Top End Power Loss
 

Have a 91 S5 N/A rx7 and it suddenly started losing top end power like flooring it past 5000 rpms the exhaust gets extremely quiet and even cruising the exhaust sounds much quieter.

Its like it wants to pull in 2nd gear but doesnt pull and doesnt accelerate like its supposed to. :scratch:

The cat doesnt glow red but at idle the exhaust shakes and puffs like theres a vaccuum leak or something. also its like theres metal shaking around in the exhaust when it pufs while its idling at 1500 rpms. Trying to give the most details.

just trying to figure what it could be before class tomorrow.

also before the exhaust got quieter it was pulling just fine and strong past 4000 rpms which was about a day or two ago. all ive done since is let it go through its normal warm up routine done my regular daily-7000-rpm-carb-kickout-merg-onto-highway-pulls..

accelerates fine before 4000 rpms but past that just seems like something is holding it back. its like the power wants to come out but its not. lol

Did you try checking for error codes? Ground the Orange wire found in the single wire Green check connector near the lead coil and/w key to on any error codes should be displayed.

no codes.

could it be a clogged cat? im reading similar symptoms and it seems that has to be it.

It's a distinct possibility.

Could be the VDI not working and the 5th 6th ports aren't opening

in order from easiest to hardest.... it rather does seem like the exhaust, but thats hard, so we should eliminate a couple of easy things first. it would suck to pull the exhaust and find out it was a bad TPS report coversheet

1. check the codes, there are a couple that won't turn the light on.
2. push the vdi and each of the 6 PI plungers, you should be able to move them by hand
3. i've had the ignition cause a lack of top end, not sure it applies to you, so you may skip this step, use your judgement. pull the plug wires and check resistance, a new set will be around 8k OHMs, the limit is 16k OHMS, the car WILL misfire @16k ohms. i assume your spark plugs are 30k miles or newer.

4. if everything else is ok, then pull the cats. its easiest to unbolt the thing at the manifold, and at the cat back, pull it out as an assembly, and then pull it apart and inspect. plan on fishing the precat out of the main cat and putting it back together. the gaskets are part number N378-40-305, they last a long time, but it would be nice to have at least a pair of new ones.

whats a vdi?

im thinking it may be those actuators ... its like the rx7's vtec wont kick in .. lol which is activated by those 5th and 6th ports right? also if they werent opening would it make the exhaust quieter?

Variable dynamic intake (VDI). Aka VTEC.

thanks. to mention, i also hear shaking of metal in the exhaust which is leading me to think it could be both the cat which was damaged from the heavy flooding i went through last week(required me to change spark plugs squirt in oil etc etc).

Oh, nice of you to finally mention that lol

Yes, rip that cat off, that is probably your problem. The car didn't sit long in or after the water did it?

I mentioned that in the opening post... Lol. Also I meant flooding with fuel. I read somewhere that depending on how heavy the flood, it can damage your cats(smoked so bad the neighbors thought something was on fire). of course I changed oil immediately.

So I'm asking if the exhaust is quieter and I'm not getting any top end would it be more so the cat? Will a clogged cat restrict that much power? Going to test my 5th and 6th port actuators today. Will post this afternoon how they went. Also going to check for codes again.

OH, i thought you meant water flood

Yes a clogged cat can cut your power and choke your engine, but anything thats been suggested is also a possibility

also wondering, can a clogged cat decrease backpressure to the point of the actuators not getting enough to open?

or worst case one of your secondaries decided to quit firing, but according to your idle and rattle it sounds like a combination of sticking intake port valves and/or dying cat.

Going to update tomorrow after I get this test pipe welded on in place of cat and if it is still pulling like its hauling a tractor trailer I will lubricate actuators and see what that does.

Just out've curiosity, you still have your air pump on and hooked up right?

Yep.

So after welding on a pipe in place of the cat, got all my power back, actuators opened up from correct back pressure, and also my headlight pops up now..

The cat was clogged was a huge white ball of honeycomb that molded together after getting so hot from the bad flooding of fuel it went through last week.. Guessing it got so hot all the honeycomb material inside melted..


Thanks guys for all the help

Glad you fingered it out