RPM Loss When Accelerating
 

Hey guys. As the OP states, when I'm driving my 90' FC and I accelerate I lose RPM. I can still drive normal but I can't use my turbo at all (also getting some backfire). I changed the oil and the spark plugs along with checking my hoses making sure there's no boost leak. I'm completely confused on what's going on. Any help would be appreciated.

I'm not sure what you are trying to say because If you accelerate the engine should speed up..
Is the Car itself not accelerating BUT the engine is revving faster??..If so that may point to a slipping clutch.

Okay, I feel like I should have worded it better. Basically when I want to floor my gas pedal at around 3K RPM I can't get anymore power and I start to backfire.
EDIT: The dial would immediately drop and continuously jump around at that point until I ease off the gas.

Styx, it sounds like he might be describing limp mode. On an FD, if vacuum isn't seen at that manifold, timing is pulled and fuel is cut. You can accelerate really slowly as long as you maintain vacuum, but the car has no power. That's why he can "drive normally but can't use my turbos at all".
Did the turbo FC's have limp mode? And if so, since he's in Japan and the car is probably JDM, did they have codes or CEL's?

I believe there's codes for the JDM FC. I've had the car for about three months now and it just recently started. I'm wondering if it's a fuel pump issue.

Have you checked your plugs? I bet you they're either done or fouled. I would start there. Does your exhaust smell like you're on the highway flooring it? Almost guaranteed to be plugs.

1990 ..missed that..Ya,sounds like limp mode.
you can pull codes on that car.
LINK:RX7 FD and Series 5 Error Codes

I can still do a pull. I can still use the turbo, just after a couple times I can't use it anymore. I honestly believe there's a boost leak somewhere. Either way I appreciate the link. I'll read through it and have it checked at a rotary shop. Appreciate the help.

I changed my plugs and oil. The issue still happens... I'm thinking I have a boost leak somewhere so I'll get it checked out at a shop soon

Check the coils too. I had the same issue, but i have PFC, swap coils and done.

Does it start ok? does it idle? Have you checked your line pressure? Those fuel filters have a very short life span... isn't it 20-30k? You might have enough fuel to ride and then not enough under load. If it was a boost leak I imagine you would have idling issues.

The car starts just fine and idles as it should. The fuel pump/filter was actually something else I was considering. I haven't replaced them yet but I'll definitely take a look into it.

When you say new plugs... how new? Do you mix your gas? At what ratio? I know you might think they're new but check them... it takes 20 minutes to uninstall, inspect and reinstall. It might blow your mind to see how quickly they foul when running rich or lower mixing ratio.

Do you have a boost gauge? If so, how much vacuum does it pull at idle?

I just bought 2-stroke oil so I'll start premixing soon. And I changed the plugs two weeks ago? The issue was happening on the old plugs too...:(

Ok. Yeah, two weeks is new. Have you inspected your fuel system yet? I'd check it in this order -from easiest to hardest.

1. Check fuel line pressure with jumper in yellow connector by passenger strut tower. Should be 33-39.8lbs. If you have stock fuel regulator is should be around 36lbs. Someone correct me if I'm wrong. This test won't test you everything but it will give you clues. One example of the test not telling you everything is this: you may get a good reading but your filter may still be toast. If your
needle flutters that is a good clue that something "could" be restricting flow. Experience trumps all in these situations. In any case the gauge will be VERY useful.

2.When you have the filter in your hand blow through from the IN side ( or connect a clean hose and then blow through it). It should have very little resistriction. If you have to try to blow through it then it needs to be replaced. At $20 CAN I'd replace it.

*After you're done this. Try and start it. If the problem persists go to 3 and 4.

3.This might be more of a pain in the ass but less expensive. Check the fuel pump strainer and confirm it isn't clogged. And while you have the pump out check the tank for rust. If it's clogged you can clean it with brake cleaner by spraying it from the inside out. These guys are cheap... I'd buy one for safe measure. No one wants to do it twice... it truly is a pain in the ass.

4. This step is the hardest because you're dealing with expensive parts and potential for error. Cleaning the injectors. Depending on how mechanically inclined you are you may or may not want to attempt this. There is a lot involved however, if all checks out good then your problem could very well be the injectors.

*Before you move on to injectors I'd test fuel pump pressure to ensure it's functioning properly. A bad pump could definitely cause this. Are you driving a stock turbo? Can anyone chime in and add anything about the fuel pump resistor? Would it cause this issue? I do not have one. Never did.

Almost a month later and no avail on my end. Since the OP I've done general preventive maintenance (plugs, filters, fuel pump, etc.) and I'm still getting the issue. Unfortunately I have little to no time because of my job so I've been doing plenty of research . I'm getting tests done on the car soon and I should have an immediate answer on what's wrong.