Sr20 giving me problems...

[BlueCoupe]

N/A sr20de             So my car is running like poop, have it nailed down to what i believe is the MAF. I believe my car is in limp mode, wont rev past 3000rpms (when its driving down the road, just sitting there seems to rev past but i am unsure because my tach isnt hooked up anymore) tons of black smoke when i rev it, idles very rough, 

Checked continuity in the MAF wires to the ecu plug. all is well there

 

Decided to check the Volts on the MAF, 

 

12v Maf wire reads 12v

 

5v signal wire reads 9v

 

(3rd wire) reads 9v

 

(From what i read the 5v signal wire should be 0.45-60 at idle)

 

So i went out and bought a new one hooked it up and still no good. same problems 

 

NEW MAF reads

 

12v

 

0.19mv

 

0.19mv

 

So i thought maybe im trying to read the  wires the wrong way, so i decided to try on my TPS and it read 0.46 at idle.

One screwy thing i noticed is in the loom from the ecu to the MAF it has 3 wires and then it also has a bare metal wire that hooks to nothing up by the MAF but it grounds with my other grounds by my ecu, now im thinking maybe i have a split in my MAF wire so that ground wire could being screwing them up? but anyways before i go cutting that i decided id see if anyone has any advice or could come down and look and help me out? does this mean my ecu is fried? im honestly so mad about this that i want to set the car on fire lol. If i could i would just buy a whole new ecu wiring all that jizz jazz but im 18 and dont make very much. someone help me out :/

 

 

 

 

[paradime]

Weird I don't know of any bare wire in the SR harness. If it's in limp mode it will be running super rich which would explain the black smoke. Do you have the consult post hooked up? If so what does it read? You'll need to run through a diagnostic on your sensors knock, maf, temps, oil press, etc. You'll also want to check ground at the ECU plug. Get a pinout for your plug and check continuity. If yo know anyone with a similar motor swap your ecu into their car to see if it's healthy. Untill you get everything worked out with the faulty connection it will not reset, so test everything one at a time. You can find diagnostic test online that will help you out with that. 

 

 

I Hate wires

[BlueCoupe]

Now the bare wire that i mentioned is in the grey shield that the 5v signal wire and other wire are in, and then it when they come out of the shield by the ECU it connects to others and i believe they are grounds then they go to 1 wire and into the ecu (cant remember off the top of my head if there grounds exactly)

Now im thinking sense that wire runs into the the grey shield with those other 2 wires and then grounds, MAYBE one of my signal wires has a cut or slice or is screwed up somewhere inside the shield that its screwing it all up by grounding which would HOPEFULLY be the problem.. 

 

Dont have a consult port, or any of the wires for that :/

 

Also as far as i know and have read only 3 sensors will cause Limp mode and thats the 

TPS, MAF,  &  IAC   (not sure though)

 

i know all my other sensors are working in properly, im just so stumped on the MAF being all goofy? i wish i could plug my ecu into someones car to check that but i dont know anyone around here with a sr20 n/a 

Now you mentioned Knock sensors (my engine doesn't have them) on the DET (does have them) would that also cause it to go into limp mode? just curious 

[Icehouse]

The bare wire you see is the shielding to suppress noise in the system.   How does the car run with the maf unplugged?  Also your ECU should have a "adjustment" screw in it with an LED next to it.  You can retrieve the error codes that way.  Look up instructions on google and let us know what it says.  Have you ever heard the engine run properly or did you buy someones unfinished project?   We can get to the bottom of this!  

[BlueCoupe]

The bare wire you see is the shielding to suppress noise in the system.   How does the car run with the maf unplugged?  Also your ECU should have a "adjustment" screw in it with an LED next to it.  You can retrieve the error codes that way.  Look up instructions on google and let us know what it says.  Have you ever heard the engine run properly or did you buy someones unfinished project?   We can get to the bottom of this!  

Idles much smoother when unpluggd, my ECU does not have the screw with the light to get the codes :( 

& no i bought the motor myself from a deal straight from japan 

[hosestop@msn.com]

Add grounds like three on motor ,make sure maf. harness is grounded near firewall ,I have seen it act funny without harness groundn .

[Icehouse]

If it idles smooth with the maf unplugged I'm also suspecting the MAF.  It should idle perfect with it unplugged.   

 

So non of the wires at the maf are a ground?  one should be.   Like above check grounds.  

 

 

We need pics of the maf plug and the SR.  

[BlueCoupe]

If it idles smooth with the maf unplugged I'm also suspecting the MAF.  It should idle perfect with it unplugged   

 

So non of the wires at the maf are a ground?  one should be.   Like above check grounds.  

 

 

We need pics of the maf plug and the SR.

 

I'll post pictures when I get home, the maf is off a 95 ka24de

Now you guys keep saying the MAF needs to be gounded? , what wire should I ground? Not the 12v wire I'm assuming but the signal wire or the 3rd one? Also how can I check to make sure I'm picking the right wire just to be on the safe side,

after I find the wire do I just cut it in half and hook both ends to ground somewhere??

[rusty12ver]

Voltage at idle needs to be less than 9mv, or (.009). If possible ground the maf to the chassis and take another reading. A lot of these harnesses had weak ground points. Doesn't help any when dropping these engines in older chassis.

 

Almost forgot: you will get two different voltage readings with the key on /key on engine running, all under that .009.

[BlueCoupe]

Voltage at idle needs to be less than 9mv, or (.009). If possible ground the maf to the chassis and take another reading. A lot of these harnesses had weak ground points. Doesn't help any when dropping these engines in older chassis.

Almost forgot: you will get two different voltage readings with the key on /key on engine running, all under that .009.

How exactly should I ground it?

[rusty12ver]

i currently don't have a pic, depending on your harness the ground wire maybe white or black. It may be the 3rd from the left, when looking at the connector, pins facing you. Do your best to confirm this. you can solder a wire to the existing, and ground it to the chassis.

[BlueCoupe]

i currently don't have a pic, depending on your harness the ground wire maybe white or black. It may be the 3rd from the left, when looking at the connector, pins facing you. Do your best to confirm this. you can solder a wire to the existing, and ground it to the chassis.

Finally someone says how go ground it lol, so I did it and I will test it out here in a few and see if it works! Fingers crossed

[BlueCoupe]

IT WORKED! THANK YOU MUCH!

[hosestop@msn.com]

Hey post what finally fixed it , was it a body ground added to Maf harness , I added my ground jumper at firewall to rear corner of sr at factory harness ground point .

[BlueCoupe]

I added a ground and grounded it to the back of the intake manifold with my other grounds

[hosestop@msn.com]

Usually I add three separate grounds from motor corners to body frame grounds to keep out gremlins .Thanks always want to know what fixed it .