weird issue

[whoareu]

engine is an rb25 S2.

here lately ive had a little bucking and sputtering when ever i hit a bump it would stop when i let off the gas though. well today i took her out for a spin and i hit a bump and it did it again only this time it didnt stop. i ended up having to stop in center of a two lane road (has a spot for people turning) anyways so i attempt to restart the car and i cant keep the car running with out adding fuel and when i do it is rough and still sputtering and hesitating. and eventually dies on me. after 10-15 minutes of just sitting there and no one stopping beaufort is full of ***holes but thats another story i try and start it and it starts right up and runs fine untill i hit another bump. i limp it home in this fashion. My thoughts are maybe a faulty coolant temp sensor or somethings up with the fueling system. any thoughts?

[Carl H]

could be anything, start with fuel pressure first, then electrical...
sounds like a bad ground/bad wiring/dying pump.

[whoareu]

it really feels like its starving for fuel when it does it. i can give it gas when its acting up and the rpms shot up then drop then shut up again then drop and then it will just rev freely and its very intermitent. only starts doing this when i hit a bump in the road. fuel pressure is solid. 40 at idle and rises with boost and holds fine. im leaning towards elctrical also.

[lexcrob]

Try unplugging your maf and driving see if it still does it.

My assumption is that obviously it rules out your maf as an intermittent problem and likely many other electical signals sent to the pcm. This could point you to mechanical problems like a boost leak or battery bounces around and shorts out or something like that......i always think of it like putting it in timing mode. Everything stays constant so you can search for outside influence.


I use the approach when I start running out of stuff to test (at least easy quick stuff) sometimes it works sometimes I get nowhere.

[whoareu]

yea thats on the list to check. thanks.

[whoareu]

so i re ran and cleaned up a bunch of the wires going to the battery and ground and then went for a drive. all was fine for about 15min. then i down shifted from 3rd to 2nd before reaching a stop sign and then she started acting up again. at this point i cant get it to go above 2500rpm's.

could bad ringlands possibly cause this issue?

[mixeds14]

Sounds like ur maf is goin bad

[rb25det250sx]

I dont think Ringlands would cause that. FP is alright. clean the MAF. Make sure pump wires are fine. really really sounds like lack of fuel. Of course ive been out of the RB game for awhile now! change fuel filter? Check the plugs after it does it once, that'll tell a person alot.

[chad b.]

Did you relocate your battery to the trunk? If so, check to see if your power wire has rubbed and is grounding on the chassis. That happened to me before and I had the EXACT same symptoms.

[whoareu]

here are the facts that i know.

1. only happens when engine is at operating temp.
2. its intermitant. meaning if i take it out for a drive it may run fine for 10 minutes then it will start acting up usually after a bump or a change in load.
3. when its acting up it wont rev past 2500 rpms. it just bounces off the 2500 mark exactly like it would if it were hitting the rev limiter.
4. wont start once its acting up. but if it cools off for 10-15 minutes it will start right up.

things i know that have happened recently.
1. i fixed my catch can setup. drove fine for say 100 miles after this so not sure if its connected.
2. it smokes significantly at the top of every gear. originally thought to be bad ringlands but after a comp test (150 across all cylinders) it could be a bad turbo seal. and i do have oil in intercooler pipes.
3. while deployed my gf's kid tried to jump the car for me to get it started and did something because i had to replace a 150 amp fuse when i got back so he probably hooked up the leads wrong or something. but ran fine for a month or so after that.
4. fuel pump is fully functional.
5. maf seems to be legit also.

what are your thoughts???

[Carl H]

kid connected the leads to the battery backwards?
proly bbq'ed the ecu...pop it open and have a look.

[lexcrob]

Smoke at high rpms - rich condition most of the time
Monitor oil consumption to confirm. (1Qrt 600 miles is the absolute maximum consuption)

Let it warm up until it acts up then start tapping on sensors kinda like carb cleaner intake leak technique. (monitor for rpm changes)

Your concern is obviously temperature dependant id point at ignitor and coil packs. "at this point swap with known good ones" -----resistance checks wont tell ya much when only happen when its hot....

Im not familiar with rb ecu but 2500 is probly limp mode deal could be caused by knock sensor when you misfire.

Is there any stored dtc's def check into that!!!!! Maybe its just a lean idle code or o2 sensor code malfuction sometimes ecm's see it as CAT conservation and pull the limp mode.

Maybe your low on coolant and when your car warms up the coolant temp sensor thinks its still cold. Maybe your fast idle thermo valve is stuck open! (i beileve it has one....<<< essentially a big vacuum leak when its not cold.

If anything you say only acts up when hot or in "closed loop" per say. Wire your cooling fans to a ignition switched source and just run em all the time just neve let it heat all way up.

^Of course im not recommending long term but maybe you can drive it for a bit and monitor oil consumption get some miles on it.

Get a consult cable hooked up and monitor current data to see what ecm see's(no idea how to do that just yet on rb)


Im shooting off the hip on all that just trying to give you more ideas.
If none of that helps and your still stuck......

try what carl said def. viable not concret to me just yet. If you live near nashville TN I have 2 of them you could try.

ALL ELSE FAILs drink a beer and START FROM THE BEGINNING YOU MISSING SOMETHING.

[lexcrob]

I looked it over your story again and im gonna again point at ignitor possibly CAS for shur.

( i had a acura integra did same EXACT thing like EXACT SAME and it was the dizzy specifically the ignition controll module inside of it)

Rb dont have Igniton control module but ignitor is similar if not same....... but cas sends signal to fire ignitor ampifies ground signal.....
NO IDEA WHAT IM TALKING ABOUT ............help.....


Do a waste fire conversion i did it to my first rb20 years ago worked great. Write ups here on nico is great followed it to a T and ran perfect. Couldnt afford or find coil packs at the time spitfires were 1200$ i believe 4-5 years ago!

[whoareu]

i wouldnt think it would be the ecu, as it starts fine and runs fine untill its at op temp and then it may or may not act up. it more than not will though.

i wouldnt think the cas either for the same reasons as above.

doesnt have an igniter, its a S2

could be the coils maybe.

coolant isnt low i am very ocd on the cooling of this platform

it doesnt throw any codes or funky dash lights.

dtc's i am unfamiliar with, please explain.

[lexcrob]

what the heck is S2 no ignitor......

dtc = diagnostic codes

ILL TELL YA WHAT TO DO

GO TO WALLMART

BUY BOX OF 100 SHOTGUN SHELLS AND A CASE OF BEER

DRINK AND SHOOT TILL THE RB IS GONE AND START FRESH !

[whoareu]

its back to its old self. running strong. i went through and leak tested everything and fixed all the boost leaks i found. most on the manifold and throttlebody. there was also a big leak from the catch can setup. all fixed. i aslo seafoamed the intake and heads. runns much better now.