Cold staring problem for Q45

[sancem]

I have a '94 Q45 with 120,000 miles.

Lately in the cold mornings or after sitting for about half a day I've had problems with it.

When I try to start it up it cranks and starts up but then right away it bogs out and will die if I dont rev it about 2000 rpm for a little while.

That "while" seems to be getting longer and longer. I have noticed a lower idle rpm as well. The problem is worse when it is colder.

Thanks in advance.

[maxnix]

How about some maintenance hsitory? Concentrate on the fuel and intake and ignition systems please.

[qship96]

I would suspect dirty throttle body/plate not allowing enough air to pass,along with possible cold high idle control system maladjustment or dirty AAC system

[Mint Q45A]

Are these symptoms accompained by a strong fuel odor coming from the exhaust - like unburnt fuel? If that is the case, look for the possibility of some flooding....It seems to me that old, hardened injector O-rings tend to fail more in cold weather, allowing fuel to sip through...
Modified by Mint Q45A at 8:02 PM 1/21/2008

[elwesso]

I would definitely start looking into that, because its been cold as hell here and IM quite a bit farther south than you. 2000 RPM isnt too good on the motor not warmed up..

Anyway, first thing I'd see is if its getting too much fuel or not enough.. if it smells gassy, then thats a place to start... Let us know.

[sdkhalsa]

As mentioned in the "My Q Won't Start" comments, you might find it useful to pull the fuel pump fuse at the time of shut down as to starve the engine for fuel. When you restart you will probably find that the engine fires up much more easily than before. Rev the motor and then pull the fuse to shut it down. With the fuse out, crank the motor through a few cycles to lessen the amount of fuel pressure and fuel in the system. If you are having specific troubles in the morning, pull the fuse and crank maybe three cycles of 5 seconds each. Replace fuse and then try starting.

[qship96]

As mentioned in the "My Q Won't Start" comments, you might find it useful to pull the fuel pump fuse at the time of shut down as to starve the engine for fuel. When you restart you will probably find that the engine fires up much more easily than before. Rev the motor and then pull the fuse to shut it down. With the fuse out, crank the motor through a few cycles to lessen the amount of fuel pressure and fuel in the system. If you are having specific troubles in the morning, pull the fuse and crank maybe three cycles of 5 seconds each. Replace fuse and then try starting.

Say WHAT? This is your "cure" to hard starting? Find and repair the problem!

[sdkhalsa]

Tough crowd. This was no cure. It was a means for determining whether there was excessive fuel enrichment during the cold starting cycle. It was also a means for getting the car started if you are flooded out. Ease up on the coffee!

[sancem]

The fast idle solenoid (2378164u11) is defective according to my neighborhood mechanic. He says that we should start by changing it but if there are other problems simply changing the solenoid won't be enough so we'll start by changing it and see if that's all that's wrong. Thanks for the input.

[sdkhalsa]

Most of the idle control is through the IAC valve with some small tweaks through an expanding / contracting wax element in the idle set. You do not want to mess around with these idle stops, as they are very hard to adjust. On the other hand, the IAC valve is easy to get at. Normally this becomes dirty and sticks. It needs to be cleaned every so often(maybe every year or year and a half), and you can find detailed information on the Q45 web site. I would start here, although some other items may be causing trouble, i.e. vacuum hose leaks, timing, , ECU temp. sensor, EGR leaks.

[maxnix]

The fast idle solenoid (2378164u11) is defective according to my neighborhood mechanic.

Your "neighborhood mechanic" obviously is not an Infiniti Technician, nor is he knowledgeable about the VH series.

Study the FSM and read the previous posts here. Search on IAC.

[Q45tech]

As far as I know a TB nor the hot wax idler has ever failed in 18 years without help from an owner or mechanic [technicans know better].

It was designed and built beyond human standards like many unique things on Q.............the remainder of the just satisfactory engineers were allowed to retire in disgrace.

[sancem]

Maxnix, you are correct. My neighborhood mechanic is not a trained Infiniti Technician nor espcially knowledgeable about the VH series. So what?!?

He is generally honest and competent and if he says he pulled the solenoid and tested it and it's not working, I believe him and I don't see why we should not replace it. I'll call Scottsdale and see if they can get me the part.

[maxnix]

My neighborhood mechanic is not a trained Infiniti Technician nor espcially knowledgeable about the VH series. So what?!?

He is generally honest and competent and if he says he pulled the solenoid and tested it and it's not working, I believe him and I don't see why we should not replace it. I'll call Scottsdale and see if they can get me the part.

Well, I am pretty sure honest and competent mistakes cost just as much to repair as dishonest and incompetent mistakes.

If he knew what he was doing, he would first disassemble the IAC and clean it then check it. Can't recall the IAC solenoid ever failing on this board, but yours may be a first. When he R&R the IAC valve, also do the same for the EGR valve and TB and look at the plenum. You may then decide to go the whole 11 yards and pull it and do the hoses and KS.

Don't forget to have the gaskets on hand.

[Q45tech]

Solenoids don't usually fail as they are all fuse protected even thru ecu.Fuel injectors are a special case since alchols in gasoline swell the plastic housing and rip the internal crimp to connectors away causing high or open circuit but still the solenoid part didn't fail just a connection to it.

The arms/valves they control can get stuck from lack of owner maintenace making the unit APPEAR to have failed.....................maybe semantics but automotive engineering is a science.

Never have seen a new IAC required in hundreds of Q, cleaning is always required repeatedly especially as the engine ages and the amount of blowby increases and owners become less rigorous concerning air filter changes.

Only source of dirt is from air filter allowing it thru..........now vaprized oil condenses and make glue with dirt.

[sancem]

Ordered AAC valve from Infiniti of Scottsdale. Part was replaced and car is now running fine.

[Q45tech]

Measure the coil resistance of the old "failed part" and report. I still believe the IAC/AAC was just dirty and stuck.

[maxnix]

Measure the coil resistance of the old "failed part" and report. I still believe the IAC/AAC was just dirty and stuck.

Yes, I also bet it is only dirty and did not fail.

[sancem]

Resistance was infinity (no pun intended).