M45 Sport vs Non-Sport front suspension parts

[SpitfireM45]

Hello M45 experts. My 230 k mile 07 M45 Sport (I recently replaced w used engine + trans) needs front suspension rebuild. Do I need to order replacement suspension parts compatible for the 07 Sport model or or will just 07 M45 suffice?

Thanks,
Mike

[Ilya]

You would need the parts that are compatible with your VIN number. Most Infiniti OEM parts sites will tell you what works and what doesn't work with your vehicle. Anything else is a gamble as it may not line up, bolt up, etc. exactly the same.

[LIBRILZ]

I ordered the KYB struts from rockauto. They creak in the cold though. If I had to make a recommendation I would say just get coilovers, if you feel like investing in the car. What happened to the old engine if you don't mind me asking?

[Spitfire39]

Thanks to both reply’s about specific front suspension parts for the Spot M45 vs non-Sport. When I get to this project, I will order parts specific to my model.

As far a why I had to replace the original engine; Head Gasket failure from a coolant service that I did a while back. I did not know that these engines are notorious for air pockets within the block and or cyl. head. Captured air within the cooling system caused a hot spot, compromised 1 or both head gaskets that resulted in coolant getting into the combustion chamber, bled the system, which led to multiple overheating events on longer trips. Confirmation of diagnosis- air bubbled flowing to top of radiator when cap off. How to fill coolant to avoid this issue -Front of the car raised with a coolant fill funnel tightly fit to the rad fill hole is the way to completely fill this system. That’s what I did for the replacement engine (114k miles) and all is good. I still have the original engine for rebuild some day. When I get it apart, I’ll be able to diagnose exactly what failed.

[LIBRILZ]

Interesting, yours is one of the few I've heard of having this issue. Usually see issues with the Bottom end on these aka rod knock. That happened to me at 138K, but I could've maintained the oil changes better, also no telling what the previous owners did regarding oil changes and such. One other thing for you to look out for, the intake manifolds on these. The butterfly valves like to lose screws and get sucked into the engine. I will be loctite-ing mine soon. I actually already injested two screws but alas things are fine for now. I saw a few engines where this lead to problems though.

[Spitfire39]

Rod knock was definitely an issue that I believed to be the result of overheating. At 235k miles (original engine), rod knock may have just been due to age / high mileage. My M45 died on the side of the road. I had it towed to my mechanic. He got it running again. Once warmed up, engine knock became noticeable. I was going to scrap the car but since it still looked in great shape and all other systems worked without issue I decided to find a used engine.Used engine had 114k miles at time of install last August. So far so good. Thanks for the tip on that butterfly valve screw. I believe that I was close to having this issue as well. On previous engine, I removed the air intake just to take a peek and found a random small screw under the air intake manifold. It was just sitting there and appeared to have no home to fit to in that area. You have answered that mystery. Thank you for the heads up on this issue. On the replacement engine I will follow your procedure to avoid this from becoming an issue. I’ll have to poke around and or research how to complete this task. Thank you very much for your help with this. Perhaps you could give me advice if the following is an issue or just in my head. Current engine seems to have higher that normal or needed RPM - like when I’m driving in my neighborhood for example. With foot off the gas pedal, the tac dial needle will bounce up a bit and the car continues to accelerate a bit. Is this an issue or just in my head. I don’t remember this feeling while driving. I’ve had this car since 2011. FYI, I did have an engine code P 1140 and replaced both cam sensors. No engine light since. Any thoughts on this? Thanks a ton for your assistance! Best, Mike

[LIBRILZ]

Hmm, never heard of that. But if you replaced the sensors with non-OEM parts that could lead to problems. Is the idle high just in Park or Neutral? That could indicate some sort of vacuum leak.

Glad you decided to keep it on the road. It is old now, but they don't really make cars like this anymore, whether it's Lexus or Infiniti. Seems like yours has treated you well most the time though. I just hit 200K.

[Spitfire39]

Thanks for the reply. Sometimes at idle (after warmed up) the tac needle will read 800 to 1000 RPM. Other times, it will read 750, which I believe is normal when not in gear. When I put it in gear it will kinda lunge forward and the tac needle will go to 1000 to 1100 and stay there. It’s the lunging forward that makes me think that something is off. After driving a bit and approaching a stop (like 500 feet ahead) I’ll take my foot off the gas and the car seems to keep traveling at the same speed for a bit and then after (I think 3 to 5 seconds) the car will start to decrease in speed a bit. With the foot off the gas the RPM’s don’t decrease right away. It just feels like it’s not responding to slow down as quickly as it should. I wonder if it has something to do with gas pedal/throttle response type of sensor? I’ve located a mechanic that specializes in Japanese. I’ll pay him a visit and see what happens.

As far as still on the road- this past weekend, I took it for the longest trip since installing the used engine and transmission. About 350 miles each way. She ran really well. I love driving this car. I could have taken my 1985 Porsche 944. It is fun and responsive on the highway but my M45 Sport has that plus all the comfortable bells and whistles.

[LIBRILZ]

These cars did have a recall for the accelerator pedal. Mine was done before I got the car but maybe check into whether that was done or not. But a mechanic with the right computers and such can read the sensors and see what is going on behind the scenes. That doesn't sound right at all. MAybe the throttle needs to be relearned as well. Not familiar with that process but it's around the web/forum.