Jumpy throttle\idle at low revs

[littlegldgti]

Hey Guys, long time no talk... but I have a question for you all.
My 1995 Ibiza GTi has developed a really odd thing... When following a slow car down a busy street or driving in a car park... first gear is incredibly jumpy and makes the car learch. When I put my foot down and pick up speed a bit more the car will jump up to regular idle and be fine... but if slowed down again, the learching starts again. This happens all the time, except strangely if i jump in the car after its been sitting in the sun for a while and the engine isn't warm. its fine... but after warmed up the learchiness happens again. My brother (gldgti) and I have looked at possibly the idle regulator valve being a bit dodgy. But I thought just for ideas or experience I'd mention it here to see if anyone else has experienced the same as me with the GTi with the 8v 2e engine. So basically travelling low speed with less than 2.5k revs in first gear this happens, and sometimes in 2nd with lower revs.

[littlegldgti]

Thanks in advance.

[h100vw]

Dodgy throttle position sensor maybe.

Gavin

[karmen]

a forked air pipe nr the carby/efi may have developed a crack...just replace it..
u should be hearing a hissing with bonnet up and eng running

[h100vw]

a forked air pipe nr the carby/efi may have developed a crack...just replace it..
u should be hearing a hissing with bonnet up and eng running

The GTI doesnt have the electric carb karmen. It's multipoint injection.

[littlegldgti]

He may have a point... Please excuse my ignorance... But does the 1995 Ibiza GTi even have a throttle position sensor? Talking about the 2E 8v engine here, not the 16v. I could be wrong, but I thought I'd chuck in some potential extra clarification seeing that it's a manual cable throttle. I've checked the throttle body inlet for any carbon buildup and found nothing, however what I assume is the gases recycling hose/pipe that circles back from the valves back to the throttle inlet... It was cracked and the previous owner had it taped up.

[Water Boy]

I think Anth had a similar issue and it was a dirty fuel filter. (On a Vr6)

[Golf Loon]

On the underside of the throttle body at the back is a rubber elbow. Bet it has a split in it.

[gldgti]

On the underside of the throttle body at the back is a rubber elbow. Bet it has a split in it.

thats the tip i was looking for!

[littlegldgti]

On the underside of the throttle body at the back is a rubber elbow. Bet it has a split in it.

Hey Golf Loon, I'm having trouble trying to locate the rubber elbow you mentioned. Roughly how big/small is it and how obscured?

[littlegldgti]

On the underside of the throttle body at the back is a rubber elbow. Bet it has a split in it.

Hey Golf Loon again, I think I have located the rubber elbow you were talking about.

Here are some diagnostic/location pics.









Hope this is what you mean.

[Golf Loon]

Hope that fixes the issue for you. Check also that the brake booster line has no splits or open ports on the one way valve.


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[littlegldgti]

Hope that fixes the issue for you. Check also that the brake booster line has no splits or open ports on the one way valve.


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Hey Golf Loon,
So this morning I got to the elbow joint and used a bit of silicone tape to seal it up for the time being. I really should replace the joint because the rubber is completely perished but I did this for the interim and it actually looked pretty good after I repaired it. Took it for a drive down to the shops and it all seemed very nice and smooth. Unfortunately when it started to warm up a bit it started lurching again at around 1500-2500rpm in most gears and lower rpms in 1st and 2nd. Maybe I need to chuck a new elbow in place there but I thought I'd give you an update on how it went.

Looks like I'll have to have a good look at the brake booster line. Do vacuum leaks often cause the car to lurch and shudder when accelerating?

[littlegldgti]

Problem solved. Went through all of the air lines with my brother and we found a couple of old lines needing replacement and the intake hose also had a crack which would have been altering the air mass being measured by the sensor.

Thanks for the help Golf Loon!!!