Smilodon

There are not many parameters relating to fuel injection that need to be correct:

On the fuel side:
Rail pressure
Injector capacity
Pulse width

ECU
Proper signal getting to it
Proper signal coming from it
Wiring between it and other portions of system in good shape
No interference with signal anywhere in the loop (id: don't braid your ECU wiring with your spark wiring)

Air measurement:
Airflow sensor
Oxygen sensor
Manifold Absolute Pressure sensor
Throttle position sensor
Temperature sensor

These are regulated by the ECU, which gathers information about airflow either by using mass airflow or Alpha-N.

Mass airflow: sensor in the intake air stream tells the system how much air mass is coming through the engine, coupled with air temperature reading. (perhaps humidity also, I do not know) If the ECU is accurately receiving airflow rate information, and if the ECU is not fried, it will output a proper signal to the injectors, varying how long they stay open (pulse width.)

Upside: Engine modifications are not so critical, because if your engine uses more or less air at any given moment, the ECU just sends in enough fuel to match it.

Alpha-N: Three main parameters are measured: Manifold Absolute Pressure (MAP), RPM, and throttle position. This method (Used on the Ferrari F40) takes a measurement of air pressure relative to a perfect vacuum (thus Absolute instead of Relative pressure.) It also receives input on how wide open the throttle is, and then injects an amount of fuel that has been foreseen as necessary by testing for that particular engine's airflow capacity at that particular RPM. For any given MAP and throttle opening, it injects fuel for how much air SHOULD be entering the engine at that time. I think, but cannot prove, that this would provide snappier throttle response.

The downside is that if you alter ANYTHING about the engine, it will not necessarily be matched by what the computer has been told the engine will need, fuel-wise, at that point.

Also, there is an oxygen sensor used in the exhaust system in some injection systems, and if it senses too much oxygen ratio in the exhaust gas, it assumes more fuel is needed.

There can only be three things wrong with your system if it is guzzling too much fuel:
Injectors are injecting more than they are being instructed to
ECU is telling the injectors to inject more than they are supposed to
ECU is being told that there is more air entering engine than there actually is

Or, worse, some combination of those three.

If your injectors are operating properly, the signal to the injectors is bad.
If your signal is bad, it is because the ECU is toast or because the information it is receiving on how much air the engine is getting is bad.
If your ECU is good and your injectors are good, then whatever system is telling the ECU how much air it is getting is screwed up.

I don't know which system RXs use. But, supposing the "this is how much air is getting in" subsystem is bad, it could be due to modifications in the intake stream or throttle position sensor, or the oxygen sensor is bad.

Bad TPS (throttle position sensor)=bad input
Bad MAS (mass airflow sensor) = bad input
Bad MAP= bad input
Bad exhaust oxygen sensor = bad input

Also, if your mass airflow sensor is of the "hot wire" type, ie: a wire is put in the airflow, and how much electricity flows through the wire at any given time indicates how much air is flowing past the wire to cool it. If a modification or obstruction is in part of the duct leading to the sensor, instead of measuring, say, 1/100th of the air going through the engine, and multiplying the result by 100 to get its result, the blockage can force more than 1/100th of the incoming air to go around the blockage and and through the sensor portion of the intake, thus telling the motor, artificially, that it is receiving more air, when it is actually receiving LESS.

Some MASes have a honeycomb air straightener in which they are placed. One of the cells of the honeycomb has the hot wire. The other cells are assumed to be carrying their share of air. If a scrap of paper, a moth, a leaf, or whatever, get sucked in there and sits across some of the cells, it will force other cells to suck more air, including the one with the hot wire in it, so it perceives that there is more airflow than there actually is.

SPiN Racing

Good info.. but as this is a 20B powered RX-7 with a standalone EMS, that was a custom install.. with a engine it didnt come with.. and I would imagine there isnt a MAF sensor at this point..... THe info is a good baseline for a stock car. And some of the info surely relates.. BUT.. as this is a COMPLETELY custom driveline.. I think it may not really apply too much...

Reese If I were you at this point... seeing as it wasnt smoking with the turbo off.. I would put the whole kit and caboodle back under the car.. Fire the beasty up....Make and sure she is running smoothly.

THEN.. GO to the local filling station.. and top her off and reset the Odometer.
THen take a nice leisurely Road trip... burning a 1/4 tank. Not a ripping drive.. a nice scenic drive.
THen see if you are getting resonable MPG. I am sure you have a good idea what she has been doing before this.
It will burn out all the crap in the exhaust.. and it will let you know if the problem persists.
Worst case.. you have a nice drive

Smilodon

Even stand-alones need to have input on RPM and/or air flow/pressure to work. In fact, any EFI system does. Stock or Custom. I think his injectors are healthy and his ariflow reading is somehow being exaggerated. Based on not actually being there.

SPiN Racing

TESTY TESTY!

I see someone trying to forge a rep I think.. and getting defensive. No insults intended.. BUT I think you were going through a long winded diatribe on things that wasnt totally nessecary. That is like describing what a car is to people driving them.
Reese isnt new to this. Obviously looking for some assistance to resolve a irritating odd problem. Not a lesson in what a EFI system is.

And Oh yeah.. Welcome to the Internet. EVERYTHING you say will be held up to ridicule by even the nicest. And no I wasnt attacking.. But I am sure you will put your foot in your proverbial mouth sooner than later. SO you will either be hailed as a god here.. or attacked by those that know more about the specifics of the RX.

BTW.. I have read some of your other posts you are defensive about.. some good points. Balancing information thread good information.. you Do appear to have a clue.. or a good book. BUT.. remember.. Not all the crowd will understand what you are talking about. And there are a contingent here that will argue aerodynamics fluid dynamics.. you name it...incorrectly.... no matter what documentation you have. Everyone's a engineer of some sort in some of these threads..
Be aware you will run into that.. as well.. Keep a flame retardant suit handy.. and a bit of tylenol for the fingers that will get tired or re-hashing explanations.

20B10AE

iTrader: (14)

Scott, thanks for the input! We just finished rolling my stock fenders last night so tonight we'll probably bolt the exhaust back on and see how she drives. I wasn't able to get the wideband installed Sunday but hopefully this week will be better.

Smilodon, thanks for the help. I'd like to echo what Scott said. The info is good and you may not have realized that some of it didn't apply to my particular situation, which is fine; however, don't get quite so defensive if someone puts up a counter to your posts. As Scott said, you'll get all kinds in here: people who truly know their stuff and people who WISH they did.

More to come...

Reese

Smilodon

You should have waited. I deleted that post and put the one you saw up there. Sometimes as I edit, I realize that feelings have no place in a discussion of facts. Which is why you quoted something I later just erased.

So, please just disregard the one I erased. I know I am.

In fact, you must have go in between edits, because I didn't see any replies as I was crafting the more rational response. Or after. That is strange.

bobybeach

in my opion you should check your throtle position sensor is reading fine, even small adjustments of your throthle position sensor at idell can cause over fueling and lead to stalling and fowled plugs.
or check that your engine temp sensor is still conected to make sure the ecu knows when the car is at operating tempratures to adjust the fuel accordingly.

Smilodon

Ah, yes, of course. The engine will run rich if it perceives that it is still cold, thus making it richer to help cold running. I did not think of that.

I remember this one place testing their product by having an engine on a dynamometer. They were pumping sub-freezing coolant through the engine to artificially keep it in "eternal warmup rich mode" to see how fouled the plugs got. It was weird to see a running engine with frost forming on the engine. How often do you ever see THAT?

cardzrule

I don understand. If ALL teh fule corrections are turned off then how could being cold cause rich running?
V
V
V

cardzrule

If teh airflow is exaggerated then how come teh engine stumbles when he reduces teh injectors flow rate?

Sorry to be a noob but how does soot or fule way back in teh exhaust system make teh engine run rich and use extra fule and flood and stuff? If it does add more fule into teh engine then do you think putting fule injectors in teh muffler would work for adding fule to a engine instead of adding another fule rail or xpensive bigger injectors?

SnowmanSteiner

The assumption that we're making here is that when Reese tried to jump start the car, he flooded it. The relevancy of the exhaust, is that once he pulled it off, from the downpipe back, it stopped smoking. So we know that the amount of carbon buildup and/or fuel buildup in the actual motor isn't what is making it smoke. The smoking is coming from after the downpipe. Whether the jump start was the ONLY cause of the flooding is still undertermined.

- Steiner

Smilodon

I guess you could just fling it at some shop that knows RXes and let 'er rip.

20B10AE

iTrader: (14)

Sorry, but while I may ask for advice or help in general from time to time, I do my own work.

A) I take pride in it,

B) this is my secondary form of income. I'm not going to pay someone else to do something that I charge for as well.

C) there are very few people I trust to touch my car anyway.

I appreciate the thought though.

Reese

SnowmanSteiner

Just don't let me near it with a hammer.

- Steiner

20B10AE

iTrader: (14)

LMAO. It may not be perfect, but the fender flaring turned out pretty damned good for your first attempt. You're on the short list mentioned in line 'C'.

Back on topic...

I promise that I'll be driving the car tonight to try to get it to stop smoking. With some luck, the problem is, indeed, simply excess fuel in the exhaust system.

Reese

newbieRX-7

ok I was having the exact same problem with the smoking, i took it to the dealership and they put in a new coolant senser (water temperture) and that took the train smoke away it was great you could try researching that but that might be the problem.
zac