Under Plenum Service to Fix Rough Idle, CEL, Faint Fuel Smell

[acfran7]

Hello Q45 forums! This is my first time posting on the Nico forums as I've been digging into them trying to prepare myself to address servicing everything underneath the plenum. I inherited my grandfather 94 Q45t a couple months back. The car will give faint smells of fuel and the CEL comes on after driving for a little bit and turns off as well. It idles what seems to be extremely low and has a "wubble" feel as its driving. After diving through forums I've realized this car most likely needs a major refresh under the plenum and most likely has one or more faulty injectors. The car is at around 245K Miles and I have no reference of when any service like this was done last reading it should be done every 100k miles.

I've had a hard time figuring out a parts list of everything needed. I plan to change knock sensors/harnesses, clean EGR valve/pipe and replace gasket, clean IAC and replace gasket, clean TB and replace gasket, replace PCV valve, replace spark plugs, check and replace any fuel lines and I'm leaning to just replacing all injectors while im at it to prevent having to go under all of this again soon. I'm pretty mechanically inclined but this job is very daunting and I want to make sure Im not missing any parts. Where should I be sourcing all of the coolant hoses and such?

I appreciate any responses and look forwards to getting more involved with the Q45 forums as I don't plan on getting rid of this beauty anytime soon.

[Jap Burd]

I had a hell of a time finding hoses 20 years ago.

[Ryantzer]

Amayama can still get most OEM Nissan parts for our Q45s from Japan. They have decent factory parts diagrams to help you figure out which hoses you'll need - there are coolant, air, and oil vapor hoses in there that are all likely to be rock hard at this age, just replace them all while it's apart. I'd plan on replacing all the injectors as well since they're a regular failure point - the OEM ones are stupid expensive to replace by the set, but you should be able to find some name brand aftermarket injectors for way less. I'd plan on replacing the 8 plenum-to-intake runner seals also, and installing new radiator hoses, OEM radiator caps, OEM water pump, and OEM thermostat while the cooling system is apart.

[Jap Burd]

Infinitiace had a gas leak last year, , I don’t remember where it was, maybe he will chime in on this. He had it fixed.

[Q451990]

to NICO acfran7!

Your plan sounds like a good one. The gas smell, particularly in cold weather, is usually fixed by replacing the fuel hoses under the plenum. Sometimes tightening the clamps (if you can get to them) helps for a while. Fuel injectors are a common failure item. Check for threads talking about "ohm testing" them - and also be sure to check out your factory service manual. It's available at www.infinitiservicemanual.com