rb20det developments and problems

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

YEAH WE ARE GOING TO CHECK FUEL PRESSURE AND IF THE O2 IS SWITCHING SOMETIME TODAY.

Post by **WDRacing** » Mon Apr 12, 2004 4:22 pm

http://forums.freshalloy.com/u...=true

Just a thought

Post by **GTR Shop** » Mon Apr 12, 2004 4:22 pm

The o2 isn't needed!Didn't I say unplug it weeks ago??Unplug it and forget about it until you sort the problem.

It amazes me that everytime someone has a problem, that they run out and buy a new O2..I've never had to replaced an O2 sensor to fix a problem.The ECU doesn't care.. we we tune RB20/25s we use the std sensor location to for the W/B.. just unplug the O2 and remove it.It has nothing to do with low octane maps either.. its purely for low throttle cruise economy.

The actual operating range of the factory narrow band O2s histogram is so small I don't know why they bother.. you can tune for economy in about 4 seconds with a wideband and SAFC.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

MY O2 SENSOR IS DEAD.... IT HAS ABSOLUTLY NO CONTINUITY AND IS CHARRED BLACK.

ANYWAY, GTRSHOP MY FUEL PRESSURE IS 43PSI PRIMED. MY QUESTION IS WHAT WOULD THE FUEL PRESSURE HAVE TO DO WITH A SPARK CUT?

Post by **Carl H** » Mon Apr 12, 2004 4:22 pm

this might be a shot in the dark but......have you replaced the spark plugs and gapped them to .8mm?it might be possible that you are blowing out the spark under boost thus causing this 'revlimit'.for 10$ i would replace the plugs and gap them.couldnt hurt.

Post by **GTR Shop** » Mon Apr 12, 2004 4:22 pm

A: Your O2 has nothng to do with it.B: Whos saying its a spark cut?? You may be blowing out spark or really fat mixture wise and its missing.

The RB25 we were tuning last nite/today was fine until we brought the mixtures clean, then it started to miss.. gapped the plugs from 0.86 to 0.74, better but not fixed. Gapped them to 0.68mm, sweet as.BTW it made 300rw hp at 12psi dropping to 10psi from 5000rpm onwards and under 80% inj dty.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

These are all brand new plugs gapped to .8mm. I'll try pulling the plugs then clean and regap them. That would explain why now with the increased airflow it starts happening under full throttle.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

I gapped my plugs to .66 and I took out my thermostat (runs alittle cooler). I noticed this problem (limiter) only happens when the car is at operating temperature, which leads me to believe that once the ecu goes into open loop its getting a faulty sensor reading.

Post by **GTR Shop** » Mon Apr 12, 2004 4:22 pm

OK.. from the start.. 13" vac is TOO LOW unless the motor is overly cammed.

You HAVE a leak somewhere or the throttle is excessivly open at idle.If the intake system isn't sealed you get the result you currently experiencing.

Forget the other sensors etc.. you require ignition, CAS, inj, and AFM for the car to work. You're not pulling any codes so everything seems ok in that department.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

We have no leaks anywhere.... and this is confirmed by three people other than me. The throttle plate is at the stock position when at idle.

This is a stock motor. Compression numbers are:Cyl 1: 130Cyl 2: 130Cyl 3: 125Cyl 4: 120Cyl 5: 125Cyl 6: 125

Fuel pressure after priming is 43 psi.

Post by **Carl H** » Mon Apr 12, 2004 4:22 pm

oh man.those compression results are hella low.should be ~170 +/-10.is that a warm compression test?

Post by **WDRacing** » Mon Apr 12, 2004 4:22 pm

No doubt, low numbers...

I experienced ignition problems on my GTS-t for awhile and narrowed it down to a bad coil pack, actually 2. They were shorting once the motor got up to temp.

PS. My buddy came into to visit from OKi this weekend, so I didn't touch that mani. I'll try to knock it out this week. Hopefully you can get this remedied soon.

WD

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

This was done after the motor sat for about 45mins. I have seen that problem before on a friends car that he blew four coil packs till we found the problem (bad ignitor ground). But this isn't showing the symptoms his car was.

WD: Its cool whenever you get a chance and I have the money ready for you when you are. If youe ever in phoenix let me know I want you to take alook at my car and see if you can find anything and so that you can experience the problem yourself.... its really hard to explain for you to truely understand whats happening.

Post by **Carl H** » Mon Apr 12, 2004 4:22 pm

hmmm.try cleaning off the MAF with a can of carb cleaner.just spray the hell out of the wire deal with the car cool and off.might help.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

I did that a couple months ago, but its really dusty here so I'm sure it wouldn't hurt to try.

Post by **Joe** » Mon Apr 12, 2004 4:22 pm

Carl H wrote:hmmm.try cleaning off the MAF with a can of carb cleaner.just spray the hell out of the wire deal with the car cool and off.might help.

i would NEVER use carb cleaner on a MAF. thats a harsh set of chemicals....if you do, only mist it on there very gently. the MAF is a very very sensitive piece of equipment.

Post by **WDRacing** » Mon Apr 12, 2004 4:22 pm

Rubbing alky would be a better choice IMO, but I use contact cleaner I "aquire" from work. Carb cleaner has to many lubricants in it. The MAF superheats the coil wire and probably cleans all the residual off, but I don't like the idea anyway.

WD

Post by **GTR Shop** » Mon Apr 12, 2004 4:22 pm

What that shows is your mototr has been sittoing for a while and hasn't had much running.. am I correct??

We has 90psi until the engine was run for a fre hours.. then 170 across the board.

How confident are you on it being a std motor? st cams, cam gears, turbo?

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

PRETTY CONFIDANT, I GOT IT FROM VENUS AND THEY LIKE TO MAKE SURE ON WHAT THEY ARE SELLING. IT HAS STD CAM GEARS, AND NO AFTERMARKET TOYS ON IT VISIBLY. MY MOTOR HAS BEEN RUNNING FOR AWHILE NOW, I'VE BEEN DRIVING IT FOR THE PAST 3 MONTHS (EXCEPT FOR THE FMIC INCIDENT). I'M JUST LOST AT THIS POINT ON THIS MOTOR, AND I CAN'T FIGURE IT OUT AND NIETHER CAN THE OTHER PEOPLE WHO HAVE LOOKED AT IT. ITS HONESTLY REALLY HARD TO EXPLAIN WHAT IS HAPPENING ON THE INTERNET AND IT IS TRUELY SOMETHING YOU HAVE TO EXPERIENCE FOR YOURSELF.

THIS IS THE TOTAL PICTURE:THE CAR IS SUCKING DOWN GAS LIKE WATER (WHILE GRANNY DRIVING -SHIFTING NO LATER THAN 4K RPMS): TALKING 9-12 MPG.THE CAR IS HITTING SOME SORT OF LIMITER AT 5500 - 6500 RPMS (DEPENDING ON GEAR AND THROTTLE POSITION), IT FEELS EXACTLY LIKE A OVER-REV OR SPEED LIMITER. IF I SHIFT WHEN THIS LIMITER HITS THE NEXT GEAR HAS NO POWER LIKE BOOST IS LACKING UNTIL I TAKE MY FOOT OFF THE GAS FOR A SEC OR SO AND GET BACK ON IT.TOTAL POWER IS LACKING.MY TURBO IS WHINING LIKE CRAZY AND IS EXTREMELY LOUD AT SHUT DOWN.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

WHATS THE MOST FRUSTRATING TO ME IS THE FACT THAT THIS CAR RAN GREAT WHEN WE FIRST INSTALLED IT. THEN IT OVERHEATED AND THE IDLE AND TIMING WENT CRAZY, THEN WE BLEW ONE OF THE HOSES GOING INTO THE FMIC AND NOW ITS DOING THIS.

Post by **WDRacing** » Mon Apr 12, 2004 4:22 pm

You might have warped the head, or jacked up the HG. How bad did you over heat it?

Post by **Carl H** » Mon Apr 12, 2004 4:22 pm

that sounds like the ecu is in limp home mode.i would try clearing any codes.i still think that the ecu temp sensor is bad based upon what youve said.

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

IT JUST WENT UP TO THE FOURTH BAR ON THE KA TEMP GAUGE AND BOILED OVER.

I'VE USED TWO ECUS AND I HAVE A NEW ENGINE TEMP SENSOR ON THE ENGINE. EVERY SUGGESTION YOU GUYS HAVE GIVEN ME I HAVE DONE. I'M GOING TO GET A STANDALONE COMPUTER AS SOON AS I SELL MY OTHER CAR SO I CAN ELIMINATE SOME OF THE OTHER SENSORS LIKE MAF AND AIR CONTROL VALVE.

Post by **WDRacing** » Mon Apr 12, 2004 4:22 pm

RB20 Limp Home mode won't let you rev over 2500...

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

I'M GOING TO GET A MICROTECH LT-8 SETUP SOON.... HOPEFULLY THIS WILL CLEAR UP MY PROBLEMS. IF NOT I'M LOST AND WILL PROBABLY BE ORDERING THE RB30DET I'VE BEEN TALKING ABOUT AND STARTING OVER.

Post by **krayton** » Mon Apr 12, 2004 4:22 pm

just curious if youve tried pushing through it?

when i was maxing out my afm, i could push through the wall (mine hit at 3500rpm). yeah it felt really bad, but im just wondering.

also, have you opened your old ecu? check if something burned out

i also tried reading it all, but can you get past 5500 if your not at full throttle? (ie half throttle?)

Post by **PROJECTRB240SX** » Mon Apr 12, 2004 4:22 pm

I HAVE TRIED PUSHING THROUGH AND IT WONT GO.... IT USED TO GO THROUGH AT ANYTHING LESS THAN 3/4 THROTTLE NOW IT WONT EVEN DO THAT.

I HAVEN'T OPENED MY OLD ECU AS IT WAS STILL OPERATIONAL AND I DIDN'T WANT TO MESS ANYTHING UP.

Post by **Carl H** » Mon Apr 12, 2004 4:22 pm

have you checked the turbo its self?branden baune was having a simmilar problem almost the same as yours and it turned out to be shot turbo seals.oil would get into the air underboost and throttle and would cause the engine not to spark.i would check the turbo for shaft play and perhaps mad oil in the intake pipe.

Post by **WDRacing** » Mon Apr 12, 2004 4:22 pm

You'd be smoking like a big dog if you were ingesting enough oil to effect the spark.

Post by **Joe** » Mon Apr 12, 2004 4:22 pm

i might have missed it, but is your engine light working? is it on?

it really sounds like i you did 1 of these

1) exploded the headgasket 2) warped the head3) somehow screwed your MAF

if i recall you were running 30 degrees BTDC timing, did you overheat while running such a greatley advanced timing?

rb20det developments and problems

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