Hello all, I am wondering if you guys could help me out with a bit of an issue.

My friend and I just picked up a turbo 2 rx7 for a good deal, but surprise surprise, it has a few issues.

First thing I should say is that it is an 89 rx7 NON-TURBO body with a fully rebuilt 89 tubo 2 engine.

The owner says the car did run fine with all the mods at one point, but it has been sitting in his garage fro 7 years. This was his track day car, and they closed the track close to him a long time ago

It has a full racing beat exhaust with no cat converter. Normally I know that this definitely causes issues with the stock ecu, but the previous owner also installed the fuel cut off disabler from racing beat as well.

Here is the problem. The car starts right up and sounds very smooth. When you take off out of first, nothing bad really happens. When you put the car in second gear and push on the pedal a little bit the car starts to bog and chug really hard.

If you are extremely light on the gas pedal and you do not let the car rev beyond 3000 rpm, the car runs fine. Hills are...mmmm annoying to say the least, but everything else is manageable.

I am wondering what we can do to try and narrow down the list of potential issues and get to the root for the problem.

If anyone can lend us their thoughts, that would be great.

 

if it sat for that long, start by cleaning/flushing the entire fuel system and get the injectors serviced

 

Thanks for the reply, just got back from having it all done.

Problem is still there.

I noticed something else too though. If you breath on the pedal, you build power slowly but surely.

If you press any more, there is no combustion at all. If you let off the pedal, the combustion comes back.

I am thinking maybe the TPS sensor is dead or maybe it just has weak spark and can not handle the extra gas?

What do you think.

 

sounds to me like it ISN'T getting enough gas, hence why its falling on its face

what all did you have done fuel system wise?

 

Like I said, we just bought it, so I am not too terribly sure.

We definitely drained the fuel system and filled it back up with high octane.

We pulled all the injectors and had them serviced, and we are trying to replace the fuel filter today.

I seriously doubt the fuel pump has been changed from stock.

The big thing here is that when the previous owner installed the racing beat exhaust, he also had to install the fuel cut off controller from racing beat.

However, that is supposed to prevent fuel loss to the second rotor at 3000-4000 rpm. We are obviously getting nothing at all at 3000 and above on either rotor.

 

both rotors are supposed to fire no matter what, if only 1 is firing, you have fuel spark or compression issue

the exhaust should have nothing to do with how the engine runs

this racibg beat fuel thing your talking about, is it like a fuel cut defender? or a switch to turn the fuel pump on or off?

if you've cleaned the fuel system and didn't replace the fuel filter or the fuel pumps sock, that honestly was a silly/redundant move, get em changed, and if that doesn't fix it, see what your fuel pressure is at the rail

 

Yeah, I know, but I can not get any of those parts for a few days still, so we gave it a shot JUST in case it was old fuel.

Here is the racing beat fuel cut controller in question Fuel Cut Controller for 89-91 RX-7 TURBO II - Racing Beat

As you can see the issue is not the exhaust system directly, but the problem is that the turbo is mechanically controlled by the back pressure the exhaust makes.

Therefore with a really open exhaust you get a lot more boost. In turn of course the ecu senses the over boost and cuts fuel to the BACK ROTOR.

That is the key word, because we are not getting any fuel to the front or back. Beyond a quarter press on the accelerator, everything cuts out. If you lift up on the accelerator everything magically comes back on line.

Today we are gonna try getting new spark plugs and wires and see if by any chance it is not simply a matter of weak spark and too much fuel.

It is cheap enough to do, so it is worth a shot.

 

ah ha, i see what your talking about now, really fuel cut defenders are not a good thing anyways, they are more like a bandaid. if the exhaust was changed and your overboosting, you need to port the stock wastegate, theres many write ups on how to do it, but it also involves removing the complete manifold/turbo assembly

which this all makes sense now, your making too much boost, and the computer is seeing that and cutting fuel off so it doesn't blow the engine, the FCD is SUPPOSED to stop that from happening, but it apparantly is not doing that it should

EDIT: i would suggest unhooking the FCD and see what the boost gauge reads just so you can make sure that IS the problem

 

what ECU?

could be limp mode. are you getting a check engine light?