'00 Echo - cold hesitation/stumble, hot engine knock

[geezer1]

I'm the first to admit I don't know jack about car repairs and I usually trust my local repair shop to treat me right with this car. However ... I'm so unsure about these two problems I thought I'd better go in well-armed this time.

2000 Echo, 235K miles, no other problems, GREAT little car. Takes a lickin' and keeps on tickin'.

Similar to the post by Jimnist a few lines below, this car hesitates or stumbles upon acceleration particularly when cold. After stumbling along for 100-200 feet I can floor it and the car will spring to life. I'm not really sure but when I floor it I may feel it drop down a gear and then it runs reasonably well although I still sense a little stumbling/hesitation and a general lack of power. Maybe it could be transmission-related? Once the engine gets good and hot, the problem disappears. The problem seems to be intermittent. To be honest, I checked the codes several weeks ago with my handy-dandy little code reader and seem to recall some mention of a solenoid something or other. I wrote the codes down but, of course, they're at home ...

So, once the engine gets good and hot (and I mean running at interstate speeds for 30-45 minutes) the engine will often (but not always) knock badly on hard acceleration or under load. I'm not a lead-footed driver but occasionally this little car just has to get out of its own way in rush-hour traffic. If I press the accelerator gently I can usually avoid the knocking. This one worries me more than the hesitation/stumbling problem. I run mid-grade, brand name fuel in this car since it seems to make it generally run a little better.

I'm no technician and I'm not likely to attempt to fix either of these myself. I just want to be fairly knowldgeable before I take it to the shop.

I'd be appreciative of any ideas or advice you could provide.

[baboon81]

Basic function of a car is Air, Fuel and Spark.

Your engine responds to accelerator inputs so air is getting in there fine.

Fuel, you put in mid grade fuel so it could be fine. The fuel system includes, fuel pump, fuel filter, fuel regulator and fuel injectors. The fuel pump could be lacking and not pumping enough fuel to the engine on acceleration. The fuel filter could be dirty and clogged up which could restrict fuel to the engine, same with regulators. The fuel injectors could also be clogged up.

Spark. I have a feeling the problem has something to do with spark. The spark includes the spark plugs and the coils. There could be damage to the coils, which sends high voltage electrical pulses to the spark plugs and in turn ignites the fuel/air to drive the engine. Sometimes the coils are intermittent and degrade with time and or damage to the plastic cover. When accelerating it can fail to ignite the cylinders causing that hesitation feeling and lack of power. You can feel it when you get up in the revs say above 2000 rpm.

Now theres one more thing along with the three things above and thats the computer. These new cars rely on sensors from different parts of the car to control the amount of air, fuel and spark. It could well be a sensor that has failed to send the correct signal to the computer and in turn failed to send correct amount of fuel/spark/air to the engine.

Only some suggestions, they may or may not help you.

Good luck.

[denman]

Ditto all Baboon's tips, but if you can fill us in on the code reader results we'll get more specific. A quirky sensor can account for all these issues, also the spark plugs themselves, cheap and easily replaced. I'll stand by pending diagnostic codes, ...