Starting on 3 cylinders

[AuSpecVr4]

Hey

Recently in the past three weeks my VR4 has been starting on 3 cylinders for a period of about 5-10 seconds before the forth kicks in and the idle jumps to 2000, I have tried making it richer with no difference, I ran 2 bottles of injector cleaner through the tank and nothing. I know basics about the 4g63 but troubleshooting is not my thing. What do you recommend I do to diagnose the problem? With Out pulling the head? I am building a new head to go in it with 272 cams and 3G lifters, valve springs and retainers, just need valves. It pops on idle and sounds lumpy but isn't consistant, it's random, I think it hasn't used any water.

Cheers, Brock

 

[fuel]

have you checked the basics like spark plugs and plug leads? have you got access to a compression tester to use before going ahead and taking off the head unnecessarily?

what area of brisbane are you in? I can come have a nosey if you want. I'm in West End.

 

[AuSpecVr4]

I have changed plugs from bp7 to 8's with no difference, spark plug leads are only a year old, 7mm. I don't have a compression tester, I live on the south side. Redlands area. Victoria point

Cheers, Brock

 

[fuel]

I would probably remain with the BPR7ES at this stage (I think they should have BPR6ES plugs standard, 8s seem just a bit too cold for my liking). Make sure the gap is about 0.65-0.75mm. Are any of the plugs showing signs of fouling? If so is one (or more) plugs just wet with fuel or is there oil on them too? Is it using/burning oil at all? What injectors do you have in there?

 

[AuSpecVr4]

Last week I checked the plugs they were all tan in colour, all good, not burning oil either, I'm buying a set of bp6es tomorrow and I will update how it goes.

 

[fuel]

get a compression tester while you're at it! definitely worth spending the $30-40 they cost. Make sure you get the one with the tube or extension so it can go down the spark plug holes.

 

[656of1000]

It sounds like it could be the lifter(s) in the affected cylinder- it bleeds down when you shut the car off, and it takes a few seconds for them to pump back up when you start the car.

 

[jepherz]

Could be fuel pump? Do you have a way to monitor fuel pressure?

 

[AuSpecVr4]

My lifters have been ticking for a while so its likely that could be true. The fuel pump is fine, brand new 301 with 42.5 psi fuel pressure. I don't have the car back till this afternoon and I will put the new plugs in. I just hope it's not something serious like a cracked block, a different head is bein built now so if it's in the head I'm not really concerned.

 

[doggietom]

This happened to me also my spark plug electrode was smashed and I had no gap.

 

[jmorri15]

try eliminating things, like switching two of the injectors and seeing if the problem follows. the cylinder should still run if one lifter bled down so it would have to be more then that. if you pop off your valve cover and the car has been sitting for awhile you can reach in and feel if a lifter is exceptionally loose.

 

[toybreaker]

Lots of good advice in this thread!

Quoting fuel:

what area of brisbane are you in? I can come have a nosey if you want. I'm in West End.


/ubbthreads/images/graemlins/worthy.gif



Sometimes, a fresh set of eyes on a problem will see a solution.





This almost sounds like a possible fuel pressure loss or injector issue



Do you have an afpr?

Have you checked the fuel pressure at start-up?

Many aftermarket afpr's will lose pressure at shutdown, and the engine will run poorly until the whole rail is full and purged of air.


I would also suggest using a mechanics stethoscope on the body of the fuel injectors at startup. You're listening for one that sounds "softer" ... sorta like a click instead of a clack ...

Many times, it's the injector itself that is bad, but I've also seen corrosion in the connection from the harness onto the injector cause this type of problem. The "well" shape of the injector receptacle will hold water anytime the area gets wet, and over time, corrosion will set in and cause some weird and hard to troubleshoot issues.

Might be worth taking a closer look/listen. /ubbthreads/images/graemlins/dunno.gif


You can also see which cylinder is being dropped by using a digital non contact pyrometer. Just shoot the manifold flange at the head. All the cylinders should show a ~roughly~ even temperature gain from a cold start. Any "cold" cylinders should be investigated more thoroughly.

 

[988]

Cheack your POWER TR UNIT.....

 

[AuSpecVr4]

Thanks for all the replys! I've narrowed it down to the possibily of a cracked head, head gasket or leaking intake gasket. It has been using water now, someone told me it could be FIAV but I have blocked that off and there is no cooling running to it anymore, I will take a spark plug out in the morning and see which cylinder shoots water out. The car has previously got hot about 3 times on this head now, I would be amazed if it wasn't a cracked head. I will update over the next couple of weeks or when I get more info on what is going on with pictures.

Cheers, Brock

 

[fuel]

Quoting 988:
Cheack your POWER TR UNIT.....

Not likely.. it would drop down to 2 cylinders or just not run at all.

 

[fuel]

Quoting AuSpecVr4:
Thanks for all the replys! I've narrowed it down to the possibily of a cracked head, head gasket or leaking intake gasket. It has been using water now, someone told me it could be FIAV but I have blocked that off and there is no cooling running to it anymore, I will take a spark plug out in the morning and see which cylinder shoots water out. The car has previously got hot about 3 times on this head now, I would be amazed if it wasn't a cracked head. I will update over the next couple of weeks or when I get more info on what is going on with pictures.

Cheers, Brock



If it is using coolant (you should have coolant in there, not just water!) then it most likely is a leaking head gasket - it's unlikely it would have completely cracked the head unless you've well and truly cooked it. The SOHC heads were bad for cracking but the DOHC heads not so much.

 

[AuSpecVr4]

Yes it's using coolant, sorry, it could be the head gasket. It has a cometic steel head gasket with arp head studs. I would be surprised if it is a head gasket.

 

[fuel]

would more likely be a warped head rather than a cracked head. MLS head gaskets withstand much higher levels of boost/stress but if the mating surfaces are not completely flat then they don't seal very well.

I would get a cooling system pressure test and a TK test done too to see where your coolant is leaking from - you never know you could have a weeping water pump or a hairline split in your radiator where the coolant is leaking from.

I cannot stress this enough - perform the correct tests (ie compression test, coolant leak test and TK coolant gas analyser test) before you start pulling the engine apart *thinking* it could be one thing, when in fact it could be something else.

 

[AuSpecVr4]

Just an update. I've done a compression test and coolant compression test. Compression is good, around 180psi each cylinder. Coolant lost presssure so removed plugs and cranked motor, cylinder 1 is pushing coolant out the spark plug hole. So in the mornings it wets the plug making it run on 3 cylinders for about 5 seconds. It's getting worse now. The car starts on 3 cylinders when it's hot and you leave it off for 10 minutes. Don't have the tools to do a leak down test but I'm sure its a head gasket which seems unlikely or a warped/cracked head. I will update when the head comes off over the next couple of weeks.

Cheers