Engine Revs.

[Paul. W]

Hello all, 

 

I am new to this forum, an older driver and keen car enthusiast. I own a 2005 350z GT4 Limited Edition, (rev up engine), which I have recently finished a 3.5 year rebuild on, (spare time), due to excessive underbody corrosion and generally poor or no maintenance over its relatively short life. I felt the car was well worth saving when I originally saw the poor condition it was in, so bought it, and 3.5 years later have now returned it to its former glory. I had virtually no history with it, so have no idea if it has been re-mapped for example. 

 

I have driven the car for a week now, and apologise if the answers are already available somewhere on this forum, but I have a couple of queries that you guys will no doubt be able to clarify. 

 

1) On starting the engine from cold the revs are around 1800 rpm before falling back to circa 650 after about 2-3 minutes when the engine warms up. Is this normal? 

2) The revs tend to "hang" for a second or so when you release the throttle pedal. It's not an instantaneous drop in revs when you ease off the throttle pedal. Is this normal? 

3) Finally, the throttle pedal seems very sensitive, just a small amount of pedal depression causes quite a high response in engine rev increase. Trying to rev the engine to 2000 revs and hold it there while stationary is quite a challenge due to the throttle sensitivity. Is this normal?

 

I would like to thank you all in advance for any feedback you provide. 

 

Thanks guys. 

 

 

 

[ATTAK Z]

Sounds wrong to me but the experts will, I'm sure, be along shortly to let you know how to fix

[ATTAK Z]

Oh and welcome to our forum

[Ekona]

All sounds perfectly normal to me. Depending on what car you've come from, all of those 'symptoms' may well feel odd at first.

[StevoD]

yea seems normal to me 

[davey_83]

Rev hang and me don't seem to get along when rev matching. Factory map and a heavy flywheel negates finesse. Welkom to the club, would love to see your GT4 as i missed out on a black one when i was looking for one. 350z is a rare car on the road, let alone a LE. 

[Ekona]

3 hours ago, davey_83 said:

Factory map and a heavy flywheel negates finesse. 

Actually that's when it's easiest, as it's numbed down so that any body can make a decent attempt at it if they know the basic theory. A remap with a sharper throttle and a lightweight flywheel would make rev matching more difficult, so the opposite way round to what you've said  

[350Butcher]

7 hours ago, Ekona said:

Actually that's when it's easiest, as it's numbed down so that any body can make a decent attempt at it if they know the basic theory. A remap with a sharper throttle and a lightweight flywheel would make rev matching more difficult, so the opposite way round to what you've said  

 

Paul W, that does all sound normal and as others have said, would be great if you could share some pics as it sounds like quite a project youve taken on there and I’m glad you’ve saved the car from a different fate. 

 

Sorry to do off topic. 

 

Ekona.....you clearly don’t heel n toe yourself as Daves right there. Factory lazy throttle paired with heavy flywheel makes for easy smooth shifts under normal driving as revs don’t drop when you depress the clutch so you can swap cogs no problem. Under more enthusiastic conditions and you’re standing on the brakes and blipping throttle to heel n toe you need fast response to give flare of revs to sync with the down shifting / heel n toeing. So remapping to a more 1:1 ratio on the throttle and paired with a lighter flywheel/clutch assembly will give you just that. 

 

 

Edited November 17, 2018 by 350Butcher

[Ekona]

Clearly don't heel n toe     Please don't make assumptions when you have zero evidence to back it up.

 

Again, I still say you've got it the wrong way round. I can heel n toe in anything, and will always endeavour to do so to save drive-train wear, and I know for a fact I can be a damn sight more relaxed about the process in a diesel Vauxhall Omega or Ford Ranger than I had to be in a VX220 or my track-prepped mk3 MR2. In the sharper cars you need to be more accurate and quicker about the process otherwise you'll lose the revs or overshoot them, whereas in something more barge-like you can take a bit more time. 

 

Heel n toeing isn't just for when you're driving 10/10ths, it's a skill that should be used all the time whenever possible to aid smooth driving.  

[350Butcher]

I actively avoid these sort of keyboard discussions that seems to be the end of every post on this forum these days regardless of the original question or reason for thread but can’t help but respond here. 

 

I thought I made a safe assumption as your post was not in line with someone who uses heel n toe technique

 

As for evidence, I can’t help feeling you provided it all in your last post

[ATTAK Z]

On 16/11/2018 at 18:56, Paul. W said:

 

1) On starting the engine from cold the revs are around 1800 rpm before falling back to circa 650 after about 2-3 minutes when the engine warms up. Is this normal? 

 

@Ekona and @StevoD

This does not sound normal to me ... I would expect more like 1200 RPM at cold start up

[Paul. W]

Thank you all for your welcome and comments. Generally it sounds as if the points I queried are normal, which is good to know, thank you.

 

Not knowing of anyone closer to my location in South Wales, I had thought of booking it into Abbey next summer just to get it all checked out, including checking the mapping is original factory and not a re-map.

 

I will endeavour to get a few photos of the car on the forum in the up coming weeks.

 

It has been a lot of work, a few pints of blood and I can't say inexpensive, but it's very rewarding to see her back in good condition and out of the clutches of the scrap yard.

 

Once again, thank you all. 

[Jay84]

Welcome along. I always thought mine revved a little high on idle too, you can do a throttle position reset, that might help. We'd love to see pictures we love that kind of thing.

As for the 'raging' flywheel debate,  I've converted mine from dual mass to single light weight, the engine picks up and loses revs quicker but will still idle the same, the rest is driving style and preference. I have to say I have found what Ekona said to be true, I've had to relearn throttle positions/rev response when heal/toe-ing because of it being quicker up and down the revs. By comparison I need no finesse in my dirty diesel daily. 

[GMballistic]

1 hour ago, Paul. W said:

Not knowing of anyone closer to my location in South Wales, I had thought of booking it into Abbey next summer just to get it all checked out, including checking the mapping is original factory and not a re-map.

 

I too live in South Wales like you and when I had my 350Z I used Horsham Developments in Berkshire who are closer to us than Abbey so there's another option for you. 

Link: https://h-dev.co.uk/contact/?v=79cba1185463

 

Welcome aboard.  

[Paul. W]

Hello Jay84, 

 

Thank you. Your comments are appreciated. 

 

I must admit, I haven't driven a sports car for about 10 years now, and then not the more modern ones of today, so I'm sure the differences I have noticed are me being out of practice. If I can crack a smooth gear up-change between first and second, I'll be happy. Showing my age now. I started many many years ago with a Ford Mk 1 Escort Mexico, then a Ford Mk3 Capri 3.0 sport and some years later,  a Porsche 928 S4. In recent years its been the old Land rovers. Most of the cars and bikes I have restored over the years have been older models, but I've always liked the shape of the 350 and now 370z's and hate to see any icon head for the scrap yard.

 

I will definitely post a few photos as soon as I pull them off my old phone. 

 

Meant to say also in my previous post, while I am learning to navigate my way around this forum, I'm more than happy to share what I've learned during the restoration, so please feel free to ask and I'll help out if I can. 

[Flashback]

Yes please Paul, get a thread going of the restoration stages, that would be a great read.

[Mark@Abbey m/s]

1500/1800 cold start RPM is normal

 

Revs hanging was a problem on the REVUP motors non of the other models seems to be as bad and it is something that isn't tunable in a ROM file

 

If the throttle is super sensitive it may well of been remapped with Uprev as the stock car is "numbed" in the lower 3 gears when stock this is removed when remapping

 

Sounds an awesome project

[Paul. W]

Thank you GMballistic, 

That's a useful contact. 

 

Hi Flashback, 

I'll try and put something together, it will end up being a bit "wordy" I'm afraid, as not realising how much work was required when I started, I didn't take that many pictures as I was going along. 

 

Hi Mark, 

Thank you for your reply. It's good to get things confirmed so at least I know what's normal and what needs attention. Having driven the car for a few more days now, I seem to have got the hang of it, albeit, I still have to concentrate a bit on being very gentle with the throttle, especially for first and second gear.

 

Yes, it did turn out to be a lot more work than I had originally expected. Fortunately though, access is very good compared to some vehicles I've worked on and spares are readily available, albeit sometimes from USA or direct from Nissan Japan.

All in all though, a very satisfying project.