Hello there!

I have a stock 99 RX 7 thats sputtering when the car gets hot.. The only thing that has done to the engine is a rebuild with a street port.

If im not light with the throttle the car will just start sputtering and backfire, the car will also die if i hold the throttle. So far i have installed a new TPS, changed spark plugs and spark wires. Also the car had a oil leak which has been cleaned and fixed.

Here is a video that a guy has posted i got the simillar problem.

I can rev up to about 2800-3000 rpm if im light with the throttle if i push it down further it will backfire as in the video.


Any ideas what the problem is?

 

Low fuel pressure, had a similar issue and found it because I have a fuel pressure gauge, hose from the pump to the hardline leaving the tank burst and I was only running 20psi fuel pressure.

 

^^^^ right on the money. I would change the fuel filter then go from there. but it most likely will be that

 

well plugs n stuff had to be changed so its fine:P

I will check the fuel pressure and also change fuel filter and see if that will work

 

The car runs terrible, if im lucky enough when the engine is hot it will run normal once i start it up but its a very litle chance that it happens. Ive changed the fuel filter but that didnt help. The grounding wires has also been changed to new ones.

Any ideas what i should do? may it be the ECU that causes the problem?

 

What ECU are you running? At a glance I would say

Fuel issue (not enough, pump pressure, filter, etc?)
Check coil packs for issues
Check coolant temperature sensor is not failing
Check MAP sensor
Check TPS

If its a Power FC car, have a look at the sensor check screen.
If its a stock ECU car, rig up the LED and resistor in the diagnostics connector and check for flashing error codes.

 

The car has a stock ECU

Ive already changed the fuel filter, will check the coil packs if there is something with them. The map sensor is plugged and i have no idea how to check it.
A mechanic checked the error codes and it showed the tps but the error code is gone now since there is abrand new tps but the car still got the problem. The car is running at 1500rpm and increases when the lights are on to 2000-2500rpm

Also sometimes the tachometer is bouncing randomly

 

I need some help ive run out of ideas what to check

Stuff that has been done:
New fuel filter
Checked fuel pressure
Changed plugs and cables
Checked coil packs
New TPS
Reseted ECU
New ground wires

And the car still has the problem

I made a video how it looks like
Link: (I can rev past 3k rpm but it wont get any boost, will rev around 5-6k rpm in 1st gear without any boost)

Could it be the injectors??
Ive ordered a power FC to the car but it wont arrive untill next week

 

I would put all my money on it being a vacuum leak...

 

HI there,

Once you have checked the fuel pressure, (hopefully it solves it!) you may wish to work through the 'list' here on boost/ vacuum issues/ problem areas.

Troubleshooting

all the best, Rusty

 

The fuel pressure is correct

Will check the link thanks!