rockinghamrx

i have a 1989 GXL and lately i've been feeling a slight power loss when i hit 6,000RPM. it feels kind of like a "flat spot". Its most noticeable in 3rd when i'm pulling a mild/moderate hill. i can feel the extra boost of power from the 6th ports kicking in around 5,000RPM or so, so i don't think there's any problem with the 6PI system. Usually when i'm pulling hills in 3rd, she keeps on hauling strong up past redline, but now when she gets to 6,000RPM she just sort of stays there.

also, why is there a difference in the S5 tachometers between the automatic and manual transmission cars? my GXL used to be an automatic transmission, and the pervious owner swapped in a 5speed from a T2, but he kept the instrument cluster with the PRND21 at the bottom of tachometer. the tachometer on the S5 RX7's with the automatic redline at 7K and end at 8K. while the tachometers on the S5 RX7's orignially equipped with the manual transmission redline at 8K and end at 9K

xfeastonarsex

iTrader: (5)

I dont think there is a difference in the clusters. I got mine laying on the floor here and there are spots for lights in the back that I assume are for the PRND21 spots on the auto cluster. I just think that plastic tags (piece that tells rpm, speed, etc) are different.

Icemark

The auto tranny falls apart above 7000 RPM, that is why the redline is lower.

The aux ports open at 3800, not 5000 RPM. The VDI activates at 5200 RPM.

Old spark plugs, and cables are the most common failure at higher RPMs, if high RPM power is being lost.

rockinghamrx

ok. thanks a lot for the help. so what would that mean for my tachometer? am i safe to rev it up to 8,000RPM? (i've been careful in trying to to exceed redline as much as possible). and if i got a 5speed tach that has the 8K redline, would i need to change anything for the new tach to read correctly, or will it just hook right up and read how its suppose to?

I'll probably try new spark plugs here in the next week or so. i mix MMO into my gas, and the plugs probably have around 23,000 miles on them (the previous owner rebuilt the engine at the same time as the tranny swap, and i assume he put in new plugs after the rebuild). so with those two factors taken into consideration, my plugs are probably getting pretty worn out by now.

by the way, has anyone done the airpump 6PI actuator conversion described on rotaryresurrection.com? if so, how is that working out for you?

SureShot

My red 91NA was set up with an electric air pump.
I used some generic brass fittings to make a pressure relief set to 6PSI.
Power was through a relay.
Ground signal came from the Aux port relay.

Icemark

Since you no longer have the auto tranny and auto tranny Computer, you should be able to go up to a 8K redline.

Generally the leading spark plugs only last about 10K-15K miles. With 23K miles (although still within factory recommendations for easy driving) they are probably well ready for replacement.

MMO should not be needed for any reason in a Rotary engines gas or oil system, and may be contributing to your problem.

rockinghamrx

i'm not quite sure if the computer was replaced. the tranny came from a turboII model. i would have to ask the previous owner about that.

and i use a little MMO in my gas to improve the ratio of oil to fuel, since i do some spirited driving every now and then. the stock OMP ratio is around 1:400 (or so i've read), so i put in around 4oz of MMO per fill up (my average fill up during a week is around 14 gallons).

so i'll try replacing the plugs and see if that helps. i'll probably also replace the spark plug wires too because when i was checking out how hard it would be to get to the plugs i noticed that one or two the end caps on the sparkplug fittings looked a little cracked.

Icemark

MMO will not help the lubrication in a rotary at all. It is not recommended for Mazda rotary engines and is really little more than ATF. Just send me the money instead and I will think good things about your engine and provide the equivalent protection. And at least you’ll know for sure that I won’t foul the plugs, injectors, sensors, and gum the combustion chambers.

If you feel the need for supplemental lubrication, you would be better off using the proper 2 stroke oil instead.

The plug wires should be replaced every 60K miles or when the insulators are cracked or damaged, or if the cables no longer meet factory specs. NGK wires are a good cost effective replacement.