me that moving the wires and or disconnecting them and reinstalling them is the cause for the #5 gremlin and probably #4 too.

 I considered valve seals too but the two dark plugs looked sooty not oily. I'm hoping that re-seating the wires will eliminate the misfire. With Alex removing and reinstalling the wires the misfire may move to another cylinder until all the wire connections are right. 

[jalexquijano]

I will do the test again from scratch in one hour. I will leave the car idling with those old plugs at the parking lot for 15 mins and will then pull the plugs out.

[Mark Maras]

8 minutes ago, jalexquijano said:

 How come i cant drive my car on traffic as i have to struggle to avoid spark plug fouling on cyl 3 and 4 which eventually leads to misfiring and lumpy idle.

 You asked. Here's my gut feeling. It's based on what I'd do (if it were mine) to get your car back to a RELIABLE DAILY DRIVER. Honestly I'd put a stock engine back in it. Zs didn't like hot temperatures from day one and Nissan never did successfully solve the problem. You'd be a lot happier with a stock engine. My daily driver (summer and winter was a bone stock early 71. The most reliable, trouble free car that I've ever owned. Don't know what the availability of stock engines is in Panama but they're pretty cheap around the Pacific Northwest. Engine and shipping costs may be cheaper than importing a mechanic and an engine swap is very easy.

[Zed Head]

Reply to Mark in #86 - 

I meant giving up on looking at all six.  That would have made the 3 and 4 problem more clear.  Which is why it was asked.  Jalex's problem on the forum has always been that he doesn't do what people ask him to do.  You asked for the other four and he only gave you one.  Should have had a picture of all six in a row two days ago.

Edited September 26, 2018 by Zed Head

[Zed Head]

4 minutes ago, jalexquijano said:

I will do the test again from scratch in one hour. I will leave the car idling with those old plugs at the parking lot for 15 mins and will then pull the plugs out.

What is the idle speed of the engine?  Engines with performance cams do better with a higher idle RPM.

[Mark Maras]

2 minutes ago, jalexquijano said:

I will do the test again from scratch in one hour. I will leave the car idling with those old plugs at the parking lot for 15 mins and will then pull the plugs out.

 I hope you've checked all the connections. Don't reuse any of the black ones.  

[jalexquijano]

Ok. Ill start with a brand new set of 6 gapped at .032 and leave it idling at the parking lot for 20 mins. Ill dump the other ones. I set the rpm to 1100. 

[jalexquijano]

28 minutes ago, Zed Head said:

What is the idle speed of the engine?  Engines with performance cams do better with a higher idle RPM.

Im setting it to 1100 rpm. At least that is what it reads on the tachometer.

[Mark Maras]

1100 rpms is a nice busy idle. That should help eliminate the plugs loading up. Watch your temp gauge. Things can get hot pretty fast at a busy idle unless your fan-or fans are pulling a lot of air.

[Mark Maras]

1 hour ago, Zed Head said:

Reply to Mark in #86 - 

I meant giving up on looking at all six.  That would have made the 3 and 4 problem more clear.  Which is why it was asked.  Jalex's problem on the forum has always been that he doesn't do what people ask him to do.  You asked for the other four and he only gave you one.  Should have had a picture of all six in a row two days ago.

 Sometimes you just have to go with the limited info and have faith that it will work out.

[jalexquijano]

Just tested with ngk bp6es brand new plugs at 1200 rpm idle for 20 minutes in parking lot. 3 and 4 are fouled. Already tightened connectors.