2000 Infiniti Q45 Slow Start

[dranobob]

Sometimes when I turn the key the car immediately starts other times it takes a few seconds to fire (3-5secs). Once it cranks it runs perfectly. When there is a delay you can hear the starter turning over just fine.

Here's some background on the car to eliminate some causes (problem happened before and after I did all these items).- Oil Change- Coolant Flush- New Fuel Filter- Replaced Battery Cable Connector (old was bent up pretty bad)- New Air Filter- Replaced spark plugs (bosch platinums)- Compression on each cylinder measured 180+psi- Ran through a tank with fuel cleaner- Replaced all Belts- I also run 93 octane all the time

- I have 95k miles on the car

I know some of these items have no affect on the starting, but I wanted to give a detailed list of what I know on the car. So far the car always starts, just want to be sure this isn't a sign of a problem to come.

Any thoughts?

[maxnix]

Bosch Platinums are death for a VH engine.

Replace now with OEM specified NGK PFRG!

All the rest OEM?

[qship96]

Not related to your current problem, but replacing battery cable clamps is always a bad idea- always replace the entire cable to maintain optimum power transfer and low resistance.

[maxnix]

And let me add, since you are in Atlanta, go by T-3.

[Q45tech]

Monitor the precranking fuel pressure from the moment the key is turned and graph the build up to 30-44 psi...............how many fractional seconds before the pressure builds enough to properly flow..............10psi is roughly half the idle flow at 34 psi.

Also the battery voltage while cranking should exceed 10 volts [9.6* absolute minimum] as measured at terminals.

Low cranking voltage means extra low coil output voltage and thus plugs lose ability to fire properly.

* As the ambient temperature drops the HIGHER the cranking battery minimum voltage must be! When 20F in ATL we use 10.75 as the minumum and 2 year old battery will barely meet it if half charged.

BOSCH PLATNIUMS are definitely asking for problems

[dranobob]

Good to know about the Bosch, I'll change them out tomorrow. I've been working on VW for years and that was always the recommended plugs. Why are bosch so bad for Infinitis?

It'll be this weekend before I can have time to graph the fuel pressure build up.

I'll measure the battery voltage tomorrow as well and see what thats does. As for the cable, the cable shows no problem. I only replaced the connector because some previous owner obviously was two lazy to get a wrench and chewed up the nut and metal with a pair of pliers.

[dranobob]

Also I see in the service manual it says:"the cold type spark is suitable when spark knock may occur with the standard type spark plug such as: extended highway driving."

I'm going to order the NGK plugs this afternoon, but saw this. I drive about 90 miles a day mostly highway, should I go ahead and use the PFR6G cold type plugs then?

thanks

ps. My family also used to always use T3 for my fathers 94 Q till he sold it. I have a decent amount of experience working on cars, so I'm going to try my best to do most of the work myself, but T3 will always be my backup if I fail.

[maxnix]

T-3 is a good analysis tool for even the most competent owner.

Bosch (and Autolite and Champion) electrodes have a habit of breaking off in the cylinder. Not a good thing.

Try ordering from IoS before the prices increase on January 1. They have killer price on M1 filters bsides air intake, cabin and fuel filters. Don't forget crush washers.

http://www.infinitipartsusa.com

[qship96]

Brian, are you assuming parts price increase as of Jan 1 2009, or has Nissan/ IOS published a notice of such?

[maxnix]

Brian, are you assuming parts price increase as of Jan 1 2009, or has Nissan/ IOS published a notice of such?

A little birdy told me. Customary for Nissan to issue a new price list each new year. With the yen so strong, we may be screwed. Fair warning to all.

Two days left to order.

[dranobob]

K, took me forever to get around to post my findings. Been busy for the past few weeks. First off, I replaced the plugs and went with the factory recommended NGKs. So thats not an issue anymore.

I tested the fuel pressure going into the regulator. At idling I'm getting around 235kPa (34psi) and after ignition being turned on I'm getting just under 300kPa (43psi)...just as the service manual states. Now once you turn the key off...the pressure drops continuously back to 0 in about 5 minutes.

The car started right up after installing the gauge...and the system was obviously at 0psi since I had to pull the fuel line off to test. So the fuel pump seems strong enough to pressurize the system instantaneously.

Any other ideas or thoughts?

[bullittandy]

You sound like your pretty competent but time the start exactly and see if it's really 3-5 seconds.

I own three of these cars (2 97's and a 99) and my mother owns a 97 and they all have the same condition 9not 3-5 seconds though-just a lot longer than any other car I've driven). It really bothered me when I bought the first one but I've grown used to it.

I think its a software design, maybe other cars have more dramatic timing changes at startup, i had a 91 Mustang LX with all kinds of work done and it started in what felt like 1/4 turn of the crank.

Good luck!

If you want a transmission cooler kit, I've got one left.

[maxnix]

The VH41DE does not catch as quickly as the VH45DE.

[paranoidjack]

The VH41DE does not catch as quickly as the VH45DE.

...and also blackens toast too much, from what I understand

[dranobob]

its about 1 in 10 starts, but it can take 3-5 secs. At this point, it never doesn't crank, so I'll just write it off as design thing or just the fact the car does have 95k on it. I love the car and just got it, so wanted to make sure I worked out any bugs the previous owner may have ignored.....cause its shocking how many people ignore major problems.

...unless it gets worse, thanks for the responses...

[maxnix]

Probably time to go through the plenum, lower runners, EGR and IAC valves, TB......

[BadQ45t]

my 97' has 90k on it and cranks over immediately and I have never had an issue with anything like this, so not sure it is normal. But the fact that it starts tells me that you might be fine to ignore this issue.

It amazes me to see people ignore issues that are so obvious on their cars. My mom's Camry at 120k still had original struts. I had to almost buy them myself to finally get her to replace them and than she sees how ignoring things doesn't pay.