Hello all,
My car has been idling erractly for several days. I did get caught in a huge flash flood storm here in Austin, TX.perhaps rain plus humidity is messing with the engine. This happen a few days ago.
The car shakes and suffers like its about to stallRpm will dip down to 600 then surge up to 1200 rpms. No codes right now but I had p0171 for a long time. I replaced all vacuum lines and turbo intercooler hoses.
my car feels like it will stall anytime now When I idle. Is this my Ivac going out or a bad fuel pump regulator. All my fuses and relays are good. I am at lost why my car keeps idling bad and random stall outs.any insight?

 

rough idle can be a few things - idle air control valve/MAF acting up, fuel pressure regulator, engine coolant temp sensor etc all play in the fuel delivery side. On the spark side, you could have a cap/rotor/wiring issue (particularly when wet). Have you replaced the cap/rotor/wires/plugs recently? Does the car have any other symptoms - hard cold starting, runs better cold or warmed up? Still could be a vacuum leak issue (maybe a hose slipped off...but that typically throws a code). Given the lack of codes, I'd probably start with wires/cap/rotor if they haven't been done in the past few years to baseline the spark, then look at fuel system stuff by starting with the pressure on the fuel rail, inspecting vacuum lines, MAF and IAC clean up (use CRC MAF cleaner).

 

Thx for the quick reply and help.
The plugs wire,cap rotor, were replaced less then a year ago.
I replaced my fuel filter, fuel pump and the fuel pum and fuel mgmt relays are replaced.how would I Check the fuel pressure regulator?

 

I am going to to check my turbo hoses and clean the throttle again and iac valve as well as fuel pressure. Should I check my cap and rotor as well? My spark plugs look ok and not wet. What else should I check? These rough idle starts to happen after 2 minutes after I start up in park. It will happen when I stop at lights. When start up, the tachometer revs high to 1900 rpm then goes down Slowly to Normal 850 rpm.it feels like the engine rumbles hard and the car sounds like a carb diesel!! The fuel rail ticks loud, and the muffler coughs like a diesel. The rpm shifts from 750 rpm to 2000! I do have rust holes near the the exhaust past muffler. Is it possible exhaust leaks are to source of bad fuel economy, and very rough idle/ stalls? How do I know I have water in the engine as well as I was caught in a huge flash flood rain tstorm in Texas 2 days ago. I drove through a rather deep puddle. It happen at night as well. Sorry for long question but this looks very bad for my car now😟

 

I am going to to check my turbo hoses and clean the throttle again and iac valve as well as fuel pressure. Should I check my cap and rotor as well? My spark plugs look ok and not wet. What else should I check? These rough idle starts to happen after 2 minutes after I start up in park. It will happen when I stop at lights. When start up, the tachometer revs high to 1900 rpm then goes down Slowly to Normal 850 rpm.it feels like the engine rumbles hard and the car sounds like a carb diesel!! The fuel rail ticks loud, and the muffler coughs like a diesel. The rpm shifts from 750 rpm to 2000! I do have rust holes near the the exhaust past muffler. Is it possible exhaust leaks are to source of bad fuel economy, and very rough idle/ stalls? How do I know I have water in the engine as well as I was caught in a huge flash flood rain tstorm in Texas 2 days ago. I drove through a rather deep puddle. It happen at night as well. Sorry for long question but this looks very bad for my car now😟

 

I lifted my dipstick and now it begans to smoke!! I replaced my PCV about 1 and half years ago. Do I need to order another kit and do it again w/ an oil change?? I have an oil leak as well on the passenger side of the engine.
Should I do a full tune up plus PCV replacement?

Any help would be great as this rough erratic idle makes my car sound very bad.

 

to check fuel pressure, there's a schraeder valve (like for a tire) on the right side of the fuel pressure rail - just pop off the aluminum cover plate. You'll need a pressure gauge to test. When the PCV was done, did the ports into the engine get cleaned out as well? You may want to watch RPSI's vids on PCV test/replace and his vid on using a cleaning agent like Seafoam if you think the oil passages are gunked up. Do a quick test by looking in your oil filler... do you see any gunk built up (staining is normal)? Does the MAF and throttle intake (ie from MAF into engine) look clean? Is the oil leak up top like by the cam gears? That can be done when you do the timing belt (assuming its not wetting the belt and you don't mind the spotting)

 

I did drove through a puddle of water 4 days ago prior to this rough idle. My car would sometimes stall out at random times while stop at idle. I will check the pcv and fuel pressure.
Should I do an oil change as well to remove any gunk in the oil?
right now I see no oil on the dipstick and no oil in the filler cap!

 

how do you mean you see no oil on the dipstick? You wouldn't see oil in the filler cap. If you pull/wipe/pull the dipstick and don't see oil you are down at least 2 quarts and should fill asap - curious if the low oil level can cause PCVs to act up. The idea of looking at the oil filler is to look for sludge (ie caked up oil deposits that can be scraped off ). A normal view would be some staining but you can see all the contours of the casting/metal of the head. Driving through a puddle may wet some of spark plug wires and if old, they may arc. When was the last time you did a cap/rotor/wires/plugs tune up? Specific to the oil, if you are down a few quarts, you might as well do a change and see what the old oil looks like. If you add a full 5.7 quarts (assumes a new filter) you should be right about the full line on the dipstick.