Problems after Oil Change

[redmanfx]

I just finished some maint of my Q. I changed the oil, oil filter, fuel filter and fuel lines attached to the fuel filter.

I have massive hessitation at 3,000 RPM and that's as far as I can go. I think air in the fuel lines screwed this all up, but I don't know. I've done this so many times but never on a Q. ONce I get to 3,000 RPMS the car wants to die. It sputters and hessitates. I hear a hissing noice that wasn't there before but nothing is leaking.

I can't get the car started easily at all. This form a car that always started as soon as the key was turned. Not now. I'm really upset! I have a master mechanic friend who was there and he was scratching his head too. Never seen him stumped before. Of course he's never worked on an Infiniti Q45A before either, but he looked concerned.

What can I do? This is my only ride and I need it running without the check engine light on and the massive hessitation. Please tell me what I could have screwed up..

Redmanfx,

[redmanfx]

Checking the CPS, MAF connections and the CAS. Sounds like a CPS problem if I can't go over 3,000 RPM... Still searching. Have to look through FSM to see where the CPS is.

redmanfx

[911/Q45]

Did you change the filter from above or below? With the hissing it sure sounds like a big vacuum leak, crack an old hose somewhere maybe?

[redmanfx]

Changed it from above and remember my mechanic friend taking the MAF connector off and looking at it. I remember it looking old and brittle. The plug is white and had some little metal wire ring around it that came off. We put it back and plugged her back in. The hoses are in not so good shape. The carbon canister was sitting on top the radiator hose and that hose had visible wear at the point of contact. We cut an old hose off one of his 8 parted out mini vans to put between the canister and the radiator hose for now. That hose was not leaking, but does need changing soon.

Point is the hoses need replacing, but I just couldn't find the vacuum leak. I need a whole new airfilter box because both bottom and top were broken and only had two clips holding it together.

The car ran sooo good though. Still looking for the Camshaft Position Sensor.

redmanfx

[DougQ45]

Wiggle the MAF when its running. Odds are its the MAF. The little pin connectors become bent and crimped over time. Carefully take it apart again, clean the male and female ends and CAREFULLY re-asssemble. It should fit very snug.

[redmanfx]

Ok, Thanks. Tomorrow will be the day to check this out again. Been out there with a flash light and everything checks ok, but it's to dark to continue. Found out the CAS is the CPS as talked about is other treads.

Almost afraid to wiggle anything as it may just crumble into a million pieces.

redmanfx

[redmanfx]

Will be checking all ECU codes for source of problem today. Got info from previous threads, Thanks... Wes. We will also be zeroing in on the MAF ans CPS. Cleaning the connections and so fourth.

redmanfx92 Q45a

[redmanfx]

Well, the problem is completely gone. I guess the system simply reset itself overnight! Went out this morning and had no problems starting it or running well past 3,000 rpm. I didn't think we had messed anything up yesterday....

Things that make you go Hmmmmm......

redmanfx

[nuQ]

kinda had the same problem as you. couldn't hold an idle and wanted to stall constantly. turned out it was the MAF connection. i took it off, used a pin to CAREFULLY scrape down the brass connecters to get good contact points, smeared a nice amount of bulb grease in there, buttoned her up and problem solved. i would go this route first and let us know how it turns out!!!jeff

[nuQ]

oops!!! missed your last post, see that it's fixed!!!!! good

[redmanfx]

The Q acted up again with the same problem, except this time it just died going down the road. Completely shut down. Could not get it started right away. When it did start I couldn't get above 3,000 Rpm again. The check engine light came on and I limped home. It died again on the way. Once I got home it still wouldn't go above 3,000.

I pulled off the MAF connector and cleaned it. I heard that Hissing noise again under the plenum. I should note that earlier this morning there was no hissing noise when the car was running fine.

After about 4 hours I started it up and and it's fine!! No check engine light, no hessitation, no hissing sound from under the plenum. What the HEY!! I also couldn't remove the ECU. It's stuck to the harness and won't budge! All the bolts are out.

Once in a while it will miss fire and I now here the dreaded fuel pump humming like it wants to be noticed. Could the fule pump cause this whole problem? I didn't really hear it yesterday, but I can now. Without being able to remove the ECU I am getting frustrated. I'll try again tomorrow.

redmanfx

[DAEDALUS]

There's a single bolt holding the harness down, and 3 screws holding the ECU to the frame. If you have the harness bolt loose, pry the harness off in little steps across the entire bundle. It should come off. If you can get the 3 screws out without removing the harness, then just do that and get the codes.

[redmanfx]

The 92 Q45 completely broke down this afternoon. It won't even turn over at all and even keeps the key locked in the steering column at times. When the key is turned to "start" nothing at all. No sounds. Can't hear the fuel pump even before the key is turn to 'start'. Could this still be the pump?

redmanfx

[maxnix]

Yep, it could have failed terminally. Hope it didn't fry the FPCU also.

[Q45tech]

Bad batttery connection, dead battery, [won't turn over] won't release key. And all the usual intermittent connections.

[redmanfx]

It was the battery connections. They were the originals and did not look to bad. Needless to say they were. Had a couple of visiting mechanics check her out and they love the Q! They had never seen one before and I couldn't get them from under the hood!! They all suggested a K & N filter, but I had read previous threads concerning the wear and tear they cause.

I have a hook up for a 95Q FPCU and need to know if it would work on a 92 and what's a fair price for it used. It's in good shape and has no blackness around the connections or visible signs of being burnt.

redmanfx

[Q451990]

I have a hook up for a 95Q FPCU and need to know if it would work on a 92 and what's a fair price for it used. It's in good shape and has no blackness around the connections or visible signs of being burnt.

90-96 are all the same, so yes - it would work. The FPCUs seem to burn in two places. One is near the connector and where it attaches to the board. The other is around the transistor-looking things that are on the middle of the board and screw through to the sides. You'll have to open the cover to check the transistor-type components.

$50-100 is a good price if you really need one, or you can search eBay for a while if you're just looking for a spare and get it down in the $20-40 range. If yours looks fine, go ahead and replace that pump now before you fry the controller!

Heath

[redmanfx]

Thanks Heath! My FPCU looks good at this point, but not being sure about the pump itslef, since it is silent now, I need backup. I'm looking around for a new 3 stage pump as well.

redmanfx