2002 Engine losing power

My wife has a 2002 Alero with the 3.4 v6 (I think, at work and tired and can't remember for sure). The vehicle has just turned over 100k miles. Before we married, she apparently was of the opinion that vehicle maintenance meant when it broke you took it to the shop, so basically it's been fairly mistreated.

On a recent trip to Minnesota (about 1550 miles round trip from Missouri) the car began acting up. When warm it would cut out at regular intervals (like an ignition short, or siezing points for anyone that remembers what points are, or completely blocked fuel filter, or dying fuel pump). After the vehicle would cool back off, everything would be fine. It would do it at idle, and progressively worse under load, and only after we had run the AC, and would not stop after it started unless we shut the vehicle off and let it cool down.

After getting back to Missouri, everything has been fine other than the engine surging and bogging (barely noticeable, but all the time).

The car always runs just on the verge of hot, and I've noticed sludge on the inside of the overflow cap that looks to me like she may have oil in the water (not a good sign)

Yesterday, coming home from a short trip out of town (35 miles) the car began rapidly losing power. We cruised 80 mph on most of the trip, and when this occurred we were lucky to manage the speed limit. It was hot out, and AC was on, but temps were normal (for this car anyhow)

The car has almost NO power. It makes plenty of rpms, but isn't getting any power to the ground. It doesn't "sound" like the tranny is slipping, and it isn't sputtering or cutting out all the time, like a fuel or ignition problem typically would, although it is bogging and losing power worse at higher rpms and speed. It's making rpms but no power to the ground. The problem is noticeably worse as the car warms up (which is almost instant now, maybe a sticking thermostat too? phhht)

After reading the forums (for the umpteenth time since I inherited this car) for about 3 hours last night, I went home and today disconnected the MAF sensor and drove the car down the block and back. It did seem to have more power at lower mph, but again lost power as speed increased. Also, disconnecting the MAF seems to have reset the shift points or something, because now it shifts really hard, and acts like the vacuum modulator thing on an old gm transmission would when it goes out... ie hard shifts at high rpms, a general slipping type feeling before the shift, not wanting to shift under load but banging into gear when you ease off the accelerator, etc. Of course the difference here is that if it were just the tranny, it would still have power and torque at rpm, this vehicle doesn't.

With the AC on it barely makes enough power to pull itself down the road.

Anyhow, I'm assuming that I probably have AT LEAST a couple of things going on... obviously there is a tranny issue, and I will be taking the car next week to the trans shop for a flush and fill and a new screen. Also maybe a head gasket problem with the oil in the water and near overheating possibly? (It's hard to be sure though, because it doesn't miss like you would expect it to with a blown head gasket, and no white smoke anywhere, and the engine revs smoothly with no load) Of course, of the 2 or 3 possible ways for oil to get into the water (or vice versa) I think the head gasket is probably the problem you hope to have...

My biggest concern right this minute though, is the lack of power to the ground.

It is possible that the only problem is the tranny, but I'm afraid it might be something else.

Any ideas?

I'm thinking possibles might be... fuel filter clogged, mafs dead (I have a muliti-meter, can it be voltage or ohm tested?), ignition/computer problems (bad), tranny slipping horribly (worse), or engine losing compression (worst)

Friday is oil change day, and if I can get a haynes or chilton book rounded up it will be fuel filter change day too. Air filter is nearly new, all the wiring seems intact, and although I'm sure it could use plugs etc, I don't think they are causing the problem.

Basically I'm pretty disgusted with the car, but my wife loves it (and she's upside down on it finance wise, so we're stuck with it...) We won't even get started on the windows falling off the tracks, pos rolling over window seals and channels, lack of a tranny dipstick, the shoddy seals, creaking struts, crapola brakes, under-powered v6, buggy electronics, the paint, or any of the other myriad things wrong with this car just in the last 6 months...

Anyhow, any help you guys could offer would be *most* appreciated.

I don't have money to take it to a shop, so I'm stuck with this project, so DIY advice will help more than "have someone look at it", unless that's the only real alternative...

Thanks,

Jeff R

You might want to start with DIY basics such as fuel filter, spark plugs, wires, pcv valve, etc. On the tranny the same. ATF and filter.

Because the 4T45E tranny is electronically controlled via the ECU/PCM, engine problems may cause or lead you to believe you have a tranny problem. After the above and problems persist, you might consider getting it odb-ii scanned for manufacturer specific (P1XXX) DTC error codes even though the SES light may be off.

On intake or head gasket, check for obvious leaks and inspect the oil for coolant contamination. The sludge in the coolant reservoir is the effect of Dexcool coolant exposed to air and may not indicate you have sludge in the rest of the cooling system. But a cooling system flush is highly recommended with the mileage on the vehicle.

Another item that could cause your problem is a clogged or partially clogged CAT convertor. Good luck!

Do you think that if it were the cat that it would set off the SES light?

Jeremy

Do you think that if it were the cat that it would set off the SES light?

Jeremy

Yes and no. I've seen bad CATs and no SES/CEL light. Normally the rear 02 sensor would generate a DTC such as P0420 after a few drive cycles and eventually generate a SES light. However, a CAT DTC error code shows up as a pending error and not a fatal error on your typical odb-ii scanner/code reader. I have a top of the line Actron scanner and the Autotap program running on a laptop and the indications are similar. It doesn't cause the ECU/PCM into limp home mode. Pending codes do not always trigger the SES light.

I mentioned CAT as a last resort because of the mileage on the car. Most GM CATs go bye bye after 80K miles which is when the emissions warranty expires. They've got over 100K on that Alero.

Thanks for the tips.

I'll be doing all of those things as money allows. Unfortunately I won't be able to give it a routine tune-up right now, but will have to concentrate on the problem at hand. PCV valve is ok, in that it rattles and such anyhow, and there wasn't any missing or anything before other than the surging/bogging thing that was barely noticeable.

This morning the SES light came on, and the hard shifting/late shifting is getting worse.

There's a definite spot in the rpm range with just virtually no power, from about 2k to about 3500 rpm. Under load it just kinda makes a throaty "waaa" sound, louder than the usual exhaust, and kinda flat and powerless, if you can imagine that... kind of like it might sound I guess if it was flooding out without chugging or missing, but it doesn't smell rich, and acceleration is zero. It acts almost like the timing is off, except it only does it in that certain rpm range, and it has all the other things happening too.

When it loses power above 2k, I have to give it a good bit of throttle to get the rpms to bump back up to 3500 where it will again have a little acceleration, then feather the throttle to get it to shift up, at which point I get to repeat the 2k-3500 rpm sequence. Once it reaches about 40-45 mph it seems to be better, I'm assuming because there's less load there with a little momentum.

Driving it in bumper to bumper rush hour traffic this morning, with basically zero acceleration, was a white-knuckle ride every time I had to try to change lanes... lol.

If it's the CAT, I'm thinking maybe it isn't making enough flow to be an issue under 2k rpm, and making enough to force some out above 3500, and the backpressure is just stifling it in between?

It will go this morning after I get off work for fresh oil and filter, and a transmission fluid and filter change early this afternoon. While it's having the tranny serviced I'll try to beg the mechanic to check the CAT for me without charging me a lot. I could just pound it out this weekend, but I don't want to mess with the CAT personally unless I have to.

Come to think of it, when I unplugged the MAF and drove it, when I got back home the CAT smelled REALLY hot, and it never has before. I only drove it 2 blocks down the street and turned around and went right back, it was already warm, but not nearly hot.

As the tranny is ECM controlled, I was wondering, is there any type of vacuum control on it at all? It really exhibits a lot of the symptoms of say an old TH350 tranny with a bad vacuum modulator. My wife used to live in the country, about 3.5 miles out on a dirt road, so the entire drivetrain has seen plenty of dust and dirt.

If the tranny fluid change helps but doesn't fully resolve the problem I may take it first chance I have and get the tranny power flushed. The shop I'm taking it to this afternoon doesn't have the equipment to flush it, only drain and fill.

Sorry to ask these questions like about the tranny that could be answered by a haynes or chilton book, but I don't have one yet to look to for reference.

Anyhow, I'm guessing you may be right about the CAT, I had thought about that and then dismissed the notion with all the other stuff going on. So, hoping this morning will bring some resolution.

Thanks again for the tips.

Jeff R

PS - thats good to know about the coolant issue. I haven't seen any antifreeze in the oil, just what appeared to an old-timer like me to be oil in the antifreeze. It hasn't exhibited any other symptoms of blown gaskets, so hopefully that isn't an issue right now.

My sister's VW Beetle is doing the exact same thing, except her car is a stick, so I don't notice any hard shifting. The CEL was on and when I accelerate in 1st gear, there is NO power until the car hits about 3.5K RPM. Plus it sounds louder exhaust wise. It set off the light and I took it in to Autozone. They told me that it's one of the O2 sensors, but didn't know which one. They cleared the code and although I'm still having the same problem with her car the light hasn't came back on.

Is something like an o2 maybe at fault with your Alero, but just not throwing a light one? BTW, my sisters car is running to lean, so there isn't any extra exhaust smell....just a thought.

Jerem

Update :

Well, we changed tranny fluid and filter, oil and filter, fuel filter, plugs, wires, checked ignition module, checked all 3 coil packs (replaced with a new one and no change), replaced IAT sensor, ran a can of seafoam to clean the cat and... it runs worse than ever. It barely runs at all and is now backfiring as well.

Took it to the shop and had the codes checked, said IAT high voltage and multiple misfires. I'm thinking it just threw the IAT high voltage because I unplugged the mafs to check it. Anyhow, it was just $10 so I went ahead and replaced it just to be sure. As far as the multiple misfires, well we didn't need a computer to tell us that lol.

We're taking it back to the shop for a full diagnosis on Saturday or Monday, I'm hoping it isn't the timing. If it is, then I guess the finance company will get to have it fixed because we won't be able to afford to pay to have it fixed and make the car payment on it :P. Oh well...

Any other ideas?

My sister's VW Beetle is doing the exact same thing, except her car is a stick, so I don't notice any hard shifting. The CEL was on and when I accelerate in 1st gear, there is NO power until the car hits about 3.5K RPM. Plus it sounds louder exhaust wise. It set off the light and I took it in to Autozone. They told me that it's one of the O2 sensors, but didn't know which one. They cleared the code and although I'm still having the same problem with her car the light hasn't came back on.

Is something like an o2 maybe at fault with your Alero, but just not throwing a light one? BTW, my sisters car is running to lean, so there isn't any extra exhaust smell....just a thought.

Jerem