Revving / Stalling Problem

[jimbobclarkie 0]

Hi Guys,

 

Wonder if anyone could shed some light on this, I cant find anything in the forums.

 

I have a 205 GTI 1.9 1989 Completley standard

 

The problem I am having is as follows.

 

Start her up she is fine, sounds a little rough but nothing unusual for 205's of this age me thinks, the problem occurs when I rev the engine wheather the engine is cold or warm it does the same, the revs go up as expected but then when you take your foot off the acceleator the revs just die to the point of nearly stalling then pick back up again.

 

I have a hole in the exhaust system atm, would this cause it as a result of loss of back pressure?

 

I have thoroughly cleaned the throttle body with carb cleaner i even removed and refitted it. Checked all the breather pipes, all are free although i have not actually cleaned them. The compression is fine, took it to the garage today to get tested. I have set up the Throttle to give me a idle of 1100RPM idling, (a little high but any lower it stalls).

 

Anyone with any ideas? Im at a loss atm.

 

Many Thanks

 

James

[Anthony 1,003]

Pretty common and to a point expected given the crude nature of the engine management - getting everything properly setup (ie ignition timing, AFM mixture, throttle and idle screws etc) tends to significantly improve matters though and can all but eliminate the issue. The fact that you're having to set the idle comparatively high is a big clue that something isn't right

[jimbobclarkie 0]

Pretty common and to a point expected given the crude nature of the engine management - getting everything properly setup (ie ignition timing, AFM mixture, throttle and idle screws etc) tends to significantly improve matters though and can all but eliminate the issue. The fact that you're having to set the idle comparatively high is a big clue that something isn't right

 

 

Cool do you have any tips for setting those things up properly?

[welshpug 1,666]

get a Haynes Workshop manual and have a good thorough read

[jimbobclarkie 0]

get a Haynes Workshop manual and have a good thorough read

 

 

Got one, Dont give much advice on my actual problem tho.

 

I can follow a manual for sure but wondered if you guys who knew and been workin on these cars for a long time know of any tips and order to do things etc

 

Cheers

[Anthony 1,003]

If you do a search you'll find plenty of information (although you'll likely have to wade through a fair bit to find it!) but a few points...

 

Firstly, make sure that everything is in good health and there's no other issues - you're wasting your time trying to get it running properly if the ignition system is breaking down, the AFM is shot, or there's airleaks for example.

 

Secondly, make sure that the ignition timing is optimised - it's not so much idling it helps, but the power, response and economy. In the case of 1.9 GTi's, retarding the ignition timing to allow it to run on 95 RON unleaded has a noticeable detrimental effect, and they really do respond to the timing being setup for super unleaded as they were originally designed and specced for (well, originally 4 star, but high octane fuel anyway)

 

Thirdly, the idle drop is often exacebated by relying too much on the idle bypass (idle screw) and not enough on the throttle body (throttle stop screw). Note that any chance to the throttle stop will mean having to reset the TPS position. Make sure that the throttle body is nice and clean first though, as a build up of oily gunge around the throttle plate won't help whatsoever.

 

Fourthly, in my experience they seem alot happier running a leaner mixture that things like the Haynes manual suggest - I tend to run them around 0.5-1.0% CO at idle, and that tends to help steady the idle and improve cold running. You'll need to have a play though, as different engines like different things - my current one runs lean enough to pass a CAT test (much to my MOT testers bemusement) and idles perfectly for it!

 

Lastly, set the idle speed to be around 1000rpm hot without electrical load, which should mean around 800-900rpm with full electrical load (ie lights, blower, heated screen etc). If it's running well you can probably get away with lower, but 1000rpm should be easy to make idle and get it to run from cold.

 

Above all, patience is key and don't expect to get it running right first attempt - many so called "experts" can't seem to do it at all!

[jimbobclarkie 0]

If you do a search you'll find plenty of information (although you'll likely have to wade through a fair bit to find it!) but a few points...

 

Firstly, make sure that everything is in good health and there's no other issues - you're wasting your time trying to get it running properly if the ignition system is breaking down, the AFM is shot, or there's airleaks for example.

 

Secondly, make sure that the ignition timing is optimised - it's not so much idling it helps, but the power, response and economy. In the case of 1.9 GTi's, retarding the ignition timing to allow it to run on 95 RON unleaded has a noticeable detrimental effect, and they really do respond to the timing being setup for super unleaded as they were originally designed and specced for (well, originally 4 star, but high octane fuel anyway)

 

Thirdly, the idle drop is often exacebated by relying too much on the idle bypass (idle screw) and not enough on the throttle body (throttle stop screw). Note that any chance to the throttle stop will mean having to reset the TPS position. Make sure that the throttle body is nice and clean first though, as a build up of oily gunge around the throttle plate won't help whatsoever.

 

Fourthly, in my experience they seem alot happier running a leaner mixture that things like the Haynes manual suggest - I tend to run them around 0.5-1.0% CO at idle, and that tends to help steady the idle and improve cold running. You'll need to have a play though, as different engines like different things - my current one runs lean enough to pass a CAT test (much to my MOT testers bemusement) and idles perfectly for it!

 

Lastly, set the idle speed to be around 1000rpm hot without electrical load, which should mean around 800-900rpm with full electrical load (ie lights, blower, heated screen etc). If it's running well you can probably get away with lower, but 1000rpm should be easy to make idle and get it to run from cold.

 

Above all, patience is key and don't expect to get it running right first attempt - many so called "experts" can't seem to do it at all!

 

 

WOW thanks Man Il b sure to try all of the above,

 

Thanks for the time you took to write this, really appreciated.

 

and if I get it running properly as a result id owe you a beer lol

 

Cheers

[dee205 3]

As Anthony said, swapping the AFM with a known good'un has worked for me a few times. Also carb or brake cleaner around the intake pipes etc as even a small split can cause heartache. I also found the small thin pipe that runs from under the tb to below vacuum advance (i think that's what it's called) under the rear of the dizzy had deteriorated and broke off. I ended up replacing it with a thin water pipe I had laying around but it did the trick.

 

It does take time and patience but if you check everything bit by bit you will end up with a goog running car. I've just sold my wee 1.6 and had it idle and run great hit or cold even with full electrical load and dropping the revs from well up to idle. I think they all dip below slightly but should bounce back up to below 1000rpm

[smithy 1]

as above follow the instructions in the haynes about checking and setting the base throttle settings,it also gives you all the details for setting up the TPS,checking SAD operation etc.

also check everywhere for air leaks using some carb cleaner,a favourite place is the bolt for oil filler neck missing so hole in inlet manifold,also i have known SAD units to be loose on the joint causing air leak.

 

on cars the age of these pugs the vac advance module on dizzy is probably shot,if you put some clean pipe on it and suck it will probably not hold vac and will draw air in.