matts86fc3s

yeah thats the only problem that the car has and its not just a hesitation it completely cut outs out 3800 it will not go abouve 3800... i can floor it all day long and it just sounds and feels like a huge *** fuel cut. and no that does not mean im not selling the car i will still sell it if i cant find this problem within a few days. i start my new job in a few days and i dont want to drive that annoying thing around town everyday so anyway i tested my tps today and it has an open in the ohmeter reading... wtf? it read good before i put it on the car

One320B

Well if it was good before you plugged it in, and its not now...your harness probably has a short.



If the car won't go over 3800 thats got to be your secondary injectors not coming on....i know you said this was tested while revving in neutral, but i dont believe you can make the secondaries come on in neutral since there is no load...

matts86fc3s

yeah i know its the secondaries that arent coming on i just dont know why. there brand new. this might be a longshot but most fuel injectors look the same regarless of flow, so i got these injectors from advanced auto new... lets say they were dumbasses and dont know anything about rx7's ( haha riiiiiight) and they just guessed it was like a 4 cylender and only required like 200 something cc of flow and thats what they are selling for the rx's, and we all know the s4 n/a's were like 480 or 550 or something. lets say this happened would that make it "fuel cut" like it does... hmmm , i dont think so tho... i guess ill just probe the 2 turqouise colored wires for the secondaries with an voltmeter and have a passenger read what it does when i hit 3800... sound like a good plan??? alright lets do it. well see what happens tomarrow. anything else i should probe with the voltmeter when i hit 3800??

matts86fc3s

this all pertains to the 3800 rpm fuel cut im getting... first i need to ask this question to establish if i need to check at ecu or not. when i read about the 3800.. people refer to it as a "stumble" well i consider my problem when i hit 3800 to sound like it runs on one rotor when i hit that mark. it doesnt stumble, it just goes rrrrrrrrrrrrrrrrr(3800rpm>dddddddddddd, make that sound in your head and youll see what i mean. it doesnt "stumble" it just falls flat if you try and go past that point in rpms. makes the same noise when i decelerate too or let off the gas while in gear (letting the gears slow me down instead of brakes). anyway...



i have an fsm that i got with a parts car i bought. ive been testing resistance (ohms) on all the sensors and such (bac, aws, cas,....ect) all resistance was read in specs. my tps has an open in it i just found out. ill see what i can do about that tomarrow also. im going to have a freind sit in my passenger seat with a voltmeter and measure the volts of certain pins (ecu) to see if i can pinpoint what is messing up. ill try the two secondary injectors first, they are two turqouise fat wires on the bottom of hte meduim sized plug on the ecu. if when i hit 3800 rpm and i still get no volts then i will recheck all the grounds, tap into them with the voltmeter and see what happens to the grounds when i hit 3800. let me know what else i should check for when i hit 3800?... i dont want a bunch of pin holes in wires i dont need to check.

matts86fc3s

i stayed up all night... its now 2:27 in the morning here. im tired of my 3800 rpm hesitation. i read that someone had put a pulsation dampner on the secondary rail and got rid of their 3800 hesitation. i think that is a one in a million shot to fix the problem. but what about this. i read that (and it does make sense) you should ground your alternator body. see, when the car is running... its running off alternator power, your battery is still being used for things while car is running but mostly uses alternator power. right?of course... so instead of grounding the battery to the chassis you should ground the alternator body to chassis as all grounds from ecu need to make it back to the alternator wich is why mazda put the main ecu ground on the rear rotor wich is closer to the alternator. (sorry for the run on). but i want to know... trying to fix the 3800 rpm problem... i have grounded the fuel pump, grounded all four ecu grounds to the mounting bracket for the actual ecu, added 2 battery cable sized ground to the negative battery cable to chassis along with original one to starter, added ground from ecu ground point on rear rotor back to chassis, ground from bell housing to firewall is still intact, added a ground to pressure/boost sensor to waterneck housing and lastly grounded the uppr intake manifold, NOW FOR MY QUESTION, i heard grounding the ecu and grounding the pressure/boost sensor at the same time will do more harm then good.(rx7club.com FAQ) i have both of these grounded, now im wanting to ground my alternator body to the chassis and to the ecu main ground on rear rotor housing with 10 guage wire... will this conflict with any existing battery grounds? or hurt anything? should i remove some of these grounds before grounding alternator body? got all this info from a guys post on rx7 club.com and made me think... ground the alternator body as it is the source of engine power while operating... hmmm... so ecu grounds need to make it back to ecu...

phinsup

no an extra ground is not going to hurt you. although i will be suprised if grounding the alt does anything as it's bolted right to the engine, would seem grounded as it is, but hey anything is worth a try right?

matts86fc3s

hell yeah anythings worth a try on this dam car. ill try it tomarrow along with some other stuff and see what i come up with

teknics

i warned you about getting injectors from advanced auto. happy youre gonna sell your car cause you dont know where to buy REAL injectors?



people must love when you work on their car, since youre a mechanic after all. how many have died?



kevin.

j9fd3s

lol, why dont you see if the secondary injectors work? the 3800 hesitation is a MOMENTARY flat spot because the ecu swtiches on the injectors, and it takes enough current that theres some lag, hence a lean spot, and a hesitation/buck. if your car stops running @3800 rpms that is a TOTALLY DIFFERENT PROBLEM!



do your secondary injectors work? is the wiring harness any good? ecu fried? there is only those 3 things it could be. and no the s5 stuff wont work, unless you swap it all

RONIN FC

I feel like buyin it just to fix it..