VW 2002 2.0L Idle Problems

[Nikolai]

I’m trying to figure out an idle problem on VW 2002 2.0L. No codes. Recently replaced spark plugs (all looked consistent), wires, MAF sensor, fuel regulator. Car burns oil.

I noticed that engine gets really rough and then smoothed out. During that fuel trim levels drop. Picture attached.

Any ideas? What would make fuel trim to dip?

Attachments:

• LowTrim.png

Topic

[college man]

Your running rich.check what your front o2 is doing.
it should be switching rapidly.

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

[valde]

Could also be evap problem. Fixed one 1.8 with similar kind of problems. Never measured fuel trim since problem did get so bad that engine run with injectors unplugged. Test it by blocking hose from evap to throttle body and putting gas cap loose (this will create fault codes). If problems stop it probably is evap canister.

[Jamie]

Is it an ABA, AEG? Its a low tech old school engine for VW but a good solid engine but no wear near as complicated as a 1.8T or any of the current engines thankfully. The first thing when there is any hic up with fueling control is the condition of the CTS – coolant temp sensor, more commonly called ECT – Engine coolant Temp. They only have to malfunction a little to cause all sorts of weird little things to happen. Normally they read colder than the engine actually is and you run richer than normal. When the poor idle happened was it still cold, warming up, or at opperating temperature?

Another thing to consider is the plugs, wires you used. Are they genuine “what came in the car” equipment or different? Bosch systems are horribly sensitive about things like that. Yes there are better plugs on the market, and most parts guys will try and upsell you to the fancy ones but in any VW always go with what it came with.

[EricTheCarGuy]

[quote=”JS” post=85478]Is it an ABA, AEG? Its a low tech old school engine for VW but a good solid engine but no wear near as complicated as a 1.8T or any of the current engines thankfully. The first thing when there is any hic up with fueling control is the condition of the CTS – coolant temp sensor, more commonly called ECT – Engine coolant Temp. They only have to malfunction a little to cause all sorts of weird little things to happen. Normally they read colder than the engine actually is and you run richer than normal. When the poor idle happened was it still cold, warming up, or at opperating temperature?

Another thing to consider is the plugs, wires you used. Are they genuine “what came in the car” equipment or different? Bosch systems are horribly sensitive about things like that. Yes there are better plugs on the market, and most parts guys will try and upsell you to the fancy ones but in any VW always go with what it came with.[/quote]

This sounds like a good place to start to me. This article may also prove useful.

http://www.ericthecarguy.com/faq/solving-automotive-performance-issues

Keep us posted.

[Nikolai]

valde:
Evap system was very promising way to go espcially since engine would run after you turn key off at times. Removing evap hose did not resolve idle issue but I did not see drop in fuel trims either. I’m thinking I need to keep it disconnected for sometime and see fuel trim issue returns. We are probably dealing with 2 issues here.

JS:
Coolant temperature seems steady and not jumping around as I would expect it from a bad sensor. However I think I can throw in a new sensor it just in case. Issue happens at all temratures. Plugs are NGK and not sure about wires.

Thanks for all the ideas

[valde]

Idling would stabilize once engine management has learned new values. I didn’t clearly say it but what I meant was to block evap hose (both ends) and but gas cap loose, maybe reset ecu and leave it idling.

[Jamie]

That year came with NGK so you should be good. I couldn’t tell you how many older VW engines I’ve pulled newish plugs out that weren’t the right ones. I don’t think that’s the issue with your engine however. If you were reading an exhaust gas analyzer and it was really rich then I’d be looking at the plugs and O2.

An exhaust analyzer might be a good idea if you can get into a shop or know someone with one. A lot of the time you can diagnose what’s not working, or at least get pointed that way simply by seeing what emissions are higher than normal.

Defiantly start with a new CTS/ECT. Buy it from the Stealership or your favorite European car shop that can sell you a genuine OEM one. Reset the ECM after you install it and then see what it does. For whatever reason the temp sensors VW uses for the fueling do not last like they used too. Even new replacements for older engines. A good rule of thumb is anytime you change the plugs do the CTS. Just make sure when you buy the sensor you buy the correct one. Different plants made slightly different enengines depending on how much beer they drank I think. Some engines up into 2002 use 2 separate sensors for gauge and ECM, some are on the single sensor. It’ll be up at the top off the head.

As far as the ‘dieseling’ is concerned I would be looking at a couple of things but its tough to dissect it over the web. Does it do it anytime you turn it off, or only when its hot? The only time I’ve personally seen a gas engine diesel even for a couple seconds It was overheating and the ECM didn’t know it, as well the timing being way off. It was a crown vic, completely un related to your VW.

You said you replaced the Maf. Did you put it in correctly?

How much oil are you going through between changes?

[Author]

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