missfire will not go away

[92finityq45]

hey every one the names Dave and im new here, just got my first infiniti on saterday, its a 92 q45 perficly taken cair of. but recently developed a miss, i have changed plugs, coil, checked for injector pulse, i am getting spark, and 164 psi on compression. what could it be.

[qship96]

Wuz it runnin like dat wen you bot it, or ded it git woorse after you chaingd teh sparkplog?

Read up on the board about testing your fuel injectors,and go to http://www.q45.org for instructions on trouble-shooting your problem.

[92finityq45]

the lady that i got it from said the her tec said that it was a coil thats why i got it, it was supost to be just a coil. yes it was running like that when i got it it has not changed.

[qship96]

Each plug has its own coil attached, are you sure you replaced the faulty one?, or maybe there is more than one that has failed? Might be worth taking car to the dealer and paying for 1 hour diagnostic labor with list of whats wrong with car, post it here, and we can show you ways to obtain needed parts at a serious discount to repair?

Generally when you purchase a old used car with engine problems, the previous owner was told the car needed EXPENSIVE repair work,and that is why they sell it cheap{and downplay whats really needed to fix the problem}

[92finityq45]

with the coil covers off and the car running i un pluged 1 coil at a time. the 1st one on the pass side when unpluged nuthing changes. also swaped the coil modual

[qship96]

Maybe you have another problem besides the coil/plug you replaced? Why I suggested taking to expert for diagnosis.

Maybe Brian{MAXNIX} will come along and read this thread and offer some friendly constructive advise, he is the resident expert for newbies and usually gets to the core of all Q related problems!!! Lets all cross our fingers for brians input!!!!

[92finityq45]

hello i am putting out an APB for Brian the Q expert if you think you may have seen or herd from Brian please point him this way Thank You and back to your program.

[goody90q45]

with the coil covers off and the car running i un pluged 1 coil at a time. the 1st one on the pass side when unpluged nuthing changes. also swaped the coil modual

So you swapped the dead coil from #2 cylinder into another cylinder and it was dead there also?

.....i have changed plugs, coil, checked for injector pulse, i am getting spark, and 164 psi on compression. what could it be.

Injector pulse was checked but were they ohmed? I'm thinking #2 FI is dead but they should all be checked if you haven't done it yet. Break out the voltmeter and let us know your readings. Connectors are at the passenger side end of the plenum.

[maxnix]

No one has asked about the timing chain guides yet?

[goody90q45]

We left that for you

[92finityq45]

I changed what was supost to be the dead coil. but with it swaped the miss did not move. same with the injecters. i was wondering when some one would ask about the guides, yes they were changed 6000 miles ago acording to dealer receipt. and the ohms where checked too 15.7 ohms. thats why im confused.

[maxnix]

15.7 ohms on all eight is out of specification if measured when up to operating temperature?

How did you "suppose" which coilpack it was? The vital indicator was....?

[goody90q45]

....I changed what was supposed to be the dead coil. but with it swaped the miss did not move. same with the injecters.

Am I reading right that the miss stayed with the cylinder when you swapped coils and you also swapped injectors and it stayed with the same cylinder.

Injectors have been known to ohm good yet be hopelessly plugged to the point where a fuel rail flush won't clean them out. When I got my 90Q it had 4 bad injectors- 2 which ohmed bad and 2 that ohmed good but were not feeding. I'm getting ahead of you here but put a spare spark plug in the end of each suspect coil and see if it sparks to ground. If all spark then you probably have a plugged injector. Lucky for you it sounds like #2 so it will be easy to R&R.

Don't worry about all 8 FI ohming at 15.8. Measure them on the next cold morning to a cold engine and they'll probably all ohm at 13.0.

[Q451990]

Welcome to NICO Dave!

You definitely want to ohm the injectors again... I have had one go from 12 to 200 in an afternoon, so a reading 5000 miles ago is absolutely irrelevant.

In my previous injector failures on my old Q the corresponding spark plug was so badly fouled that that cylinder still had a dead miss. These injectors were presumably clogged... it was a long time ago and I don't recall ohm testing them - but they were accepted by a rebuilder as a core, so I think the coil was fine. As you have probably read here - the current plague of injector failure is due to the 10% ethanol blend introduced in the last 6 - 8 months in areas that previously had real gas.

Might as well pull the plug on that cylinder and clean it. I was able to use gasoline and a toothbrush to get it cleaned up well enough to fire and the combustion process did the rest. The FSM recommends cleaning them with a sand cleaner designed for the job, which can be obtained inexpensively from Harbor Freight tools. Of course, if the plugs are old, it would be better to just replace them...

Heath

[92finityq45]

i cant thak everyone enough the injector is cloged pulled it out last night its a mess. how can i keep this from happening agin?

[Q45tech]

92 q45 perficly taken cair of

Paint, body, and interior condition always LIE.

Start with looking into gasoline tank, examining fuel pump sock, and replacing fuel filter, flushing fuel lines and rails.

If one injector is bad from junk they all are, just haven't failed yet.

When you add injectors to the mix all old financials go out the window, where we use to say prepare for $3,000 expenditures, now it's $5,000.

[92finityq45]

well the fuel pump was replaced in jan. the filter was done when i did the plugs, and already ran 2 cans of 44k through the tank. it does not have the active susp. and acording to the recipts the shocks were done with the fuel pump, the bose speakers were replaced 2 years ago, the exhaust is a little over a year old, new alt and battery, water pump was done when the guides were. and the tires are new. but the ignition switch sticks some times the key doesnt want to turn. and the trans was done in 2001

[maxnix]

B44K before or after new fuel filter? How long was the filter in service?

[92finityq45]

one before one after. after looking at the recipts real quick the filter was in there for about a year and a half.

[maxnix]

The first one probably just got the junk into the injectors from the filter.

The answer to the second question is......? (miiles and time)

[92finityq45]

well the car only has 123000 on it and if the recipts and my math are right it was on the car for 7341. i whent and did some checking the one before thet was on the car for over 65000