Surging issues

[RadarRick]

Hey guys, i need some advice. My GF has a small car, it's a 1.5 liter - 4 cylinder hatch back. Lately it's been surging, like one of the injectors are blocked. I thought of just putting some high octain gas in it, and giving the cara right old flogging to clean everything out. At the service, the mechenic said all is good with the car. So what next?
RR

[ATS666]

Year, make and model?
is it surging at idle or at speed and what speed?

[Synbios]

high octane gas is a good idea or just regular fuel injector cleaners.

It sounds like a D15 civic hatchback or something of the sort.

[wanderingmind]

Try some Sea Foam - I love the stuff.

1) With engine warm, slowly pour 1/3 to 1/2 pint through carburetor or throttle body throat. (If vehicle is port injected slowly pour SEA FOAM through direct manifold vacuum line that will feed all cylinders, possible sources are P.C.V. valve or brake booster line.) This will pull SEA FOAM down on top of the pistons and to the back of the intake valves to dissolve carbon. Turn ignition off. Restart engine after 5 minutes. If severe carbon build up is apparent, use more Sea Foam as previously directed. Make sure exhaust is well ventilated when using Sea Foam in these various ways as fumes will be extreme for a short time.

2) Pour 1/3 to 1/2 pint into oil crank case to clean rings, lifters, dirty parts and remove moisture.

3) Pour 1/3 to 1 full pint into fuel tank to clean injectors, carburetor jets, fuel lines and remove moisture.

Immediate Results: Smoother idle, increased R.P.M.'s better throttle response and improved performance. See label on can for detailed results for use in each area.

If that doesn't work - try replacing the fuel filter. If that doesn't work, it might be the fuel pump. But, it is very hard to diagnose a problem over the internet.

[Synbios]

I don't know your mechanical skills but check your this article to clean your FITV.

http://honda-tech.com/zerothread?id=1564019

[RadarRick]

Thanks guys. I'm on to it now
RR

[nautica2o3]

Surging during idle or while on the throttle? I would check the sparkplugs first if it feels and sounds like not all cylinders are firing. It's pretty cheap to replace the sparkplugs, wires, and distributor cap. You might as well do it if they haven't been replaced in over 30,000 miles.

[RadarRick]

Surging during idle or while on the throttle? I would check the sparkplugs first if it feels and sounds like not all cylinders are firing. It's pretty cheap to replace the sparkplugs, wires, and distributor cap. You might as well do it if they haven't been replaced in over 30,000 miles.

Ok then. It's actually on both, the idle and throttle :shock: It's a 2002 Mitsubishi Mirage with 112000kms on the clock. What really pisses me off, is it's been extensively serviced by the same mob since it was purchased 3 years ago, an authorized dealer. They said it's in perfect working order, even though, during the last service 5 months ago, a "must check note" was left of this particular problem. Still, it's running rough and unfortunately i don't know enough about cars, only bikes

Any other idea's guys?
Rick

[V1 Dave]

Think I found your problem, I have had the same thing for a while.
Did complete tune up, fuel filter, fuel pump, oxy sensor, air filter, fuel injection cleaning, (needed all this except oxy sensor)

Problem with rough idle and surging at low speeds was EGR valve area.
Simply pull off your vacuum hose to your EGR valve and test drive.
If the problem goes away I guess you can leave it that way but if you want to fix it correctly or pass smog it might not be the valve itself.

Quick valve test with vacuum line still connected is to push up the EGR diaphragm while idling and it should choke engine if EGR is still good.
Trouble shooting involves previous valve malfunction test, intake manifold plug up, which involves testing intake and exhaust side of EGR port valve area, EGR vacuum solenoid malfunction = (think this is my problem) ECM malfunction, bad lines, or it could be and one of these if equipped on your vehicle,
EGR VALVE PRESSURE SENSOR
EGR TIME DELAY SWITCH
EGR TIME RELAY SWITCH
EGR POSITION SENSOR
EGR VACUUM SOLENOID
As you can see EGR has gotten very complicated in modern Vehicles

[kpatz]

Check all your vacuum lines/hoses for cracks/leaks.