rb25det sII updated list of problems!

[mikalkouki]

so I've got an update of all the issues present keeping my rb25 from running right.

the problem is a constant misfire during idle and when the car warms up the idle fluctuates from 500-1k rpm. when driving the car it seems to run ok until you give more than 20% throttle or so, then it backfires, studders, bogs and all that good stuff.

the list of issues I've noticed present are as follows:1. The alternator has been changed 3 times and every one of them keeps the battery charged a dead constant 12v and no higher for an extended period of time. (and no i don't have electric fans hooked up)2. The tps is showing .5v on all three wires at closed and WOT. When throttle is moved, the voltage remains indifferent. I've also tried 2 tps's, one off of a running car and get the same thing. I also removed the tps and checked resistance and it is pretty close to spec.3. Throwing ecu code 34 (Knock sensor). and both knock sensors are getting continuity to ecu pins 23 and 24.

[gawdzilla]

sounds like a big wiring nightmare. who did your wiring?

[mikalkouki]

it was me and a buddy of mine... I can't think of what could possibly be wired wrong. Followed the guide from racebread.com and tested wires from m63 plug to ecu pinout before splicing as well as testing for continuity from splice to ecu pin. The only thing that confuses me is the tps. The tps just runs straight to the ecu from the rb harness, requires no splicing.

[USMCgetsome]

you using the stock maf or z32/q45 also about the throttle body rb/q45? if all stock you need to start check voltages from the tps, maf, water temp sensor knock sensors. Once you check those then also check to ensure all your injectors are firing and clean and treat your coil packs springs and copper contact area.

[eh?]

Are you sure it's a constant 0.5v and not 5v?

[mikalkouki]

you know what.... I kinda feel like a jackass now. My multimeter for some reason reads .012 when it gets 12v. it's reading .05 on the tps so I bet that makes it 5v. Does the fact that it stays at 5v instead of .05v constantly make the situation any better though?

[mikalkouki]

you using the stock maf or z32/q45 also about the throttle body rb/q45? if all stock you need to start check voltages from the tps, maf, water temp sensor knock sensors. Once you check those then also check to ensure all your injectors are firing and clean and treat your coil packs springs and copper contact area.

everything is stock. I've tested the tps and it gets the voltage I posted above. My maf checked out right I believe, but what voltages should the ECT and knock sensors be getting?

[eh?]

Yes that means you don't have a bad ecu. Is the TPS getting a good ground?

[mikalkouki]

seems as if the tps isn't getting a ground at all.... which one of the wires is supposed to be ground?

[mikalkouki]

ok... so scratch what i mentioned before, it seems i may just need to get a new multimeter for one. I put a test light to the three wires and none of them are getting enough voltage to light the bulb (5v should be enough i would think) and one of them gets good enough ground to light the bulb about half as much as 12v would. Any more insight???

[eh?]

Don't use a test light. The cicuit is most likely low amperage so you don't want to use something like a test light. I think the black/light blue wire is the ground. Use this site to get all your information.http://paulr33.skylinesaustralia.com/diagrams.html

Pin 30 is the ground.Check for continuity at the tps AND at the ecu coolant temp sensor

[mikalkouki]

Don't use a test light. The cicuit is most likely low amperage so you don't want to use something like a test light. I think the black/light blue wire is the ground. Use this site to get all your information.http://paulr33.skylinesaustralia.com/diagrams.html

Pin 30 is the ground.Check for continuity at the tps AND at the ecu coolant temp sensor

ok... so i got a different multimeter just for the benefit of the doubt and now everything seems to check out right, except for the tps signal voltage is way off, but at least it's responding.

I've got continuity between the tps and ect at the B/L wire as well as at pin 30 on the ecu. The Y/B wire on the tps is a constant 5.7v. But the R/L (signal) wire on the tps shows 4.94v at closed throttle and 5.06v at WOT.

I really appreciate your help and patience man, this has become quite the headache for me, any further help is greatly appreciated.

[eh?]

Sounds like an ecu problem, are all your ecu grounds hooked up? Try adding a ground to that wire, see what happens

[mikalkouki]

Sounds like an ecu problem, are all your ecu grounds hooked up? Try adding a ground to that wire, see what happens

wow... how bout this!!......

ecu was getting good ground to pin 30 and continuity to the tps/ect, however the tps/ect wires were not getting ground at all. So I took your advice and spliced in an additional ground to the block and VOILA!! The tps is working perfectly now. Unfortunately I'm not completely out of the dark it seems. Now I'm throwing codes 13 (ECT) and 34 (knock sensor). I looked at the wiring diagram and can't seem to find the knock sensors to help me locate which wire is ground. I'm thinking maybe it's the same problem with the knock sensors and need to splice in an additional ground.

any idea what would cause the ground to lose it's strength while keeping continuity?

[USMCgetsome]

time to open up that harness and redo the grounds.

[eh?]

Kinda hard for me to understand what's going on. When you disconnect ecu coolant temp sensor plug do you get a good ground at the black/light blue wire?

The knock sensors are on the lower harness, did you hook it up? They are single wire sensors, look at this diagram, the plug is A-24 and the wires are af14, and af21. http://www.gweeds.net/carpage2/rb25diagram.jpg

[mikalkouki]

Kinda hard for me to understand what's going on. When you disconnect ecu coolant temp sensor plug do you get a good ground at the black/light blue wire?

The knock sensors are on the lower harness, did you hook it up? They are single wire sensors, look at this diagram, the plug is A-24 and the wires are af14, and af21. http://www.gweeds.net/carpage2/rb25diagram.jpg

believe it or not.... with your help and the correction of me retardation I think I may almost have everything straight....

one of the knock sensors wires got pulled out of the plug. I thought i felt both of them plugged in, but the second plug i thought was the knock sensor was something else coming out of the same wire loom. So thats taken car of!!!

the alternator issue.... i found that the two wires coming out of the brown plug on the alternator are cut at the end of the wire loom, any Idea of that would cause a problem and where that is on the wiring diagram?

[mikalkouki]

good stuff!!! got the alternator problem taken care of... everything seems to be hooked up properly, however I've reset the ecu and it's still throwing codes 13 and 34. Although the car seems to be running much more responsive... Seems to bog and sputter sparadically under WOT, changing the plug gap back to .8mm and replacing the ect with the one off my old ka that i know for a fact is good.

Hopefully replacing the ect and regapping the plugs helps the motor fire better and makes the knock sensor code go away.... I'll keep ya posted!

Edit: Changed ect.... still throwing code 13 and 34 and still has slight misfire at idle.
Modified by mikalkouki at 9:11 PM 12/15/2008

[eh?]

Sounds like you have grounding issues. I checked out the internal layout of a s2 ecu and pin 30 just goes to case ground. Make sure all your ecu grounds are good.For the knock sensor make sure the socket is secure in the plug. I think I've had mine pull out when I connected it to the sensor.

[mikalkouki]

Sounds like you have grounding issues. I checked out the internal layout of a s2 ecu and pin 30 just goes to case ground. Make sure all your ecu grounds are good.For the knock sensor make sure the socket is secure in the plug. I think I've had mine pull out when I connected it to the sensor.

dood... thanks so much!!! you've been extra helpful and I finally got this thing running strong... there was one more ground that didn't get wired somehow, so i hooked that up, reset the ecu, set the timing and everything works perfectly now!!!

p.s. to reset my ecu all i had to do was jump the diagnostic pin to throw a code, jump it back out of code mode, and jump it back in again. disconnecting the battery and pressing the break didn't work.

p.s.s. the car pulls like hell now... runs just as fast if not faster than my tuned and moded rb20det with no tuning or mods whatsoever.