no power when first started

pcdj64February 22, 2013

i have a 2000 VW beetle GLX with a 1.8T engine and 01M automatic transmission.
i got a code a few days ago for a faulty mass airflow sensor so i bought a rebuilt done by A1 Cardone, i disconnected the negative terminal on the battery and installed the new sensor.
i cleared the code and then started the car, at first it was a little hard to start and would stall at stops, that has gotten better, i am told that it takes a few days for the computer to set the new perimeters for the new sensor, i have 90 percent new vacuum lines, a new secondary air pump, the original seized and i have new hoses on the new pump since the originals were shot.
the engine had a new cylinder head, timing belt and water pump just before i got the car last october, for the most part it runs excellent, lots of power and smooth idle etc. but i did notice that 2 days after the sensor was put in it bogs down on takeoff after you first start it even warm, after a minute or less it runs like nothing was wrong.
i am wondering if it isn't the computer still calibrating.
the only thing the CEL is on for is a bad charcoal canister, no other codes present and no freeze frame data available.

i appreciate any help i can get, thank you for taking the time to read the long post.

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I am not familar with the Volkswagon power plants, therefore can only speak in generalities. You said you have the 1.8T engine; I assume this is 1.8 liter, turbo-charged. Since you have power after getting underway, the turbo must be working at that condition. However, you are experiencing bogging off the line and this can be due to several things. It could be: more than normal turbo lag, lean out of fuel mixture, improper ignition advance, weak iginition, or the mass air flow sensor.

What about that replacement mass air flow (MAF) sensor? It could cause the problem you describe. You got a trouble code concerning the MAF, but was the engine yet performing as it should after this code was set, or did had the trouble begun? The replacement sensor was a rebuilt unit. How do you know it is working? Maybe the replacement sensor is no good or slow to respond. From what I know about MAFs, these have a 4-wire connector. Two of the leads supply a regulated supply voltgage to the sensor and the other two leads exports the signal.

You do need a repair manual to sort things out. For example, one check on the MAF is to measure the supply voltage to see if it is present and of proper value. You'll need a manual that identifies the leads.

When you disconnected the battery, you probably lost the volatile settings. This possibly incudes transmission shift points, radio station settings, and a few other things. The engine control computer does indeed reset engine management settings after a few cycles of warm up and speeds above 45 mph. After 3 of these cycles, things should be getting back to near normal. Most of the transmission settings will be restored in the first driving cycle assumming there were sufficient number of shifts to reset shift timings. Reverse shift is not used much and can be a bit notchy until several reverse shifts have occurred.

There could be other problems. Have you read the trouble codes again? That'd be a good idea. If you do not have a code reader, go to a place like Auto Zone and they may read the codes for you. Do not reset the code until the problem is resolved.

If all this is getting over your head, take it to the dealer or a garage you trust and have a set of diagnostics done. If could be something simple, like an oxygen sensor or a manifold absolute pressure (MAP) sensor.

Several items were disturbed under the hood from recent repairs and maintence. Did the problem show up iimmediately after one of these repairs? if so, suspect items associated with that repair. For example, was the tubing reconnected to the MAP sensor?

A significant amount of vacuum lines were replaced. What about the fittings? Were any of these changed? In todays auto systems, their can be "ported" vaccuum fittings present. Some of these are fittings may not be the usual, all hollow connector, but have a precision orifice in them. This orifice provides a calibrated constriction to air flow. Externally, these fittings appear the same as an ordinary fitting. If one of these fittings gets broken or dropped, it is easy to mistakenly replace these with ordinary ones.

    Bookmark   February 23, 2013 at 3:51AM
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Thank you for all of the info and for replying to me.
It is the 1.8 20 valve turbo engine.
At the time the MAF code appeared there was no problems with how the car was running, it surprised me that I got the code at all.
Right now the only code I have I was aware of from when I got the car, the charcoal canister is bad, I have the new one just not the warm weather to install it.
With the bad canister I have to hold the pedal about halfway to start the car the first time after filling the tank even with only a gallon of gas, after that first start at the gas pump the car starts fine.
The bogging off the line is only present for a very short time, within a ¼ mile I have normal take offs.
The fittings that were changed were all hollow, there is one with the fitting inside you mentioned and that one runs the boost gauge.
The engine has 10,000 miles on the new cylinder head, it was done before I got the car.
I have gone for several drives including highway and the only thing that corrected was stalling, the shift points are all normal including reverse, sometimes when I take my foot off the pedal to come to a stop the rpms go ay down and then come up to 900rpm again, but no stall.

The MAP sensor is electronic only, no vacuum line to it.
I am wondering if I didn’t get a defective MAF, it might be a good idea to get a replacement while it is at no cost.

The turbo has 10 psi boost, virtually no lag, the spark appears strong, the engine has incredible pickup speeds and power, it is only since the replacement MAF my trouble started with initial takeoff on the first takeoff after starting engine and being told it takes a few days to learn perimeters I failed to question the new part being defective.

I will replace it again and see what happens, am I supposed to disconnect the battery to replace the MAF? It is a pain with VW and disconnecting the battery.

    Bookmark   February 23, 2013 at 7:27AM
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i went and exchanged the MAF, had the battery negative disconnected, installed new sensor and let it run for a few minutes before driving, it drives great, tons of power BUT.
if i am at a stop and i just tap the gas and let go it will stall and won't restart unless i hold the pedal part way, if it doesn't stall it starts up fine. i am wondering if since i only went for one 2 mile drive if it hasn't yet calibrated everything, the shift points are fine, i didn't program the gas pedal but the EPC light has not come on and it idles fine.
i am wondering if the issue with not starting after getting gas isn't progressing, i can put in $5 or fill it (no top off) and have the same thing happen, it will not start at the gas pump unless you hold the pedal half way, after that one hard start up it starts fine, i do have the code for incorrect purge flow and the purge valve is new and tested to be functioning, the original valve was dead. i was told a while ago the charcoal canister was shot but i don't know if that would cause the issue of not starting. i do hear noise at the charcoal canister when the purge valve is on, like a pulse sound, hard to explain.
to give an idea of the power, i did 60 up a hill in a little over an 1/8 of a mile to test it.
if it was a fuel pressure issue i don't think that much power would be possible.
no codes present (except evap) and no freeze frame data, tested it before disconnecting the battery to replace MAF.

    Bookmark   February 23, 2013 at 10:36AM
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i am stopping messages from this server.
i have gotten one response, no one else bothered.
thank you to the person that did respond.

    Bookmark   February 24, 2013 at 12:57PM
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