Yesterday I came around to changing the original (80k miles) spark plug wires on my FD. Reading instructions on the net I went to work. Since I always underestimated time to perform work on my FD, I thought this would take like 5h or so In the end it took me about 2.5h, but if need be, next time I think I can do it in less then an hour, now knowing which tools I need and where all the bolts & stuff are.

First I took off the intake elbow. Problem was I didnt know there were 2 bolts underneath - as they are not as shiny as the top ones I also had to disconnect the vacuum line on the back of the elbow.

With elbow removed I could already see all the plug wires. Next to come off was the throttle body. There are again 4 bolts that need to come off, 2 on top and 2 on lower each corner. I also had to disconnect throttle and cruise control cables. Additionally, there is a coolant line on the bottom of throttle body that had to come off aswell.
Then I put a rag on the UIM and put the throttle body on the rag.

Now I had an access to all the plug wires. Starting from right I started to change them. No big problem to pull them off and put back on. The last one required the loosening of the oil filler neck plastics and some time & patience to come off (I couldn't find the third screw in the oil filler neck so I had to leave it on).

I put it all back together in reverse order and she fired right up. But then brap, brap, brap... vacuum at 8-9mmHg and shitty idle. Crap.... I checked the MAP sensor and it seemed OK.

I went to lunch and came back to locate the problem. I could hear boost leaking somewhere around MAP sensor. To my surprise, MAP sensor WAS disconnected, but not at the MAP sensor neck, but at the little filter that is about 2 inches away from MAP sensor. Plugging that back together and she ran like a charm

Then I picked the hi-fi wires that I bought few days back and replaced the UIM ground and added new ground from negative battery pole to the left fender.

Now my idle is very stable and the car lost some of that stumbling when still cold. 3k RPM hesitation is still there, so is the hesitation and bucking above 6k RPM at 12 or more psi. But overall the car feels smoother. I'll see how the car will feel after I change the oil and put in new spark plugs (scheduled in some 2k miles).

Next on my list are high-flow muffler that will hopefully lean out my top end a bit and if that one doesnt help, the HKS TwinPower.

 

nice write up

gotta do mine soon too

mike

 

why did'nt you change the plugs at the same time though.

Kai

 

My 7/9 plugs are only about 1000 miles old. No need to. And I order my plugs from the States, so I dont feel like trashing them just yet

I already have a 9/9 set at home.

Btw. I just came back from some hard driving and its very cold outside. Only about 15°C (very unusual for this time of year). At only 10psi she ran like bat out of hell, lol I think new/better grounds added quite some finesse to the power delivery. I like it... I wonder how it will feel with some better muffler

 

What color are the factory wires? Just to check if mine are factory or not? Black right?

 

2 blue and 2 black..mine is all green mazdaspeed..

 

I heard of using 9/9 plugs instead of the factory 7/9 helped in hot engines. My `94 is pretty much stock. Only upgrades were reliability upgrades to engine and K&N filter, DP. Does it make sense to use 9/9 on my car? What's the benefit?

 

They say 9/9 when over 350rwhp.

I'm still thinking if I should go 7/9 or 9/9.
Since I like tracking my car, I will rather sacrifice some HP to reliability and go 9/9 though...

 

Actually when I put my plugs on I really didn't need to remove anything. I really don't think its necessary to remove the intake elbow and all that stuff off, as long as you remember what plug goes where. It only takes me like 5 minutes to pull and reinstall the plugs. I usually have the front up just in case I have to pull them from the bottom.

 

Lol... u think I did that write up for the spark plugs ?

Mate... topic is about spark plug wires, but then it got slightly offtopic to spark plugs

 

quick question... how do you know when it's time to change wires? Any thing noticeable during driving? idling? Just curious. I only have the reliability mods done. DP, and catback.

 

Its good to change spark plug wires after 80k miles or after 10 years

Engine runs stronger and smoother (but I also added some bettere grounding at battery and UIM-firewall, so it could not only be attributed to plug wires).