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 it. 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. right? so instead of grounding the battery to the chassis you should ground the alternator body to ground 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. 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... with this conflict with any existing battery grounds? or hurt anything? should i remove some of these grounds before grounding alternator body?

RotaryEvolution

iTrader: (30)

if you really want to fix it i will tell you how, though it is a mask for the real problem it may actually make you happy since you seem really unhappy with the car.

invest $100-150 in a used SAFC2 and hook it up as per 1300cc.com instructions and try richening up the 3600-4000RPM range, this should smooth out the seam for the injector staging.

J-Rat

iTrader: (2)

The SAFC is merely a band aid fix. He needs to figure out what sensor is malfunctioning and go from there.. Grounding the crap out of the motor isnt going to make this go away.

classicauto

iTrader: (3)

true he does need to find the root of the problem...but by the sound of it - the guys up all night trying to figure it out, id slap a bandaid on it and enjoy your car for a while instead of beating your head against the wall

trochoid

iTrader: (6)

The alt grounds to the engine just fine, if the ears and thier mating surfaces are clean. I found this out the hard way after powdercoating my alt. I lost the ground at the ears and killed the battery. Once I removed the powdercoat from one ear, the alt was working properly.

matts86fc3s

alright well listen to this: eveyrone says the 3800 problem is like a stumble... or bucking for a few seconds. well think of it like this: when i hit 3800, if your looking at rpm gauge and listening to engine, it just hangs at 3800 will not go any higher regardless of throttle unless you back off, feels like theres a wall there. you cannot go any higher than that. unless you creep like hell past it. and when i say creep i mean the needle will move so slightly past that point you can hardly notice it moving. but when i do hit the "wall" the engine changes sound, like it would when your driving and let off the gas while stll in gear as to brake with the tranny instead of the brakes,.

J-Rat

iTrader: (2)

Yep, you have injector issues. Your secondaries arent coming online. So you have a busted pressure sensor (as I previously stated), or you have dead or disconnected secondary injectors. What I think hailers recommends for a test, is to remove the vacuum line to the pressure sensor (passenger side strut tower, black box), and see what happens.

matts86fc3s

alright ill try that. how much do new ones cost from dealership?

Dcrasta

Ground the injector harness ring connector. To do this properly you will need to remove the UIM. WHen your there u can replace/retrofit the pulsation dampner and check for leaks, replace the rats nest vacuum lines, etc. Trust me I am going through the same thing but I am also replacing my injector seals, and putting a rtek 1.7 chipped ecu in my car (along with 750cc injectors).

racatech

some questions bout the rear bell housing grounding where too???? i saw some loose wire there and one near my secondaries what is it? what are those wires connected too? i also have a loose wire end from the 02 sensor????

matts86fc3s

the wire from the bellhousing connects to a prong on the firewall, right above where the wire comes from on the bellhousing, about 10 inches above that, the wire just slips onto that prong. the wire near your secondary is probly where your o2 sensor plugs into. its supposed to come from under the upper intake behind the engine. but that could be it

racatech

so at the secondaries wiring harness its taped with this single wire that suppose to connect with the other end of the o2 sensor???? and the firewall ground i dont see it. my s4 can somebody snap a picture to me?