1996 VW Jetta with 2.0 engine. Dies when slowing from high RPM

What is the fuel pump pressure? When you put the throttle down, there is not enough fuel to match the air inlet and it dies.

have a compression test done to check head gasket and cracked head/s. Flushing a radiator is a waste of time as blocked cores will not clear so have a flow test done on the radiator to gauge the number of blocked cores. Check the fins condition on the cores . If you have a viscous fan hub on the fan then replace it ( indications are that it overheats at lights ,when going slow or high rpms going slow but cools down when moving at speed). Check timing and air/fuel ratio as lean fuel mixture will cause overheating Check that the bottom radiator hose is not collapsing under high rpm blocking off the water flow.

check competition. sound like they did not check valve height. or you have the valve to tight. valve are over lapping

!st thing is get the revised head gasket (used on 1993 up) for this engine from VW or Felpro, always use new head bolts or a repeat failure will occur. Using the revised head gasket here is the procedure to torque the head down, it is done in stages. PLease go to this site and read the whole procedure.

Seems you have a blown head gasket. To replace a blown head gasket, the cylinder head must be removed from the engine. Once the head is off, the mating surfaces of both the head and block should be inspected for flatness as well as any damage that might have contributed to the gasket's failure or might prevent a new gasket from sealing properly. If the head is warped, it will not seal the new gasket properly and sooner or later it will again fail. Resurfacing and/or straightening the head may be necessary. An inspection of the head may also reveal cracks or other damage that will have to be repaired before it can go back on your engine.

sounds like a possible idle air sensor and or a failing head gasket if it has the 2.7 I would suggest having the journals in your heads clean or blown out because they had a flaw in those heads that can cause catastrophic damage.

it could be a 1.8 or 2.0 you must check the engine tag under the hood look for a white factory sticker it has the engine size printed on there under engine family.

P0422 - Catalyst below threshold.

Catalytic converter is clogged or out of medium.

Replace it.


ACTUAL DIAGNOSTIC:

Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.

Symptoms

* Check Engine Light will illuminate
* In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

* Defective Catalytic Converter
* Engine misfires have damaged the Catalytic Converter
* Internal engine damage resulting in high oil consumption and/or a leaking Head gasket has damaged the Catalytic Converter

Common Misdiagnoses

* Oxygen Sensors are replaced when the real problem is a damaged Catalyst
* Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
* Catalyst is replaced when a misfiring engine is the real problem



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i would start by cleaning out the throttle body. they collect soot and not have to be a lot either for it to mess up the idle speed, i had trhis on mine soon as i dipped the clutch to slow down the rpm dropped to about 400 to stall, i cleaned throttle body out ( taking air intake off and wipe round inside and the butterfly will be enough) and now it idles and the rpm dont drop below 900

you probably mean the valve head gasket.

In this case this is serious work and you should contact a local VW dealership or mechanic and have them do this work for you to insure a job well done. If you simply mean your Valve cover, then this is no big deal and can be done by taking out the 4 screws found at the corners of the valve cover and then simply lifting the cover free and replacing it with a new one/tightening the screws back down.

hope this helps :)