Well i am back to the drawing board..here is the issue. I have a 2001 caravan with the 3.3 and it surges when dring around 50-60 mph only when it is warm and it also cranks longer when warm. You can also put it in drive and give it gas and around 1200 rpm is runs rough. I also have a hesitation at take off. I have replaced ALL the sensors, ignition coil, plugs and wires. I unplugged the vacuum line to the EGR and plugged it up and it runs Great!!! All the symptoms went away. I bought a new EGR and installed it. I still have the issues. I unpluged the line again and runs great. What would be causing this? When is the EGR suppose to open and close? I dont understand that when I plug up the vacuum line no more problems. Any help would be great. thank to all who reply!!!
adam

 

When you got the new EGR valve, did it come with a new vacuum transducer also? If so, remove the vacuum line from the valve after the transducer and see if your getting vacuum to the valve at idle warm engine.

 

Yes it came with it also. I am so stumped at this.

 

No I do not get vacuum after the transducer before the EGR at idle warm. Give it a little gas i would say aroung 1200 rpm and it has vacuum. The van idles good.

 

the hesitation could be the EGR valve coming on too strong or too quick.

 

So here's a little write up on how the EGR valve works. Maybe your convertor is starting to plug causing the valve to come on to soon and too strong.


OPERATION

Refer to Monitored Systems - EGR Monitor in this group for more information.
The engines use Exhaust Gas Recirculation (EGR) systems. The EGR system reduces oxides of nitrogen (NOx) in engine exhaust and helps prevent detonation (engine knock). Under normal operating conditions, engine cylinder temperature can reach more than 3000°F. Formation of NOx increases proportionally with combustion temperature. To reduce the emission of these oxides, the cylinder temperature must be lowered. The system allows a predetermined amount of hot exhaust gas to recirculate and dilute the incoming air/fuel mixture. The diluted air/fuel mixture reduces peak flame temperature during combustion.
The electric EGR transducer contains an electrically operated solenoid and a back-pressure transducer (EGR Valve and Transducer - Typical). The Powertrain Control Module (PCM) operates the solenoid. The PCM determines when to energize the solenoid. Exhaust system back-pressure controls the transducer.
When the PCM energizes the solenoid, vacuum does not reach the transducer. Vacuum flows to the transducer when the PCM de-energizes the solenoid.
When exhaust system back-pressure becomes high enough, it fully closes a bleed valve in the transducer. When the PCM de-energizes the solenoid and back-pressure closes the transducer bleed valve, vacuum flows through the transducer to operate the EGR valve.
De-energizing the solenoid, but not fully closing the transducer bleed hole (because of low back-pressure), varies the strength of vacuum applied to the EGR valve. Varying the strength of the vacuum changes the amount of EGR supplied to the engine. This provides the correct amount of exhaust gas recirculation for different operating conditions.
This system does not allow EGR at idle.
A failed or malfunctioning EGR system can cause engine spark knock, sags or hesitation, rough idle, engine stalling and increased emissions.

 

How can you tell if your converter is starting to plug?

 

Only way to see is to perform a backpressure test...

 

Is a backpressure test something a dealer has to do? If it is not that what else would cause these symptoms? I am so frustrated with this.

 

well if you had a prob with your egr.. I would make sure the passage way in the intake manifold is clear is it can clog the path to the egr and have it not work properly. and bassically if you add vaccum to the egr while its running with a vaccum pump or a longer piece of hose just suck on it.. if the engine stumbles or stalls its working fine.. if nothing happens its your egr..