[yamin]

Greetings

I purchased an 04 ZX5 with the 2.0L Zetec for my daughter with 205K. We have been having a problem with a rough idle and just got the code for a lean condition on Bank 1.

What we have done -

- changed the fuel filter, spark plugs, changed the Bank 1 O2 sensor, ran cleaner through the fuel system, cleaned the TB and MAF, checked the EGR valve, PCV valve and have done a quick test for vacuum leaks in the hoses. Checked all ignition wires and plug wires. No issue off of idle so don't think dpfe problem.

My question is - could it be the IAC valve? I have cleaned it from the top of TB and sprayed from inside the intake manifold but have not been able to get to it to take it off. Engine runs fine as soon as off idle so makes me wonder if IAC is stuck open to allow too much air? CEL light did not come on when used for highway driving - only when more intown driving so more idling? When a friend added acetylene to intake at air filter it smoothed out the idle. Or is it more likely a vacuum leak somewhere that I am missing?

Any ideas appreciated.

[yamin]

In case anyone else has this issue we found that the EGR valve gasket had started to break apart and created an air leak even though everything was still bolted together. Pulling off the valve and replacing gasket fixed the lean issue.

[ZTWsquared]

Not sure why I didn't see this before but anyway thanks for the update. Do you remember what the exact code number was just in case anyone is searching on that.

And how did you figure this out btw - sounds like it might have been a tough nut to crack.

(11-24-2013, 03:58 AM)yamin Wrote: In case anyone else has this issue we found that the EGR valve gasket had started to break apart and created an air leak even though everything was still bolted together. Pulling off the valve and replacing gasket fixed the lean issue.

[yamin]

Originally didn't have a code - just a rough idle but smooth as soon as on the gas but that was with mainly highway driving. After more in-town driving got a P0171 code.

First thing we did was change the front top O2 sensor cause looked like original anyways but no difference. Visually checked all the most common trouble areas in the hoses for a leak and the pcv valve. Did a quick check of EGR valve on car to see if diaphragm ok and was.

Do not have a smoke machine so was going to try the cigar smoke route but my friend said to run a wand end (cutting torch end) connected to propane tank around the air lines. When we held under the EGR valve the idle smoothed out - when pulled away got rough. Thought then it was the EGR valve but when we pulled off could see the gasket was shot. Replaced this and has been fine with good idle and no codes.

(11-25-2013, 12:58 AM)ZTWsquared Wrote: Not sure why I didn't see this before but anyway thanks for the update. Do you remember what the exact code number was just in case anyone is searching on that.

And how did you figure this out btw - sounds like it might have been a tough nut to crack.

(11-24-2013, 03:58 AM)yamin Wrote: In case anyone else has this issue we found that the EGR valve gasket had started to break apart and created an air leak even though everything was still bolted together. Pulling off the valve and replacing gasket fixed the lean issue.