car only starts at wide open throttle and other problems

[S13 240SX]

my rb20det only starts on cold starts when throttle is wide open... also when driving when i literally push gas pedal to the floor the motor stops going at 4 grand and like feels like it just shuts off and stalls becasue you can't even hear it run or hear exhuast... but then seconds later engine turns back on and i can hear all the exhuats sounds... its like it does not wanna respoond to throttle... plus at idle every 4 minutes it does a little miss-fire... the mafs is wired correctly now too so its not that, and m coils tested good.

but i do have an unkknow wire cut hanging from one of the throttle postion senors plugs.. i have no idea where it goes. its yellow with some silver in it.

is that my probolem???

[Coolwhip]

have you ran the car fine b4 this and it just started to give problems or no?

Checked for boost leaks

[Darius]

I was going to suggest there's a problem with your TPS from the first line in your post, then read further about a random wire hanging loose. It sounds like you are only getting a TPS signal at WOT because it is a separate wire I believe. Someone correct me here if I'm wrong. Otherwise the ECU doesn't know what to do with 0.0V. Definitely look into the wire you described. I'm almost certain that it's your problem.

[S13 240SX]

it has to be that random wire.. I unplugged the whole tps and now the car drives fine! but when i plug it back in it runs like ****..

i need help where does this wire go?????

[Coolwhip]

my SR did the same thing so i ended up driving with out a TPS till I replaced it. hm

[S13 240SX]

ok but someone told me not to drive much with tps unplugged cuz it'll make it run lean... so thats not true?

[Coolwhip]

i did eventurally blow the ringlands on cylinder 2. But to blame it on the TPS idk, there were other things going on as well.

I wonder if you can use a q45 tps since the rb25 s1 tps can be used on that the Q45 TB.

Could probably pick one up at a parts store.

[S13 240SX]

well can anyone explain to me where i can hook up this one wire?? so i dont blow my rings.

[Darius]

The Y/B wire should be connected to the TPS and the ECU. Look for the other end and reconnect it.

[S13 240SX]

there is no other end for it though.. i looked everywhere under the intake mainfold. : (

[Darius]

Then, check for continuity in the wiring between the TPS and ECU. Verify that the TPS signal is making it to the ECU. Maybe check the continuity between the Y/B wire that is hanging out and the TPS wire at the ECU plug.

[S13 240SX]

how do i do all of that? whats y/b the color... cuz if thats what u mean its not.. my wire just sticking out is yellow and silver and coming off the black plug from the throttle sensor.

[Coolwhip]

To check continunity:

You get a volt/ohm meter and set it to check continunity (should be a little symbel like this) ->|

You get one contact lead / probe and you touch the exposed wire (coming off the plug)

Take the other probe and probe the ECU plug in which the TPS sensor wire goes to (don't know off hand and my FSM pdf is on my home computer).

If the meter beeps or shows continuity on the screen or analog meter than its on the same circuit. If not than the 2 wires are unrelated.

Defentantly check the FSM and see what wire that is as well if that doesn't work. I do not have either my harness or TPS infront of me to help out on that.

Good luck

[S13 240SX]

well the person who wired my tps for me said its different so the extra wire is for nothing he said and that i dont need it... he said something about i have a series B rb20 and the throttle sensor came off a series c and he said for that reason is why i have the extra wire i dont need...

so what the heck does he mean by all of that talk?

[Darius]

Just an FYI on wire color. The first letter is the color of the wire and the second letter is the color of the stripe. If there's no stripe it is only one letter.

Most of the colors are self-explanatory

B=BlackL=BlueGY=No, not "gay"...GrayG=Green

[S12_hybrid]

It really sounds to me like you've got your feed wire polaritys switched for your TPS. Think of it this way, its a potentiometer right? So it reads a varying voltage which is delivered by altering resistance.

This may be backwards, i'd have to test a working tps sensor but lets say:

5v = idle (closed plate)0v = WOT

If your polarity was reversed you would read:

0v = idle5v = WOT

This would literally wreack havoc on your ECU.. If would be expecting the engine to be under massive load at idle, and would adjust fueling appropriately (Combined with maf signal, which would just get confusing). When you would go to WOT the engine would attempt to idle - which is why your engine would seem to shut down as modern engines do not inject fuel on over-run.

At least, thats my theory.

-Dan