Recurring hesitation problem.

[aussiedave]

I have been posting on this forum with this problem for over two years with this problem.
In that time I have cleaned or changed:-
air filter
Plugs, wires and distributor module
fuel filter
PVC valve
Cleaned IAC and Air flow sensors.
I think that's it...
The problem seems greatly improved each time I perform some operation, but not quite completely fixed.
Recently put it into the shop with another problem where the car wanted to stall in gear and stopped in traffic - turned out it was the PVC valve and they tell us they can't find the hesitation problem either.
Any further ideas would be appreciated.
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[behlinla]

More info please. Year and engine. When exactly do you have hesitation (from a stop, from cruise, from coasting closed throttle, etc). Is it above a certain RPM range? Check engine light ever on? Fuel trim info if you have it?

[Lgbpop]

Check your vacuum lines, one at a time, for dry rot and/or cracks and pinholes. Also check the vacuum storage tanks buried inside the outer front fenders. That's a general possible cause for hesitation, rough idle and stalling - certainly not the only cause, but worth doing as preventive maintenance at the very least. I started out checking each of mine, then just decided to systematically replace the lines with all new hose and tubing. Each one I track down and replace results in smoother idle.

[aussiedave]

Originally Posted by behlinla

More info please. Year and engine. When exactly do you have hesitation (from a stop, from cruise, from coasting closed throttle, etc). Is it above a certain RPM range? Check engine light ever on? Fuel trim info if you have it?

'03 3.0L, not duratec. Problem happens after stopping in traffic in idle. Problem caused check engine light to come on but reset after replacing PVC valve.
If I push the gas pedal hard, that is when the hesitation is most noticeable.
Thanks.
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[Breeves002]

Check engine light isn't on? Did you just clear the codes? They could still be there. What were the codes? Does the CEL flash when you have this hesitation?

[behlinla]

2003 OHV engine. Got it.

I would start by checking the fuel pressure. You'll have to do this with a scan tool. Check the pressure at idle, at 2000 RPM (or while driving), and monitor it while doing a throttle snap. Fuel pressure should appear to remain the same level on the scan tool. Now remove the vacuum hose from the fuel pressure sensor and repeat the throttle snap test. Fuel pressure should not drop significantly.

How long ago was PCV valve changed and codes reset?

[aussiedave]

Originally Posted by Breeves002

Check engine light isn't on? Did you just clear the codes? They could still be there. What were the codes? Does the CEL flash when you have this hesitation?

The repair shop must have cleared the codes and I don't know what they were - the missus picked the car up - she mentioned something about fuel mixture.
Not sure about the CEL flashing - wife didn't mention it.
Sorry I couldn't be more helpful.
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[Jeff K]

03 is a returnless fuel system, and there is no schraeder valve on the rail for checking fuel press with a gauge. You need a scan tool to get pressure reading from the rail press / temp sensor. That is if you believe the sensor reading!

[aussiedave]

Originally Posted by behlinla

2003 OHV engine. Got it.

I would start by checking the fuel pressure. You'll have to do this with a scan tool. Check the pressure at idle, at 2000 RPM (or while driving), and monitor it while doing a throttle snap. Fuel pressure should appear to remain the same level on the scan tool. Now remove the vacuum hose from the fuel pressure sensor and repeat the throttle snap test. Fuel pressure should not drop significantly.

How long ago was PCV valve changed and codes reset?

PCV replaced and CEL reset was 1 week ago.
Thnx.
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