Q45 - Hisitation and Random Quiting

[Ceashure]

Hello, i have a Infinity Q45 1990. I have alot of problems with this car.

First- The car starts up completely fine in cold weather, yet if the car is warmed up or if the weather is warm/hot the car will hisitate to start. I have to pump the gas to get it to start.

Second- The car idles at about 1,000 RPMS when it runs fine, but runs about 500 RPMS when its not (usually when it hesitates starting).

Third- When the car isnt running fine it will hesitate to exceed above 3,000 RPMS. It will just fluctuate up and down untell the gas peadle is released and is re-applied.

Fourth- The car will randomly completely die on me. ( i have noticed that it usually dies (or always) while the gas is not being applied.)

Things i have tried:

I did try unpluging the MAF and the same problems occured, yet hesitated at 2,000 RPMS instead of 3,000. I am almost possitive it is the MAF or the connection that is causing all the trouble.

Please help if you can! Thanks a buntch!

What does the MAF sence other than the air flow?

[elwesso]

Lucky for you I was just reading up on this in the FSM today!!!

Sounds EXACTLY like your CPS (camshaft position sensor).... Engine speed wont rise about 3000 RPM and everything else sucks..... But the car drives......

The hot start thing could be a fuel filter, i had that problem with my Q.....

[Q451990]

Sounds like the MAF to me - but it could be the CAS as well. Have you tried wiggling the connections to these sensors while the car is idling? Any change in idle speed indicates a connection problem.

Another area of concern is the fuel pump and it's control unit. Any loud humming noises from the back of the car - especially with a low fuel level in the tank?

Welcome to NICO!

Heath

[Ceashure]

no loud noises....and yes i have wiggled the MAF wire,but it didnt do anything... where would i find the CAS? and what is it?

[Ceashure]

elwesso- yea i replaced the fuel filter already...no help :-/ where could i read up more about the CPS? how much do you think it'll cost me?

[elwesso]

Do you get a CEL....? If not, that might eliminate the CPS.....

Look into checking your diagnostic codes, much can be revealed!!!

[Ceashure]

yea...but i was trying to surpass the 200$ code test, for that much i could get a new MAF.

[elwesso]

You can do it at home for free!!! Do a search for codes, its been brought up many times (by yours truly!! )

[Rex]

They can't spell Infiniti, but the codes and info are right.

[Ceashure]

oooo THANK YOU SO MUCH!

[Q451990]

Ignore the other stuff, but the CAS is labeled in this picture.

[Q45tech]

Remember the CAS has a socket on the body [where the 360 pulses come out] and another cable that mates under the front decorative cover [which has the 90 degree pulses] either/both can have corrosion/pin problems.

[Ceashure]

Yea, now i'm going to try to find out the ECU code to find out whats wrong later tonight. I checked out the MAF male connection pins, they look pretty dirty and corroided. I am going clean that connection a bit.

[elwesso]

Great, you definitely have some stuff to check out.....

We'll get your sick Q back healthy again!!!

[Ceashure]

heh...its taking forever just to take out the ecu so i can read it.

day one: got the side kick panel off

day two: figured out the switch and LED was on the side of the ECU that faces the firewall. I then had to unscrew the screws, yet the very top screw was placed right where you cant reach it

day three: took the whole glove compartment out just to reach the ecu screw.

i will now try to read the ecu as soon as i have time...lol

[Q451990]

Yeah... I bet the percentage of top screws that get put back in at dealerships is less than 30%.

Heath

[elwesso]

Take out the ECU, undo the big harness connector (10mm) and pull it out, and then put the harness connector back on....

I didnt put my top screw back in, mainly because I dropped it under the carpet!!

SOMONE didnt do a little searchy!!! http://www.nissaninfiniticlub....31834

[Ceashure]

here is what the ECU turned up:

CASMAFKnock Sensor

[elwesso]

Dang.. Im surprised the car runs!!!

Your gonna have to start looking into getting those things fixed...

Youd be better off looking into getting a used part of a wrecked or whatever Q.... Especially the MAF, I didnt think the CAS would fail that much... The KS can wait for a while, as its perfectly driveable with them bad (but poor gas mileage and acceleration)....

[Q451990]

I'd think dirty connectors on all of them are a real possibility. In either case, I'd check that first. The CAS and MAF are "gotta be done right now" items - the knock sensors will make a major difference in performance, but the car will run and perform better than 90% of what's on the road with bad ones.

Heath

[elwesso]

yes... ALWAYS check connections first!!!

I cant say however that I noticed a HUGE difference in performance.... Definitely noticeable, and definitely worth the agony!!!

[KFL]

Sounds like a bad maf, I would check all connections first and test it out. Did you pull any codes from the ecu.

[Chally]

Clean all connections carefully, both the Male & Females, then cancel the codes, drive a while & re-check again.

NB You don't need to put the computer back in place as you test etc.