Bought a 1996 Q45 Yesterday fuel problem / question

[wantingwing]

I bought a used 1996 Q45 yesterday from a small dealer. I drove it several times before buying it and when I drove it home it was driving fine. In the morning my wife took it out and filled the tank with 87 octane (the middle grade). After about 5-10 miles of driving the car started to sputter a bit the engine light came on and it gets stuck at 20 mph until it would seem to jerk to the next gear it does the same thing at 40mph. Is this from the gas or is there something more sinister at work here. I have a call into the dealer but they are at a meeting.
Modified by wantingwing at 3:15 PM 8/23/2007

[96Qowner]

Probably just the gas. The Q45 does NOT like 87. Of course, now you have a tank full of it. Ugh. Is it as hot there as it is everywhere else in the South?

And a warning: You have to avoid ethanol. NO ethanol if you can help it - it eats Q45 injectors. Best to run Chevron or Shell premium. I've been ok running 91, but I lose power. The car was designed to run on genuine 93 - hard to get these days, in many areas.

Your knock sensors are probably also shot, and they're a real pain to get to. Here's a simple way to check them:

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

So, it's likely a combination of the heat and the bad gas and the fried knock sensors.
Modified by 96Qowner at 2:55 PM 8/23/2007

[qship96]

my guess is this is a MAF related problem. bad knockers negate any effects of running 87 octane fuel

[cccpman]

I would agree with this being a mix between a maf and a fuel problem

Don't waste your money on an octane booster, most wont even advertise how many points they raise the fuel (for good reason, they dont!). Just dilute the fuel with the best you can find as you find it, eventually it will ween back onto the fuel its made for. Other option is to drain the tank - I just cant stand doing so because of the cost

As for the MAF, removal is easy and cleaning it is also. Buy yourself a can of 'electric parts cleaner' and spray that bad boy down, however dont actually let any part of the can or the tube touch it (in fact, don't use the tube). Might as well use the (almost) entire can, be sure to get both sides. Let it dry for a couple hours to be safe. Cleaning the connectors is the other part, you can get a conductive grease to smear on their with a q-tip, but before that rub down all the little pins with a Q tip and maybe a little of that can of electric parts cleaner (whatever, worked for me)

This was a sooner or later type fix, the car is 11 and probably never had a good electric parts cleaning, and its very inexpensive to fix

If the car had overheated sometime in the past, or just due to age the KS could be bad. The majority of folks here recommend you buy your parts through Joe at http://www.infinitipartsusa.com/ (Call them up and ask for Joe, he seems to be more customer oriented then the others ). Replacement is a DIY job if you have a decent knowledge of how things work, however you will be needing to buy at least a couple new hoses (usually the coolant hoses), some new plenum gaskets, some RTV, and have a torque wrench handy so you dont over torque the bolts on the plenum (easy to do). If not replacing the KS will be anywhere from $400 to a couple grand depending on your local $tealerships pricing (also, some wont install parts you buy yourself even if they are new in the box and OEM). It is NOT advised you take the car to a non Infiniti mechanic but hey do what you have to do

BEFORE you actually replace the KS test them first

Good luck, keep us updated

[wantingwing]

I checked out the "MAF How To" and it said "If dirty, the sensor fails to measure airflow accurately and results in rough idling, poor acceleration, sputtering, bucking, and heavy fuel consumption."

This pretty much is exactly what the car started doing almost imediately after I put the 87 octane in. Would the MAF needing cleaning trigger the engine service light though? if so Ill go ahead and do that in the morning.

Im not familiar with some of the technical terms what does KS stand for? Im trying to search for a bit more info on that aspect.

[cccpman]

ks stands for Knock Sensor. Its under the plenum and coolant jackets (the spider looking thing on top, and below that is the coolant jackets, its a pain in the *** to fix but can be a DIY)

search is your friend, Q45.org has THE writeup for the KS replacement (but test first, it has the steps for that too and that only takes a minute to do!)

[wantingwing]

So I have taken my MAF off according to the guide http://q45.org/maf.html the first thing that I noticed is my air filter assembly is quite different in that is has a cone filter and no box any thoughts on this is it common? Is it a poor fix for a problem that had happened at one time? Here are some photos of what I found.



MY MAF is drying right now I had another thought while lookiing abour the forums. I hear a constant Whirring that matches my movement on the gas pedal i cant tell where exactly its coming from sounds like mid to rear of the car. Could this be the fuel pump? Im not familiar with the sounds a Q is supposed to make so it may be nothing.

Modified by wantingwing at 6:59 AM 8/24/2007
Modified by wantingwing at 7:18 AM 8/24/2007

[goody90q45]

Open your trunk and listen to the area behind the back seat. Does it sound like a swarm of bees? That's your fuel pump.

Edit: The sound of a swarm of bees is not a good thing. It means your fuel pump has gone bad and needs replacement.
Modified by goody94q45 at 7:36 AM 8/24/2007

[wantingwing]

I'll check for bees once I get my MAF back on.

I added some photos also to show what I found (on a side note these forums are pretty flipping sweet.)

thanks for all the insights
Modified by wantingwing at 7:41 AM 8/24/2007

[Q45tech]

Cone filters allow HOT HOT HOT [150-170F] underhood air into MAF which fools the ecu especially in idle and traffic. Often takes 10 miles at 60 mph before air returns to near normal.

Oem box and system best for summer temperatures.Every 11F hotter decrease engine power by 1% [2.5-3HP]Every 5F above 196F coolant does ~~ the same.

Cool air and normal [176F] coolant are rquired for optimal performance.

[maxnix]

Best thing to do is to replace with a OEM stock CAI unit.

[96Qowner]

Your aftermarket cone filter was assumed by some previous owner to improve intake flow. It doesn't. If it did, it might have some use. Unfortunately, it simply makes a fun growling sound and causes the engine to ingest hot air. .At some point, you should locate a used OEM airbox and dump the cone.

I considered the MAF, but I thought the coincidence with the gas was just too odd, and a bad MAF usually causes jerky bucking - cyclic total loss of power for a fractions of a second - jerk, jerk jerk, like a carnival ride. Your symptoms sound more like a severe power loss - "it gets stuck at 20 mph until it would seem to jerk to the next gear it does the same thing at 40mph". And if the MAF was bad, you really should have had symptoms on your test drives, too.

Now that you mention hearing the fuel pump buzzing, you may be having trouble with your fuel pump controller (FPCU). The pump draws its current through the FPCU. When the pump gets old and corroded, it draws too much current, the FPCU heats up, and you get intermittent failures in the solder connections. Here're some threads about the problem:

zerothread?id=34503

zerothread?id=18148

zerothread?id=3984

zerothread?id=57683

In the third thread, tangalora lists a bunch of threads from the old NICO board. You can still access these threads by manually typing the thread number into the browser address line, ie, forums.nicoclub.com/zerothread?id=xxxxx

However, intermittent FPCU failure usually results in total loss of fuel pump pressure, not lower pressure, as yours would seem to have.

I'm still betting on the gas. But, it's good that you're examining these other Q45 common issues. Keep us posted.

[wantingwing]

after a bit of fussing with the dealer I bought the car from they took it in today to have a look. They werre pretty confused but after about 3 - 4 hours they found a cluster of wires that had brken free and apparently got cooked on the exhaust. They said this fixed the problem but I wasnt able to pick the car up tonight so we shall see if its true tomorrow thanks for all the insight Ill keep yall posted