Itermitant Rb30det Problems

[platinum]

Hey,

Just been having a few little 'niggles' with my new rb30det setup - and thought perhaps they all lead to the same issue.

1) on idle, occasionally for no apparent reason it will surge from about 500rpm to 1200rpm back and forth until you take off.

2) while driving it very occasionally just cuts in and out (doesn't stall) but if you were cruising at 60km/h it will jerk (power on, power off) about once a second alternating between the two, can't give it more power, and backing off doesn't help either. It only seems to happen on long drivers (ie greater than an hour).

2) a) very very occasionally (has happened twice) it will to the above, and then cut out entirely, and take quite a lot of cranking to actually get it to fire again (ie 6 lots of 10 second cranking while it splutters).

It's running a freshly tuned powerFC, I'll check with where I had it tuned after the weekend, but if anyone has any ideas in the meantime....

I'm thinking is might be perhaps coilpacks heating up, or the ignitor, or perhaps AFM related? It's a bit hard to check things because it's a very itermitant problem!

[barnoon]

Sounds a lot like AFM related problems to me, maybe try cleaning your AFM with some electrical contact cleaner, I had very similar problems with my RB20DET and ended up replacing the AFM and all has been fine since.

[platinum]

Might see if i can borrow/steal one to test

Also, what rpm to people generally have their idle setup at - mine is at around 700rpm, and it *just* doesnt seem quite enough, if I slip it in to neutral at the lights (auto) it idles at about 750-800rpm and is _much_ nicer.

Just wondering what sort if idle speeds other people have? Is there an idle adjusting screw - or would this be done via the powerFC?

[The Mafia]

do the idle via the power fc. Nad every engine is different. If it idles better at 750 - 800, then set it to that.

700 is too low for my RB25. It struggles. 800 works niceley, and 950 is good for the aircon.

[Lithius]

Yeah just to add my 2c, I agree with Dave's suggestion. My little RB20 used to do that exact thing so I got a new secondhand AFM and it fixed it entirely.

[platinum]

Upped the idle over the weekend, it's so strange though.

It was set at 800, upped it to 900, and in drive, it still only idles at 800ish, which is a ton better than it was - I think the powerFC is a bit confused about the auto trans? Anyway seems to be all fine now.

The other issue is still there however - is there any way to diagnose a faulty AFM by its voltage readings. Also, is it normal for the car to instantly stall when the afm is unplugged?

ta

[mr_rbman]

i thought u couldn't put a power fc on an auto car gav?

[platinum]

You can't using skyline auto boxes, VL's pull through with the goods though since they aren't electronically controlled.

[paulr33]

what afm and air intake are you using? could be compressor chuffing on the airflow meter pipework

[platinum]

I'm using an stock intake pipe, and stock AFM, although it is hooked up to a pod filter.

[TTT]

my similar problem and fix..

http://www.skylinesaustralia.com/forums/in...opic=118437&hl=

[Cubes]

With regards to idle....

Simply setting idle in the pfc isn't enough, you must first set idle via the pfc, disconnect the idle control valve plug then manually adjust the idle it sits basically smack on but not over the value entered in to the pfc.

Then disconnect the battery, reconnect and have the pfc go through its idle learn process both.

Also when starting... Be sure you don't touch the throttle.

I've found alittle bug in my PFC that appear to show its head when the car is cold. The problem is it doesn't always do it but only does it if I start the car as I am slightly touching the throttle. The cars fuel cut is thrown out, as a result the first cm or so of throttle input cuts fuel, as a result causing a huge flat spot.

If I raise rpm slightly within this first cm or so the idle will raise to 2000rpm or so then fuel cut will occur dropping throttle.

Apart from your little problem.. How is it on fuel?

[platinum]

Apart from your little problem.. How is it on fuel?

I've been driving it to work, and basically cruising very lightly, it still seems a tad high. Since the tune though I havn't done all that many calculations on it's fuel economy. Before the proper tune it used a tank in 350km of highway driving haha.

I might fill it up this week, reset the trip meter and see how it goes. Although I'm extremely happy with how it cruises on the highway, so effortless.

To be honest, not entirely happy with the tune as it is - and I'm not even sure if they even road tested it, because the idle was extremely crappy and there's no way you couldn't not notice it unless it was all done on the dyno under throttle. Anyway, will be upping the boost a little more soon and will get it tuned again, although getting the hang of the PFC now, makes me wonder if I should just purchase a datalogit box instread.

[platinum]

my similar problem and fix..

http://www.skylinesaustralia.com/forums/in...opic=118437&hl=

That sounds like a similar problem, thanks - should the AFM voltage be doing funny things when it is stuffing up?

[mr_rbman]

You can't using skyline auto boxes, VL's pull through with the goods though since they aren't electronically controlled.

u learn something everyday!

i'm having a problem at the moment with my cold starts, i've adjusted them to what cubes has said and worked for a while but now it takes a few cranks for her to get started!

[platinum]

mine has a fair problem with cold starts too, going to have a look at the AAC valve on the weekend, although it was all sand blasted, etc a while back. Seems to take 2 goes of 5-10 seconds, and then a final crank of about 2 seconds before it starts.

Even totally warm, it takes probably 7 cranks to start. The old VL used to start at the flick of the key :\ tuner assures me it's totally normal though.

Edited May 31, 2006 by platinum

[mr_rbman]

mine has a fair problem with cold starts too, going to have a look at the AAC valve on the weekend, although it was all sand blasted, etc a while back. Seems to take 2 goes of 5-10 seconds, and then a final crank of about 2 seconds before it starts.

Even totally warm, it takes probably 7 cranks to start. The old VL used to start at the flick of the key :\ tuner assures me it's totally normal though.

FOOLBOOST has had the same problem and his was sand blasted which turned out to be the problem!

Mine probably takes 2-3 cranks to get going with a little throttle!

[FORZA-MOTORSPORT]

FOOLBOOST has had the same problem and his was sand blasted which turned out to be the problem!

Mine probably takes 2-3 cranks to get going with a little throttle!

Today i noticed she took 2-3 cranks to get going then cold start picked up and she crused up to 1500rpm , i think a little throttle would have helped her get there a bit quicker, does it have something to do with the cold start valve??? LOL maybe that has sand in it too!! Not! It wasnt sand blasted! Maybe the cold start valve isnt big enuff for a 3L???

Edited May 31, 2006 by FOOLBOOST

[Cubes]

Mine always takes 2 turn overs to start, which is nothing like it was on the std values where it would most of the time take a good 5-6 turn overs.

The 3ltr has never been as instant on cold starts as the rb20 was. I've fiddled a little with the +10degree's cranking ms but i'm happy with 2 turn overs until it starts.

I really think furthur tweaking of the cold start values + tweaking of the water temp correction.

Tweaking takes so damn long though as cold starts only happen once per day and before you know it coolant temps are pushing 30+degree's, I might try throwing a little more fuel in the cranking ms and see if it does anything tomorrow.

If that doesn't appear to improve cranking time I will throw a little more fuel in the +10 water temp correction.

Once I've got a perfect set of values I'll post them up.

Has any one left the warm start (80+) value at the default 4?

I did, pulled over, shut the car down went to start it and the damn thing wouldn't start until coolant temps dropped, I had no idea what was going on as it was only when I just began fiddling with the pfc.

With regards to idle speed. I've recently bumped it up to 800 as the RB25det's idle at as I found 650-700rpm was a tad low with the wipers, lights and heater on while idling in traffic. 800 appears to be just right with a/c idle being 850.

[Craved]

anyone seen issues with the power FC causing long cranking starts due to the dash lights flashing off then on ??

sort of related to the current conversation.

i turn mine over, the dash lights switch off, engine still cranking, then about a second later they turn back on and the car starts .. wierd annoying issue..

only happened since install of power FC..