Rantings of a Sparkless Lunatic
07-06-04, 01:45 PM
#1
Rotary Freak
Thread Starter
Join Date: Dec 2002
Location: Slovenia, Europe
Posts: 2,522
Likes: 0
Received 0 Likes
on
0 Posts
Rantings of a Sparkless Lunatic
Taken from:
http://www.sportcompactcarweb.com/pr...05scc_projrx7/
We blamed the solenoids. We blamed the wires. We blamed the coils. We blamed the remapped ECU. We even thought about blaming the All-Mighty Himself. No matter what we replaced or at whom we pointed our grungy fingers, we just couldn't seem to clean up the high rpm misfire that made full throttle blasts to the 8000 rpm cut-off less than enjoyable. But finally, we ran into the source of the stumble: A damaged electrical connector in our ignition sub-harness.
With one wire barely making contact with its terminal, the front rotor's spark plugs wouldn't spark during unusually heavy load or at high engine speeds. Not only was this the source of our top-end torque roll-off, it also explains the partial-throttle "bucking" we experienced during single-to-twin turbo transition. Of course, trying to buy an ignition sub-harness from the dealership without having to purchase the complete and very costly electrical harness is like trying to extract teeth from a digestive orifice other than the mouth.
Fortunately, famed RX-7 drag racer and proprietor of SR Motorsports, Ray Lochhead, came to the rescue, finding the object of our desires in a pile of unused parts. As they say, one person's garbage is another's treasure.
But our sparky misadventures didn't end there. Several weeks and a few track testing days later, we began to notice yet another ignition quirk, this time only during secondary turbo transition. As we were preparing ourselves for yet another fantastic voyage deep into the RX-7's dense engine bay, Brian Richards of M2 Performance posed a thoughtful question, "When was the last time you changed the spark plugs?"
Good call. Once removed, our leading spark plugs showed evidence of excessive wear. Perhaps a result of our excessive track testing, eh? "A track-driven RX-7 is very hard on its spark plugs," Richards explained, "and they won't last nearly as long as many people would expect. Sometimes they'll last 15,000 miles and other times only 7,000 miles. Either way, they are the first things that should be inspected anytime misfire becomes a problem."
Since the stock plugs fail to offer the longevity we would expect from a not-easily-replacable-without-using-a-lift-or-burning-your-forearms item, we took two steps in the right (colder, that is) direction by replacing our old NGK BUR7EQP leading and trailing plugs with four nearly identical NGK BUR9EQP plugs. Why the colder plug? Well, it appears as if the stock plugs are being put through hell. The culprit? Extreme heat, of course. And the colder the plug is rated, the less heat it retains during combustion. And the less heat it stores, the less hell it goes through and the longer it lasts. But, like everything else, there is a downside to using a colder plug. Since they don't run as hot, they don't do as good a job of burning themselves clean. As a result, they are more prone to fouling during thumb-in-the-mouth, sissy-boy driving. The solution? Duh. Do you really have to ask?
Thought someone might find it usefull...
http://www.sportcompactcarweb.com/pr...05scc_projrx7/
We blamed the solenoids. We blamed the wires. We blamed the coils. We blamed the remapped ECU. We even thought about blaming the All-Mighty Himself. No matter what we replaced or at whom we pointed our grungy fingers, we just couldn't seem to clean up the high rpm misfire that made full throttle blasts to the 8000 rpm cut-off less than enjoyable. But finally, we ran into the source of the stumble: A damaged electrical connector in our ignition sub-harness.
With one wire barely making contact with its terminal, the front rotor's spark plugs wouldn't spark during unusually heavy load or at high engine speeds. Not only was this the source of our top-end torque roll-off, it also explains the partial-throttle "bucking" we experienced during single-to-twin turbo transition. Of course, trying to buy an ignition sub-harness from the dealership without having to purchase the complete and very costly electrical harness is like trying to extract teeth from a digestive orifice other than the mouth.
Fortunately, famed RX-7 drag racer and proprietor of SR Motorsports, Ray Lochhead, came to the rescue, finding the object of our desires in a pile of unused parts. As they say, one person's garbage is another's treasure.
But our sparky misadventures didn't end there. Several weeks and a few track testing days later, we began to notice yet another ignition quirk, this time only during secondary turbo transition. As we were preparing ourselves for yet another fantastic voyage deep into the RX-7's dense engine bay, Brian Richards of M2 Performance posed a thoughtful question, "When was the last time you changed the spark plugs?"
Good call. Once removed, our leading spark plugs showed evidence of excessive wear. Perhaps a result of our excessive track testing, eh? "A track-driven RX-7 is very hard on its spark plugs," Richards explained, "and they won't last nearly as long as many people would expect. Sometimes they'll last 15,000 miles and other times only 7,000 miles. Either way, they are the first things that should be inspected anytime misfire becomes a problem."
Since the stock plugs fail to offer the longevity we would expect from a not-easily-replacable-without-using-a-lift-or-burning-your-forearms item, we took two steps in the right (colder, that is) direction by replacing our old NGK BUR7EQP leading and trailing plugs with four nearly identical NGK BUR9EQP plugs. Why the colder plug? Well, it appears as if the stock plugs are being put through hell. The culprit? Extreme heat, of course. And the colder the plug is rated, the less heat it retains during combustion. And the less heat it stores, the less hell it goes through and the longer it lasts. But, like everything else, there is a downside to using a colder plug. Since they don't run as hot, they don't do as good a job of burning themselves clean. As a result, they are more prone to fouling during thumb-in-the-mouth, sissy-boy driving. The solution? Duh. Do you really have to ask?
Thought someone might find it usefull...
Thread
Thread Starter
Forum
Replies
Last Post
Sterling
1st Generation Specific (1979-1985)
36
12-18-08 10:06 PM
banzaitoyota
2nd Generation Specific (1986-1992)
3
06-14-02 07:45 PM
RarestRX
2nd Generation Specific (1986-1992)
25
01-03-02 12:08 PM