Help needed, missfire at cruise & idol only. Driving me crazy :wacko:

Hello everyone,

I'm after some help on what might cause this missfire at idol and cruise (90% of the time, then the car ups the idol & is good for a minute or 2), The car is fine under power and WOT.

I've changed the PTU, checked the injector plugs to see if they was cliped in & also cleaned the contacts as well as the coil pack plugs.
Cleaned the PTU conection, the TPS, AFM, O2 sensors plug clips, CAS... YET still no luck. :thumbsdown:

The thing is that it's fine when I 1st start the car up in the monring until it starts to warm up.
And it also does it when the car is warm and if i park it up even for a few min's, start it up & it's fine for a few 100m's.
The only thing is that I'm thinking is the O2 sensors could be stuffed??? (Being good under power the ECU doesn't need them & the fact that when the engine is cold they wont be working as yet until they get hot?)
could faulty O2 sensors cause a missfire like that?

I'm getting a new set of spark plug tomorrow to see if that does anything. (The old plugs look not too bad i guess)
And if that doesn't work the injectors might need a good proper clean, can they be cleaned on the car? OR do they have to be taken off?
Thanks in advance & I hope someone can help me out.
Cheers.

 

what sort of air filter do you have?

 

Have had the same problem with my NA for months, now...

The only thing I haven't done yet is a proper injector clean (I've used bottles of injector clean, and had a fuel system chemical clean, but to no avail). I'm waiting for other jobs to become necessary before I remove the plenum. I've checked and cleaned all the connectors, new Iridium plugs, new O2 sensors, etc, etc.I did notice that it was only apparent with an aftermarket cats-back exhaust... I had the standard exhaust refitted and could not detect the "miss", but whether this was due the exhaust being much quieter, or whether it is a back-pressure issue, I don't know! Anyway, it doesn't seem to be hurting the car, so I'll put up with it for now... it's just a bit embarrassing when you're driving alongside a WRX or Commy and the car is popping and farting!

To answer Fleet's Q, I'm using a Unifilter.

Late thought: Unifilter has been on for about 12 months and is (over)due for a clean... I'll try that and let you know if it makes a difference.

 

Hey Doug.........>>

When are you going to bring your car down so We can check for boost....I mean vacuum leaks? Could be the cause of your miss. We can also hook the old conZult up and see how everything else is going. Feel like coming down a little early on Sunday before the cruise?

 

Sounds good to me, Peter. However...

if I've got Marks ECU on board then, there's not much point. I'll let you know before the w/e!

PS: Wouldn't mind some boost!! :LOL:

 

Can still do the leak test.......>>

And I'll have ConZult with me at Easter so I'm sure we can find some time to play with it then.

 

OK, see you Sunday morning. Is 0830 too early?

Lee, sorry to hijack your thread

 

Mods

The only mods i have to the car is a blitz air pod (Missfired B4 i put that on) & twin 3" turbo back exhaust, that was already fitted to the car when i brought it.
The car was fine when i test drove it (Always the way ain't it) & it started to missfire about half-way on the drive back from the Gold Coast to Townsville on the hi-way at cruise, like i said power & overtaking was great.

Sounds to me like it has trouble going into closed loop mode cause thats the only time when it missfire's at idol & cruise.
O2 sensor's wont show up on consult will they?
Is there a way to test them? They should read lower than 1 volt is that right?
How much for new O2's?

Thanks for the reply so far guy's. :thumbsup:

 

Get a conZult reading on it. That will isolate your problems

A few of us in Bris have them, (I'm in Mansfield)

Takes all of five/ten minutes with the laptop and will save you any more $ on trial and error parts replacements... Let me know if you want to do anytime this Friday onward.

PS: 02 Sensors DO show up on conzult...

 

Lee is in Townsville Mark!

ConZult should show if your O2 sensors are cycling correctly if they aren't replacement NTK O2s are available at about $100 each I believe.

Cliff:zlove:

 

Yeah it sux to live up here sometimeZ

Yep I'm up here in Townsville, Thanks for the offer mate !!!
How much are they to buy? (Sorry I'm new to owning a TTZ & not sure with this sort of thing)
Will the injectors show up if they are cloged & not pulsing good?

I've had a look to vacume leaks & couldn't hear or see any line's to be off, & the fact that it only does it sometimez would lead me to belive that it's not a vacume leak.
Sounds like a loose conector to me, But I've checked just a bout everything i can check, all good & tight and cliped on.
I've also tried moving the conectors when the car is running, I moved the #2 injector conector & that made it missfire.
So i got a new injector conector & it still does it.

 

Got a laptop? You can get a conzult cable and software

cheaply from member K-Zed here and do all these tests yourself!

As for the injector connector causing a misfire, they are probably all dirty. You can get to them with the plenum on once you take off the centre top cover. Clean out all the green gunk and check the injectors themselves with a multimeter, resistance should be between 10 and 14 Ohm.

Here's a fantastic tech article on misfire from Maciej

 

I think the best thing to do

is first of all check and clean all the connectors that go to each coil pack and each injector. Then clean the 2 connectors that go to the PTU. It probably wouldn't hurt to throw in a set of iridium plugs either.

If you have access to a laptop computer K-zed can sell you a cable connector and datascan software that, whilst it's not the full conZult, will give you an idea of what the sensors are all doing.

You'll get there Lee:thumbsup::thumbsup:

Cliff

Just noticed Mark beat me to it while I was typing this post - well duh!!

 

All been cleaned.

Yeah i cleaned them all yesterday, Both the injector and the coil conectors, again no luck.
Getting a new set of Iridium plugs today, see if that helps, I'll keep you posted how it goes.
Thanks again for the help.

 

How about 9:30.

 

OK, cya then

 

Persevere... Getting a conzult program/cable will solve a lot of

problems for you in the long run and save money. Just replacing things on trial and error is the hard/long and expensive way...

Conzult/Datascan etc can isolate in a few minutes what might take you hours/days to solve the hard way...

Can you get a computer down into your garage or know someone with a laptop? Or perhaps post a fresh thread asking if anyone else in Townsville has the program.

ALternatively, gotta be a performance shop up there that has one you could use for a small fee.. It really is worth it...:thumbsup:

 

DO A BOOST LEEK TEST

IF YOU HAVE A LEEK @ +BOOST U WILL @-VACK
:thumbsup:

 

changing the plugs didn't do much.

I put a new set of iridium spark plugs in yesterday, still no luck, (But they needed to be done anyway)
Yeah I'm trying to get a conzult lined up.
Looks like the only way to go.

 

ECU diagnostic?

I just done that ECU diagnostic (With the check engine light) & at 1st nothing came up error code "55" (repeated this 3 times)
So then i unpluged the coolent temp sensor to see if it would show up as Error code "13" and it did, then i pluged it back in & it just flashes error code "13"
(Coolent temp sensor) all the time when i do the test.
Could this be the reason why my car is playing up?
Can a faulty CTS cause this misfire @ idol & Cruise?
Altho the little conector (On the right hand side to the square temp sensor) is loose....
What does that sensor do?
The car has been running very rich & smells of fuel, hence me thinking it would be the O2 sensors not going into closed loop mode.
Thoughts anyone?
No boost/vacume leak either.