thejallenator

iTrader: (14)

i just tested the boost sensor or pressure sensor or whatever the hell it is. the thing with the vaccum line going to it. and the fsm says to check voltage at the brown and red wire. i did and got ~2.5vdc so im guessing that my boost sensor is bad and causing the issue and this would explain why it seems to hit a brickwall while in boost at the higher rpms right?

jinxed4dub

iTrader: (7)

I was having a simular problem awhile back it was the large positve wire that goes to the fuse box. it also goes somwhere else. the last 4 inches of the wire were fried, try wiggling that wire around if it changes the problem, its the wire. I'd look into changing that alt also. If the car will start and drive I'm thinking the ECU is still good. But deffinately fix the alt issue!

Also how many miles do you have on the motor? You shouldn't be reving past 6K with less than 1000 miles on it. Have you checked compression?

thejallenator

iTrader: (14)

the alt is brand new! i just swapped it. im almost thinging i bought a bunk ecu. the last one i put in worked fine till the voltage got too high. but i will check out that wire you speak off. your talking about the read on that goes intot he 40A fuse, second from engine? cause thats the only red wire i can see.

HAILERS

Possible misprint/typo in the series five FSM. Beware.

I'd find someone on this forum with a seies five turbo and have him look at his output at the ECU prior to buying another boost sensor.

I assume this is a series five ECU your working with and a series five boost sensor and the car is Turbo.

thejallenator

iTrader: (14)

actually hailers. that is completely wrong. its a series 4 ecu with a series 4 boost sensor in a non turbo car, i did a motor swap.

HAILERS

Then with series four ECU N332 and series four boost sensor...........the two and a half volts is good according to the series five FSM ........jpg attached.

Thats 2.5 vdc with the vacuum line off the boost sensor measured at the brown/red wire at the sensor or brown/red at the pin 2B of the ECU.

Car seems to be for sale.

Fuel cut on a series four Turbo car happens when the ECU sees approx 3.65 vdc from the boost sensor. EDIT: might be a touch higher, like around 4vdc instead.

IF you had a source of pressure and a gauge you could watch the output of the boost sensor and see what the voltage is around 7-8 psi.

I do remember prior to RTEK 2.0, I could apply pressure to the boost sensor and make it cut fuel to the rear rotor while idling in the driveway. Can't duplicate that now cause of the RTEK removed fuel cut in the ECU and I can't put a non RTEK in the car 'cause I'm running E -85 and the injectors would be too large for a stk N332.

thejallenator

iTrader: (14)

hmm interesting. cause the page i seen said 2.5-3.5vdc should be seen at high alt and 3.5-4.5vdc should be seen at sea level. and im about ~100 ft above sea level. but i did do the test with the vac line still on and the car not running. it never said to do it another wat in the FSM. and here is the page i seen..

HAILERS

************************************************** ************************************************** *************************************************

The ATMOSPHERIC PRESSURE SENSOR is located in the passenges foot well and has no vacuum line going to it. The ATMOSPHERIC PRESSURE SENSOR just measures the .......atmospheric pressure in the area/city you live in.

The boost or pressure sensor is in the engine bay on the left side and has a vacuum hose attached to it. The page called CONTROL UNIT has you test it two ways. One way is with the vac hose off the sensor and the other way is with a vacuum pump attached to the sensor pulling 100 in/hg vacuum.

IF you measured the output of the boost/pressure sensor with key ON, engine OFF, and came up with 2.5vdc.........that meets the specs in the FSM.

I kinda overdid this post and the reason I did was in case you did not know about the atmospheric pressure sensor in the passengers foot well and confused it with the boost/pressure sensor.

Or maybe I just misread your posts.

I do agree the FSM is a bit silly when they have you pull the vacuum hose off the boost/pressure sensor and plug it and then read the output of the sensor. Might just as well just turn the key ON engine OFF and have at it.

thejallenator

iTrader: (14)

oh jesus i see what you mean now hailers. those are two different things on that page. im an idiot. sorry.

well damn now im just stumped.. the only thing i can see as being my issue is the guy sent me a bad ecu:/ because with a known good one it would start by just turn of key. and i know i didnt burn this one up, i could barely get the car to turn on. ugh

HAILERS

Yeah if you put a known good ECU in the car and it worked fine...........and then bought a ECU of your own from somebody and it acts funny.......you'd come to the conclusion the one you bought is kaput.

I'd try borrowing that known good ECU and put it back in and see if the car still runs good with it.........or not.........before buying another ECU. N332 ECU's? right?

thejallenator

iTrader: (14)

yea i thought about borrowing a known good one but then i remembered the nearest person to me with one of those is roughly 100 miles away. but i shall talk to hte seller.
and actually its been 1 n332 and 2 n333. the n332 ran the longest before the alt finally took it out. and the first n333 ran for a few hours before the alt. then this one just never went. do i nee to have a n332? cuase it seems i got the best results from that on e

jinxed4dub

iTrader: (7)

Its not a red wire its just positive should be black, I'm not shure exactly where it goes since I tryed running it from the alt strait to the fuse box, car wouldn't start, I had no power. but its the larger wire on the alternator, theres the plug then the 10G wire with a ring terminal. thats the wire that caused my issue.

thejallenator

iTrader: (14)

oh are you talking about the wire that hooks to teh b terminal? on the alt

jinxed4dub

iTrader: (7)

Yes, that wire was burnt on mine for about 4 inches or so so I cut it back and fixed it. that problem went away. it pissed me off so bad, car would start up fine run fine and then blah. no guts. I don't remember how I found the issue, I think I was just digging around with the car running and moved it and it would go away or get worse, fixed it and haven't looked back. I'm having a simular issue now, but its somthing differant I think. my car somtimes jerks when I WOT or anything more than half way. I think its somthing with the ignition. cause it sounds like it fires off a few flames afterword and durring.

thejallenator

iTrader: (14)

i see. well i will check that out today when my new ecu comes hre in a bit

zeal

iTrader: (7)

have you tried unplugging the tps and driving the car?

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/will-not-rev-past-6000-closed-loop-913439/

thejallenator

iTrader: (14)

i have not. i will give it a try. but that still doesnt cure the starting issue.