Cylinder #1 Dropping Completely

[SkudR33]

Hey guys,

Been trying to troubleshoot this issue which occurred one day while I was driving the car during the stinking 35+ degree hot weather.

My 1st cylinder is not firing at all. Some days it starts running fine and gives me false hopes that she's okay - the next day it f**ks around again!

I've tried the following things to rectify this issue:

- Replaced coil packs with brand new YJ coils.

- Replaced coil pack harness.

- Sent ecu to microtech to get to checked. It cleared the diagnostic tests.

- Dry compression tested the engine. Compression results were all within 3-5 psi of 150psi.

- Replaced CAS.

- Tested all ignition related wiring continuity. It all passed the diagnotic tests.

Some things to know about my car that relate to this issue:

- it has a microtech ltx12 ecu

- YJ coil packs.

I'm at a point where I've hit a dead end.

Does anybody have any decent advice they could give me?

Secondly is there anybody in Sydney that would let me plug their ecu into my car because I get this feeling that my ECU is screwed and it's not worth taking a gamble and buying another one if I can't confirm it's the issue.

Thanks in advance guys!

[GTR_JOEY]

sounds like you have eliminated compression and ignition, are you sure its specifically no1 cylinder?

have you checked your loom and plug to your injector?

what condition are your injectors in and do they need cleaning?

[SkudR33]

sounds like you have eliminated compression and ignition, are you sure its specifically no1 cylinder?

have you checked your loom and plug to your injector?

what condition are your injectors in and do they need cleaning?

Thanks for your speedy response.

I know it's cylinder 1 because when it's misfiring if I unplug coil pack 1 the misfire doesn't change.

I've replaced my injectors 3 months ago with brand new ones and also forgot to mention that I checked the injector plugs with a node light. I also used a stethoscope and could hear the injector ticking.

Other thing I should mention is that it's running extremely rich while the cylinder doesn't fire.

[GTR_JOEY]

sounds like you have the basic elements of combustion

Possibly an ECU/ electronic issue man, the guys at UNIGROUP are very good at what they do, they should be able to sort it for you but they don't do it for free

[SkudR33]

Yeh I totally agree with you! Just hoping I can find another microtech owner who would let me try their ecu...

Might even ask the guy at microtech - might be nice enough to help me out

[Kane_R32]

might be silly, but couldnt see it in your posts... changed plugs?

[SkudR33]

might be silly, but couldnt see it in your posts... changed plugs?

Haha any help is good help - I knew I'd missed some things out of my main post.

So yeh I also replaced my spark plugs.

[Kane_R32]

lol figured as much!

What other mods does it have?

[SkudR33]

Full list of mods:

- GCG highflow stage 2 ball bearing turbo.

- cam tech 256 cam shafts

- tomei adjustable cam gears

- supatech tech valve springs, retainers and stem seals

- blitz dual sbc boost controller

- microtech turbo timer

- gates racing belt

- microtech ltx12 ecu

- YJ coil packs

- Bosch 044 fuel pump

- five-o 660cc fuel injectors

- front mount intercooler

- arp head studs

- cometic mls head gasket

Also the head was recently serviced and had a mild polished.

I'd say that's pretty much everything that's been done to my car.

[KiwiRS4T]

If Microtech have tested your ecu and can't find a fault sounds like you need a good dyno operator. it could be something else or maybe the ecu is failing under load conditions that can't be replicated on the test bench.

[..::R33GTS-T::..]

is any coolant leaking into the cylinder ? been told that that will cause a serious misfire

and is there defiantly fuel getting into the cylinder?

Edited January 25, 2014 by ..::R33GTS-T::..

[wildeagle44]

Does it have an ignitor?

[SkudR33]

Well I spoke to my tuner and he reckons the bench testing isn't a good indicator as its missing the environment and load of a realistic situation.

If Microtech have tested your ecu and can't find a fault sounds like you need a good dyno operator. it could be something else or maybe the ecu is failing under load conditions that can't be replicated on the test bench.

How could I definitely confirm that coolant would be leaking into the cylinder. I've checked the coolant in the overflow bottle and radiator - fluid levels haven't change. Fuel I can definitely confirm because of the tests I did on the injectors and secondly because the misfire is causing the care to run extremely rich.

is any coolant leaking into the cylinder ? been told that that will cause a serious misfire

and is there defiantly fuel getting into the cylinder?

I have a serie1 rb25det but the ignitor has been removed becuase the ecu I have has an inbuilt ignitor. Tuner reckons ignitor in ecu is probably screwed....

Does it have an ignitor?

[blind_elk]

I know it's cylinder 1 because when it's misfiring if I unplug coil pack 1 the misfire doesn't change.

What happens if you then swap #1 #2 coils? Does the failure follow the coil ie now #2 is failing, or does #1 continue to fail?

[SkudR33]

What happens if you then swap #1 #2 coils? Does the failure follow the coil ie now #2 is failing, or does #1 continue to fail?

Hey bud,

Misfire stays on cylinder 1. Doesn't follow coil packs or spark plugs.

[scotty nm35]

Well I spoke to my tuner and he reckons the bench testing isn't a good indicator as its missing the environment and load of a realistic situation.

You can replicate anything given enough time. What exactly does he think can't be tested with regards to an injector?

I have heard of a few issues with five-o's lately, it would be the obvious next step to test the injector imo, unless it did the same thing on the old injectors?

[SkudR33]

You can replicate anything given enough time. What exactly does he think can't be tested with regards to an injector?

I have heard of a few issues with five-o's lately, it would be the obvious next step to test the injector imo, unless it did the same thing on the old injectors?

The tuner was referring to heat and vibration of the ecu unit as opposed to it sitting on a work bench. Reckons something could be getting hot and loosening up causing the igniter not to fire correctly.

With the injectors, I checked the plugs with a node light and also used a stethoscope to listen to the injector. Node light went off in the same sequence as the rest of the injectors and the injector also had a tapping noise in the same sequence of the others.

Is there anything else I can do to check the injectors???

[GTSBoy]

Yuh, swap it to some other cylinder. See if either a) the miss moves, or b) goes away because you "fixed" the injector by moving. In either case, you would then fix it permanently by moving it to the bin.

[XKLABA]

compression tests can lie !!!!, when engine is cold remove radiator cap then start motor and see if air comes out through the radiator when the motor is missing

I have seen this happen, in very rare cases HG can seal at non operating pressures ( comp testing) but then "open" once the motor is at running pressures

[SkudR33]

compression tests can lie !!!!, when engine is cold remove radiator cap then start motor and see if air comes out through the radiator when the motor is missing

I have seen this happen, in very rare cases HG can seal at non operating pressures ( comp testing) but then "open" once the motor is at running pressures

I tried this - water didn't really bubble. A tiny amount of white froth developed as the coolant started to get hot. Not sure if that's meant to happen but I read up that it froths a little when the radiator starts to build up pressure.

Massive head f**k it has become!