Revs dropping under slight throttle
Revs dropping under slight throttle
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kenny320

Original Poster:

1,598 posts

274 months

Thursday 26th February 2004
quotequote all
Just spoken to my chim-owning friend. It seems that after startup depressing the throttle slightly is causing the revs to drop slightly. Any ideas what to look for?

shadowninja

79,993 posts

311 months

Thursday 26th February 2004
quotequote all
mine does that

so i dont release the clutch so quickly for the first 5 minutes while driving. basically, depress gas, revs sink then rise, then let clutch out. if you just drive as normal the car can easily stall.

kenny320

Original Poster:

1,598 posts

274 months

Thursday 26th February 2004
quotequote all
shadowninja said:
mine does that

so i dont release the clutch so quickly for the first 5 minutes while driving. basically, depress gas, revs sink then rise, then let clutch out. if you just drive as normal the car can easily stall.


I see This is exactly the kind of info I'm looking for. Cheers Shadowninja

Could it be a case of They All Do That Sir? If it is that's fine, just trying to find out what the situation is. Still a stunning machine

beano500

20,854 posts

304 months

Thursday 26th February 2004
quotequote all
They all do that, Sir!













Does that help? Anyway my Griff does this too - leads to an embarassing stalling situation about once every six months or so!!!! When will I learn?

kenny320

Original Poster:

1,598 posts

274 months

Thursday 26th February 2004
quotequote all
beano500 said:
They all do that, Sir!


Does that help? Anyway my Griff does this too - leads to an embarassing stalling situation about once every six months or so!!!! When will I learn?



Yes it does thank beano500. I'm prepared to expect that such a wonderful car will have a few "features" but when explaining this to others it helps to have a bit of background from other drivers.

I guess you'll learn just to plant the throttle every time

>> Edited by kenny320 on Thursday 26th February 23:45

chimhunter

906 posts

278 months

Friday 27th February 2004
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Mine does it too for the first minute or so. I find that letting it warm up a little first and then bringing it up to 2k rpm for a little bit tends to stop it pretty quickly.

Just one of those things you need to get used to...

M@H

11,298 posts

301 months

Friday 27th February 2004
quotequote all
I seem to remember mine going that originally, having been run on unleaded, however using Optimax I do't recall it happening... (either that or I subconciously got used to it..)

Cheers
Matt.

mongoose

4,360 posts

284 months

Friday 27th February 2004
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my previous chim used to do this badly.it was sometimes very difficult not to stall from cold.when i bought the griff with few miles on it,it didnt do it at all,but now its started to do it ever so slighly and only occasionally.id love to know how to stop it as i dont want mine getting as bad as my chim was.

kenny320

Original Poster:

1,598 posts

274 months

Friday 27th February 2004
quotequote all
I thought this might be the case. I'm not sure which fuel it normally gets filled up with. Maybe that's part of the problem. Thanks for the info all of you

aaandy

764 posts

281 months

Friday 27th February 2004
quotequote all
I think they all do a bit, but may be a little more pronounced when it is very cold and wet.

When you start it hold just hold it on 1200 to 1400 revs for 15secs or so and then just let the engine tick over for another 30 secs or so before you move off.

Only ever normally need to do this first thing in the morning when it has been outside, for the rest of the day it is just start and go. There's nothing wrong with it it just needs a little warmth in it.

IPAddis

2,512 posts

313 months

Friday 27th February 2004
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Is this a closed loop cat problem? Car is cold, extra fuel to warm up, lambda says no more and ECU shuts fuel off again.

Anyone had this who is running in open loop mode (no cats)?

Ian A.

PeterC

386 posts

298 months

Friday 27th February 2004
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I find it best to check for neutral, start car with feet off all peddles and then let it tickover. As the engine is cold this is at a higher tickover speed than normal. Do not be tempted to engage any gear or touch the throttle for at least a minute or the tickover will drop and stalling/re-starting problems may occur.

I often start the car in the garage before actually getting in and let the engine warm up a bit.

This all may be a problem for some of you as it will mean getting out of bed a little earlier!

malloryn

45 posts

281 months

Friday 27th February 2004
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IPAddis said:
Is this a closed loop cat problem? Car is cold, extra fuel to warm up, lambda says no more and ECU shuts fuel off again.

Anyone had this who is running in open loop mode (no cats)?

Ian A.


When the engine is cold it will be running open loop.

BTW mine also does this. I was suspecting that the throttle sensor was slighty offset. If the throttle sensor is offset then the ECU can think its in idle even though the throttle is slighly open.
It would then be a fight between you and the ECU as to who is controlling the idle revs.With the throttle slightly open the ECU would reduce the revs back to 850. When you then close the throttle the revs would dip and sometimes stall.

Steve_T

6,356 posts

301 months

Friday 27th February 2004
quotequote all
Ian has it spot on. Engine runs very rich at startup in the cold. If you depress the throttle, the ECU intervenes and cuts the fuel. If you try to drive away while the car is warming up in this way and you stall it will be a total pain to restart. Solution, start the car and leave the throttle alone. The revs will start low, then build up gradually, in mine to about 1200 rpm, then start to decay back to the normal idle, about 800 rpm for me. Provided you let the natural warm take place until when you lightly depress the throttle the revs go up, you won't have the nightmare stall problem. If you do have this problem, you need to remove the fuel pump fuse, start the car, let it catch and die and then replace the fuse and start as normal (thanks jeremyc for the tip). Easier to just wait until the car sorts itself out.

Steve.

wildego1

110 posts

282 months

Friday 27th February 2004
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First discovered this last autumn.
I usually always warm it up but was in a rush so tried driving cold.
It stalled then I flooded it. Learnt my lesson though.

ALWAYS WARM IT UP!

Will lessen engine wear too of course.

kenny320

Original Poster:

1,598 posts

274 months

Friday 27th February 2004
quotequote all
Thanks for the info. This confirms what I suspected, that its a feature to be lived with rather than a problem. Thank u all for the info. I'm just hoping I get to play with the chim again this weekend

CMJ

201 posts

276 months

Sunday 29th February 2004
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Steve_T said:
Ian has it spot on. Engine runs very rich at startup in the cold. If you depress the throttle, the ECU intervenes and cuts the fuel. If you try to drive away while the car is warming up in this way and you stall it will be a total pain to restart. Solution, start the car and leave the throttle alone. The revs will start low, then build up gradually, in mine to about 1200 rpm, then start to decay back to the normal idle, about 800 rpm for me. Provided you let the natural warm take place until when you lightly depress the throttle the revs go up, you won't have the nightmare stall problem. If you do have this problem, you need to remove the fuel pump fuse, start the car, let it catch and die and then replace the fuse and start as normal (thanks jeremyc for the tip). Easier to just wait until the car sorts itself out.

Steve.


I feel better its not just me gropping around in the dark outside looking for the fuel pump relay when I have stalled. Until reading this thread I put the problem of revs dropping if you touched the accelerator as part of my cars 'personality' nice to know they all do that. Only problem is using the car each day and having to reverse off a drive in the morning and reverse out of a parking space at work you do get wip lash because the gear is low but you have to give it a lot of revs to over come the problem.

pigpen

262 posts

279 months

Sunday 29th February 2004
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Yup, mine does it too. In fact it all but stalls if I touch the throttle when cold, let alone try a gear! But let it warm a bit and it's no problem. I'm also glad to hear I'm not the only one!

Cheers

Mike

crimsonchim

424 posts

299 months

Monday 1st March 2004
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Mine does this when very cold or damp. Like everyone says, just let it warm up a little bit, just a few seconds a bit above idle and mine's fine. Does seem to be worse when not running optimax or when a service is overdue!

If it's any consolation, I've owned 3.5, 3.9, 4.0 and 4.2 versions of the rover V8 and all did that to some extent!!

Cheers,

Andy

trefor

14,780 posts

312 months

Monday 1st March 2004
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You chaps need to get a Mark Adams tuneup. Mine doesn't do this even on the coldest of mornings - it used to be a bit grumpy before the tune up. Mark replaces the std ECU chip with an EPROM which he optimizes the fuelling for you car with. This is not a performance enhancement - it is adjusting the fuelling map for your individual car on a rolling road. The timing is not affected by this chip, just the fuelling - it's not specifically a 'performance' chip.

The biggest change is definitely the driveability of the car after Mark's attention. Any increase in performance is a bonus.

Even so, my Chimaera went from 210 to 228 to 241hp under Mark's fettling. Do it, you know you want to.