Revs Are Jumping Like Crazy !!!

[james in Norway]

Please exuse my stupidity, but what is a TRIAL remap...i undersatnd remap, but does trial mean a specific type of remap, i presume that an official skoda dealer is the best bet...

[ap0gee1978]

If it ain't any of the sensors, then it's possibly the ECU itself. Legend has it you can do a sort of 'soft reset' by turning the key two clicks in the ignition and leaving it there for at least a minute before starting the engine. Otherwise, you could do a 'hard reset' by disconnecting the battery overnight (although you'd better be sure you know the radio code if you do this!!!) This will supposedly reset the ECU to factory settings, in which case you'd do well to go for a long-ish drive and then leave the car idling for a good ten minutes before you eventually switch off. According to my Haynes manual, the ECU's 'learned' settings play quite a big part in determining idle speed, so if they're screwed, it might just cause your problems. The more I think about it, the more I think that it kind of sounds like it could be 'hunting', like on a lawnmower or petrol generator when you don't have any load and the throttle's not adjusted properly...

Anyway, got my fingers crossed for you!!!

[KenONeill]

A trial remap is exactly that; one that reverts to standard after a set period, unless made permanent.

As for the car hunting, well, that's possible too, but would indicate a failed Lambda sensor that's not showing up on diagnostics.

[james in Norway]

fantastic hint there, i will try the 1 min reset, should any lights come on or off 2 let me know its reset?? or is it just 1-2 mins then its done, by the way doesent the second click coase the starter motor to cick in, or is that the 3rd?

If that does not sucseed, i will do a 12 hour batt reset, then i will drive to work, thats motorway for 40ish miles (70 km) do you think that is a safe bet to do a drive like that after the reset, or just a gentle 10 min one ??

Cheers James...

[james in Norway]

A failed Lambra sencer, thats the one on the pipe?

Is there a way to check this, can i do this with my mutimeter or is it a garage jobby??

James.

[KenONeill]

Yes, that's the one on the pipe, and it is a multimeter job. At idle, you're looking for a steady voltage, about 0.7v IIRC ( I know I'm in the ballpark, I'd start on the 1 to 10 v scale, and then come back one to be safe).

[james in Norway]

should the engine be hot or cold running when i test it, and what kind of reading would it give if it was obviously damaged??? Correct me if im wrong but it is on the front downpipe, yes ???

Thanks

[KenONeill]

Hot to be certain of the mixture enrichment being off.

Look for a fluctuating value to get the symptoms you're describing.

[james in Norway]

thanks, i will try it after work, i will let you know the outgoing tomorrow, cheers again...

[james in Norway]

:(tried the sensor. all is good.

tried the 1 min reset, i dident seem to do any anything

Tried the battery disconnect for 15 hours, no change...

i am at the point of giving up, i am off to skoda again today to try a 3rd no 4th no 5th no i cant remember how many times, but another reset....

Heeeeeeeeeeeeeeeeeeeeeeeeelp !!!!!!!:(

[james in Norway]

I have had a suggestion from the Skoda garage, they said after hearing the engine that it could be an air leak somewhere, they said they could not hear where from but that was what they are sure it is, they suggested that i spray stop/start around the manafolds etc and wait to hear if the engine revs, i have done this but cant seem to find a leak?

Has anyone else hed this problem, and where did it leak? Skoda said that this is fairly common problem on the 1.6 engines (never herd that before)

The more i think about it the more it seems that an air leak somwhere is axcactly what is cousing the reving and the throttle to drop rapidly if i lift of the acelorator slightly.

Can anyone shed some more light on this idea??

Thanks, James...

[KenONeill]

Has the oil consumption changed (probably increased) since this issue first arose? I'm wondering if you're burning just enough oil to act as an extra fuel source, without hurting the Lambda or the cat.

Otherwise, with an air leak I'd suspect a split or loose breather hose, rather than a failed inlet gasket.

[james in Norway]

no houses are cracked or torn, that much i do know, they are all in tip top condition, ...

Yes it is burnning more oil, how did you know that????? it doesent give out any smoke out the equest, the only reason i know its burning more is that i check my oil every week without fail, and now i top it up everyweek !!!!

What does this meen then ??????

Do you think you have the answers to my rev problem ????

[paul1978]

Hi All, I have a 1.6 GLXI 1998, and had exactly the same issue you r having, the rev would jump around and teh idle would occassionaly settle anywhere around 1200-2000 rpm. I use the same tactics to rest the throttlke body, disconnecting the battery etc but made no diffenence

Put the car into the dealar, who intially suspected the Throttle Body, not being to fussed about the cost(gulp) I told them to go ahead and change it, and, well it made no difference. They then check all sensors, completed a full electrical check and yet again no faults.

The then contacted Skoda Technical Helpdesk and they said you've got an air leak somewhere. The dealer then checked all hoses, joins etc and, well again found nothing.

But then, then skoda technical people told the dealer again it must be an air leak(Again) and told the dealer to remove the intake manifold, and check it for hairline cracks, unlikely but worth checking, and erm well nothing found.

So the dealer then said sorry, but we just can't find anything wrong. And being at the end of my patience I told the dealer to put the intake manifold back on etc

They used a new gasket doing so. The car has iddled perefectly ever since.

It took a while to find the fault as it unusual, but the car is running better than ever.

[james in Norway]

Did you have the same problem with the revs falling when you lifted slightly off the acellotator at say 3000 revs, did they jump down and then back up to the held re??

Was it the intake manafold or the equest manafold gasket, if you tell me what one it is i will go home and pull it of and change it.....

You have just decribed the exact proplem i have, ooohhh i hope this is it...

[paul1978]

yes i had exactly the same problem as you've described, the dealer told me they changed the intake manifold gasket, I'm not sure which of the 2 it was as they didn't charge me for it, its not on the invoice, the sevice manager didn't charge me any labour costs either and they had the car for 3 weeks.

But it did solve the problem. If everything else seems okay its worth a try, change it and then rest any error codes.

[james in Norway]

i am on the phone to skoda as we speek, seeing if they have the gaskets in stock......you mentioned 2 gaskets, does that meen you also changed the equest outlet gasket as well???? or are you unsure, also do i HAVE to have the reset afterwoods????

They just told me i pick it up at Audi (same engine) its only 40nok, thats a couple of quid...i am almost wetting myself with exitment that i might cure the problem tonight, oooohhhh so happy with the idea !!!!!

If this fixes it i will send you a big bottle of Whisky as a thanks via imaganery e/mail !!!!

[KenONeill]

It might be a porous manifold gasket then.

Otherwise I think it's something to do with burning the extra oil as fuel, so check any atmospheric vents for the oil system aren't blocked.

[james in Norway]

as you see from the message above, it looks like its a gasket, lets hope so, but i will check the vents at the same time, where are they?? and what do they look like , how do i clear them???

Thanks again

[KenONeill]

If there's an atmosphere vent, it probably looks like a cap with some wire mesh in or over it.

As for how you clean it, that really depends on exactly what it looks like. Afraid I'm better on the diesel engines.

[james in Norway]

Well thankyou for your help, i will look in my trusty Haynes manual and see if, where and how to clear it, thanks again, check me out tomorrow for the answer on good car bad car,

Untill tomorrows episode, same time, same place, i will say good night.

Cheers, James.

[james in Norway]

Damn it, damn it, damn it.....If you have been following my story (almost a novel) you will see that i have been suggested by this site and by Skoda that i should change the air intake gasket as it sounded to many like it was coming from an air leak and thats the only place it will pull it in from....So happily i went off to skoda and picked up the gasket set (it comes in 4 green rubber rings for the seal to the side of the engine block, and 4 wide black rubber rings that seal the 2 piece intake together in the middle, 400nok a set)

Took the set home, striped the intake system, cleaned it, checked for hairline crackes, and checked for any and all damage to the intake system, including wire damage on the injectors etc, and all was perfect, anyway i changed all the parts, resealed and put back together (all in 1 hour, proud of myself for that) and started the engine....and.....and.....rev, rev, rev, rev....no change...AArggggghhhhhh.....

I also had a look at the valve stems with a torch and checked to see any internal damage and all is clean and perfect...

I will list what i have changed for you to see if anymore ideas spring to mind...

Throttle Body.

Air mass + intake pipe.

Spark plugs.

Upper and Lower intake gaskets.

5 + engine managment/computer checks.

Oil + Filter change.

Temprature sensor (new)

I have so ran out of ideas...is there any where alse an engine pulls in air/fuel etc

It runs perfect when driving along, and i still return 7 litres per 100km on my way to work (very good on fuel)

I am getting desperate, its been in 1 garage for 2 weeks, and skoda twice !!!!!!!!!!!!

I must have spent about 20 of my man hours and still no joy!!!!

Please Please Please help me.....

You say it is compensating for somthing, hence the throttle body twitch, what other reason will couse this to flick apart from air ???

From a very very desperate man,,,,,,

[bk1]

Having skim-read all of this thread, only one thing comes to mind, and that's a throttle potentiometer. Try finding out more about that.

I'll post some info from an Audi site here:

over-revving problems on my s3 were due to a mixture of a broken pre-cat lambda and a dodgy throttle potentiometer (only applicable if yours is DBW).

The most likely culprits are those responsible in the idle adaptation - i.e. lambda and coolant sensor. Idle speed is dependant on information on these to ensure that the idle mixture is adapted to the engine temperature AND the output exhaust gas. If any of these are intermittent, then the idle mixture will be wrong and you'll get fluctuations.

another part could be the throttle potentiometer on DBW cars. If it's sending incorrect information about the accellerator pedal position, the ECU could be continually switching between idle and accelleration maps.

Other than the above sensors, you have the obvious physical factors. These factors are those that would affect either the fuelling or air getting to the engine, such as clogged throttle body or air leaking out before it reaches the engine.

[bk1]

So is your car drive-by-wire, or cable-controlled throttle? The potentiometer (i.e. throttle sensor) info I posted will only apply to drive-by-wire (DBW) models.

From what I read, the DBW cars have a throttle position sensor built into the pedal, and it sounds like you replace the whole pedal in order to install a new sensor.

However, I'm also seeing informaiton that says the potentiometer is part of the throttle body housing, and you say you've had a new one of those, so perhaps someone can explain all of this better than I am.

Some people have found a new MAF to solve nasty rev problems, others found it was the throttle sensor/potentiometer, some found it was the clutch switch.

[james in Norway]

its cable driven, standard old fashioned type..

OOOOoooohhh and i also changed the clutch switch on the pedal, in DESPARATION !!!!!