need a lil help trouble shootin my problem

[jmac85]

i own a 1990 skyline gts-t. it has an RB20DET. i hav a few mods done to it but nothing major. my car started doin this thing every once in awhile. it will sometimes act like it doesn't make any power past 4500 rpms and then sometimes it feels like it wont snap into power until like 3000-4000 rpms, and other times it act like it has no power all together. i am still makin boost but i think its still pretty close to where it would normally hit. i need a lil help figuring out what is goin on here. i was thinkin it was my turbo goin out but i think its to irregular for it to be the turbo goin out. any and all help is greatly appreciated. i need to get it runnin right again cuz it is my daily driver as well as my toy.

[USMCgetsome]

grab a nissan consult off ebay and log your data! get a a/f gauge as well. What your describing could be anything starting from a boost leak to a fuel issue to a timing retard during boost caused by who knows what(sensor, leak, knock).

If you have a power fc or something like that look at all your sensors for proper voltages

[jmac85]

ok thanks for the help. i am able to trouble shoot sensors off of my friends car cuz his is in a garage to do body work, so while i am tryin to get my s*** figured out. i do not hav a power fc yet.

[Cjmartz2k]

Does the exhaust note change when you loose power? 90% of these type of problems can be attributed to bad coil packs/fowled plugs/ignitor, especially in your situation (i.e. stock motor, not swapped into an S-chassis.)

A video would help.

[jmac85]

yea the exhaust note changes, it doesn't sounds as ballzy. yea i think it might be my plugs or spark related cuz its has been startin to not fire up as easily. i was readin on someone elses post and i was thinkin it could be my knock sensor, but thinkin about it, it could just be spark knock trippin the knock sensor and that would cause the other problems.

[Cjmartz2k]

Where are you located?

[jmac85]

misawa japan.

[Cjmartz2k]

Shouldn't be to hard to go find some replacement coils and trouble shoot then. That's where I would look first.

[jmac85]

yea i am plannin on goin to pick some up tomorrow. and if i can't get to the junk yard i can just trouble shoot off of my buddies car

[Sil240]

I would definitely checkout the ECUtalk consult cable
That's what helped me get my car running right.

Good luck.
It does sound like a ignition problem.
But you should also try the MAF

[jmac85]

yea i already tried the maf. i would of already did the coil packs but my friend didn't hav any alan wrenches

[jmac85]

hey i check my coilpacks over the weekend and i hav 2 that r dead. and the plugs proved it. i hav to wait to find some replacements but i was wonderin if any one knew where i could find some upgrade coilpacks?

[jmac85]

does anyone know if coil packs off of an rb25 will work?

[Cjmartz2k]

Series 1 coils off an RB25 or even an RB26 will work just fine. N/A ones are just fine also. Stock coil packs in good shape are good above 600hp and 2.0 bar+ of boost. Considering how cheap/easy it is to get replacement coil packs in any number of junkyards around Japan, spending the coin for upgraded coil packs would be a TOTAL waste of money for you.

[jmac85]

thanks man i really appreciate the help. i hate havin my baby runin like a bag of crap. the car is pretty much stock. i am workin on gettin an rb26 but i wont have that until spring.

[Cjmartz2k]

Well, RB25's are a lot cheaper (even over here) and will make the same power. The wiring is a little harder (unless you are getting your RB26 from a 33/34), but other than that, I'd go RB25. Just my opinion which is obviously a bit biased.

[jmac85]

i am goin rb26 cuz i can get a lot of stuff for it for cheap

[Cjmartz2k]

Well in that case the wiring will be super easy. I think you just need to re-pin like 7-8 pins at the ecu and your done. Anyways, hit up a local junkyard and go find you some coils. Hunt for n/a 4 door skylines and grab the coils, CAS, ignitor, and various other sensors that are the same for spares.

[jmac85]

yea i am goin to try to hit the junk yard up today after work, i hav bn unable to get there b4 they close after work.

[jmac85]

i was able to get some coil packs off of an r33 4 door. i think that they hav the positive terminal and i am guessing the spark signal terminal switched around, if so would i be able to just rewire my plugs and be fine? if i hav to rewire them i am fine with that. i was unable to get the coil packs off of an r32 thats the same as mine cuz the r33 was on top of it.

[Cjmartz2k]

IF they are series I RB25 coil packs they will plug right in. If they don't work they are either shot also, or maybe series II. Look for the ignitor pack on the back of the spark plug valley cover (series I) or lack of ignitor (series II.) It just looks like a little black box for series I, or just a plug if it's series II.

[jmac85]

ok well i grabbed the series 2. so do i just need to get the wiring from that plug to the coils or how do i make it work, if i cant make it work its goin to be a pain to get the ones i need.

[Cjmartz2k]

get the right coils

[jmac85]

ok so there is now way to make the series 2's work?

[Cjmartz2k]

Make 2 or 3 work mixed with series I coils? No, not practically. Just get the correct coils. Trust me, especially considering your in Japan, it's BY FAR the easiest and cheapest way.

[jmac85]

ok well i guess i will be headin over to the junk yard tomorrow to try to get the coils i need. its just a pain in the butt cuz the r 33 4 door is on top of it which is y i didn't grab them in the first place.

[jmac85]

well i got the coil packs swapped out from my friends car and my car is runnin strong. i just picked up another set of coil packs for my car today. i just wanna say thanks for all the help.