1996 q 45 "bucking"

[Eagle 18]

Thoughts regarding the following:1996 infiniti Q45 154,000 miles got full 150,00 miles service in June - Last week "Check engine" lite came on.. usually means emission problem...but started to "buck" about the same time...not all the time cant predict when. perhaps about twice each day. Got word that diagnosis turned up the "camshaft positioning sensor" , a $950 job. Not sure, however, that that is what is causing it.

It may be time to let this car go. Have spent $2000 in last year on tires and other stuff.

Anyone with experience with this bucking and any thoughts about what it might be?

[Q451990]

Got word that diagnosis turned up the "camshaft positioning sensor" , a $950 job.

Tell us about this diagnosis... is this from a qualified Infiniti tech. with experience on older Q45s - or just the result of quick code scan? When was the fuel pump replaced last? If it's the original, that would be my first suspcicion. It may be worth your while to have someone check the fuel pressure and flow volume. The second suspect would be the MAF (Mass air flow) meter. If it hasn't been cleaned, try that.

Quote »It may be time to let this car go. Have spent $2000 in last year on tires and other stuff.[/quote]Doesn't sound too bad depending on what maintenence was deferred before that...

Good luck!

Heath

[maxnix]

Welcome in Eagle18.

Did you buy gas recently at a different station? Ethanol used in your area's winter fuel formulation?

Try a can or two of ISO-HEET and see if the prpoblem is condensation in your tank. When was fuel filter changed last?

Maintenance will average $0.20/mile or more if continually dealer serviced.

[lino]

I have a similar problem too. I get 160 miles per tank. Anyone know which gas station is best to use? I use Esso here in Canada which is similar to Mobil in the US. Which companies use ethanol?

[statichead2k]

Wow 160!!?? I am pretty bummed about 290-300 miles. It does not seem to matter where I fill up. I try to stick with name brand stations. In AZ all the stations have stickers saying they use up to 10% Ethanol mix during certain parts of the year.
Modified by statichead2k at 6:13 PM 1/2/2007

[Jesda]

Don't bother with anymore troubleshooting. Go buy a used MAF from car-part.com. A MAF from a 95 or 96 will work fine.

[96Qowner]

What Jesda said, yeah, that's exactly how the car behaves with a bad MAF.

You can try cleaning the MAF and connector, according to these instructions from Q45.org:

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

But with that many miles, you may have to replace it. If you clean it and the symptoms go away for awhile, at least you've ruled out the CPS.

I rarely read about an Infiniti dealer anymore who seems to have any idea how to fix a G50, or what typical symptoms point to. At least your dealer didn't want to replace all the coilpacks.

Oh, and the CPS shouldn't cost anywhere near that much.

[lino]

I cleaned the MAF and connector, according to the instructions from Q45.org around 8000 miles ago at the same time I did a pressurized fuel rail flush, changed the spark plugs, fuel filter and air filter and tune up etc..

Since I can't test a used MAF, what kind of mileage should the donor part have? I don't want to purchace a used part that has the same mileage or higher as my car and end up with a part that is at the end of its life. Also, is the 95-96 MAF different in any way than my 91?

Sometimes a car ends up in the salvage yard, due to an accident for example, and the previous owner could have just replaced some parts that month, so I've always regarded used parts a roll of the dice anyway.

[96Qowner]

Lino, if yours is bucking, too, I'd say get a used MAF. I spent about a year dinking around with mine, cleaning it at decreasing intervals (less than 1000 miles near the end), until I finally got fed up and bought a replacement. My gas mileage didn't suffer, though.

The connector changed on the MAF during the 94 model year, so you'll need a 90-93 to be certain.

As far as ethanol, it's hard to know which stations use it and which don't. You can try talking to the station owner or manager - I did that at the station I use and I trust this guy to actually know - not necessarily normal, though. Since ethanol raises the octane, one clue can be 91 octane versus 92.

[lino]

I thought I'd wash the car this afternoon, check the MAF and the resistance of the fuel injectors and knock sensors.

My DMM didn't want to co-operate. All I got was this screen:

So I couldn't check my Knock Sensors or Fuel Injectors.

I did manage to wash the car though:

Sorry about the poor quality pics.

Here are some pics of what my MAF looks like:





It looked too clean to evewn bother cleaning it.

The Connector:

Air Filter still looks clean too: