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Matt
Matt, Engineer
Category: Dodge
Satisfied Customers: 21706
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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I have a 1999 dodge stratus 2.4l non turbo it idles rough

Customer Question

I have a 1999 dodge stratus 2.4l non turbo it idles rough dies and has erratic fuel pressure between 50lb-60lbs of pressure the needle on the gauge moves so fast you cant even see it
JA: How many miles are on the car? Have you had the fuel pressure tested recently?
Customer: 85,000
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I buy fix and sell cars.ive tried fuel filter check timing because the belt was done recently checked the spark plug did a compression test
JA: Anything else you think the mechanic should know?
Customer: its sounds like the fuel pressure regulator to me but just want to double check with someone before I spend the money and not have the problem fixed
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Dodge Mechanic about your situation and then connect you two.
Submitted: 1 year ago.
Category: Dodge
Expert:  Matt replied 1 year ago.

Hello

the fuel pressure can fluctuate like this as the vacuum pipe to the top of the regulator should be connected to the inlet manifold

so try disconnecting this pipe and see if the pressure fluctuation stops

I suspect that doing this won't solve the fluctuating idle

and I suspect this could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattenedpiece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Expert:  Matt replied 1 year ago.

Hi

do you still need help?

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