Resealed my IP and engine started running away. What to check?

Well I had a big success tonight in getting my new to me Jetta running. I resealed the IP, pulled a vacuum until I saw fuel, then started it.

The engine popped a little and smoked; then smoothed out. I let it run about 2 minutes. After it smoothed out, it started to run away. I ran to the car as fast as I could and shut it down.

I'd say the engine climbed from idle to around 2k in about 10-15 seconds at the time I caught it and shut the key off. I think if I'd have left it, it would have kept going.

Any idea what this could be? The P.O. did a lot of cranking I'm sure. I also noticed there is an oily valve cover. No doubt there's some blow-by.

EDIT: Update. Just got VCDS Lite and took some readings. Do these look ok?
http://forums.tdiclub.com/showthread.php?t=482266

Thanks for any tips.

How's the IQ? Maybe you've upset it with having the thing apart. Might need to loosen the bolts and knock the top over a bit

I ordered a cable off ebay a couple days ago and downloaded the vag-com lite. Might not be able to check IQ with that... not sure but was hoping to. I figured I could get in the ball park by watching for black smoke when flooring it perhaps.

Seatman nailed it.. Without vcds it's going to be hard to get it right but you can get it better by loosening the four bolts holding the quantity adjuster down and tapping the QA towards the timing belt using a dead blow hammer, mallet, 2x4, etc. Adjust till you get s stable idle then go a couple taps further.
Pro tip: before you adjust, with a sharp blade, make a registration mark from the ip body to the QA so that if you get it too far out of whack you have a reference to go back to

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If it's to far the wrong way though the engine can just rev crazy. You could try tapping it one way to see if it's better at idle, if not then try the other. It'd do till you got vagcom sorted out.



Haha ^^ beat me to the post

Odd that it idled for two minutes before taking off. If it was the position of the QA causing the overspeed I'd have thought it'd take off right away.

Unless the QA did not engage the collar and it moved on its own. I don't think this could happen. If it isn't engaged I think you get an immediate run away or no start depending on which way the collar is offset.

How long since it was last run? Why was it in a not running condition? Is it possible the intake was full of oil?

Thanks for all the help. This is the first time I've tinkered with a TDI.

I believe it wasn't a runaway I was experiencing. I took it on an Italian tuneup drive just to knock any suspect oil out of the intake and that wasn't the issue. It seemed to have LOTS of power. I could take off nice and easy with the clutch then lay into it and chirp the tires. I was surprised. Way faster than any of my old 300Ds.

But back to the car... it was purchased as a non runner. The IP leaked so bad that it was bone dry and wouldn't even think about priming. I changed the seals and long story short... it now is fuel tight.

What I'm noticing now is that when I give it gas, it doesn't really want to idle back down. If I hit the brakes and pull the RPMs down as I decelerate, it'll chill out, otherwise, it pretty much just sort of levitates at 3 grand. If I turn it off and restart it'll calm down as well, but it eventually climbs back up.

I did make tick marks on the IQ in relation to the pump body before I took it apart and believe I am close to those marks for what it's worth.

Your IQ is off. It likely didn't immediately rev up to 3000 because of air in the system. Give the pump a few taps as mentioned and you should be on your way.

So I take it there's probably too much fuel? It sort of pops every few seconds as it idles. The normal chug-chug-chug-chug- but then pop... repeat. I can see it in the tach as well. It'll dip maybe 50rpms for a second. It is smooth as silk at any power band range. It's got better pickup than most gasoline cars.

If the IQ is "set" too low you more fuel and power off idle and, of course, more smoke.

Does it smoke under acceleration?

Maybe the pump is gummed up from sitting? Maybe a can of purge will help.

I just went through this same thing yesterday.. Re sealed a pump, lined up the pre surgery marks, fired it up... It fired right off, ran great for 30 seconds then started stumbling and sputtering. The go pedal smoothed it out until it was allowed to idle.. Went right back to sputtering. Then the revs started climbing on their own and it hung around 1700 before I shut it off and fetched my vcds. Plugged it in and it showed an iq of .2 (note the decimal). After a couple taps with the dead blow hammer, it purrs like a kitten.

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He does need to read the IQ, no doubt about it.

^^^ I concur, you need to adjust the IQ. The procedure is called the "hammer mod" and there are lots of write ups on this website.

REMEMBER: raising the IQ lowers the amount of fuel being delivered, and lowering the IQ raises the amount of fuel being delivered.

UPDATE: I knocked the IQ adjuster toward the timing belt about 0.020 to 0.040" ish from the pre-surgery marks in the parking lot and drove it home from work. The idle is now smooth as silk and the pedal responds as it should and not on it's own anymore.

The one and only drawback is that the crazy acceleration power is not quite the same as it was. It was pretty extreme in power. Now it's about what I thought a TDI should be like. It's plenty peppy and I can hear the turbo but it's not extreme.

Anyways, thanks for the guidance. This is my first TDI experience... very good cars.

777funk said:

UPDATE: I knocked the IQ adjuster toward the timing belt about 0.020 to 0.040" ish from the pre-surgery marks in the parking lot and drove it home from work. The idle is now smooth as silk and the pedal responds as it should and not on it's own anymore.

The one and only drawback is that the crazy acceleration power is not quite the same as it was. It was pretty extreme in power. Now it's about what I thought a TDI should be like. It's plenty peppy and I can hear the turbo but it's not extreme.

Anyways, thanks for the guidance. This is my first TDI experience... very good cars.

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Once you get access to vagcom/vcds though you can tweak the IQ to get that oomph back without the lumpy idle. You really don't have to move the top much.

With most things on these tdi engines, if you see it move you've gone to far

^^^ I agree, and sometimes if you thought you saw it move, it did; it moved too far.

It was WAY over-fueled before. It's smooth as silk now and drives nice. The exhaust smells clear also. Before it smelled of unburned diesel.

I might try turning it up just a hair to see what happens.

777funk said:

It was WAY over-fueled before. It's smooth as silk now and drives nice. The exhaust smells clear also. Before it smelled of unburned diesel.

I might try turning it up just a hair to see what happens.

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Like has been mentioned many times before in this thread, you need to see what the IQ is with VCDS. It is important and it's not something you can willy-nilly guess at. Just because it "runs fine" doesn't mean the IQ is correct. The IQ is altered by the ECU while cold then the ECU stops altering it once the engine reaches full temp.

Is there harm in being a hair too lean? It's not a 2 cycle where it's lubricated by it's fuel.

At this point the engine seems to run well and the exhaust smells like it should.

I have vag-com lite but can't see spending $300 plus on the full version at this point.

777funk said:

I have vag-com lite but can't see spending $300 plus on the full version at this point.

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Vag-com lite (free version) will do everything except the timing graph.
I registered it and can do the graph. $99 or so

I picked up an ebay cable and am having no luck installing it. I use computers regularly and can follow directions. I think the cable is not liking my computer(s) or vice versa.

I read on the Vag Com light site tonight that it also has the timing plug in. I didn't know it could do IQ.

777funk said:

I picked up an ebay cable and am having no luck installing it. I use computers regularly and can follow directions. I think the cable is not liking my computer(s) or vice versa.

I read on the Vag Com light site tonight that it also has the timing plug in. I didn't know it could do IQ.

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I've been in the IT field for 25+ years now.
I could not get 2 or 3 com port cables to work before I stumbled on the one I use now.
USB cables did not work either because they become a higher com port# then 4 which is the limit for VCDS Light.
The cheapo Bluetooth ones do the same.
Unfortunately there's no numbers on the one that works for me and I lost the info on it when my e-mail started deleting saved messages older then 3 years.

I read you can change the com port and I was able to change mine from 4 to 2 but I believe I must have gotten a dud cable. They refunded my purchase price thankfully.

I've used this one successfully with VCDS Lite, $10 on Amazon.
https://www.amazon.com/gp/product/B00JQ7V49Y/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Just ordered one of those. Thanks for the tip.

There's a thread around here somewhere that shows you how to set up vagcom if you're having connection issues. Setting up ports and all.

Seatman said:

There's a thread around here somewhere that shows you how to set up vagcom if you're having connection issues. Setting up ports and all.

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What I need is how to get VCDS lite to recognize a non standard port.
I can choose com 1 t0 4 but my ELM Bluetooth adapter becomes 7.
I think the address it uses is also non standard.

Can you still go into device manager and change parameters for associated hardware? Assign it a different port number?

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\/\/0J0 said:

Can you still go into device manager and change parameters for associated hardware? Assign it a different port number?

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Tried that, didn't have an option for it

It's been a while since I've dug into a Windows machine... Back in the days of XP, it was no problem to change parameters as such but I know Microsoft has been taking away features like this in the name of simplifying the computer experience

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