Random Stalling, Pinging, Massive R&r...wtf!?

[benro2]

Hey guys, last weekend I changed the spark plugs and did a radiator flush myself - and unless this is a massive coincidence - I think I may have stuffed something somewhere. Here are the problems:

1. When car is below normal operating temp, randomly the engine will idle really roughly, almost like it's on 5 cylinders (could be but doesn't seem quite *that* rough) then return to normal. It will also run REALLY low timing (like 0 deg BTDC) on even light throttle, even in a low gear - seemingly after I've given it a bit of throttle just beforehand. Returns to normal at random times, or when the car is up to operating temp (I think). Just tonight I was driving in between a couple of walls at very low speeds on like 5% throttle and I could hear random pinging, say 2-3 pings per sec - quite sure this wasn't happening at all before.

2. When my ECUTalk indicates I'm at 80C water temp, for the first 5-10 mins after this it'll boost to 7-8 psi (I have a manual boost controller fitted but everything else is dead stock) but I will get almost no power. I actually saw the ECUTalk indicate 3-4 deg *after* TDC! Feels like I've hit a wall - absolutely bugger all acceleration!

3. When car has been up to temp for 5-10 mins it all seems OK, however it seems like if I fang it around a bit, after I start driving normally again the car will either stall or start acting really weirdly - like fluctuating between 500 rpm idle then up to 1500 rpm, etc. If it stalls I can just start it straight back up again.

WTF is going on!? All of this only started *after* I changed the plugs and flushed the radiator! One thing though, I had a bit of trouble changing the plugs so I had to take the large air intake pipe off that runs over the top of the engine and a few others around it. I've made sure they're all reconnected but it was a bit of a job getting the big one on - it looks like it's on properly but is it possible it's not? Surely that wouldn't cause problems like this?

Edit: oh yeah, this could be it (I hope not) - when trying to get the new plug in that sits directly under the large air pipe, I accidentally cracked the white brittle insulation and had to take the plug out. Obviously before I did this I picked out all the pieces and then got the vacuum cleaner out to get all the small bits. It is possible, however, that I didn't get some of the really small bits, and these may have fallen into the cylinder. I was really careful to ensure this didn't happen, but possibly my eyes just aren't that good Would something that tiny be able to cause problems like this? Oh, and of course, I threw away that plug and put another new one in

Some notes:

- Car is auto S2 R33 GTS-T, stock everything apart from Turbosmart (?) manual boost controller set to 7.5 psi.

- Car was in gear when it stalled. Was luckily in a car park and it just died without warning. All electricals were fine and I just restarted, no probs.

- Also running a turbo timer which has some loose wires. They have been loose for a long time and all I've ever seen this do is turn off the turbo timer itself, never the engine! Last night I fixed it in another position that has less stress on the wires, yet all the above problems have happened since then, so I doubt this has anything to do with it.

- I've just reset the ECU but nothing changed.

- Plugs are copper NGK heat range 6 gapped at 0.9mm. Previously they were around 0.8mm but I can't recall which heat range - but pretty sure they would have also been 6.

- Running Splitfire coilpacks, only a few months old.

- Replaced CAS recently (with 2nd hand unit), didn't touch when changing the plugs.

- AFM was cleaned recently, also didn't touch.

- Slight misfiring at idle. This was happening before all these problems above. If I stand at the back of the car to the side of the exhaust pipe I can hear slight "bassy" pops. Not sure if these are actually "misfires" or not but doesn't sound right. With the old plugs, with the A/C off, it was pretty bad and you could feel it in the idle. With the A/C on you can hear it from the exhaust but not feel it, except for one every few seconds or so, usually after the A/C compressor has turned off or something.

To me, it seems like an ECU or some signal corruption or electrical fault. It seems like the ECU is detecting some bad pinging or something and retarding the ignition as a result. Is it possible this is still happening at idle so it retards the ignition so much that the car stalls? Any ideas?

Edited March 17, 2011 by benro2

[DVS JEZ]

Dont stress about the small pops in the exhaust at idle. Very common.

Try bleeding the cooling system again. With engine cold.

Heater on radiator cap off and open the bleeder to make sure water comes out. Then bleeder back in.

Start the engine and let idle. Let it get up to temp with the rad cap off and see if any air comes out.

Try this and see how u go.

Is there any blue smoke etc from exhaust

[Tony de Wonderful]

Can you rev it over 2 grand?

[turael]

so ECU doesn't pick up any errors? (have you done the self diagnostics)

[benro2]

Dont stress about the small pops in the exhaust at idle. Very common.

Oh OK, that's interesting. What's it caused by, and is it there from factory when new?

Is my slight misfiring problem related to this in any way?

Try bleeding the cooling system again. With engine cold.

Heater on radiator cap off and open the bleeder to make sure water comes out. Then bleeder back in.

Start the engine and let idle. Let it get up to temp with the rad cap off and see if any air comes out.

Try this and see how u go.

Is there any blue smoke etc from exhaust

The engine was actually cold (35C) when I was doing this. This, I think, was part of the problem - I only got around 3L of water out of it! Apparently it's supposed to hold 8.6L!! I'm guessing that's because the water in the block couldn't be accessed due to the thermostat being cold, so I'd have to flush with hot water to keep it open?

The reason why I was doing a flush/clean is because my temps were getting pretty high during summer - around 95C after going up a big, long hill - and even at idle they'd hover around 92C and stay there, whereas a couple of years ago the thermo fan would kick in at 92C, cool the car down to 87C, then cut out - like it's supposed to do. It seems now it can only hold it at 92C. Also, on some of the hottest days I've ever driven in, during one of my previous trips to Melbourne it would only reach around 89C on a huge long hill. Seems to be getting worse with time!

I think it was a Nulon branded radiator flush. It's too early to tell if it's made any difference, but I would guess that if I've only gotten 1/3rd of the dirty water out, I don't think it would!

I bled the system by squeezing the top radiator pipe with the radiator cap off, and gradually adding more water as the level dropped, until it wasn't dropping anymore. Is it possible there's still air in the system?

AFAIK, there is no blue smoke from the exhaust, however last night after I'd been showing a friend the engine (just after resetting the ECU), it was idling roughly just as I started it. He said there was some smoke and although it was dark, I'd say it was just dark smoke due to a rich mixture.

Are you thinking possible blown head gasket? I hope not! AFAIK it never blows any smoke other than in the above situation.

Can you rev it over 2 grand?

Yes, I can drive it as normal once it's been warmed up for a few mins. I can give it WOT and it seems to have pretty much full power - possibly down a few kW but that's probably my mind playing tricks on me

Are you thinking AFM plug or something has been disconnected? I've already checked that and all the surrounding pipes - they all seem to be fine!

so ECU doesn't pick up any errors? (have you done the self diagnostics)

I haven't plugged in the ECUTalk to a laptop, if that's what you mean by self diagnostics? The ECUTalk itself is supposed to pick up error codes and so far nothing has turned up - incidentally, this is the original reason why I bought the ECUTalk in the first place, but I've never seen any error codes appear!

As you can see, the unit claims to read ECU error codes: http://www.ecutalk.com/consultlcd/userguide.pdf

Thanks for the replies guys! Please keep the ideas coming

[turael]

Hey

Yeah I was thinking fault codes from the ECU - if ECU talk picks them up and it's not showing any, then the electrical side of things is probably OK

Just reading over your post here, you need to flush out your cooling system ASAP - you have mixed coolants, and this is a big no no. There is a bleed bolt on the top of the engine on the intake side near the throttle body - open this and drain from bottom of rad, fill up with water, run the engine (with heater on inside the car so the coolant is flowing through the heater pipes), keep draining with water until its flowing clear. Then run some cleaner through. Then repeat the rinse until flowing clear (the nulon cleaner is orangey), and finally do your nulon longlife coolant. Remember to let engine cool a bit before draining it.

That's what I would do right away.

Next, check all the plugs you would have fiddled with to change the sparkplugs - all coil packs, ignitor maybe.

[DVS JEZ]

I have noticed when tuning that wen trying to get a stoich mixture 14.7 afr at idle that most nissans start to pop on idle.

I richen it up to fix this. But unfortunately if u dont have an ecu that can be tuned u will have to live with it.

U could try a new ecu coolant temp sensor. Might be playing up causing an excessive rich mixture causing black smoke

[benro2]

Thanks for the all replies guys.

Turned out the timing was way off. I have no idea how it got this way, but apparently it was about 15 deg advanced!! The ECU must have been compensating for it but the mechanic said he could hear bad pinging on WOT. I couldn't hear it because I wasn't listening for the right type of pinging, like the "tink tink" sound - he says on the RB25 it's more like a white noise (which I honestly didn't notice either, but anyways).

So that's pretty much fixed all those issues I had, including the idling issues. However, I have another issue but that's for another thread...