OK guys, sorry for thread jacking... but I've got the EXACT same problem happening with my car.... (strange huh...) Anyways, I read the thread, and my brother tested all the crap, and on my car neither 1A/1B are getting any voltage (now) when he first started testing he said 1A was getting around 3-4 volts but latter dropped to 0... Also I have gone ahead and pulled the body harness most of the way out, and found a ground wire (assuming this is caused by the short, and not the acctualy problem) that has had the insulation melted off of it in numberous places, and also the blue plug that the wire ran threw under the fan box on the passengers side floor board (right around the ECU) was fused together/melted, because of the heat!



Can you point me to were I should be looking for the problem? Is in in the body harness, dash harness, fuse box (which I swapped with a known good one, and didn't change anything, along with swapping many relays.)



I would greatly appricate ANY help!!!!

 

well as i have been told that if pins 1A/1B have zero voltage then there is a break in the wires that run from those pins throught the harness to the battery...I have yet to pull my harness out yet ( knowing its going to suck I'm waiting until i have alot of time to do it, and i finally got a used full harness)...i was going to just try and replace or fix the broken wire if i could find it but think it may be easier since im pulling the harness out just to put a working one in..yes it may cost a few extra pennies but at least i know it works.....

if you find anything more out please let me know

Ryan

 

i have a question about vaccum readings..

my car has the stock ports with mostly all the bolt ons minus pullies and pfc..

my car idles perfect at 18in..i noticed that when im driving (lets say 3rd gear) and when im about to slow down, decelerating while still in gear, ill look at the gauge and see the vaccum has risen to 21-23in..then ill put it to neutral and it'll sit at 18in again..is that normal??

cause it gets annoying to be driving, then slowing down, then it will go to 21-23in, then when you get back on the gas, the engine gives that little jiggle i guess cause its getting back to proper vacuum or something..

theres no boost leaks or anything, car boost fines, just shows a different vacuum reading when decelerating in gear..

normal?

 

ulost2my7,

It is normal for an internal combustion engine that is throttled, whether a piston or rotary, to show a higher vacuum when accelerator foot is lifted and car is slowing in gear. When the throttle is closed, the engine is pumping all the air out of the intake manifold and into the exhaust system. It basically becomes a vacuum pump. On my Miata, the deceleration vacuum is about 25 in. Hg, if revs are above 2500 rpm or so when right foot is lifted.

 

OK, something I just noticed about my problem.... I had a plug done by the ECU that was melted together (it's a blue plug with 8x2 pins I believe), and the melted wire (only one was) is black with a white stripe. Anyways, I thought the wire was on the wiring harness that runs on the firwall (behind the dash) Turns out after looking closer it is acctually the blue plug that comes off from the engine harness, and conects to the body harness!!!! Ahhhhh, does anyone know what this wire controls???? I thought it was a ground, but I can't imaging that they would send a ground all the way threw the engine harness.... Would this affect my Power-FC not turning on?

 

thanks for the info man

the thing is that i never even noticed it. i guess im being more paranoid now since my car has been acting funny lately and im noticing the little things that i think might be wrong.