whats most likely cause for hesitation immediately off idle ? It seems like it delays and does not seem as powerful yet no CEL ,nothing obvious showing .thanx all

 

Hi wsv3424,

How long has it been since you performed a basic tune-up on the car (spark plugs, plug wires, air filter, fuel filter, top up all fluids, etc.)?

Off the top of my head, some of the things that can contribute to hesitation are (often in combination):

1. Stretched throttle cable needs adjustment:

Welcome to Jag-lovers - Members Photo Viewing Page


2. Clogged air filter and/or fuel filter

3. Fouled or eroded spark plugs

4. Dirty Mass Airflow Sensor or corrosion on its electrical connector

5. Coolant Temperature Sensor (CTS) signal out of range, electrical connector
corroded, or wiring harness damaged, leading the Engine Control Module (ECM) to apply incorrect fueling enrichment or enleanment

6. Fuel Pressure Regulator and/or fuel non-return valve/check valve no longer holding proper pressure in the fuel rail, leading to momentary fuel starvation when the throttle is opened:

http://www.jag-lovers.org/snaps/snap...?id=1366662355


7. Throttle Position Sensor (TPS) or its electrical connector fouled with oil:

http://www.jag-lovers.org/snaps/snap...?id=1383323851


8. O2 Sensor lazy, leading ECM to apply incorrect enrichment or enleanment, but not so far out of range that DTC FF44 is triggered:

http://www.jag-lovers.org/snaps/snap...?id=1365433282
http://www.jag-lovers.org/snaps/snap...?id=1365378120


9. Intake manifold air leak between the MAF and the cylinder head, leading to a lean air-to-fuel mix.

10. Partially clogged or sticky fuel injectors

11. Collapsed fuel tank due to plugged Evaporative Emissions system


If it's been awhile since you did a basic tune-up, I'd start with that plus adjustment of the throttle cable, cleaning the MAF with special MAF Sensor spray and cleaning the MAF and CTS electrical connectors with zero-residue electrical contact cleaner spray, and checking the CTS wiring harness near the connector for any breaks or other damage. If things haven't improved noticeably, I'd then rule out the other possibilities one by one.

Cheers,

Don

 

Thanks very much Don. It threw a code and got it right w/new Denso EAC 7905 switching valve ..EGR .
Off to install now .
HAVE A HAPPY ONE! Thanx again!~
Will

 

Hi Will,

Was the old EGR solenoid causing the EGR valve to be stuck in the open position? For the benefit of others who may have similar symptoms in the future, what code did you have?

Has the hesitation now been resolved?

Cheers,

Don