Hello,

So I have been having this problem lately with a weird mechanical sound coming from my engine after a cold start, mainly when it has been sitting outside for a long time and the temperature is below 0 Celcius.

Here is a full history:

1) Bought the car in July 2009
2) Changed both engine mounts in Sept. 2009
3) Cat and rear O2 sensor replaced under warranty in Oct. 2009
4) Two weeks later, the front O2 sensor needed replacement and was replaced out of my pocket.
5) Was having loss of power issues so dealer replaced metering oil pump in Nov. 2009. Out of my pocket, very pricey.
6) The loss of power was slightly improved but there was still an obvious problem, so dealer finally found low compression and ordered a replacement engine. This was about the first week of Dec. 2009
7) The new engine was installed 2nd week of Jan. 2010
8) Immediately started to get a flashing CEL at high RPM, 5000RPM and above along with rough idling.
9) I replaced the coils, plugs, and wires immediately myself last week. Definitely increased performance but the flashing CEL still comes on at high RPM.
10) For the last 2 week or so, I have been noticing this strange noise during a cold startup, kind of sounds like a 'hiccup' or a 'deep pop' but it then goes away after a few seconds.

So I am looking for answers for 2 questions:
Why do I still have a flashing CEL?
What causes that noise during startup?

 

Very Interesting. . .

Lots of work done to the car.

I'm sure you know this, but the flashing CEL is a mis-fire. So, you're getting a miss under high load of the engine.

This points to ignition, which is back to coils, plugs, and wires.

The quick check is to confirm all your connections are tight with your coils, plugs, and wires.


Now, the noise at start-up. . . that is an odd one. With everything that was done that could be a hard one to diagnose.

 

Thanks for the quick reply. With regards to the misfire, I have checked all of the connections on the coils, plugs, and wires but the CEL still flashes.

For the engine noise I will try capture the noise on video and hopefully that will help with the diagnosis. It only started happening since the new motor was installed.

 

Since your getting a flashing cell which is normally indicative of misfire (you should be storing codes that confirm this which any dealer can read for you, Autozone will check for free, or you can check yourself with a scanner), the 'popping' sound may be a little backfire blowing through to the exhaust from the misfire condition.

Grab the codes for the flashing CEL and post along with your video - that will help get a better overall understanding of what may be going on here.

If guesses here are correct, you should be returning to the dealer who did the reman engine install to get your issue resolved permanently. If ignition system components do not prove to be the culprit, there are other possible sources. Worst case, you may be one of the folks who get the occasional bad remanufactured motor. Best way to confirm this is with compression test of the replacement.

 

Hello. I'm not here to steal your thread but your not the only one with that problem. I have a 2005 MT, and my motor was replaced less than 6 months ago and I have just over 3000 miles on the new motor. Now that it's gotten cold outside when I first start the car up I get a strange, Deep sound from the exhaust and seemingly the engine, along with that "deep pop" and "hiccup" sound. Although I dont get a flashing CEL at high RPM I do get it on startup when it's cold and occasionally a solid CEL that will go away shortly after driving the car around. Also when the car is warming up the engine will sound like it's about to stall.

Dont want you to think I'm stealing your thread. Maybe we're both having the same problem. Let me know if you find out anything. Good luck!