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  • 4 months later...

I'm having this problem after my turbo/injectors upgrade and tune, apart from this niggling startup sputtering and choking, car runs beautifully smooth and is a real rocket. The idle is crap though, bit rough and sounds like a grumbling racecar idle. I'm thinkin its the injector settings on startup/idle that needs to be tweaked.. :wacko: The injectors are 630cc Siemens Deka top feeds on RB25 NEO..the tuner did say they are nortorious for a rough idle..

Edited by rondofj
  • 1 month later...

ummm so has anyone here actually managed to fix their problem?

mine was getting pretty bad, would have to hold the throttle a bit longer on start up or sometime stab it twice...
i changed my powersteering fluid the other day cause i thought it was causing a weird noise...

and now my cold start issue for the last two times i have started yest and today have been fine :s i have no idea how it would make a difference on start up....

the only other thing i have done is change timing belt and water pump, but it was still rough on start up for the last two weeks before i did my ps fluid

its still not 100% as in when i bought it cold start would his 1500 and stay there, now it will go to 1100, maybe i just need to adjust the idle as well, we'll see....

Edited by MatthewT85
  • 5 weeks later...

Ive had this issue, like, forever. Here are a few things, partly in response to suggestions above:

- Had the TPS replaced a few years ago.

- Have cleaned the AAC

- Have cleaned the air flow meter

Nothing has really fixed the issue.

However, try keeping the battery on a charger overnight, and unplug it just before you go to start the car in the morning. A fully charged battery helps to give a strong spark and starter motor. This was enough to make the engine speed pick itself up on occasions.

A blip of the throttle has always worked for me though.

yeah ive cleaned all those and also cold start valve, and never really made it go back to normal...

i always just blip once or twice, just would be nice to have it back to what it was meant to be :(

I have had this problem for 4 years and now and i bought the car with the problem before i changed all these parts, and its still sticking around. Its getting to winter and is getting worse again

Gone through a full engine rebuild (from the piston, rings, crank, rods, oil pump, water pump etc etc to the head being rebuilt compleatley and all the rest ... everything ACL racing or genuine)
Changed all my breather hoses, evaporative hoses, PCV hoses, fuel hoses, coolant hoses. Every hose in the car is a new genuine nissan hose ..... all of them
New battery, AFM, TPS, both coolant temp sensors, AAC vavle, cold start regualtor (under plenum), O2 sensor, Spark plugs, Coilpacks + harness, injectors + harness all new and genuine
All the cars fluids have been changed with Redline equivalent.
I can keep going with the rest of the parts changed on the car but im less than half way. i dont care that much about the problem I chagned all this stuff because i can, not to fix this problem.

Ive changed pretty much everything to new with my car except for the
ECU
CAS
knock sensors
Throttlebody
Starter motor
Alternator

Hope that knock some parts to try off your lists

Edited by central coast person
  • 2 months later...

I had some spare cash so i B/Ordered a new genuine throttle body for my car and have fitted it and tested it over the past 2-3 weeks to be sure and my car has started every morning (some mornings 6 degrees) like brand new, even at a point where i left it for 3 days it started like brand new.

The idle needed to be adjusted via the AAC valve and also TPS when i first put it on as the throttle body was setup way different to who ever stuffed around with it. It has a silicone paste around the butterfly from new the same as the GTR to seal it completely tight and a few other things adjusted differently. I dont think many of the throttle bodeieshave the silicone there anymore as they are so old and when i looked the butterfly in the old throttle body had a constant gap there so its had to be creating the ruff idle on start up and a higher idle overall, my ACC screw was screwed almost all the way in to keep the idle down to 700RPM because of the butterfly being slightly open on idle all the time, now its screwed out way further because of the constant seal.
The cars are most likely running rough because the TPS is expecting fully sealed throttle as its set inbetween 0.4-0.5V but the gap in the butterfly is making the ECU run a wrong start up due to more air. The ECU would be smart enough after a few seconds to adjust to it and make it idle out. I would also guess Aftermarket ECU's with an adjustable start up could be tuned around this by adding more fuel at start up.


No more run like i had left a hose off or had a stuffed AFM on cold start up. No need to touch the accelerator pedal in the morning anymore.

After reading through all of these posts (rather entertaining i might add) a couple of things come to mind.

CRANKING FOR A SECOND LONGER

First of all, the reason why holding the key down for that split second longer is working for most of you is because your crank maps in the ecu are different to idle and load maps. how it works is while the ecu is getting the signal that the starter motor is still cranking, it is throwing in that little bit extra fuel until you come off the key. so holding the key for a split second longer is exactly the same as tickling the throttle.

THROTTLE BODY

something to have a look at for i would say most if not all of you is your throttle bodies. someone already mentioned that theirs was held ajar the slightest bit, whether it be by the TPS position, worn out or old spring or throttle body, a busted TB gasket (very common and often overlooked) or a layer of gunk on the inside of the TB. The layer of gunk only has to be minimal. Sometimes you cant tell by looking at it, but it is definitely enough to affect it. best way to remedy the gunk is to start the car up and load her up on carby cleaner holding the accel cable open slightly.

Better yet, pull the TB off. You dont have to have a gasket to replace the old one with (the old one will break) just have a tube of gasket goo. It works perfectly on the throttle body, you wont tell a difference between goop and gasket. But pull off the TB, clean everything with a tootbrush and petrol, or Carby cleaner or Metho then put it all back on. Dont lose the spring for the accel cable though, you wont have fun if you do. I would highly recommend doing this even if you are not having troubles with start up, its just a great little bit of maintenance.

CRANK ANGLE SENSOR

Check that your CAS is nice and tight and has not wiggled its way around one way or another. even if it only moves a millimetre it will be enough to give you troubles. But not necessarily enough to see any change whilst driving or when warm, but it will make start up a little harder.

THROTTLE POSITIONING SENSOR

Check that your TPS is adjusted correctly with 0.45v CLOSED and +4.5v at WOT. TPS can play havoc on an angine, especially with something as niddily as an idle.

COOLANT TEMPERATURE SENSORS

Make sure that your ECU coolant temp sensor is working and connected. Not the single wire sensor that controls the dash temp gauge, the twin wire sensor that sits next to it. If it is faulty, your ecu will run on two maps, one for 20c and one for 80c. meaning at start up it wont be getting enough fuel to combust properly at certain temperature ranges.

KNOCK SENSORS

Check that BOTH of your knock sensors are connected and working. A knock sensor controls (in a way) your engines timing. If the engine receives a signal from the knock that it is pinging, it will advance the timing until the pinging goes away. This can have major effects on your cars ability to run. But they are also sensitive equipment. They run a single 16g shielded wire to each sensor (both are a green plug underneath the plenum on the drivers side) You can see the forward most one by looking through your plenum runners just near the top radiator hose, the rear most one you can see by looking down into the engine from over the strut tower but is a little harder to see, best off going from under neath and they will be on each side of the engine mount and oil filter.

Both of the knock sensors need to wired up and functioning correctly. Also check the wires going to them all the way back to the ecu. Make sure there are no breaks or pinches in the wire. As I said they are sensitive equipment. If the wire, or even the plastic tubing, or the shielding around the wire is broken, the sensor will pick up "noise" (similiar to the whirring you hear through your radio when accelerating) and throw a code to the ecu to change your timing.

This problem can very well be only present during start up if the wires are in bad shape as they are both on the same side, and close to the starter motor. So if they pick up noise during cranking, the ecu will advance the timing on you for a couple of seconds until the sensors realize there is no pinging and stop throwing the code.

ECU "THROWING CODES"

The next step would be to check your ECU for codes. Either do this by plugging your laptop in with a consult plug (if any of you are located on the Gold Coast I am happy to help with this as I have the equipment) and reading the ECU codes through a program like ECU Talk, Data Scan or OBD Scan Tech. You can also do this without a laptop by turning the screw on your ECU to diagnostic mode and counting the flashes either on the LED on the ECU itself, or the check engine light on the dash. If you are using the E CU LED and it only has one LED, 1 long flash = 10, 1 short flash = 1. so 34 ( knock sensor code ) would be 3 long 4 short flashes. Find out if your ECU is throwing a code and check it against the FSM or with this list http://motorswaps.myfreeforum.org/archive/rb20det-ecu-diagnostic-procedure__o_t__t_57.html

ECU RESET

The last piece of knowledge I can impart to you on this matter would be to reset the ECU. It can do absolute wonders for these little problems. do this by disconnecting your battery for a couple of minutes and holding your foot on the brake, flashing the headlights or beeping the horn to remove any residual charge the ECU or any capacitors may be holding. Keep the battery disconnected for lets say 5 minutes then reconnect it back up. start the car up and go for a drive.

For the first 5 minutes, the ECU will be making big changes to everything, A/F ratios, timing, injectors, everything. After 5 minutes (thereabout) it starts making very small incremental changes until everything is running at the very peak of its performance. Resetting the ECU like this will make sure that the ECU is now taking into consideration any new changes or upgrades you have made to the engine in whole as well as it will be compensating for things that may not be working at 100% of its abilities. I did this with a healthy running engine and saw quite a note able difference, so doing it on a car that is not running 100% "SHOULD" make monumental changes to its drive ability and performance.

In saying this, resetting the ECU to allow it to recalibrate will not be as efficient as a dyno tune, so do not get mistaken with this. It will not automatically dial in new "stage" cams, or bigger turbo or injectors.

CONSTRAINTS OF ECU RESET

I should also note, that it is really worth holding off doing this until you have checked everything else over with a fine tooth comb, do this as a last resort for the "Pièce DE résistance". This way it will have the highest opportunity to make the best adaptations to whatever is needed for the car to run perfectly. But you should also do this with a full tank of gas, and some performance booster, such as n octane enhancer, or a mixture of 98 octane and a little bit of E-85. This way the car will tune itself to the highest possible performance standards it is capable of.

I hope that something is this wrist breaking post I have written in my current drunken state both makes sense, and is also relative to the situations you fellas are experiencing. Wouldn't want this to be a waste of time LOL.

Let me now if any of these pointers helps out in any way.

Kind Regards,

Michael

hmmm interesting, i didnt really look at the throttle body that closely recently when i was doing the rocker cover seals, how much was the throttle body?

Nissan List (RRP) is around $380. Well worth it , its the last problem my car has/time being and was on going since 2008 when i bought it.

Yeah Michael, your drunken post make sense but. That was most of my check list when a problem came up on my car, works well. I noticed it was the throttle body the other night when i cleaned it out and my idle went from 700RPM to 1000000RPM. Also because i work for Nissan i got a few opinions for some people and Nissan throttle bodies shouldn't be cleaned unless you can re-seal the butterfly yourself. People with GTR's will know what i mean when you i say don't clean the throttle bodies unless you know what not to clean off/what to clean.

  • 2 weeks later...
  • 2 weeks later...
  • 6 months later...

have you tried what I mentioned ?

dammit this is getting worse... car shudders on cold start and really struggles to start up...even when holding key in longer.

Will get my mechanic to have a look at this , dont really want to clean the tb myself and stated above. Im mechanically retarded so wont be touching any of it.

I cringe every time I start every morning and my mechanic can only get to it on the 4th of March :(

  • 3 weeks later...

Ok , im getting really worried now

Its gotten very bad , if the car sits for two days , it struggles to starts and and im hearing popping and banging sounds from the engine until it starts up. Once it starts up it revs and drives fine.

Im worried that the this constant issues when strartig up is wearing away at the internals. Do I have any reason to worry. Booked it in with Paden for the 4th of March but scared something will happen between now and then.

Cleaned AAC valve

Cleaned cold start

Check for vacuum leaks

Cleaned throttle body

Splitfires installed

Any ideas on what I can do except make sure I start it every 14hrs or so to prevent it from getting to cold?

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