Volkswagen Cold Start Shifting Problems
Many, many VW owners face similar issues with their cars. While it can happen to just about any year model, there is a frequent problem with model years from 1998-2005. Of those, it seems the 2002-3 models are the worst offenders. Whether this is because of design or just an anomaly, the solution mystifies the untrained mechanic. The symptoms are rather universal.
After the car sits for a long time, overnight, and the engine is cold, when the driver starts the car and immediately drives off, common symptoms are:
- Jerking or bucking to some degree from 1st-2nd or 3rd gear.
- Shifting delay between gears. To the driver, it seems like the tranny slipped into neutral for a second, enough to be dangerous if accelerating from a stop or sudden acceleration.
- There are no engine codes lit up on the dash. No engine light is showing.
- Some experience this at higher gears, or maybe, if the engine is not cold.
- Weird shifting pattern when hot, like in stop-and-go traffic (holds gears a lot longer than it should when in D, but will willingly shift when signaled to in Tip mode).
- Unsettling downshifts when cold.
- Odd clunk just before coming to a complete stop as it shifts to first (not audible, more of a feeling like you just ran over a small bump -- makes smooth stops nigh on impossible without shifting to neutral).
First, the reason why there are no engine codes sometimes, is that, tranny solenoids are both electrical and mechanical, like fuel injectors. The car’s ECM does not read a problem because electrically, the part is fine and in spec, yet, failing mechanically, which does not activate the ECM. With solenoids, they can fail by sticking or just breakdown.
The mysterious cold engine issue baffles many mechanics who are not savvy enough. The first run to check codes, which may not be the answer. You might be wasting money. The VW automatic tranny has nine solenoids to regulate shifting. After the car sits overnight or a long period of time. The tranny oil cools and turns cold making it thicker. If the solenoids are sticking or slow, the car will not shift smooth. In the mornings, after overnight, the oil is thicker and causes a delay in shifting when accelerating and produces a jerk or buck at times. Just changing the tranny oil (should be changed every 30K) usually does not solve it because the solenoid is mechanically failing or has failed. If it fails, you may be stuck in 1st or 2nd gear. If it is failing, if may shift fine AFTER the car is idled and warmed up for 10 minutes or more. You can also rev it for 5 minutes or more at 5500 rpm, to heat the oil to thin it.
Some, with this issue, have found it was a major vacuum leak, specifically from the Y shaped breather hose connected at the top of the engine and the lower hoses found under the intake manifold. After replacing these hoses the cold start issues were gone and transmission shifts smooth.
If you go to a tranny place or VW, although they claim they don’t know, most will think solenoid right off. Many will try to sell you a new tranny for thousands or tell you it must be rebuilt. Before doing this, replace the N92 solenoid ($70) at minimum to see if the issue is fixed. The N88, 89 and N92 shift the low gears. You might want to replace them also or all nine of them.
All potential areas of fault of the symptom include:
•ECU/TCU/engine torque sensor – In vehicles with Electric Accelerator Pedal Control (ECU) engine torque data is sent to the TCU via the ECU. The TCU tells the ECU when it wants to change gears and the ECU lowers engine torque to allow the TCU to close clutches/breaks at lower pressure, making the gear change smoother. Therefore, if there were any problem with the ECU, TCU or engine torque signal, this would manifest in less than optimal gear changes.
•ATF temperature sensor (G93) – TCU uses ATF temperature data from this sensor to control gear changes. A high shift pressure is used at low ATF temperatures and varied as temp rises. If sensor fails, gearbox performs gearshifts at higher ATF pressures. This data is used at ATF temps <70 degrees Celsius.
•Solenoids – N88, 89 and 92 are used in 1st gear, but N92 is de-energized to go to 2nd.
•ATF fluid itself – If chemically exhausted, or wrong level, it won’t work as reqd.
•ATF pump – this pump moves oil from the sump and transfers it. It is responsible for ATF pressure.
If there are no codes indicating sensors or solenoids are bad, then, the electrical resistance is fine, but the solenoid is stuck mechanically, or there is a bad seal. This is not detected by the ECM. If the car shifts smoothly after it is warmed up after being cold, it is most likely a stuck solenoid. The solenoid can stick solid and if this happens then you end up with "no upshift" at all instead of "no upshift cold".
According to VW mechanics, it is quite possible to have shifting problems that do not trigger a code. These may or may not be solved by a set of solenoids. A set of nine solenoids was about $360 online. If money is an issue, only replace the n92, n88 and n89 solenoids. At the very minimum, replace the N92.
For 2002 VW made in Mexico with 5 speed auto transmissions EYP, EEF, ELD,
GPC, EYN, and GNZ:
09A 325 039 H - Valve Body applies to EYP, GNZ, EEF
09A 325 039 J - Valve Body applies to GPC, ELD, EYN
Valves fit both bodies:
09A 927 331 - Solenoid valve N89 (brawn)
09A 927 331 A - Solenoid valve N92 (green)
09A 927 331 B - Solenoid valve N88 (brawn)
09A 927 331 C - Solenoid valve N90 (black )
09A 927 331 D - Solenoid valve N282 (black )
09A 927 331 E - Solenoid valve N91 (black )
09A 927 331 F - Solenoid valve N283 (white)
09A 927 331 G - Solenoid valve N281 (white)
09A 927 331 H - Solenoid valve N93 (green )
ATF fluid is part#: G052990A2.
- Volkswagen Technical Site (VWTS) - Фольксваген клуб
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