Spark Or Fuel Problem?
 

Hey guys I need some help, my 1st gen Rx7 has a S6 engine with single hybrid TO4e/b T66 turbo, 3" exh, front mount i/c, 4 x 900cc injectors, Microtech Digi ecu tuned for up to 18 psi boost, 300psi Bosch fuel pump, Porsche fuel filter, 2L surge tank, 1/2" lines and Malpassi fuel reg making 352 rwhp on 98 octane.

I'm not sure of the ignition system except that it has a Microtech ignition controller and heavy duty leads, I'm not sure what origin the coils are, It has no distributor, S4? maybe S6?

It was idling extrememly roughly and was undrivable, so I pulled out the plugs (NGK BUR9EQ leading and BUR9EQP trailing) and replaced them with NGK B9EGV leading and B10EGV trailing plugs gapped to 0.022 and it fired up nice, idled and drove nicely till I got the revs up to 4500-5000-5500rpm-6000 and it would kind of miss or hesitate, no nasty backfire or anything though. I thought perhaps that I got the trailing plug leads mixed up so I swapped them around, and I really couldn't tell the difference when driving, it felt pretty much the same with the leads around either way, I thought that didn't seam right somehow. I then went down to the service station and filled up with a fresh tank of 98 octane as I thought the 1/4 tank I had might have been the problem because it's 3-4 weeks old, but it still missed randomly between 4500-6000 rpm. Could it be the fuel filter (Porsche) needs a clean out? Injectors a bit blocked or do I need to get the ecu re-tuned for the new plugs?

Or is it something else?

Cheers

WHOA! That's a serious 1st gen:)

Tough call. If you can take a pic of the coild we could tell you if they are S5 or S6, or you can browse my website and see if my coils match yours.

If it was running fine before when you had the old plugs in, a long time ago, and the new plugs don't seem to fix it I kind of doubt it would be the plugs fault. That would lead us towards the coils. Make sure you have good solid grounds and that none of them have loosened over time. To my knowledge there is no easy way to tell if the coils are strong. I know you can test the S5 leading coils by taking the trigger wire off and with the car not running but in the ON position tap the trigger wire very quickly to ground and you should get a nice spark.

If you feel the coils are up to task then I would clean the fuel filter before messing with the injectors.

Hope this helps kiwi-dude:)

Aparently it could be the leads, so tomorrow provided it's fine and sunny, will try the leads from my turbo celica and give it a run, hopefully everything will be perfect and I'll go buy me a new set of leads :D I might take a pic of the coils and lead setup anyway, I wouldn't mind knowing what they are off, then I just have to host the pics somehow.

Nice car by the way Cosmo Donk, Matt Leicher was going to tune my ecu before the last 4&Rotary Nationals but ran out of time, and I took Shane for a hoon in my rx7 a while back, small world :D

Looks like it's not the plugs, I purchased a new set of BUR9EQ and BUR9EQP's today (same that it had before trying B9 and B10EGV's) and it's still missing between 4500-6000 rpm, 8 new plugs and $220 NZD later! I know the plugs were stuffed before because replacing them did make it reasonably drivable till high in the revs, where as it wouldn't even idle before and was undrivable.

But anyway, so now i'll look at the fuel system, what I want to know is, how do I clean the fuel filter (Porsche) and the injectors (900cc x 4), what do I use to clean them (filter and Inj) out?

Oh, and aparently I have S4/5 coils.

Cheers.

I am not sure how to clean the filter. Could you backwash it with some cleaner?

The injectors you can send out to a performance shop that cleans injectors or up here in the U.S. you can find some diesel shops that can clean them, just not blueprint them.

If you had some time you could make a little tank with some fluid in it attached to the injectors and then create your own testing center. Put pressure in it and if they don't leak they are good:) You could even TAP 12V to them and get them to squirt.