Stalling Q

Post by **demhaizar** » Sun Mar 12, 2006 7:30 am

1992 Q - ~180,0003months ago changed all under plenum hoses and fuel filter, 6 months ago the knock sensors. Fuel pump changed 2-3yrs back (no humming yet)

Now it starts and idles smooth as can be, but driving around it will stall, i mean all power loss, so i pull over and put it in neutral or park and crank, and it fires right up. then i drive maybe a block and the same thing happens.There is no pattern to this happens any time. last time it happened was when I was letting her warm up in the driveway, she fired right up but after a few died again, the message displayed was 'low charge/battery' for a few seconds, and then back to normal operation again.

Any help would be great

YouTube · Post by **Jesda** » Sun Mar 12, 2006 9:32 am

The error message is useless, so dont worry about it.

Going at it blindly, I'm suspecting a failing FPCU or a bad MAF, though a bad MAF will make the idle go up and down like a kangaroo on speed before it finally stalls and cause bucking and jerking at cruising speeds.

FPCU seems like the biggest culprit. Check your FPCU plug and see if one of the holes in the plug looks black or burnt.

Post by **demhaizar** » Sun Mar 12, 2006 5:14 pm

jesda, thanks, that is what i was thinking but, not willing to admit to myself.

Alright time to rip the back seat apart, pull the FPCU and check it. are those still $400-$600

Will do a follow up repost if, it turns out that is the problem

Post by **elwesso** » Sun Mar 12, 2006 5:24 pm

id try and get a used one from one of our lovely parts cars in the classfieds forum....

Post by **gniknave** » Sun Mar 12, 2006 7:28 pm

Does it stall when coming to a stop, or while driving?

Post by **Ozzie** » Sun Mar 12, 2006 8:07 pm

What's the fluid level like in the trans?

Once I had a flush and fluid replacement, my similar problem disappeared...

Post by **demhaizar** » Mon Mar 13, 2006 11:22 am

No stalling when braking/stopping seems very random, i would say mostly while driving at any speed.

i did read the post about the tranny fluid and checked mine, seems to be at the correct level.

Post by **96Qowner** » Mon Mar 13, 2006 11:29 am

Jesda wrote:FPCU seems like the biggest culprit. Check your FPCU plug and see if one of the holes in the plug looks black or burnt.

Yeah, it sure sounds like the FPCU to me. There's a bunch of good info in the archives. Here's one to help diagnose (with posts by the incomparable and sorely missed Tangalora):

zerothread?id=18148

YouTube · Post by **Jesda** » Mon Mar 13, 2006 12:07 pm

Before you go pulling out the rear seat, remove the cover in the trunk that conceals the gas tank, then pull the FPCU connector and see if it looks burnt on one pin.

Post by **96Qowner** » Tue Mar 14, 2006 7:09 am

Ya know, this is so very similar to problems I had when I first bought my Q. After thinking it over, I think it could very well be your MAF. You don't have the bucking/coughing symptom, but I had that same sudden stalling you describe. It would stall on me when I let off the gas coming down an off-ramp or approaching a stoplight, for instance. I never had any idle hunting, either, like others have described. I replaced the fuel pump and also pulled the FPCU out to take a look inside. I didn't see any burnt spots and it's been working fine ever since. The new fuel pump didn't make any difference. My problem was a dirty (and eventually failed) MAF.

What made me reconsider is your description. When it stalls on you, you haven't been accelerating, ie, kicking your pump into high speed and heating the FPCU circuits. Of course, you should pull the FPCU anyway and take a look at it. Dennis has said that he's seen these intermittant problems with FPCUs long after the pump has been replaced, but I'm thinking you're having MAF troubles. I think PopPop has a couple MAFs for sale in the Infiniti Cars/Parts section. You should consider picking one up and swapping it - extremely easy. Short of that, you can just give the MAF element a cleaning according to instructions on Q45.org:

http://www.q45.org/maf.html

I cleaned mine whenever the symptoms reappeared, but it eventually became marginal and I replaced it with one I got through car-part.com. No trouble since.

They're both easy fixes. Check your FPCU for symptoms of circuit board failure and clean your MAF, then go from there.

Post by **demhaizar** » Tue Mar 14, 2006 5:52 pm

Alright, I have the FPCU in hand and sure enough one of the pins is brown at the board and the plastic connector. Iam good at soldering so i redid the solder at the board.Question, if this is the ground then why can't i just supplement it by adding a splice to the wire going to the fuel pump and ground it, that way the pump won't be completely dependent on the FPCU to supply the ground,... or am i being a retard?

Razi

Post by **demhaizar** » Thu Mar 16, 2006 7:10 am

Thanks everyone for the help, definitely gave me several options.: D

After resoldering the FPCU and driving the car I have same symptoms, so I bypassed the FPCU and went for test drive same symptoms again.

I checked the function of the relay and replaced it anyway, no joy!. I am down to the MAF or the fuel pump itself

Is there a way to isolate the problem to either the MAF or the FP? some sort of quick test.

Thanks again for your help.

Post by **elwesso** » Thu Mar 16, 2006 7:13 am

if it were the fuel pump, fuel pressure would be less than adequate... check fuel pressure first... if you have good pressure, then its the MAF.

Post by **rsiwicki** » Thu Mar 16, 2006 8:13 am

sounds just like my car when the MAF went out on it....buy one from the classifieds for like $75~100 and then spend 5 minutes swapping it out.

Post by **breaksr** » Thu Mar 16, 2006 8:21 am

My two cents. Recently my car has also been stalling as I slow to stop signs or traffic lights. Fuel pump is a couple of years old and the MAF is original (191K on a '91 Q). One day when it was in the 30's outside I had the classic strong smell of gas. I opened the hood and could see fuel leaking out of one of the rubber fuel lines near the passenger fire wall. Tear off the plenum and replace a bunch of breather hoses and all of the fuel lines (three little ones under the plenum and the two big ones next to the fuel filter). Put everything back and the car so far seems to be fine (only about fifty miles of driving). So when you changed those under plenum hoses did you change all of the fuel line hoses?

Post by **demhaizar** » Thu Mar 23, 2006 1:03 pm

Thanks for the support from all you guys, i would still be looking at my Q through the window if not or it would be at the stealership getting raped.

I replaced the MAF (air flow meter) and have she has been acting like has been born again, I cannot hear or feel the engine running at stop lights , etc....

and yes I replaced ALL the hoses including and especially the fuel hoses.

Thanks again

Post by **maxnix** » Fri Mar 24, 2006 5:33 am

There was a thread that showed how to wire around weak ground on the FPCU board. Probably in the archived posts if the picture is still available.

Glad the MAF repacement cured your problems. One must sacrifice at the altar of the MAF on occasion.

Post by **blind6** » Fri Mar 24, 2006 6:51 am

Does it matter the year on the MAF or are they universal?

Post by **96Qowner** » Fri Mar 24, 2006 7:29 am

The G50s had two different plugs, 90-95 and 95-96.

Not sure, but I would think all the Y33s are the same?

Post by **blind6** » Fri Mar 24, 2006 7:57 am

Can G50 MAF's work in Y33? Just thought I'd ask. Most of the classifieds don't specify year.

Post by **elwesso** » Fri Mar 24, 2006 8:15 am

no im pretty sure Y33 MAF are smaller.

Post by **blind6** » Fri Mar 24, 2006 9:32 pm

Purchased a used one today, we'll see if that solves my problem. Should be here mid next week.

Stalling Q

Stalling Q

Re: (demhaizar)

Re: (gniknave)

Re: (Jesda)

Re: Stalling Q (demhaizar)

Re: (demhaizar)

Re: (elwesso)

Re: (demhaizar)

Re: (breaksr)

Re: (demhaizar)

Re: (maxnix)

Re: (blind6)

Re: (96Qowner)

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Re: (elwesso)

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