Jump to content
SAU Community

Recommended Posts

hey guys iv just finished putting an rb25 into my VL, and yesterday on first start up it hunted at idle quite badly, then sometimes the revvs dropped really low and it made a bit of a tapping or knocking from near the fuel reg. then i started it again last night, i didnt let it warm all the way up to running temp so not sure if it would have begun hunting again, but it just idled a bit high and not very smooth, with a very slight hunt. i have checked everywhere for a vacuum leak etc, i am only left with rather a sensor is screwin round or my BOV is leaking or something. any other causes of this? anyone who knows about these would be a huge help!

Edited by r32drifter1
Link to comment
https://www.sau.com.au/forums/topic/204942-some-quick-help-please/
Share on other sites

Could be your air flow meter is not working properly (that's asuming your setup is still using an airflow meter) are you using a nissan ECU or an aftermarket item?

other possibility is the AAC valve is dirty..maybe.

thanks heaps for the quick reply guys, yeah airflow meter im not sure, i am using one of my old silver top rb20 because i was told they are the same? any chance thats the problem. and lol i dont know alot about these engines. the ACC were is it? there is a sensor and plug just below the idle control motor, a purple plug from memory, its a little damaged from transit, does that play a role in idling etc? oh and yer using standard rb25 ECU, ive tried spraying crc around looking for an air leak but im starting to get more convinced its not the problem

Edited by r32drifter1
the import place that i bought my engine from. could it be making it run wrong?

quite possibly. i haven't looked at an rb20 motor to see if they use the same airflow meter. but if they don't it could be sending completely wrong voltages to the ecu which would definitely cause idling issues.

yeah its a S1, iv just found that DIY cleaning the AAC valve and realised that is the part which has a damaged plug on mine, that could probably be the reason yeh? are these a part only on rb25s? cause i have an rb20 and 30 manifold in my shed i could swapping if not!

unplug the AFm and start it up... if it idles fine then your AFM is the issue

*note, with the AFM unplugged the engine willacctually run and idle very well... but wont rev more thne 2000 ish rpm, where as an AFM that is plugged in but not hooked up to the intake pipe or popped off intercooler hose will run like shit.

the ecu limp home mode works with the AFM unplugged.

ok i have some more symptoms its got me confused now, ill try get some pics up if i dont get it fixed soon. i actually took it for a drive yesterday and it was wet so hard to really test, but it looses traction easy etc. but on grippy surface it doesnt want to go. it makes all the noises just doesnt accelerate like it should. also the idle hunting, it only does it when the car is warm, and if you gently accelerate it will stop. lastly on cold start up it wont revv at all, if you give it any throttle is just wants to die, and is a bit of a pig to get started cause of this. so yeah theres the million things wrong with it, anyone got any ideas?

yeah i have a feeling there is a faulty plug in my loom, which is involved in giving power to the fuel pump. hopefully that will fix the sluggishness, i dont understant why it would hunt and not revv untill warmed up. maybe some of the sensors take power from it too

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
    • You don't have an R34 service manual for the body do you? Have found plenty for the engine and drivetrain but nothing else
×
×
  • Create New...