Running prob - keeps fouling plugs

[jasegould]

Willy wrote:

Hi guys,

My first post here. Very nice forum. It's great to see so many GTi-R enthusiasts in one place.

I just bought a 'R last Wednesday. It's stock except for a FMIC and now 'scoop-less' bonnet. Wednesday night I was out cruising around with mates as you would and after about 2 hours of hard driving it started hesitating and idling really bad. With black smoke pouring out the back.

I got it home and it was OK for a while and then played up again. I pulled out the plugs and cleaned them (they were very black and they were cheap ones too) and it played up soon after. Yesterday I replaced then with NGK PFR-6B and it idled for about a minute before going back to it's old trick again. I checked one of the plugs and it was already black!!!!

I've replaced leads and coils with the ones out of my mates import U13 bluebird and that didn't fix it.

I think it may have gone into limp home mode now. I'm gonna do an ECU self test when I get home. Anyone had similar problems? I contacted the previous owner who said he replaced the plugs 3 months ago cause he had a similar problem. He has now gone away til Thursday...typical.

Sorry about the long post. It's just very frustrating to have this happen within the first week. I should be out enjoying the 'R.

Oh yeah, when I was driving it hard for like 2 hours I did 100km and used half a tank. Is that normal if you're driving hard?

 

[Willy]

Thanks for that Jasegould. I just spent all night playing around with it. I got out there started it and it started idling rough within 30s. I then decided to do an ECU diagnostic. After I shorted the pins and started it, it ran fine for about 10 mins. Pulled one of the plugs out and it was clean!! I then put the plug back in, started it and it ran bad again!! I then pulled each injector plug off one at a time and each cylinder made the engine run differently, as it should.

I then got the ECU diagnostic pdf off these forums and checked the voltage at every pin. They were all fine. The final thing I did was disconnect the battery for about 20 mins and since then it has been fine. I just took it out for a hard drive and it ran fine. A little slower than before, but I think that's because the timing could be out (due to me taking off the distributor cap at some stage).

So now I'm stumped. Hoepfully it won't play up anymore, but I doubt it. Oh yeah, I thought it could have something to do with the fuel pressure regulator. The vacuum hose on that is pretty soft and it has no clamp and has small surface cracks, so leaks in that are possible. Will have to check it better in day light.

Sorry about the long post. Any ideas??

 

[charlie]

i had a fault which sounds similar to yours and i think it turned out to be the connector from the wire that goes into the back of the dizzy (usually mounted on the back of the front tmic bracket) i thnk its for crankshaft position or something. :?

 

[Fast Guy]

What code did the ecu come up with. There's only 6 codes, so the pdf file you mean maybe the 200sx codes.

It sounds like you're massively over fuelling with the black smoke, so it maybe your afm. The plug are just a symptom of this.
Removing the distributer cap shouldn't affect the timing, unless the dizzy is very loose on it's mountings :shock:

 

[AJ4]

I had a similar problem, turned out to be a hole in the diaphram of the fuel pressure regulator. The car started running richer and richer, as fuel was being leaked through to the vacuum side of the diaphram and straight into the inlet. Eventually the whole thing gave up in one go, and filled all four cylinders with fuel ! :shock: Couldn't even turn the engine over, it was solid.

Don't think its the same problem as yours, but might be worth a look if it gets worse and worse. The easiest way to check is to take the vacuum hose off and see if it has any petrol in it.

 

[Anonymous]

Fouling plugs eh............sounds familiar! 6-8 weeks tops out of them. I changed my AFM as it was coming up in the fault code check. I disconnected the battery for a while but this still never cleared the fault though so out of interest i left the battery disconnected for an afternoon and hey presto all clear again :idea: . Took it for a run and its still all clear. The boost only goes up to the line before the '7' though on the standard gauge. It used to got up to the '7' until it went into the limp home mode cos of the fault.

Still idles bad though, even after changing plugs/leads/rotor cap,arm etc etc...... At least its an improvement on what it was. Think a boost controller is called for

 

[Willy]

Thanks for all the help. The ECU came up with code 55, which means 'all clear' if I'm not mistaken. It's very weird. It's been OK since last night and I just drove it to work (only 5 mins). I'll check the condition of the plugs when I get home. I'll also have to check that wire into the dizzy and the fuel pressure regulator. I have a FMIC, so that wire to the dizzy could be moved or disconnected. Mine seems to hit full boost at about 2 lines from the '7'. It has no boost controller

 

[Anonymous]

I would say that was where mine was reaching when it was going into the limp home mode. As far as i know standard is the '7' mark on the gauge. If you can get your's to reach that, by means of a bleed valve or boost controller, your car will feel a lot more lively

Correct me if i'm wrong,but i'm led to believe the standard wastegate is set at 0.5bar. The little solenoid then bleeds off 0.2bar if there are not any faults so thats how you get the 0.7bar standard boost pressure.

 

[Willy]

OK, well it's still going!!! I drove it about 50km around town yesterday and it's still fine. It's not going as hard during the day, but then last night it was planting me back in the seat like it should. It probably makes more boost at night, because the air is cooler. I live in the tropics, so the air is a bit warmer than it is in the UK. It is 31 during the day at the moment and in the mid 20s at night. Not good weather for performance cars.

 

[mattygti-r]

lmao "bit warmer" lol 31 degrees

:lol:

 

[Fast Guy]

Correct me if i'm wrong,but i'm led to believe the standard wastegate is set at 0.5bar. The little solenoid then bleeds off 0.2bar if there are not any faults so thats how you get the 0.7bar standard boost pressure.

Correct as far as I know

As far as i know standard is the '7' mark on the gauge. If you can get your's to reach that, by means of a bleed valve or boost controller, your car will feel a lot more lively

The 7 on the standard gauge is 700mmHg, which is just over 0.9bar (13.5psi) That is not standard.

I think standard is about 550mmHg. (that's roughly what mine was reading)

 

[Willy]

OK, well it hasn't gone into idleing completely terrible for a few days now, but it still seems to me that it's running a bit rich at idle and when cruisin. I don't think it's as quick anymore either. I haven't had a chance to have a good look at it yet, but I'm going to check that connector that charlie was talking about. I just dashed outside in a spare 5 minutes and tool some photos of the engine bay (it's dark now). I noticed that on top of the dizzy there is a small connector that looks like it should be grounded. I doubt it'll make much difference, but I thought I'd mention it. What do you guys reckon. It's in the photo below.

You can see that my engine bay is very dirty. I haven't had a time to clean it yet.

Thanks for everyone's help.

 

[Willy]

So does anyone know what's meant to go onto that connector?

I think the problem is coming back again. Yesterday I made the stupid mistake of checking a spark plug!!! It looked fine, put it back in and the idle wasn't as staeday as before. This morning the idle was jumping up and down between 800 and 1000 when it is normally about 1200 when I first start it in the morning. I could also smell the unburnt fuel smell again!!

I was thinking it could be a fueling problem like the O2 sensor or something, but now I suspect ignition again, since disrupting the leads seems to have brought it back. This happened in the past too. I checked a plug and it came back!!

 

[Willy]

I had a bit of a look at the car over the weekend. Thought I might check the timing. Turns out the timing was advanced to 25 degrees!!!!

Knocked it back to just under 20 and the idle settled down straight away!! It's been running good since. Hopefully that's all it was!!