racerlinkfd

ok so i have a 1988 mazda rx7 NA with all emissions equipment removed race headers and full exhaust i am currently experiancing a huge bog at 4k rpm seems like fuel loss but i checked everything i can and found nothing a friend suggested it might be the wiring harness not sending a signal is there anything else anyone can suggest it might be? any bit of knowledge will def help me .

racerlinkfd

ok just some more info i replaced the plugs fuel filter airfilter all fluids thinking there might have been something clogging it checked all vacuum lines see if i had any leaks and nothing replaced some lines with new ones just cuz it looked like it was time to change em out and still i experiance a bogging at 4k rpm in any gear do any of you know what it feels like to get smoked by a ******* honda when before i used to point and laugh at them as i flew past them i have grannies pulling on me in old lincolns anyone please help!

FelixIsGod29X

iTrader: (50)

Are your secondary injector clips on properly. Sounds like the secondaries aren't coming on.

Clean all four ground wires. http://www.aaroncake.net/rx-7/grounding.htm

racerlinkfd

ima go outside and take a look at that now a buddy did say it is the secondaries and they are clipped on tight but ima go check the grounds now

racerlinkfd

cleaned em up still no fix what would cause the secondaries to not come on ? could it be a bad harness? any suggestions

satch

iTrader: (1)

If you have an LED light you could test the ECU to see if the problem lies there. pin 3H corresponds to the front secondary injector and pin 3F corresponds to the rear secondary. You would place the negative lead of the light into one of the two pins mentioned above at the ECU and the positive lead of the light into a pin which has voltage which pin 3I would be an example of one. With the car running as you tried to get the secondaries to come on the light will flash quickly if firing properly and if the light just stays on constantly then the secondary injector being tested is not being sent a proper ground signal that allows it to fire.

To differentiate which LED lead is positive and which one is negative you would touch each lead to both terminals of the battery and if it lights up then you know which is which.

racerlinkfd

thanks for the info i tried what you recommended tested it and the ecu was bad replaced it with one from another running rx7 and it still has the issue at this point im leaning towards the wiring harness being bad or possibly the secondary injectors being bad taking it to my mechanic see what he can come up with as im running out of options im also gonna replace the fuel filter i replaced it when i dropped in the new motor last year so it may be time to replace it again see if anything changes if anyone else has any ideas to what it may be ill greatly appreciate it thanks

satch

iTrader: (1)

Before you take it in you need to verify if the grounds are connected and working properly.

Secondly, can the car get above 4000 RPM if you ever so slowly try to get it above that level or does it occur "only" when you punch the throttle for quick acceleration?

When you tried the test I supplied you with are you "certain" you identified which wire of the LED was positive and which was negative for if you had them switched by accident the test would not work. You could also use a multimeter set to voltage DC and the voltage reading on the meter would drop from 12 volts to around 8 or so when you tried to quickly accelerate. This could be done in the driveway as well.

Lastly you could also check the boost/pressure sensor as being the culprit by disconnecting the vacuum hose connected to it, plug the hose, disconnect the electrical plug to the TPS sensor and with the car running bring the RPM up to 3000 RPM or so and gun it.

Double lastly, make sure your TPS sensor is set at one volt on the Green/Red wire when the car is properly warmed up.

EDIT:
When doing the test suggested are you also certain you used the correct pins? 3H= Light green/White and pin 3F = Light green/Red.

new2mazda

iTrader: (1)

also check ur fuel pump voltage make sure its gettin full power or it will do this at full throttle

SirCygnus

iTrader: (1)

yank the injectors and test their resistence across the pins on the injector. not the injector clips on the harness.

ill bet one reads zero.

racerlinkfd

i have left the car sitting for a week had work have the appointment at my buddies shop this week he was almost certain that the secondary injectors arent working but hes gonna test everything he did check the ecu and everything that was suggested and we ruled that out im gonna test the tps sensor in the morning as this seems like something i can easily do at home also gonna test the fuel pump . to re-iterate on the symptons the car goes past 4k only when turning then on a straight away while slowly accelerating the car begins to bog (lose power) then every gear when shifting i get to 4k the car bogs im gonna pull the fuel filter as well friend said it may be clogged ill see if that does it but im pretty sure its the injectors or harness pins as the hraness pins to the injectors are busted but are holding on to the injectors ill have em check both plus check the tps sensor the car is old bound to need new sensors im sure

scrip7

iTrader: (6)

Don't forget the sock filter at the bottom of the fuel pump. However, the symptom most often associated with that is bogging on left turns. Still, it's a fine-mesh filter that should be checked. I also had a fuel pump resistor/ relay go bad on me once and it ran lean especially high rpms.

beefhole

iTrader: (29)

Guys really... It's more like 3800RPM's. You no longer have working 5/6 port actuators after the installation of the full exhaust, you will have a loss of power. A bog is not caused by too little fuel, it's caused by too much. Hesitation is caused by too little fuel. Your secondaries are kicking it, but you no longer have the airflow and the motor is "drowning" in fuel when you hit 3800RPM. You need to get your 5/6 ports working again.

FelixIsGod29X

iTrader: (50)

Ive ran my S4 with the aux wired open and with them closed to 6k. There was no bogging or hesitation. Just a loss of power.

Also a bog can be caused by not enough fuel, and a hesitation can be because of many things. There are lots of variables that can cause bogging and hesitations.

I'd replace the fuel filter if you dont know how old it is. Also pull the fuel pump and check the sock on it. Ive once bought a 7 for very cheap because no one could figure out the hesitation, the sock on the fuel pump was DIRTY. Replaced pump, filter,& sock. Ran great afterwords. Also set the TPS once the engine is fully warmed up.

beefhole

iTrader: (29)

^Wired open or closed? And how would they stay closed till 6k?

HAILERS

The wiring to the secondarys is checked reeeeeeeeeeal simple. Pull the small plug off the ECU and with a digital meter see if there is batt pwr on the green/red and green/white wires with key ON. IF there is, then the harness is good.

Did this engine ever act right with you driving it?

Do you KNOW the secondary injectors are 460's and not something else, like 550's. That would explain BOG which is a RICH conditon. Hesitaions are LEAN. Hesitations are BUCKAROO and not BOGGARO.

You sure the plugs are on both secondarys and that none of the sockets are PUSHED BACK inside the injector plugs?

rx-7 obsessed

if its a racing beat header it should have a pipe for the 5th/6th ports. you need way more fuel then the stock injectors can flow to litteraly fill it with fuel....i had 4x1000 on a stock ecu and i could get it up to 4.5k thheeenn it would fill with fuel as they hit a high duty cycle. ....check your injectors do the resistence test with a volt meter. also sounds like your unsure about the clips, if you are you can buy new ones very cheap.

FelixIsGod29X

iTrader: (50)

Both. One time wired open, the other time closed because i didnt have the aux tube hooked to my presilencer.