R33 "surging"

[Logikal]

Skyline went to the mechanics 4 months ago. Prior to this the car had been off the road for about a year and a half. Got the car back from the mechanics after a major service (timing belt, bearings, water pump, head gasket, rocker cover gasket and the battery were replaced) and started having a similar issue with the engine surging at low rpm/rough roads.

Resoldered the AFM contacts which solved the problem up until 3 weeks ago when the same kind of issue returned. Took it back to the mechanic and he advised no AFM error codes were showing and it may be the fuel pump on its way out.

Last Sunday I replaced the fuel pump with a Walbro intank pump (GSS 341) and it stopped the surging for a day. This morning it came back. I am really at a loss at what is causing the issue but I am starting to think its electrical.

I am going to check the coilpacks for cracks and the wiring loom going under the right-hand side wheel arch this weekend. Until then - can anyone possibly think of some other areas to check that I am missing?

Cheers.

[hypergear]

Can you define "surging" in detail? in terms of your car's behavior when this happens.

[Moodles2]

Walbro and Bosch pumps seem to work so much better when they're at alternator voltage (making a chassis ground for the pump)

[Logikal]

Can you define "surging" in detail? in terms of your car's behavior when this happens.

Revs range from 500rpm > 2000rpm. If I keep my foot stationary on the accelerator the revs jump up and down quite quickly - the car sometimes accelerates when it happens. You can hear the engine note increasing/decreasing and the turbo sounds like its still spooling. The issue only seems to rectify itself after I pull over and restart the engine.

I've tried to accelerate out of it but the issue either continues or the engine stalls. No mods apart from an Apexi pod filter and the Walbro pump. Engine is idling at 600rpm is this normal?

[James_03]

Check;

ECU for fault codes (Potential CAS issue)

Coil packs for cracks (Could just duck tape them to test initially)

Spark plug condition & gap

Failing that put a FP gauge onto the rail and check what your getting against factory values.

If the AFM was bad previously, it may have fouled the plugs due to running in safe mode.

Edited July 20, 2010 by James_03

[Logikal]

Check;

ECU for fault codes (Potential CAS issue)

Coil packs for cracks (Could just duck tape them to test initially)

Spark plug condition & gap

Failing that put a FP gauge onto the rail and check what your getting against factory values.

If the AFM was bad previously, it may have fouled the plugs due to running in safe mode.

Just bought a Consult cable so should be able to check for ECU fault codes alot easier on the weekend.

I was going to tape the coil packs after inspection as well. As for plugs NGK bcp6res should do the trick yes?

[R3N3]

Just bought a Consult cable so should be able to check for ECU fault codes alot easier on the weekend.

I was going to tape the coil packs after inspection as well. As for plugs NGK bcp6res should do the trick yes?

yep, gap them to .8mm and youll be all good

[Spurdo]

aftermarket pumps arent supposed to work properly without a simple modification to the fuel pump wiring, i know the r32s had this from factory and i assume r33 would be the same. when engine is under load the fuel pump receives 12v but under low load conditions (idle, low throttle conditions etc) the pump will only receive 6v as full pressure isnt needed. the stock pump is designed to handle 6v obviously. aftermarket pumps usually aren't, and when u run this system through them they do all sorts of wierd things. i found this out when i upgraded mine to a walbro pump and it did not like this at all. it would start and idle fine, but the moment u give it some gas it would cough and splutter and miss all over the place. it was driveable, but trying to accelerate was a painful procedure.

the workshop who fixed it for me showed me a little grey box that they removed to fix it, located near the turbo. this little box is what switches the output voltage to the fuel pump. from memory they essentially just joined the 2 wires that went into it and the fix was as simple as that. from then on it received a consistent 12v, problem solved.

[hypergear]

Revs range from 500rpm > 2000rpm. If I keep my foot stationary on the accelerator the revs jump up and down quite quickly - the car sometimes accelerates when it happens. You can hear the engine note increasing/decreasing and the turbo sounds like its still spooling. The issue only seems to rectify itself after I pull over and restart the engine.

I've tried to accelerate out of it but the issue either continues or the engine stalls. No mods apart from an Apexi pod filter and the Walbro pump. Engine is idling at 600rpm is this normal?

This sounds like a throttle position sensor or AFM issue. But more towards throttle position sensor.

Or unless if you have a really really dirty fuel tank. Which dirt clogs up the pump or fuel filter casing inconsistent fuel pressure. You fuel pump would sound very loud when that happens.

[Logikal]

This sounds like a throttle position sensor or AFM issue. But more towards throttle position sensor.

Or unless if you have a really really dirty fuel tank. Which dirt clogs up the pump or fuel filter casing inconsistent fuel pressure. You fuel pump would sound very loud when that happens.

Mechanic did say that because the car sat idle for 1-2 years that a whole lot of sticky residue looked like it was in the fuel tank (he replaced the fuel filter that same visit). I replaced the stock pump with the Walbro to see if the residue had gummed up the pump. But alas - No change. I suppose that the only way to clean the tank is to drop it from the car?

Edited July 20, 2010 by Logikal

[Logikal]

Wife just took the car for a quick test drive (long time car enthusiast) and said that she was getting the same issue going up a hill so she turned on "Snow" on the A/T and it seemed to reduce the severity of the surging. It also misfired whilst she was reversing slowly.

Problems seem to be getting worse

[OVADRV]

Sounds like low fuel pressure.get it checked with a fuel pressure tester,at least you can eliminate that.had the same surging problem with my VL auto( Fuel regulator)

[CHRIS AUSSIE]

reminds me i need to get mine serviced

[Logikal]

Well hooked up the CONSULT cable and ran ECUTalk and a couple of other programs.

O2 Sensor voltage seemed to be jumping about between 0.00 to 1.00 - Is this normal? When I turned the car over (Has not been turned on since Wed last week) it ran rough as guts and a strong exhaust fuel smell was present. Is there any parameter I need to watch specifically or would a log of my car running from ECUTalk be enough?

Edited July 24, 2010 by Logikal

[hypergear]

Thats normal for o2 sensors to jump around. If it doesn't jump means its dead.

[Logikal]

Ok - Well that's good. As I an a complete novice when it comes to tuning, when changing the fuel pump is it advisable to change plugs / re-tune the ecu? The exhaust Also seems to smell of unburnt petrol. Is it running rich perhaps?

[Logikal]

Replaced spark plugs.

Reseated all hoses.

Taped up coilpacks.

And she is still playing up - argh!

[blinksta]

Filter could be clogged same with injectors, if the car is running rich you should be able to spot that from the spark plugs and check for a vacuum leak

[Bliksem]

Have you inspected the AAC valve?

[Logikal]

I am going to clean the AAC valve tonight - will report on that tomorrow.

When I took the spark plugs out, I matched them to a thread on spark plug condition here and they ended up in the rich fuel/faulty ignition system category (hence why I taped the coil packs to see if that helped). One of the old plugs also emitted a noticeably stronger oil/fuel smell compared to the others.

I don't know if this is valuable info - but after the changing the plugs, reconnecting battery - I took it for a drive. Car started up and idled better than before. Took it for a test drive (30-40mins in both 60km/h and 100km/h zones) no issues and revs were stable. Took it for a drive last night - seemed to run a tad more rough than the test drive before but still had stable revs. Which brings us to this morning when the engine started to drop off and come back by itself nigh 5mins after driving the car.

It just seems every time I disconnect the battery/drain ECU it comes back nice for a short time then goes to the crappers again. I guess in the interim I will schedule a fuel system check/clean with someone. Any recommendations for workshops on the Sunshine Coast?