VN 5L drives like a pig after installing cold air intake. Needs a tune?

[raw]

PROBLEM
I installed a cold air intake which sits on top of the radiator and clutch fan shroud. When I drove it the temp gauge starting rising higher than normal (nowhere near overheating though). Later on I realised the bonnet had been pushing down on the cold air intake and had been pushing the fan shroud into the fan. So I put the stock air intake back on.


SYMPTOMS
Ever since then, the car is slow, sluggish, stutters and has even stalled a couple of times (but I've never had any trouble starting the car)

The worst time is after it’s been driven and then parked for a while, then when you go to drive off it ‘stutters’ like it’s about to run out of fuel, and is unbeleivably slow and sluggish. It's sluggish and stutters when revving in neutral/park too and sometimes won't go past 3500 RPM

Sometimes however (very rarely) when its driven hard it will start off sluggish but then ‘surge’, and will go very hard and sound very powerful.

Car also sounds a lot different, instead of a ‘rumbling’ sound, the car sounds like it’s ‘straining’. Often you can hear the clutch fan spinning very fast but the car is hardly moving.


THESE PARTS HAVE BEEN TESTED/REPLACED AND HAD NO EFFECT (List updated 11 March 2011)
Airbox + Air filter
Throttle body cleaned
Throttle cable
Kickdown cable
Fuel Pump + Filter
Fuel pressure test
Oil + Oil filter
Auto trans service
Ignition coil
Spark plugs + leads
Distributor cap
Rotor Button
Timing
entire Exhaust system
Radiator + hoses
Water pump
Clutch fan
Greenfoam tune
Alternator
Battery
Engine light has never flashed
No fault codes when tested manually

[delcowizzid]

if it does it with the original back on as well you have issues elsewhere that just happened to show up at the same time you did the cai havnt knocked any hoses or wires off

[raw]

Oh damn, I was hoping you wouldn't say that. I've been investigating any other sources of the problem for ages just in case like you said something else might have happened coincidentally at the same time. But after taking it to mechanics, transmission place, dyno place (not a tune but just to check it out), visiting forums, talking to all my mates and their mates, no one has any idea.

All the places I've taken it to I've known the people so they wouldn't stuff me around, except I didn't know the dyno guy so when I left my car there for all I know it might've been sitting there in the same spot the whole time with nothing done to it. I know that's being a bit cynical but I've become that way a bit over the last few years haha. Yeah it's been that long I've had the problem, although I've hardly driven the car over this period so it was down the list of priorities in life to sort out.

I'm absolutely certain I didn't change anything else apart from the CAI at the time though. Tried disconnecting the battery to reset the computer but didn't do anything. Before I stuffed around with the CAI the car was mechanically sound and, and even since then I've changed parts galore with no effect at all.

Asking people such as yourself and greenfoam who are reknowned was kind of my last hope. I'm stuck for ideas now. There is one interesting little nugget though...Sometimes, and I mean very very rarely, when I drive it hard it actually 'hits the sweet spot' as they say and it hammers as it should, plus it sounds like a totally different car (v8 supercar-ish), so it is definitely capable but only like less than 1% of the time.

[delcowizzid]

coil ,ignition module,hall effect sensor in the dizzy,fuel pressure regulator fuel pump could be so many things have you checked for error codes

[raw]

It's been so long I can't remember exactly what I've done, but I would assume those were covered. But it's worth me doing again just to double check or even in the case they weren't initially done. Thanks for the advice. You know if or when I fix the problem I'll be looking at a tune just to put the icing on the cake, but first things first, I gotta finish this witch hunt or wild goose chase whatever you'd like to call it haha

[raw]

Also, I've NEVER had the engine light come on and NEVER had any problems starting the car. If that narrows it down any more? probably not

[88GreenVN]

Have you changed the leads and plugs of late? If it gets upset going up hills - it could be leads.

[raw]

Have you changed the leads and plugs of late? If it gets upset going up hills - it could be leads.

Yeah have tried that since they had to be replaced sooner or later. I also put in a new dizzy cap and rotor button which alot of people rave about, but not only did it not fix the problem it had no effect at all which is odd because I know that both had never been replaced before.

[88GreenVN]

The ignion module would be the next suspect I'd say. Would be good to get that tested

[Darren_L]

fitting a CAI will have no negative effect.
the timing of your engine performance problem is either purely coincidental or you have disturbed something when fitting the CAI.
The ignition or trigger module is near the airbox, make sure none of the terminals have backed out of the connector - it won't always throw a trouble code. See if you can borrow another module and note if it makes a difference.

also you mentioned the check engine light has never come on ? Have you checked if the light works at all ? If you turn the ignition to the 'on' position (don't start engine) the light should come on (self test). If it doesn't, then the light globe may be blown and you may in fact have trouble codes.

[Jayme]

I vote fuel pump. Dying fuel pumps can come good for a second after a jolt etc. I would put a fuel pressure guage on it and even sit it under your wiper blade and go for a drive. will give you a decent indication if that is the problem.

[raw]

The ignion module would be the next suspect I'd say. Would be good to get that tested

fitting a CAI will have no negative effect.
the timing of your engine performance problem is either purely coincidental or you have disturbed something when fitting the CAI.
The ignition or trigger module is near the airbox, make sure none of the terminals have backed out of the connector - it won't always throw a trouble code. See if you can borrow another module and note if it makes a difference.

At first I was convinced it needed a tune due to the bolded paragraph in my original post, but now I'm starting to believe I have done something else accidently, like the module as you say because it's right near the airbox, with the wires actually touching my airbox.

Also, it seems odd that only I would have trouble with the CAI since just about everybody who owns a Commodore, or any car for that matter, fits some type of modified air intake and I've never heard anyone else complain...just me

also you mentioned the check engine light has never come on ? Have you checked if the light works at all ? If you turn the ignition to the 'on' position (don't start engine) the light should come on (self test). If it doesn't, then the light globe may be blown and you may in fact have trouble codes.

When I turn the ignition on my engine light does come on, so it's working. Perhaps there should be some type of 'check engine light' light feature But should I even bother checking the fault codes manually, since the engine light has never come on before it should be ok?

If it gets upset going up hills - it could be leads.

It's funny that you should mention about going up hills, and what angle the car is on etc. because I've noticed that although it's bad pretty much 100% of the time, it's at its worst when I've just gone over a speed bump and begin to accelerate. It just revs and hardly goes anywhere. Also, even going downhill sometimes it does it. You know you've got a problem when you can't accelerate downhill, well I can it just takes a while. I've driven a few other cars and compared it to mine such as similar Commodores, even a Barina and an old crappy Camry wagon and they all seem to have more guts than mine

Anyway I'll try and check all the things mentioned, and give an update after I've gone through the checklist:

hoses and fittings etc.
coil
ignition module
hall effect sensor in the dizzy
fuel pressure regulator
fuel pump
fault codes

[88GreenVN]

You could get an old spark plug and see if you have good spark from the leads. If the spark is nice n strong - it could point to a fuel problem.

Have you changed the fuel filter of late?

[raw]

You could get an old spark plug and see if you have good spark from the leads. If the spark is nice n strong - it could point to a fuel problem.

Have you changed the fuel filter of late?

Not long after the problem started I did a full service since it was just about due anyway. So I changed fuel filter, oil, oil filter, spark plugs, leads, coolant, dizzy cap, rotor button, cleaned the throttle body and had the cable adjusted, plus an auto trans service. Hell I even changed the windscreen washer fluid None of that fixed it, or even made the car better at all really, but that's probably cos everything was in decent condition anyway.

[88GreenVN]

Not long after the problem started I did a full service since it was just about due anyway. So I changed fuel filter, oil, oil filter, spark plugs, leads, coolant, dizzy cap, rotor button, cleaned the throttle body and had the cable adjusted, plus an auto trans service. Hell I even changed the windscreen washer fluid None of that fixed it, or even made the car better at all really, but that's probably cos everything was in decent condition anyway.

So probably down to the ignition module or fuel pump/regulator.

Hmm - how are the injectors - put a tube of cleaner though the fuel?

[Brett_jjj]

If the sound of the car has changed,check for a blocked up catalytic converter or muffler.This will also kill the performance of the engine.

[baza]

maybe check your timing , put in diagnostic mode with a paper clip and connect timing light . mark on pulley should match up with at least the 10 degree mark , you could go to 14 degrees if you have the standard memcal. your timing may be retarded , nothing to do with CAI , but if your dissy was a bit loose when you changed plug leads you could have accidently moved the dissy position .

[raw]

So probably down to the ignition module or fuel pump/regulator.

Hmm - how are the injectors - put a tube of cleaner though the fuel?

I've never used any additives but I've heard Holden top engine cleaner is good though. Can you or anyone else recommend it too?

If the sound of the car has changed,check for a blocked up catalytic converter or muffler.This will also kill the performance of the engine.

I see where you're coming from, as I once had a hole in my cat near the flange and it was giving the same symptoms I'm experiencing now. But I've since had a new high flow cat and had the exhaust checked numerous times as I've experimented with my exhaust alot over the years. For me having a loud exhaust helps detection too, as it sort of magnifies some problems

maybe check your timing , put in diagnostic mode with a paper clip and connect timing light . mark on pulley should match up with at least the 10 degree mark , you could go to 14 degrees if you have the standard memcal. your timing may be retarded , nothing to do with CAI , but if your dissy was a bit loose when you changed plug leads you could have accidently moved the dissy position .

Apparently when I took it to the dyno place they increased the timing to 12 or 14 degrees advance. It couldn't hurt to physically check it though, but I don't have a timing light so I'll get someone to check it.

---------------------------------------------
Just to update my situation so far:

I've already checked the hoses and fittings etc. and my engine light has never come on (apart from when turning on ignition - so it is working) so I assume there is no need to manually check the fault codes??
Apart from that when the long weekends finished I'll be able to start on my checklist which is:

coil
ignition module
hall effect sensor in the dizzy
fuel pressure regulator
fuel pump

Just on the coil and ign module...if there was a problem with either then wouldn't that mean the car wouldn't work at all? i.e. all or nothing

[Brett_jjj]

and my engine light has never come on (apart from when turning on ignition - so it is working) so I assume there is no need to manually check the fault codes??

Some engine management errors dont always make the engine light come on,so its always a good idea to check for logged error codes every now and then.

[Mr_Calais]

check its getting spark to all plugs

[raw]

my checklist which is:

coil
ignition module
hall effect sensor in the dizzy
fuel pressure regulator
fuel pump

OK so I finally got some spare time to start checking things out. First I manually tested the fault codes (used the paperclip trick) and got code 12, so nothing wrong there.

Then I tested fuel pressure with the car idleing in Park was sitting at 270 kPa...was told that was satisfactory so fuel pump and regulator should be working ok too.

That's all I've done so far, and next I'll pull out the dizzy cap and check out the hall sensor, and while I'm there will pull out the coil and test it with a multimeter.

Just gotta find the resistance specs for the coil... Is the stock coil in a VN V8 is a Bosch MEC 718? If so I found the resistance specs here. Can anyone confirm?

[HARVZ-6]

Just skimmed through the posts,

Could be a blocked cat converter, my sisters ute did this, didnt want to rev, sluggish as hell.. maxed at about 4000rpm, cat had collapsed,,

easy thing to check just drop the cat out and have a look, if you can see through the honey comb its fine

[raw]

I've just remembered something. Two things actually.

1. I am an idiot.

2. when I put the over-the-radiator CAI on there are two screws which hold it down on top of the radiator.
I must have either over-tightened these, or the plastic CAI was too big for my car, because the shroud was being pushed into the fan blades when I went for a drive.
At the time of installation this didn't occur to me (see point 1 above), but when I took it for a drive the temp guage increased a little more than normal.
So I pulled over and popped the bonnet and with the engine still running (and hence the fan too) I could hear it hitting the plastic. So I immediately took it off and put the standard intake back on.

Could that have stuffed my clutch fan? It makes sense as alot of the time I can hear the fan revving furiously.
Also this would explain why my car is always cool because even on hot summer days it won't go above 1/3.
When the car is completely cold the fan is hard to move by hand, but when the car is hot the fan is easily moved by hand and after spinning it continues to spin for a short distance.
Is this normal or should it be the other way around?
I've heard conflicting answers about this.
Anyway, I'm going to take the fan off and go for a quick test drive.
Also, the clutch fan is connected to the water pump right, so maybe that has a problem.

So does it sound like there's a problem with either the clutch fan or water pump?

[Not_An_Abba_Fan]

The fan is made of metal, the shroud is plastic. Metal beats plastic every time, just like scissors beat paper.

It doesn't sound like there is anything wrong with the fan.

You haven't put a screw though the wiring loom that goes across the top of the radiator have you?

I would also check the ignition module earth incase it has come loose.

[raw]

I have tried everything mentioned in the thread, except for the hall effect sensor which I will do eventually but have been putting it off because I'm not looking forward to taking out the dizzy, replacing the HES, re-adjusting the timing etc.

In the meantime I've thought of a couple of much simpler things I might try

condenser - when i replaced the ignition coil I used the same condenser that was on the old coil. Perhaps I should get a new one as they are cheap and easy to fit ???

Also, i've got a greenfoam tune which i will try as well

NOTE: I've updated my original post so that it's straight to the point and easier to understand.