97loudcut Posted May 5, 2007 Report Share Posted May 5, 2007 Okay. For starters this problem was occurring before and after the upper intake swap. About 1 out of every 15 times I start the car it idles really rough, almost sounds like it is heavily cammed, then I give it some gas and it idles fine. It is almost like something is choking it out. It kind of reminds me of how the car runs when you Seafoam it and too much Seafoam gets into the system. Now I did plugs and wires last summer. The throttle body is spotless. Fuel filter was done last year, about to do it again. What could this be? Quote Link to comment Share on other sites More sharing options...
Euro Posted May 5, 2007 Report Share Posted May 5, 2007 you said the plugs/wires were good, what about the coil pack? My Lumina had a problem like this. Once in a while I'd start it and it would just chug, idle rough. Turned out it was my injectors clogging. You could check those too? Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 We had the injectors out when we did the swap and they all tested good with an ohm meter. As far as I know they are original coilpacks. Quote Link to comment Share on other sites More sharing options...
Euro Posted May 5, 2007 Report Share Posted May 5, 2007 We had the injectors out when we did the swap and they all tested good with an ohm meter. As far as I know they are original coilpacks. Ah ok, so forget the injectors. Do the coils look ok? Any cracks or anything. If they're original, then I'd consider it being that. But I'd wait for more people to chime in lol Quote Link to comment Share on other sites More sharing options...
slick Posted May 5, 2007 Report Share Posted May 5, 2007 Did you check the gap on the plugs? If it only does it like 1 out of 15 times, I'm really gonna lead towards some sensor starting to fail or get stuck(like the IAC or TPS getting stuck closed or open). Hell... MAF could be on it's way out also. Do you ever get the SES light? You still may have codes without the SES light being flashed, some codes don't throw a light. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 No SES light..the MAF looks to be in good condition. I'll look into replacing my IAC and TPS. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 Where can I buy a TPS & IAC? Well I am going to replace the fuel filter and pick up some ACDelco Rapidfire plugs, a TPS, and an IAC. If it is still happening, I will resort to replacing the coils. If it STILL is happening after all that.. then I don't know. Quote Link to comment Share on other sites More sharing options...
slick Posted May 5, 2007 Report Share Posted May 5, 2007 Like I said, not all codes throw the SES light. Have it scanned just to be sure. You should be able to pick up the IAC and TPS from the local parts store. I could be that they aren't actually going bad, but they are just stuck. Pick up some carb cleaner and a little wire brush, and clean the carbon off. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 Well I just pulled the IAC and cleaned it. It was really bad, I was actually surprised. I pulled the TPS too, but I didn't understand what I had to clean, and everything looked clean, so I just put it back in. I started the car up, no issues.. but who knows it could just be 1 of the 14 times it DOESN'T idle rough Anyways.. I think I will do the fuel filter Monday (it's been a year since my last one) and then hopefully take a stab at some new plugs (ACDelco Rapidfire's). Quote Link to comment Share on other sites More sharing options...
shyguy164 Posted May 5, 2007 Report Share Posted May 5, 2007 Oxygen sensor Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 Oxygen sensor Any explanation? Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted May 5, 2007 Report Share Posted May 5, 2007 Oxygen sensor Yeah, remember I told you to change it?! And you said it was too much!!! This is directed to Matt.. Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted May 5, 2007 Report Share Posted May 5, 2007 Oxygen sensor Any explanation? Yeah, you're supposed to change it at 100k. I would do it. LOL. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 Theres two of them, which one? Quote Link to comment Share on other sites More sharing options...
runt Posted May 5, 2007 Report Share Posted May 5, 2007 Upstream should be the first one to replace. Typically, thats the one that causes the issues. Quote Link to comment Share on other sites More sharing options...
shyguy164 Posted May 5, 2007 Report Share Posted May 5, 2007 From my experience (I've owned 3 w-bodies), the oxygen sensor can cause all sorts of odd problems. Recently, my check engine light was coming on in my 95 convert (3.4L DOHC). I took it to my mechanic to find out what the code was. The symptom was quite similar to yours. Starts then dies, starts then dies, starts then runs like shit, idles like shit, etc., etc., etc. The engine was violently shaking the idle was so screwy. Acceleration and cruising was fine though. Check engine code was lean exhaust - replace oxygen sensor or something like that. My mechanic tells me to check for vacuum leaks. I asked why he wouldn't just change the o2 sensor. He said to check for leaks. The computer is saying replace the o2 sensor, the mechanic is telling me to look for leaks, replace intake manifold gaskets (which i just did too), etc. I didn't look for leaks, I replaced the o2 sensor just like the computer said. Guess what? Problem solved. The convert has never idled so well since i've owned it. Same prob on an 88 intl (2.8L). Check engine light, crappy idle, etc. Engine code says to check/replace intake manifold gaskets. I replace o2 sensor, check engine light goes out, idle is wonderful. Here's the way i go about it. If my car is running crappy, check air filter, plugs/wires, throw in some injector cleaner, etc. If none of the basic stuff works, I replace the o2 sensor as the next step if it hasn't been done in the last 30,000 miles. The poor thing sits in the exhaust stream. Any oil or whatever that may be burnt by the engine is flung onto the o2 sensor. This greatly reduces the sensor's ability to accurately measure o2 levels in the exhaust stream. Once the o2 measurement is off, then fuel-to-air is screwed up, idle is crappy, and for some reason, the sun is rising in the west and setting in the east. WTF? Anyways, even if it's just "clean" exhaust flying past it, I still wouldn't trust one to last past 30,000 miles or so. Plus they're pretty cheap, at least mine was anyways, $30 or so. I'd replace the upstream one first, before the cat. From what I understand, the sensor after the cat is a slow reacting (read as:doesn't do much) sensor. Hope this helps. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 5, 2007 Author Report Share Posted May 5, 2007 How hard is it to replace an 02 sensor? Quote Link to comment Share on other sites More sharing options...
shyguy164 Posted May 5, 2007 Report Share Posted May 5, 2007 I'm not sure on your engine, I've never done one of those. 2.8L is easy, just rock the engine forward and boom. 3.4L DOHC is dumb just because you need to take off the upper intake plenum. Use an offset oxygen sensor wrench, a swivel connection, a long ass extension, and a freaking breaker bar. I sprayed mine up with Tri-Flow first and let it sit overnight before attempting to remove it. I dont care if you put anti-seize on it or not, nothing will stop the sensor from seizing in there after all that high temp and length of time that it's sitting there. Quote Link to comment Share on other sites More sharing options...
5speedz34 Posted May 6, 2007 Report Share Posted May 6, 2007 How hard is it to replace an 02 sensor? Easy, you and I can do it if you want. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted May 6, 2007 Report Share Posted May 6, 2007 I would do plugs, fuel filter, check air filter, and replace the oxygen sensor. I would not replace the tps and iac. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 7, 2007 Author Report Share Posted May 7, 2007 DUDE!!! Bill Fox Chevrolet wants $130 for an ACDelco upstream o2 sensor. All the other places carry Bosch, or Denso. I am for sure not getting s Bosch. What other brands are decent? If you know, post a link. Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted May 7, 2007 Report Share Posted May 7, 2007 Are you getting any kind of codes or anything? Im sorry but it just seems like people here are making random guesses as to what could be wrong. Before you go out and spend money that you prolly didnt need to, investigate the problem, and try to find out what it is. Otherwise your wasting your money on things that worked in the first place. Quote Link to comment Share on other sites More sharing options...
97loudcut Posted May 7, 2007 Author Report Share Posted May 7, 2007 Well it has not happened since I cleaned the IAC! But.. who knows? Quote Link to comment Share on other sites More sharing options...
19Cutlass94 Posted May 8, 2007 Report Share Posted May 8, 2007 Well that needle in the IAC is suppose to be within a certain spec. When you cleaned it, did you push it in or pull it out at all? Quote Link to comment Share on other sites More sharing options...
slick Posted May 8, 2007 Report Share Posted May 8, 2007 Like I said, scan the car, even if your not throwing any SES lights. There are codes that don't throw the light. Murray's, Napa, Autozone, etc.... will do it for free. Quote Link to comment Share on other sites More sharing options...
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