Ok so car has been running fine untill,last week was driving it around and it started to hesitate and stumble all over it self.So here is what normaly happens I fire it up,drive about a mile and does fine.Then after then I have to play with the throttle just to make it get up to speed anything after half throttle forget it just stumbles and hesitates.Whats weird also is if I turn it off for a few minutes and jump back in it,it will be fine for like a said about a mile.
No cats on car and
racing beat header so I know the exhaust is ok.
Fuel filter replaced did not help.
New Plugs did not help

anyone possibly know what this could be?
Fuel pump possibly going out?

 

is it flooding? pull the plugs and see if they're fouled. i don't know much about rx7's other than the older ones flood really easy

 

After about a mile, your engine will have warmed up. It runs much more rich when warming up then after it is warmed up. This rich operation covers a multitude of problems.

It seems strange that it does not run at Wide Open Throttle, this would indicate that it is not a vacuum leak (which would have been my first guess).

Sorry to say, but I will need more information.

Is this issue related to engine RPM? If so, how?
We can already guess that it is related to engine temperature.
I think I gather from your post that it is worse with increasing throttle.

If you shut the key off while driving (not too far or you lock the steering wheel) and then turn it right back on, does the engine behave any differently?

My best advice without the above requested information is to plug in the LEDs and have the computer do a self-diagnostic. You can find out how to do the self-diagnostic on This Page.

I hope this helps.

 

Ok so here is some more info.
I thought it was related to engine rpm because at first it starts to stumble bad at higher rpms around 4500,the longer I drive the more it stumbles at lower rpms.Its not just under full throttle.After a good 10 to 15 minutes of driving and its properly warm It will hesitate and stumble giving it hardly any throttle.

I did the ignition switch thing and a no go.It still hesitates.
Like I said though cold start she will run perfect for a couple of minutes.
Car does not have to be under a load either.I can be under the hood giving it throttle and it sounds like someone has stuck a rag in the pipe.

 

Check the voltage on the fuel pump during idle and under load.

 

Will do

 

The fuel pump voltage is a good suggestion, I don't think GXLs had resistors to fail in the fuel pump relay, but the pump could be failing, as could the wiring.

I would watch fuel pressure if I were you, just tap into the line at the back of the engine that goes from the primary fuel rail to the secondary fuel rail.

Anyway, if fuel pressure is good, more information may be helpful. Does it pop and crack (lean) or does it smother (rich)? If you can't tell, plug a multimeter into your oxygen sensor and measure the output voltage to determine if it is a rich miss or a lean miss (the engine must be good and warm).

I am not suggesting that it is the oxygen sensor, this is merely for information. The O2 sensor can't adjust the fueling enough to make much difference, nor does it operate while revving in the driveway (really only cruising on the highway).

If it is a lean miss, (Voltage less than 0.4V) I suspect the fuel pump or some other fuel related issue (maybe bad engine/sensor grounds, but that is a stretch).

If a rich miss, (Voltage greater than 0.6 V) check your engine coolant sensor. If I hadn't broken mine when I went Haltech I'd give it to you.

Please remember that the O2 sensor is only accurate if the engine is not missing, it will always read lean if the engine does not burn every charge (unburnt oxygen is coming through). The only Idea I have is to watch the trend (ease into the gass and watch O2 sensor voltage just before engine starts to miss.

I hope this helps you a little. For what it is worth, this is an interesting problem.

 

Will do thanks for the help.

 

roy- your car is too pimp and has too much *** in and out of it to still be NA- when are we going to do something about that?

 

The red tII just made it to the paint and body shop.She will have some *** to it.

 

Check the sender behind the Waterpump..the Coolant Sensor..I am thinking it is OK when cold,but once the car is Warm,it is still saying that it is Cold..so it is Running like it is Choke on,so to speak...(look into the water thermo switch.,.under search..read up and see if I am making any Sense..OK?)..anyhow.That is my 2 cents.

 

Well I changed the sensor out on the water pump housing.Nothing changed.
What about the one on the motor near the oil pressure sensor.For the hell of it I went and snagged one off my tII to replace on the motor but its different the top to it takes a different piece to snap on the one on the gxl is just a strait piece.
Would this sensor cause the problems?
I also noticed today while taking it out to test even when I get it to the point it starts to stumble real bad and I down shift to slow down its sounds like ***.Just stumbling all over the place.

 

try adjusting the tps very slightly in one direction, drive the car and see if it changes, remember which way you ajusted it- if it gets worse go a little bit in the other direction, if it gets better try a little more in that direction.

then try it cold.

forget the lights- I always have better luck adjusting by feel
adjust it like 1/4 turns, dont go crazy on it


meanwhile did you touch anything else under the hood prior to this or have it worked on anywhere?

 

The water pump went out around the same time it started doing this but it never overheated.I changed out the water pump but I will be damned if I can figure out whats happened since.As far as I know I did not touch anything that could be causing this or undo anything.

 

The sensor near the oil pressure is for the guage.

I wonder if you somehow got enough air in the system to lose the engine water temp signal to the ecu (sensor at the back of the water pump).

Anyway, did you watch if it was a lean or rich miss?

One more question, does it use coolant? It is possible that a bad coolant seal may make it run poorly when hot.

It is also possibly a vacuum line or the TPS, as I said earlier - the rich mixture on startup will cover a multitude of problems.

I guess more information would be nice (rich or lean problem).

 

ok so after further screwing around more I took it out and did the ignition turno off and back on again after it started stumbling real bad,and yes she drives fine after that or at least untill I turn the car off again and drive it later in the day.
what the hell is going on???????