2000 4 cyl hesitating
 

I have a 2001 4 cyl that is having some stalling/hesitation issues. The problem seems to occur mainly when opening up the throttle past idle. IE: hitting the gas again after braking or coasting down or starting from a stop.

When it happens, it flat out falls on its face, then catches and goes. The rpms do drop off and power steering and brake assist drop as well, telling me the engine really is losing power. Occasionally, especially after a high vacuum situation, the car will completely stall, but will fire back up immediately.

I have read that the crank triggers on this engine are known to be problematic and cause these symptoms, but they seem a little too linked to vacuum load to be coincidental. Also, when the crank trigger died on my truck, it flat out died inside a week, and this has been going on for a few months.

So, does this sound like the ckps or something else (like ignition mod)? Is there an easy way to dx the sensor? I can't reproduce it with the car in park, so I would have to be able to drive it.

Seems like you should have a pending trouble code if the problem is that bad. A dealer or a mechanic with a Tech II or equivalent can record data while you are driving, maybe giving you a better shot at a real diagnosis.

Just a question, when was the last time you replaced your PVC valve and fuel filter? not saying this is the fix but there could be a chance , for under $25.00 it should be done anyways.

It's my wife's car; we've been married for 2 years, and I haven't done anything other then change the oil, and I don't think my wife ever changed those before I met her, so if they were changed, its been 4 or 5 years.

Pcv valve should be easy to do, but do I need to drop the tank to reach the fuel filter?

I do have another symptom too. On the highway with the cruise on, the cruise will sometimes kick off at the base of a hill when the system tries to open the throttle.

I'm also going to get have the codes pulled. I have a wheel bearing going out, so I already have the 'service vehicle' and 'check engine' lights on for that. Is there a trick to get it to throw the codes to dash?

No, the codes can only be read by an OBDII capable scanner, you can't use a paper clip and count flashing lights anymore, sorry.

The fuel filter is outside the tank, no special tools/talent required. It is in a kind of tight spot, though. Before you loosen the lines, pull the fuel pump fuse and crank the engine for a few seconds, this will relieve the pressure in the lines so you don't get sprayed. It will still drip some, though.

I have had the exact same problem with my wife's old alero which has become my DD. It all seems to have started after the fuel pump was replaced, but now I have the SES light on. I don't want to pay for a diagnostic on it so I'll probably have to buy the code reader since you can't buy and return them from Autozone anymore here in CA.

I will probably go do that today and post back what I find out, since it seems like we have the same problem.

Autozones around here will read your codes for free. I've heard of other car parts places doing it also.

The cruise control may turn off because of the bad wheel bearing.

The fuel filter is pretty easy. Its right in front of the spare tire well under the car, right in the center. There is a evap canister right behind the filter, pull the 10mm bolt that holds the canister and let it hang. That give you a little more hand room. The hardest part is the stupid clip on the line. Its gotta pull in and over.

I haven't had a chance to dig yet, but I'm pretty sure its the crank sensor going out.

Yesterday I was starting from a stop with the windows down and tghe radio off when it did it. I could hear the engine missing as it struggled to go and saw the tach jump up to 4000 rpm for a second or two before dropping down to 500 and dieing. Once again I pulled over, put n park, and it started right up.

I was bored today so I decided to check the plugs and pcv to see if they needed to be changed.

I couldn't actually find the pcv, or any vaccuume lines coming off the valve covers. When I looked up the part online, I couldn't even find a pcv valve for this engine. Does it actually have one?

When I pulled the plugs, they were obviously in need of replacment.....30k miles ago. So I ran out and bought a set of bosch double platnums and it seemed to fix the problem. It did bog once while starting from a stop, but the learned fuel trims are probably still messed up from the old plugs.

So here's another Q. When I pulled the bolts holding the cover down to get to the plugs, they had a good coating of oil on them. I had the cover on and off a few times, and it seemed they would recoat with oil after driving (but the inside of the cover was completely dry). The exhaust valve cover has an oil film on it towards the drivers side and there is evidence of a leak in the valley (for lack of better word) down by the driver side. The driver side bolt entering the exhaust side (firewall side) of the head had the most oil on it. There is a sensor that screws into the intake side of the head (I'm assuming cam sensor?) that may be the source of the leak.

Any idea what might me leaking?

Exhaust cam tower gasket. Very commen on the 2.4L. It leaks oil down under the IDI cover into the spark plug hole. Oh and no you don't have a PCV. I would get rid of those crappy ass bosch plugs though. They are garbage. Get some Ac Delco's.

well I thought I had it figured out.

I think the bad plugs were just exaggerating the main problem. The worst bogging is now gone, but I'm still having funny issues from time to time.

1. Starting from a stop, it still wants to stumble from time to time.

2. Once I get up to speed, I can feather back the throttle to a point just above idle (seems to be consistently around 1500 rpm), where the RPMs start to randomly flutter. I can't tell if the tranny is gear hunting (or maybe the TC switching in and out of lockup) or if its the engine. It doesn't appear to be missing.

3. When I come to a stop after driving for a while as idle settles down to the 500 rpm range, occasionaly I'll start picking up a miss fire.

4. It still dies on me. I was coasting down a hill and applying light brake, so the engine was idling. When I started applying throttle at the bottom, I initially had zero response, followed by the rpms shooting up to around 3k and it 'catching'...similar feeling to downshifting to pass on the highway. I let up on the throttle again and as the rpms fell back towards idle, they hit 500 rpm, hesitated for a second, then continued to drop until the engine died.

Does the check engine light come on at all?

Yes, but I have a bad wheel bearing which is making the dash light up like a christmas tree. I'm trying to have them read, but I live in podunk MI and am having problems finding a place to do it for free

So over the past few weeks the car has gotten worse.

Now when I'm sitting still with it in drive, the car surges back and forth. If I'm coasting down, sometimes the engine will settle into idle around 1000 rpm, and other times it will just keep falling until it stalls and dies. When I give it gas to keep it from dieing, I have to stab it...I can't just feather the throttle a little. It seems that I have to push the throttle almost to the trans kick down point to get it to respond. The other thing is that if I do feather the throttle and try to hold it just above 1000 rpm, the engine will oscillate between 800 and 1200 rpm in a very steady manner.

Could the bosch plugs be causing some of this (the hesitation at least)? I find it odd that new plugs made such a big difference in drivability and since then the performance has started going down hill again.

I would change the plugs out just to see if it makes a difference.

i have a 2000 alero and it has the same problem. i got the codes read and it turns out to be the camshaft position sensor

Camshaft or crankshaft sensor?

I've heard the crank sensors tend to die (and was thinking it might be the issue), but I haven't heard anything about the cam sensor

i have actually had codes come up from both of those sensors

My 2001 4 cylinder has been giving me the same exact problems (hesitation at take off, dropping to almost non existant RPM when coasting then randomly flying up to 3k all with no "Service Engine Soon" light... well today it got to the point it would hardly stay running without being above 3k RPM and my "Service Engine Soon" light finally came on so I went to the local part store and had it scanned. I got "P0172" "System Too Rich" because of its inconsistency I had a feeling it could be vacuum related... I limped her home and started thoroughly checking my Vacuum lines, starting at the throttle body with the car running (wiggling and pulling the ends of each line) The 3rd line I got to about 4 inches long running from the front of the intake manifold to some random sensor directly under a part of the air intake (something like a secondary airbox with no filter with 2 bolts and 2 hose clamps holding it in place) as soon as I touched it my throttle started bouncing around and stalled upon further prodding. I removed the dry rot hose and replaced it and... Voila its like someone bought me a new car and swapped my keys without telling me.

Check yours out let me know what you find.

Just got the car back from the shop. I took it in for the wheel bearing and while it was there they pulled the codes. I had a code for an O2 sensor fault, so the mech took a look and found one of the leads right at the sensor had been cut clean in two.

With that and the wheel bearing fixed, the car is much better. Idle is still a touch rough but I think the base injector timing is still screwed up from the O2 sensor and the plugs may be hosed.

Glad you got her fixed. I didn't even think about the O2 sensor. I'm sure you got charged an arm and leg for the repairs.

I paid $315 for all of it, which is quite reasonable considering I have had other shops quote that much and more just for the wheel bearing.

What's weird is how different it drives now. It feels like the steering is tighter (harder to turn) and the brakes are less responsive (same pedal pressure, less stopping power). However, I can't tell if it is different or if I just had that bearing noise so long that I learned to use it as a reference.

I would check and see if the shop twisted the brake line when they put the caliper back on the side they replaced the bearing. I don't know about the steering. Check the fluid. If its something that you think is dangerous take the car back to the shop and have them look it over, if they messed something up they have to fix it.

After driving it for a while it seems to be driving about the same, so I think it was just me not used to the noise.

However it is still dieing on acceleration after coasting down hill. It just does it less.

What's interesting is that when it gets ready to stall, rpms drop to 500 and hold steady. Giving it any throttle makes it bog and the rpms drop. If you ride it out, the rps will eventually climb back up to 800 and everything is fine. It feels like I'm driving a 5 speed let the car coast down in a high gear.

I wish I knew more about the 4 banger, I could probably be able help more. Go over to www.aleromod.com or www.grandamgt.com. Some of the members on the sites know alot about the 4 cylinder motors then I ever would.

Have you looked at the idle air control? If it is stuck, it could cause your problems.

The mystery deepens.

Over the past few weeks, the car has been driving equally crappy and the power steering has been feeling sort of weak.

This morning, it was sort of cold outside. I started the car and it was running rougher then normal. When I backed up out of my spot, the car acted like it was struggling and I had no power steering. I stopped and let it warm up for a minute and while in park I reved the engine up to around 2000 rpm. When I did this, I felt a distinct POP in the steering wheel followed by the power steering coming back. When this happened, the check engine light went off and the car started driving better. Since then the light has remained off and the car is still driving better.

The only problem that remains is that it bogs from light throttle at 1500 rpm. A sharper jab or letting the rpm drop to 1000 and the issue doesn't happen

Well I finally figured it out.

I am visiting the parents, so I finally had a near by advance auto that I could stop by and get the codes read. I had a handfull of downstream O2 codes (low volt and heater), a MAP code and a poor mixture code.

So I started looking at the MAP and throttle body and found the vac line connecting the sensor to the TB had dry rotted in half and was being held together by a thread. I actually checked this area once, but the way it was ripped, it was hard to see without a good light.

Fixed that hose and all is fine. Idle is normal, throttle response is fantastic and she actually has power again. Makes me wonder how the shop that looked at it missed it...I can't imagine the MAP code wasn't set. Sort of also makes me wonder if the O2 they replaced was really bad. The wire they showed me had been cut (looked like by a set of dikes), not rubbed or burned through

I read this over on aleromod earlyer today. Glad you figured it out finally. I think it seams weird you had all those codes and the shop told you it was an o2 sensor wire, that so happened to be cut. Seams like they couldn't find the problem so they made a problem they knew they could fix. I think you should go talk to the manager of the shop and try and get some money back. If he doesn't want to help go to someone higher on the food chain. I know were I work if someone called and complained about something our district manager would give them their money back or the problem would be fix at no cost to them.

I would bring it up, but I don't think it's worth the effort. It was a small, independent mechanic, and the guy that did the work was one of the owners. I also don't have the old part or a print out of the codes that were in the computer when I brought it in. So it would be my word against his; its a small town, he's a local and I'm an out of town college kid.....not so sure I'd find sympathy from anyone. It's also only over about $90 worth of parts and labor.

So I'm just not going to go back there. I also just made the trip to my parents, so I now have the bulk of my tools again, so I shouldn't need to bring it anywhere for service.

More trouble than its worth, I understand that. Yeah Its nice to have your own tools so you don't have to pay someone to do something for you.