QuestionHello, the car ran perfectly until one day at the first of winter when a light coating of ice fell. I hard a hard time getting into the car due to doors being iced shut. I don't know if this has anything to do with it or not but it is exactly when it started happening and has steadily grown worst. I live in the Mid-South so now its 90 to 100 degrees everyday. It seemed to have gotten better when it warmed up a little in the spring but is now lasting longer and happening more often.
I went about 1/4 mile down the street from my house when the car suddenly started what I call surging. Like it just stops getting gas for a split second. Maybe a hiccup is the best way to describe it. It did not happen everyday at first and sometimes went for a week or two. It would do it for a mile or two and stop and it would not happen for the rest of the day, even after it had set all day on a parking lot. It has steadily grown worst, lasting longer and starting to do it at lunch and after work too. It hardly ever fully dies, but has on an occasion or two as soon as I put it into gear and start to back up or at the first stop sign about a 1/4 mile down street. Only once, as I slowed behind traffic did it really start bucking and the service engine light came on. It stayed on until I got to work but has not came back on since. This was probably 4 to 5 months ago, with that first occurrance about 9 months ago.
My husband has ran numerous bottles of injection cleaner thru it, has changed the fuel filters, put on new wires and plugs, and even put a new fuel pump assembly thing on it, cause we thought the lines may have rusted and was sucking air. Nothing has worked and as I stated it is getting steadily worst to the point that I am leary of it letting me down on the expressway. The car has excellent acceleration, and otherwise runs excellent.
Any ideas or should I just take the thing and have the sensors and all checked out. I just don't want to wind up spending more than the car is worth a this point.
Thanks and any help will be appreciated.
Deborah
AnswerHi Deborah,
With the surging, I would connect a fuel pressure tester, just to convince myself that lack of fuel pressure wasn't the problem.
I doubt it is the problem, but connecting that tester is cheap, and reassuring.
You might be able to borrow one from a parts house if you buy parts from them.
Assuming the fuel pressure maintains properly, I would clean the idle air control valve, and the EGR valve. That is all pretty much free. The EGR valve can close on carbon, and act like a vacuum leak. It can also be opening at the wrong time, so that is something else to consider. Unhooking it to see if the problem quits is a good diagnostic tool.
But the surging, if not fuel pressure related, may well be a fuel mixture problem.
One thing that can cause that, aside from the EGR valve or vacuum leaks, is the throttle position sensor, or the mass airflow sensor.
The throttle position sensor can be tested with an ohm meter.
The mass airflow sensor can be cleaned.
I will send a link about the mass airflow sensor.
http://www.fordscorpio.co.uk/cleanmaf.htm
It is a Ford link, but they work the same.
Another thing that rings a bell of possibility, since it only seems to be when the engine is cold, is the temp sensor. See this link.
http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279
You might also want to sign up for that Chevytalk....it is totally free, and a wealth of information. You can ask questions there, and get dozens, if not hundreds of answers.
A lazy oxygen sensor is also possible, but I hate to list possibilities that cause people to just run out and buy parts on a guess, and them not fix the problem.
That statement about excelent acceleration would seem to indicate there is plenty of fuel pressure, and a sensor unbalance situation is the problem.
Good luck,
Van
