I just bought an 86 NA base model RX-7 and from what Ive read through searching, the 5th and 6th ports are probably not opening due to the lack of back pressure. I dont think the cats are gutted but there defiantly not stock cause its loud but its not unbearably loud. Any way several threads mention that the s5 uses the air pump to open these and that there is a thread explaining how to make the s4 do that. I cant seem to find that thread and I was just wondering if any of you guys could explain that to me so I could get it running right.

Just in case ive miss diagnosed the car runs fine until you hit somewhere around 3500 rpm and then it loses power. if your trying to accelerate hard it almost throws you forward.

Also since Im new to the rotary world here a shot of what I assume is the air pump. Thanks in advance guys.



Steve-O

 

Stuck 5th and 6th ports would show no symptoms at all, because they aren't essential as evidenced by the fact that most other cars don't have them at all (or anything similar), even older rotaries. They are purely for extra performance, not getting around town (regardless of rpm). You are probably having trouble with the secondary fuel injectors, which are supposed to kick in at 3800 rpm. Do a search for 3800 rpm hesitation. You can also check the FAQ.

 

Try moving your actuators by hand to see if they are stuck or sticking. If you don't know where they are download the FSM(Factory Service Manual) for your series in the FAQ for 2nd Gens and that will give you a good idea. Wire your actuators open and see if there is any difference in power on the top end. That will rule out clogged injectors if it works. Racing Beat also sells a presilencer that has a tube for actuating the 6pi. I made an electric setup for my old N/A, but I had VDI as well as it was an S5 and there are some good writeups on doing that as well.

 

Thanks for the info. Ill check that on my next day off and return with the results.

Steve-O

 

If you decide to try and use the air pump to actuate the ports, you will need some type of RPM switch. The S5's came with it built into the ECU. The S4's didn't though. So, you can hook an valve up that switches when power is applied, and supply that valve with pressure from the air pump. I use the summit racing RPM switch. They are pretty cheap and I haven't had any problems.

 

www.aaroncake.net has a guide to test the 5th and 6th ports. Then if they're bad you can actuate them via the air pump or an electronically controlled pressure source to regain the lost horsepower. But like I said, since you said:
The 5th and 6th ports are not your problem at all. Do a forum search for "3800 rpm hesitation" and find out what's going wrong with your secondary fuel injectors (which are used above 3800 rpm). The 5th and 6th ports are like a nice new exhaust; great for power but not at all related to mechanical problems you might be having.

 

I found that website while looking for pictures of the injectors. I'm not yet familliar with the engine bay and my next day off is tomorrow. I'm going to check the grounding points and dig through the workshop manual to find and clean the injectors. Thanks again for the info guys.

***edit*** the reason I'm cleaning the grounds is because it says on the aaroncake site that that can be a cause of the 3800 hesitation. Great site btw. Lots of great pictures.

Steve-O

 

All the grounding points seemed to look freshly redone. I didnt find the one under the intake manifold but if I have a bad injector Ill check that when Im in there. I found and tested the secondary injectors. The manual said they should read between 1.5 and 3 ohms each. the on towards the rear of the car read between 2 and 3 while the front one read 1 so Im assuming that one its bad? looks to be alot of work to replace that thing too. The manual says to remove the whole intake system. Is there away around that or should I just quit being a panzy and just do it. Thanks again for the info

Steve-O

 

Measuring 1 ohm on an injectors doesn't necessarily mean it's bad. I'd assume you just had a bad connection, since measuring resistance can sometimes be hit and miss. Even if it is slightly low, that should only improve the response time of that injector.

For future reference, the secondaries on an NA are easy to change. The manifold can stay there; all you should need to remove is the fuel rail. It should even clear the throttle body on an S4.

 

ok well if that injector is good im back to square one... at a lose for what's wrong. The reading was a hit though rather than a miss. I read them both five times and then double checked that. Wheres a good place to order some injectors from that are not too expensive? Autozone has them for 120 where other places online have them for 40 to 100.

Steve-O

 

Did you ever wire the actuators open? You can do that then unwire them and see if there is a difference in power. You can find injectors on here for pretty cheap, but it doesn't sound like that is the problem. I even have 4 S5 N/A injectors I could get rid of. But I would suggest you take your injectors out and send them to witchhunter (just google it) to get them cleaned if you feel you must. It costs like 15 per injector and they are very quick. Wire the actuators open with a zip tie or some wire twine and report back.

 

So is this answer wrong? The actuators move. I haven't wired them open because the above post said that wouldn't cause the huge power lose I'm getting at 3500. Thanks again for the info.

Steve-O

 

I think the OP needs to clarify - is he experiencing a stumble @ 3500rpm, or is he saying that power vanishes, period?


On the ecu:

That's at the ecu. I think it's the small plug.

 

No that post isn't wrong. I was saying to "try" to wire them open then see if the problem persists or not. It very well could be your secondaries, but it is a hell of a lot easier to test the actuators then to take the secondary injectors out that is for sure.

 

Its a loss of power not a stumble. I'm talkin if you trying to accelerate it throws you forward at 3500.

Steve-O