Should I be worried?

[Bornunder Dutchess]

Since Roxanne took a trip to the garage to have what seemed to be half of her moving parts replaced I've noticed she's developed a strange little characteristic that I dont think she had before.

When the engine is idle (Ie waiting at traffic lights or sitting in traffic, something we do alot of here in London) the revs are usually at a steady 1000 or so but now every so often the car judders ever so slightly, the revs drop down to 0 and then instantly go back up to 1000)

I diddn't notice it the first few times I drove it after her trip to be fixed, but it seems to be getting a bit more frequent now, this morning she did it three times at one set of lights.

Is my car developing yet another problem? Is this something anyone here has come accross before?

[Simply Si]

could be a blocked injector or dodgy spark plug?

[BRMark]

Didn't the change the HT leads? might be worth a trip back in to get them to check everything is fitted properley.

[spankyban]

Didn't the change the HT leads? might be worth a trip back in to get them to check everything is fitted properley.

Well done that man.

If there is a split in one of the leads that is causing a pluse to arc on the block this does lead to erratic idle.

[Bornunder Dutchess]

I'll give them a call and take her back in. I had a feeling it might be related to the new HT leads. Hopefully its just that and nothing more sinister.

Cheers Team BRM.

By the way, she's booked in for an Alloy refurb now, and to have some chips and cracks in paintwork refinished.

After a good clean and polish at the weekend she is looking rather fantastic. (I know your all wondering if I did the work myself. Answers no)

Once the Alloy's are done and the crack in the paint on the wing sorted, I can't see any reason why she won't be alongside the Bosses track car in the line up at the NEC Classic Car Show next November.

[Daz!]

Dont mean to scare you here or anything.. and it most likely has nothing to do with it just a separate problem but my car started doing this 2 or 3 days before my head gasket went.

So might be worth having a quick peek for some mayo just to be safe.

[Adam]

Could just be a dirty throttle position sensor. Worth checking the easy things first before worrying too much :)

[Bornunder Dutchess]

The head gasket was my worry too. :(

What's Mayo??

[Bornunder Dutchess]

It had an Upgraded Head Gasket fitted before I brought it but that was prob about 40 K miles ago :(

[BRMark]

The head gasket was my worry too. :(

What's Mayo??

Classic sign of head gasket failure is the appearance of a mayo like susbstance on your dipstick or under the oil cap - this is caused by the oil and water being allowed to mix because of the failed gasket.

[Bornunder Dutchess]

I just ran her over to the garage and they checked her out for me. The guy there worked for Rover for years and checked it all over. Said the head gasket was fine and explained to me what to look for if I was worried.

He also did something which re-set the comuter on it, he said that as it had been running with a misfire over a period of time the engine apparently can adjust itself to run slightly differently. I kind of thought this sounded like nonsence. Is it?

Anyway, We ran the engine for 20 mins or so and the revs stayed steady..but I will reserve judgement for now as it was only doing it intermittently and Roxanne is a stubborn one when it comes to showing us her problems.

More news on this later sports fans!:)

[BRMark]

You can do a reset on the throttle sensor - comes in handy when you've changed over to a 52mm throttle body - I assume this is what they did.

[Bornunder Dutchess]

Is it a little lever on the back of the engine?

[BRMark]

No its something you do in the car with the pedal and the ignition

Try resetting the throttle pot.

Ignition on, depress accelerator fully 5 times, ignition off. Then ignition on and restart, that *should* cure it.

Dave

[BRMark]

Unless you mean the throttle itself, in that case yeah it's near the back of the engine where the air intake meets the engine - the lever could be were the accelerator cable attaches to the throttle body.

[Bornunder Dutchess]

Humm..well he said he was doing this

Originally Posted by DVAPower
Try resetting the throttle pot.

Ignition on, depress accelerator fully 5 times, ignition off. Then ignition on and restart, that *should* cure it.

Dave


So I will see if its solved the problem then :)

[benjid24]

it may be ur idle control valve my zed used to do that so i just disconnected it and cleaned it and its fine now never done it since if u dnt know where it is its just infront of the throttle body its a little sensor hope this helps

[Bornunder Dutchess]

Interestingly shes going the other way this morning. Slight judder then the revs jump then drop back down to 1000 again.

Full of surprises.

[Bornunder Dutchess]

Could just be a dirty throttle position sensor. Worth checking the easy things first before worrying too much :)

How do I check the Throttle position sensor...and how did you escape from my basement??!

[benjid24]

it definitely sounds like ur idle control valve just disconnect it clean the terminals with a cloth then connect again see what happens then? but it sounds to me like its that most people i have spoke to who have a rover/mg get this problem:thumbsup:

[Poledriver]

Hi all! I've got a similar problem which has developed recently. If I am in traffic and am in low gear at around 1,500 RPM the car starts to 'kangaroo'!
It seems more RPM related than throttle opening.
I have the larger (metal) throttle body fitted.
Any thoughts?

[BRMark]

Mine does that too! sort of lurchs like you're running out of petrol? wonder if it's a blocked injector now I'm thinking about it. maybe some redex will help?

[Bornunder Dutchess]

it definitely sounds like ur idle control valve just disconnect it clean the terminals with a cloth then connect again see what happens then? but it sounds to me like its that most people i have spoke to who have a rover/mg get this problem

OK I will try that too..Where do I find it? (Explain as if you were explaining to somone VERY dumb) :)

[Bornunder Dutchess]

Mine does that too! sort of lurchs like you're running out of petrol? wonder if it's a blocked injector now I'm thinking about it. maybe some redex will help?

Whats REDEX?

[BRMark]

Redex is a fuel additive, you put it in with your petrol and it's supposed to clean the fuel delivery system.


Poledriver: seems to be inconclusive over on .org

http://forums.mg-rover.org/showthread.php?t=147127&highlight=lurching

[Bornunder Dutchess]

I first read that as Redex fuel is addictive.

Humm.

[Bornunder Dutchess]

Hi all.

She's still jumping around, the reset seemed to solve it for a little while but revs are up and down in idle again now.

Where do I find the idle control valve to clean it?

[benjid24]

if ur looking at the engine its the sensor on the front of the vvc inlet manifold (the bit thats says vvc lol) its fitted on a angle u just unclip it and clean the terminals with a cloth then clip it back into place start it then rev it one full rev let it settle then turn ur car off then just start it as normal and see what happens maybe take it out for a drive should solve it the one way u will know its that is before u clean it disconnect it then start ur car and see if it idles high then clean it and connect it again bcos u may need a new one u can pick them up for about a fiver max from a scrapyard or a rover breakers make sure the terminals are the same colour bcos there are 2 different kinds hope this helps :beer2:

[soberphil]

I've got similar erratic idle / revving issues going on at the moment.

Firstly is this "reset" thing where you press the accelerator 5 times real or urban myth? I only ask because there doesn't seem to be any mention of it in the RAVE technical documentation. At least not that I've found.

Second - I thought it might be my IACV. I changed it. It made no difference.

Logically the IACV must be working if it can affect the idle speed - but something is giving it bad instructions.

I now believe it to be an electrical gremlin or a faulty sensor or the fact that I think I have a slight leak from my exhaust manifold gasket causing false readings for O2 sensor, or something else.

My plan is along the lines of:
change IACV - done, made no difference

Change exhaust manifold gasket - this will be a world of pain as some of the nuts are rusted beyond recognition. I can see the studs being ruined. Get MGB mot'd first in case BRM ends up being off the road for a while.

Change coils + leads (not been done in my ownership so must be due)

Scratch head. Drink tea.

[garythesnail]

Erratic idling - for some reason, I've got it in my head that this be caused by air getting in to the combustion mixture between the throttle and the combustion chamber - leaky gaskets,joints or pipes on the 'input' side of the engine - somehwere along the induction tract.

I have no direct experience of this and can't recall any particular mention of it anywhere, so would welcome comments from the engine experts on the site.

[The Flying Dutchman]

What's Mayo??


it's what posh people use instead on Salad Cream LOL !

seriously, hope it's something simple. I beleiev you can usually see a 'mayo' type substance around the oil filler cap if the HG's on its way out.., but it's not conclusive.

My problem is Not having a BRM at the moment, :wacko: All the one's i've found have either been Modded or Thrashed :police:

good luck with the motor :beer2:

[Bornunder Dutchess]

Would say the "reset" thing is real..the guy at my garage worked for rover and has a clapped out 25 in the yard that he is currently restoring as his own little project. They are actually a Merc and BMW only garage but he loves my BRM and so has made it his personal project to look after her. He helped build them apparently..so he claims.

He had a look at it and couldnt see any of the signs of HGF.

Anyway, I'm going to try cleaning the idle control valve and see how that goes, if not he's offered to take her back in and run diagnostics on her to try and work out what the problem is.

Keep reguarly checking for "Mayo" no sign as yet. Other than this little quirk she's developed she seems to be ok.

[brmatty]

Would say the "reset" thing is real..the guy at my garage worked for rover and has a clapped out 25 in the yard that he is currently restoring as his own little project. They are actually a Merc and BMW only garage but he loves my BRM and so has made it his personal project to look after her. He helped build them apparently..so he claims.

He had a look at it and couldnt see any of the signs of HGF.

Anyway, I'm going to try cleaning the idle control valve and see how that goes, if not he's offered to take her back in and run diagnostics on her to try and work out what the problem is.

Keep reguarly checking for "Mayo" no sign as yet. Other than this little quirk she's developed she seems to be ok.

you sure its not "driver error" related due to those 6inch heels your wearing lol!! try a shot of carb clean in the throttle body..it could all be cacked up internally!!...or as said previoulsy either tps or iac could be at fault...

[Bornunder Dutchess]

you sure its not "driver error" related due to those 6inch heels your wearing lol!! try a shot of carb clean in the throttle body..it could all be cacked up internally!!...or as said previoulsy either tps or iac could be at fault...

Mark drives in 6 ionch heels and he dose'nt seem to have any problems! :)

(its definitely the car)

So shot of carb clean in the throttle body. (I have no idea where the throttle body is)

Shot of redex in the petrol tank (that bit I can manage)

Clean her bits...then if that dosen't solve it...panic.