Possible cat or fuel issue, help! [Archive] - GrandAmGT.com Forum

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redhotalero
11-25-2007, 10:00 PM
Have a 2000 Alero 3.4L w/ 105k miles on it. Just tuned up (plugs, wires, fuel filter, air filter, steering flush, oil change, etc.) and a new LIM...

The problem happened twice on the freeway to and from Thanksgiving at my folks. I was cruising along at 83mph with the cruise on, and i felt a little jerk, a hesitation. I was like, um, what was that? Then it happened again, and again, just a few seconds (5 max) between one another. All this time the jerk (better described as a hesitation feeling, as if I was 'letting off' of the gas) was slowing me down, to the point that the cruise control was freaking out and downshifting like mad to keep speed. Funny thing, if I would WOT it, it would go away, power was there, BUT if I would only lightly press the gas it wouldn't even make the rpm jump at all, like there was no fuel or power...

The first time it was flat ground, going 83 with about 2/3 a tank of gas. Second time it was on flat ground, going 80 with 3/4 tank of gas. Both times all it took to fix the problem was pull to the side of the road, turn it off, wait a tick and turn it back on. It is fine around town...

Frustrating thing is that the first time it threw a code (02 sensor front) so I fixed it and figured that was it (light went off), then when getting up to speed (freeway onramp) light came on again and it started doing it.... ARG!!

Any thoughts? Maybe a bad cat or fuel related? Oh, also the second time I pulled over to shut it off it actually bogged and stalled ---

cardude007617
11-25-2007, 10:04 PM
sounds like the normal problem a lot of us have with the jerking kinda. does ur tach bounce up like 2-300 RPMs? and only above 40mph it does this right?

ryanbgb22
11-25-2007, 10:07 PM
my guess would be fuel pump. However, before messing with that I would check the maf, you said you just got a lim replacement/ changed plugs and what not so that could be a possibility.

bigstribs
11-25-2007, 10:11 PM
mine does it in second gear around 33 to 37 no matter how im on the gas little bogging 3 times normally...

lone_wolf025
11-25-2007, 10:32 PM
Bad cats don't happen to often on our cars, but you can check with a vacuum gauge. Hook it up to a line and goose the throttle a few times and it should be quick movements. If it lags and slowly draws back to full vacuum after a throttle blip its a sign of clogged exhaust...but then again it wouldn't necessarily do it at only one time.

cardude007617
11-25-2007, 11:00 PM
wouldnt it almost be a semi good idea just to get a hi flo cat anyways? cuz at 100,000; dont they kinda start to "have it". or am i totally wrong here. iv been thinkin about doing that, for 50 bucks plus install cant be bad. yes/no?

redhotalero
11-26-2007, 07:58 AM
No, I have the rev bounce too - like if I'm going up a hill and I give it a bit of gas to keep going, it will bounce 200-300rpm every few seconds, as if it is deciding to downshift or not...

When the above happened I was going fast (75+), on flat ground, and you could feel a jerk or shudder, but no bounce on the tach... Just the jerk and hesitation that would result in a crazy power loss....

Odd thing is that around town it's fine - just when at speed on the freeway. Around town it behaves like it should and always has, it's just on the freeway when you're trying to stay ahead of the tractor trailer that it happens....

SSRacer
11-26-2007, 08:14 AM
I had my cat go bad at around 50K. The car totally bogged down and had zero power. The more I got on the gas, the worse it got. This was right before my wedding a few years back, so I had my dad take it to the dealer while I was on my honeymoon. They found that the cat was clogged and replaced it under emissions warranty.

redhotalero
11-27-2007, 11:21 AM
I don't think the plugs and wires are part of it - I did that weeks before this, so why would that be a problem? If my LIM problem existed after the plug change, why didn't it do it then?

I'm going in today after work to get the code pulled - hopefully that will shed some light on it

Graxall
11-27-2007, 11:34 AM
I had my cat go bad at around 50K. The car totally bogged down and had zero power. The more I got on the gas, the worse it got. This was right before my wedding a few years back, so I had my dad take it to the dealer while I was on my honeymoon. They found that the cat was clogged and replaced it under emissions warranty.

x2 but it wasnt from fast speeds all speeds


You should try checking your intake and egr. Could be a bad egr valve. Or the in take could be clogged. You said it doesnt happen around town, my problem is around town, if i try to take off fast, sometimes it will bog out(sometimes stall) and then take off fast outta nowhere...but my car is all focked so idk...check egr valve and clean ur intake.

redhotalero
11-27-2007, 11:45 AM
Okay, what am I looking for in the EGR? Will it be all dirty and gunky if it is bad, or what?

Also, is it common to have things act up after an LIM change? I changed it the day I left and it was working fine before -- what would suddenly make everything go nuts?

Graxall
11-27-2007, 12:06 PM
Okay, what am I looking for in the EGR? Will it be all dirty and gunky if it is bad, or what?

Also, is it common to have things act up after an LIM change? I changed it the day I left and it was working fine before -- what would suddenly make everything go nuts?

no to the LIm

the egr, yea it would be dirty and stuff. Theres a certain spray you are supposed to use to clean the intake...i dont know whats its called tho..

redhotalero
11-27-2007, 07:12 PM
Alrighty, just got back from getting the codes pulled -- I'm showing a p0101 and a p0131 - arg!!

So the p0101 is the MAF and related things, so I'm taking it to the shop that just did my LIM -- perhaps they didn't assemble something right or maybe they cracked something -- since everything was fine before they fixed it, it's a good start!

The p0131 (bank 1 sensor 1 -- meaning before the cat) is the O2 sensor, but I just changed that on Saturday! Would one trip the other?

ryanbgb22
11-27-2007, 07:56 PM
Alrighty, just got back from getting the codes pulled -- I'm showing a p0101 and a p0131 - arg!!

So the p0101 is the MAF and related things, so I'm taking it to the shop that just did my LIM -- perhaps they didn't assemble something right or maybe they cracked something -- since everything was fine before they fixed it, it's a good start!

The p0131 (bank 1 sensor 1 -- meaning before the cat) is the O2 sensor, but I just changed that on Saturday! Would one trip the other?

Didn't i say check the maf first lol ^^.

redhotalero
11-27-2007, 07:58 PM
Yep, nicely done -- the place that did the LIM is going to figure it out -- they were the last to touch it. Nice to know it wasn't something I did!! :)

Any ideas about the O2 sensor?