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NIGHTMARE problem with Car Running Terrible (Stutters, Bucks, Dies out, etc)

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Old 11-08-13, 06:53 PM   #1
mgmprofits
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Default NIGHTMARE problem with Car Running Terrible (Stutters, Bucks, Dies out, etc)

Hello there guys,

Thanks for all your replies and help here. It sounds like some of you know what you're talking about. I have a 94 SC400 that has been an absolute NIGHTMARE trying to figure out the problem.

I haven't brought it into Lexus yet because they charge a fortune for every little thing and I don't trust the dealers around here after getting ripped off by them in the past. But I have brought it to my trusted mechanics who haven't been able to figure it out. If you have ANY ideas, on what I should try next it would be greatly appreciated.

Here are my symptoms-

The check engine light is usually on, but it turns off randomly and back on again at times. It was not on at all when I first bought the car, but after I brought it into the mechanic (for stalling out in a drive-through ///and it WOULD start back up but then stall out right away again. Then it started fine after sitting for a few hours. But I had it towed in anyway) Also in the MORNINGS only when it was cold, it would take a few seconds to crank/start before it started.

But if I turned the key to the drive position for 10 seconds before trying to start it, then it would start right away. I was told that meant I had a fuel pump issue) So I figured the car dying out was my fuel pump going bad so I have it towed to the shop as I said (Please bare with me here as the list of symptoms is kind of long and crazy but I need to get to the bottom of this) and the shop tells me that my fuel pump is OK, it tested fine they said under the pressure test.

But I hear these tests are not always accurate? I still suspect it could be the feul pump but I need to tell you my issues and how the car progessively is getting worse with new symptoms. Everytime I bring it into the shop they tell me I need a new part, which has not fixed the problem. First they told me I needed a Crankshaft Positiion Sensor, because they said the Computer code told them I needed it. Now they say the computer no longer tells them it needs that(to try and justify them installing it), and now it points to some kind of timing issue they say.

Well, I am 99% SURE I did NOT need that crankshaft sensor. Never had any symptoms of a bad crankshaft sensor. My car always started up everytime, it never FAILED to start, which is what happens when that sensor is bad. So I fear the computer might be giving the wrong codes. I had an idea that MAYBE my problems are tied to a bad Computer in the car? Should I try to replace the main ECU for the car?

I recently replaced the FUEL PUMP ECU, the 2nd time I brought the car in, as it DIED again, same symptoms, stalled out and it WOULD start again right away, but then die right away. I kept trying to get it to stay running and I could not. So I knew I got ripped off on that Crankshaft Posiiton Sensor, as it never fixed the problem.

Also I forgot to mention that AFTER they put that sensor in, my car had a NEW problem (which they denied causing, but it NEVER did this before I brought it to the shop) The new problem, which is really bugging me, is that when the Car is COLD, it STUTTERS AND BUCKS EXTREMELY BADLY. Infact the RPM's are hard to get over 2000 RPM. And it won't go faster than 20 MPH when it's cold. As it starts to warm up, it stop bucking so much unless I hit the gas harder, then it still does it.

So, the symptoms are COLD- I barely hit the gas and it bucks/Stutters. HOT- I can hit the gas LIGHTLY and it won't stutter and I can drive over 20 MPH. lol But this is soooo annoying that they have done this to my car. It all started after they put that CPS Sensor in (Crankshaft position sensor) which I have no idea if it's connected to that or not. I think they might of messed up some wires or created a vacuum leak or something in the process of their repair. So I bring it in again, and the 2nd time they tell me I needed a FUEL PUMP ECU and that is why my car is stalling.

So, I bought the part myself and had it (Fuel pump ECU) installed, and since then (This was only 2 weeks ago) the car has NOT stalled yet, but I fear that it will again and that they diagnosed it wrong again. Who knows. But I am more worried about this BUCKING/STUTTERING problem, as the car is basically undrivable until it gets warmed up. Even then it doesn't seem to run as good as I can never hit the gas hard to speed up or it will bog down again.

Another thing which I find strange is that my Check Engline Light was NEVER on before I brought the car in there, and it even had a SMOG cert when I bought it. I think they may have messed it up and caused the light to come on (that would mean they are dishonest though, since they told me my Light bulb was just burned out and they even charged me for a new bulb) I believe they are honest, as the reviews say they are and I never had a bad experience with them. I think they just have NO clue how to fix a Lexus.

I am leaning towards something to do with the MAF sensor (although they claimed they checked this and it was good, but it could still be the wires or something right?) I also have a REALLY BAD SMELL (Not rotton eggs) coming from the exaust. Smells like I am running rich or something. There is definitely some kind of problem(s) going on with the car and as I said before the Check engline light turned off for a BIT when they installed the Fuel Pump ECU (Also they claimed they changed the spark plug wires for me as well, since they said those were bad, but that did nothing to help this problem) And they said they checked out my Spark Plugs and those were good.

PLEASE HELP!! Anyone, if you know what part I should try to replace next let me know. Should I try the fuel pump itself? even though it passed the pressure test and they assured me it is not the pump? I think it very well could be from what Ive read online. Or should I try replacing the entire MAIN CPU for the car? Can a BAD CPU cause these problems I am having?? Because I can get one on Ebay for $30 so it would be really cheap, and I could have them put it in and see if maybe that's it.

They have run out of ideas themselves, they said they have no clue what is causing this. I know they didn't check the whole car though. They told me it would cost me $1000's of dollars for them to even begin to look deeper into the car (They mention the timing belt could be a culprit since the "cover" to the belt is MELTED. But I dont believe I have an issues with timing, I hope not. I couldnt afford to get a new timing belt. So I am hoping this is something simple, as again MY CAR NEVER HAD THIS PROBLEM UNTIL AFTER I GOT IT FROM THE SHOP! So whatever it is that is causing this "Bucking/Stuttering" (It feels like the car is starved of gas....) is something that THEY CAUSED during the repair. I initially only brought the car in for DYING OUT as I stated. But could this BUCKING problem be connected to the dying out problem??

I really need to fix this before it really damages my engine. Also I am sure it won't pass smog like this. I just put over 5k into this car and now I have to get another smog test in a couple of months. If I can't figure out what's wrong I will have to lose the car and all the money I put into it. Nobody would even think about buying it in this kind of condition.

Thanks a million for reading this long horror story. Hopefully someone here has had this same or similiar problem before and can lead me into the right direction.
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Old 11-08-13, 07:11 PM   #2
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A rotten egg smell usually has to do with the cats. Have you checked the o2 sensors in the cats yet? Maybe they somehow went bad right after the smog test?
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Old 11-08-13, 07:12 PM   #3
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I should mention, in the mornings or when I start the car cold, it no longer takes a few seconds. It starts up right away, so they DID fix that at least temporarily. But the made the car a LOT worse than it was before I ever brought it into them, because now it does that Terrible Stuttering problem when the car is cold. It never did that before, so I really need to figure this out as the car is not really drivable till it gets warm. And that takes over 15 minutes in this cold weather.
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Old 11-08-13, 07:13 PM   #4
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Yardie, there is no rotton egg smell. There is a terrible smell that has ALWAYS come from the back of the car ever since I bought it. It smells like gas almost, but a lot more toxic and like burnt gas or something I can't really explain it. It's like something you'd smell coming out of an old truck. There is no blown head gasket I did check for that and it passed all those tests. Also blown head gaskets are rare for this car so I am sure that is not it.
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Old 11-08-13, 07:21 PM   #5
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I think I also forgot to mention that when it's cold and idling in PARK (To wait for it to warm up before I drive it) The RPM's also move back and forth a bit, not as bad as like a vacuum leak but just slightly. And the car engine feels like it's under a lot of pressure to stay running. I feel like this problem they caused to my car could ruin this engline and I hate to drive it anymore like this. I really think it must be a simple fix, if only I could figure out what went wrong when the shop was putting in that crankshaft sensor (That's when I started getting all these stuttering problems when the car is cold, after they put that sensor in) But even before all this happened, I still has a problem with the car. ....If I hit the gas TOO hard it would stutter like the spark plugs were bad or something and once it even revved way up and never went back down. Even turning the car off and back on did not work. It IDLED AT 3000 RPMS! So it was undrivable until I had a friend come over and fix it within 2 seconds. He simply slammed the gas pedal to the floor and it fixed it. He said it was "Stuck in Cold Weather Mode" or something. But he said I could have only put it in cold weather mode if I floored the gas while in Park. I never did that, I only hit the gas a BIT hard like normal accelerating, and I was driving when it happened! SO something very strange has been going on with this car. But I thought I'd mention these symptoms as well, as all this happened before my car ever was brought into the shop. These could be connected to the same problem....

They claim my timing is off by a tooth as well but they say none of the symptoms fit that.
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Old 11-08-13, 08:04 PM   #6
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Cold weather mode? I have never heard of that. I hope you find the fix and hope it's cheap. My other car has been sitting in the driveway not starting since summer and I haven't had time to find out what's wrong with it.
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Old 11-11-13, 02:32 AM   #7
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Thanks, I hope so too.

Yeah he said there is something called cold weather mode which makes the car automatically idle very high. But I havent had that problem since that time and he fixed it within 2 seconds so that wasn't too big of a deal. It's mainly the stuttering and the fact that the car won't go past 20 MPH until it warms up that bothers me. That and the check engine light keeps coming on randomly and I wish I knew why.

If anyone has any idea, I'd really appreciate it. These shops out here don't seem to want to figure it out unless I pay them $1000's of dollars, so I am hoping it is something that others have experienced before. The symptoms all seem to point to MAF sensor or something, but the shop tells me it works fine. I dont know if I believe them, since they dont really know a lot about these cars. Could be the wires maybe. But should I try replacing the main CPU for the car?
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Old 11-11-13, 02:34 AM   #8
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I should also mention that the car stutters now, even while in park, while the engine is cold. So, you can feel and see the RPM's moving a bit because of it. And it reeeaaaaly affects the driving. It's like the car won't even go because it stutters so badly. It's hard to get it over 20 MPH and people honk at me when Im on the road and I feel like it's going to break down at any minute because of this problem. I really think it's electrical related.
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Old 11-11-13, 06:53 PM   #9
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How long has it been doing it?? First id check for spark in each cylinder.. Then do a comp test and a pulse test on injectors..

On another note is your battery dying at all? I had a problem before where one of my alt wires broke so it wasn't charging up the battery and cause major lag n eventually no power
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Old 11-11-13, 06:54 PM   #10
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Sorry didn't see all other posts till now.. Stupid iPhone lag
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Old 11-12-13, 09:10 AM   #11
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Ecu going bad. CEL going on then off is a good indication of this.

LOL at your trusted mechanic saying it needs a crank position sensor. I guess he doesn't know what a distributor is. Get a new mechanic.
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Old 11-24-13, 02:26 AM   #12
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Thanks for the replies guys. I finally sold the piece of ****. I only got $1100 for it but hey it's better than nothing. That shop really ****ed it up, I still wish I knew what the heck they did to it , as it must of been an easy fix. But the smell coming out of the back was too toxic for me anyway. The shop actually told me the people who had it before me messed with it and did some wierd things. They also said the timing belt cover was melted.

Thanks again
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Old 11-24-13, 02:26 AM
 
 
 
 
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