Hi, I have a 1997 Skoda Felicia 1.3MPI and recently have been having trouble, the engine starts fine and then runs alright however if I park the car after driving for several miles and then start it again the car starts but the idle is irratic - the revs go high and then low and continue to do this, this problem seems to be happening when the engine is warm.

 

Any help or thoughts much appreciated

 

thanks, Luke

Edited 21 January, 20188 yr by lukestar

Unless it is something obvious faulty, like a cracked hose around throttle body, I recommend cleaning the throttle body.

Thanks, I have already looked at it and it was not dirty, fault only happens after the engine has warmed up and has just started happening for no reason

16 minutes ago, lukestar said:

has just started happening for no reason

You mean for no apparent reason.

Use an OBD scanner to check for evidence. Any other option means blind guess.

@lukestar - With an electronically controlled engine like this, other than an air leak, my thoughts would tend to the cold enrichment or idle stabilisation control having a fault. The only way to prove faults here other than throwing money at the car is to use a good code reader.

Also take a look to the MAP Sensor

@nimbus My experience is that a duff Mass Air sensor makes the engine run (even more) like a bag of spanners.

Thanks for the responses and advice.  Have plugged it into VAG and got the following fault code 00518 Throttle Position Sensor, G69 open or short to ground - intermittent.

 

Have read about using Motordiag software to reset the thottle body, has anybody had the above codes or used this software?

 

thanks

 

Luke

On 22/01/2018 at 17:51, KenONeill said:

@nimbus My experience is that a duff Mass Air sensor makes the engine run (even more) like a bag of spanners.

Ah okay

19 hours ago, lukestar said:

Have plugged it into VAG and got the following fault code 00518 Throttle Position Sensor, G69 open or short to ground - intermittent.

That means either you're lucky and there is a bad wiring/connector issue or the TPS is faulty.

20 hours ago, lukestar said:

Have read about using Motordiag software to reset the thottle body, has anybody had the above codes or used this software?

You are asking about two distinct things as if they are related. Motordiag is not used to 'clear' or 'solve' TB error codes. Its main purpose is to reset the TB. As for having the 00518 code, IF it is due to a faulty TPS (which btw is a potentiometer), that happens because the cursor doesn't make good contact anymore in the area 'rubbed' most often, idle.

Thanks for the replies, have cleared fault codes through VAG and now need to reset the throttle body through motordiag, has anybody done this before?

6 hours ago, lukestar said:

have cleared fault codes through VAG and now need to reset the throttle body through motordiag

I am not sure you understand the purpose of VAG-COM. First you have to repair the fault that caused the error code. Only then you clear the error code. Otherwise the code will reappear after starting the engine.

 

Did you repair anything?

Hi, the codes were cleared and then I reset the throttle body using motordiag software, the car was working fine for a few hundred miles but then yesterday it started alright, I drove for about 20miles parked the car for an hour or so and then would not start but eventually did and at idle and when driving the revs remained excessively high.  The temperature also rose to just under 110, despite not being sat in traffic, after about 10mins of driving the revs just went back to normal.  Any ideas?  cheers

Can you borrow a known good throttle body? Install it, reset it, drive to see the result.

Thanks for the response, unfortunately I do not know anybody that owns a Felicia otherwise yes that would be a good idea, have looked into buying a new one but it appears the original that is fitted (Pierburg) is no longer made

Then you have to go back to VAG-COM. See if error 00518 returned. If yes, there is a faulty TPS and you need a new throttle body anyway.

thanks, thats exactly what I have done and the fault code was there saying intermittent, short to B+ which I think could just mean Throttle Body is faulty, although it does look alright, not easy getting hold of one though.  cheers for the response