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Larry Loiselle (aka loiselle) [ View ] [ ditvenet@hotmail.com ] [ Car Ads ] [ Blogs ] Manor, Texas (512) 272-5770

1992 Oldsmobile Cutlass Supreme 3.1 V6/Auto, 89k miles I know this is probably off subject and I will get my butt kicked for it, but I need to ask a mechanic's advice. My mother-in-law gave me a nice 1992 Olds Cutlass Supreme about 7 months ago and it ran great. Suddenly I am having problems: The problem is intermittent (off and on although more on lately). Sometimes it is hard to start. The real problem comes when you try to accelerate. It stalls and cuts out. Often you can feather the gas pedal and gradually accelerate. It misses sometimes and cuts out on acceleration sometimes. We have already replaced the fuel pump, fuel filter, map senor, and IAC sensor. We also cleaned out the throttle body. With all of this effort, nothing really has changed ... in fact it may be worse. You can unplug the IAC sensor and/or IAT sensor and it does not make any difference. I just went outside and tried it. It start up and idled fine. As soon as I put it gear it stalled. I feathered the accelerator and drove it a mile. If I gave it too much gas it died. Sheesh. Maybe my shotgun can fix it. Help?!? Thoughts: I think the TPS (Throttle Position Sensor) is a potentiometer that tells the ECM that I have stepped on the gas pedal and how much. Then the ECM tells the injectors how much gas to give it. Right? If it is not working properly (like a bad dimmer switch) I probably will get too much or too little gas. It acts like an old car with a carburrtor with a bad accelerator pump. What say you? Thanks.

Comments

Posted by reneg8d  -  08/03/2008 09:07 AM Larry, See if you can borrow a scan tool, or hit up your local Auto Zone and try to pull any codes from the computer.. If you can access a true scanner rather than just a code reader, look at TPS voltage. It should be about .5 V closed throttle, and slowly rise to 4.5 -5V as you press the accelerator(engine not running) to the floor.. Watch the voltage.. It should be a smooth transition from low to high. Any skips or jumps and the TPS is toast... Good Luck! ASE Master Auto Tech [ View ] [ Email ] [ Blogs ] [ Car Ads ] Thoreau, New Mexico Charter Member since July 2005   Posted by sach  -  08/03/2008 09:41 AM Cleaning the element in the mass air flow sensor may help also. sach [ View ] [ Email ] [ Blogs ] [ Car Ads ] Cana, Virginia   Posted by housrace  -  08/03/2008 10:06 AM Check your fuel pressure. see if pressure bleeds off quickly when the key is turned off. Pull the vacuum line off of the regulator and check for fuel in the line. Those are prone to failing and letting unmetered fuel to get sucked into the engine thruoght the intake. If you have a scanner, check the coolant temp sensor. I have seen them fail and read stone cold or full hot. But, it soundslike ,to me, you have a bad fuel regulator. housrace [ View ] [ Email ] [ Blogs ] [ Car Ads ] Spfld., Illinois   Posted by JAWS  -  08/03/2008 10:20 AM Just helping to eliminate possible causes, how recent are the plugs and wires? Have you changed the Crank sensor? or Cam sensor? How old is the ignition module(DIS), have you tried another known good one? Without a scanner, so you can see the actual readings off the tell tale sensors, your are gonna be a parts changer till you find the one you have issue with. Not really the way I would prefer, but we don't have much choice. We will help you as much as a blind man can. Keep feeding us anything you can think of and all the results you get from changin out each part. -Brant An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004   Posted by loiselle  -  08/03/2008 10:38 AM I have a friend who has a real good OBD I and II reader. Unfortunately, there are no codes. Sheesh. loiselle [ View ] [ Email ] [ Blogs ] [ Car Ads ] Manor, Texas   Posted by blade58  -  08/03/2008 10:42 AM my sister had the same car and it was the fuel pump just enough fuel pressure to idle it would stumble on acceleration or stall you could feather the throttle on flat ground it progressively gets worst, check fuel pressure and all the other component, the scan tool will pin point your problem blade58 [ View ] [ Email ] [ Blogs ] [ Car Ads ] apopka, Florida   Posted by JoeP  -  08/03/2008 02:32 PM I think Blade58 is is going in the right direction , sounds like a fuel problem to me also, start with the simple stuff. How long ago was the fuel filter changed, if ever? Joe [ View ] [ Email ] [ Blogs ] [ Car Ads ] Somerset, New Jersey   Posted by dmtm125  -  08/03/2008 05:18 PM had a 95 chevy van egr valve caused a similar problem. dont know if the cutlass has 1 or not Doug Mars [ View ] [ Email ] [ Blogs ] [ Car Ads ] Okeechobee, Florida Charter Member since October 2007   Posted by blade58  -  08/03/2008 09:09 PM had this happen too ,the fuel line from the pump to the assembly was full of tiny holes when i pulled the whole assembly it still had gas in the line you can see the fuel leaking out like a sprinkler blade58 [ View ] [ Email ] [ Blogs ] [ Car Ads ] apopka, Florida   Posted by JAWS  -  08/03/2008 09:24 PM I was thinking fuel pressure as well, but he noted that he change the pump and filter. I assume that was after this problem started showing up. A code reader is not a scan tool. You need a scan tool so you can "see" the readings from each sensor. Just because a computer doesn't notice a failure in a sensors parameters, doesn't mean drive wise it is working as it should. It doesn't care about performance or drivability as long as the car doesn't fail emissions. As long as the emissions out of the tail pipe are within the preset parameters, the ECM sees no problems. An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004   Posted by blade58  -  08/04/2008 09:59 AM Jaws i agree with that most mechanical challenges are not detected by the scan tool,one time they gave me the wrong pump ,there is also the fuel regulator , with the car not running there is a way to check the regulator ,it requires a pressure gauge on fuel rail and a hand vacuum pump blade58 [ View ] [ Email ] [ Blogs ] [ Car Ads ] apopka, Florida   Posted by JAWS  -  08/04/2008 11:12 AM Right on about the pressure reg test. Usually if the reg is bad, it will full pressure and I can't see that with his issue as he would have an abundance of fuel, more than enough for acceleration. I am wanting to know the fuel trim % and o2 readings when under acceleration. This will as you know, tell us whether it is leaning out from lack of fuel volume or pressure or both, and/or a misfire from the ignition system will show way rich The fuel trim will be showing the ECM is trying to lean it self out to compensate for the extra fuel or vice versus if the fuel is lean it will show dramatic richening. -Brant An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004   Posted by blade58  -  08/04/2008 01:22 PM wouldn,t that trigger a ""check Engine " light? blade58 [ View ] [ Email ] [ Blogs ] [ Car Ads ] apopka, Florida   Posted by JAWS  -  08/04/2008 08:12 PM As long as it doesn't fail emissions or max either parameter for the ability to richen or lean out for an extended period, then no. As soon as it does it will save as a soft code and not turn the light on. If the ECM "sees" a consecutive failure of I believe three in a row, then it will become a hard code and the light will show. Rule of thumb here, but some systems will wait longer or not as long. An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004   Posted by loiselle  -  08/04/2008 09:17 PM The Cutlass ran great for a couple of days. So, Karen and I decided to give her a road trip and see if it is fixed. We first drove to Georgetown and then to Burnet. If ran fine. At Burnet we stopped to have lunch. When I started it again it stalled out upon acceleration. This lasted several blocks. I would start it and it would stall. Finally by feathering it we got it moving okay and it stopped stalling. So, we drove to Lake Buchannon and stopped at the park. When we got back in it started and ran fine. From there we went to Fredericksburg where we stopped at Walmart to get some stuff. Once again it started and ran fine. When I got to Johnson City I was low on gas so stopped. When I started it this time it stalled. I kept up this start/stall ritual for probably a half dozen blocks and managed to get it back on the highway. I feathered it and got it out of town where it got real bad. I would start it and it would immediately stall. Finally I got it to stay running and feathered it and got it up to 50mph. After a few miles it ran fine and ran good the rest of the way home (about 60 miles). It is like something (valve or whatever) sticks and causes the problem. Several folks have suggested the EGR is the problem. It has three pistons that rise and fall - could get stuck. It is the digital type and has three little pistons operated by solenoids. These pistons are on springs and have seals at the botton of them that blocks off the exhaust. If one or more of them got stuck it would flood the intake with exhaust gas. Can it be taken off, cleaned, and made workable or not. These mothers are around $180 new. I hate to spend that kind of coin and it not solve the problem. I dunno. There are no codes ... and the check engine light does not come on until the engine is off. Sheesh. loiselle [ View ] [ Email ] [ Blogs ] [ Car Ads ] Manor, Texas   Posted by JAWS  -  08/04/2008 11:27 PM The EGR valve is a valve as you said that is intended to recirculate burnt exhaust back in to the combustion chamber. By doing this, in varying amounts based on throttle percentage and the engine being up to temp, the amount of fuel/air mix needed to fill the cylinder is reduced, thus reducing emissions. If the EGR valve sticks open it will continually reroute exhaust, which is not combustible back into the chamber, basically "blowing out the candle" in a sense. This is usually found, if it is a problem at part throttle just above idle where the engine would be if you would be at cruising speed. This would make a jerking or missing feeling. The EGR valve is mostly open then when the engine under those circumstances. When it would require less fuel/air mix to maintain rpm, and the chamber volume would then be at it's most saturated by exhaust from the EGR valve operation. With more throttle and depending on how fast it was opened, the EGR would normally close and close fast upon more demand for power. What you need is a fuel pressure gauge in line and visible when the condition occurs so you can watch the pressure. You are entering the drivability diagnostic realm that surpasses most techs and where an actual mechanic with good old fashioned common sense and knowledge of how these systems work is needed. you might get lucky by just changing parts, but you won't find out why it's happening and what really fixed it. THIS is the reason it gets so expensive when having your car diagnosed for an intermittent issue. It never fails, just like when you are sick and go to the doctor, you always feel better when he is checkin you out, same way your car wont act up at the shop. I hate that. There is one way to tell if the EGR is the culprit when it is acting up, you must give it a whack, and a good one at that at the base where it bolts to the manifold. This will usually dislodge the carbon keeping it open and free the valve. Trouble is it doesn't seem to do it when you can get at it. If it ever does it at idle or when it is doing it at start-up, have a buddy whack it with a drift punch and hammer, and see if it frees up. Hopefully it will. Keep us posted. -Brant An electrical headache can make a great car a pain [ View ] [ Email ] [ Blogs ] [ Car Ads ] Boise, Idaho Charter Member since August 2004   Posted by loiselle  -  08/08/2008 01:15 PM A couple of days after sitting for a day or so, it was hard to start. A small blast of starting fluid solved this problem. I unplugged the wires to the EGR valve and drove it. There was no change. It started and idles (idle is a little low), but when you try to accelerate fast it stalls. It will accelerate if you do it slowly. It acts like an older car with a bad carb accelerator pump. Does this indicate the EGR is probably okay? What about the possibility of a bad TPS sensor or Coolant Temperature Sensor? Help? Larry loiselle [ View ] [ Email ] [ Blogs ] [ Car Ads ] Manor, Texas   Posted by TYCHOOCHOO  -  08/08/2008 02:05 PM I had the same problem a few years ago. One of the fittings was sucking air when I tried to accelerate. Fine while sitting and running. TYCHOOCHOO [ View ] [ Email ] [ Blogs ] [ Car Ads ] MT. SINAI, New York   Posted by blade58  -  08/09/2008 11:01 AM Check Vaccum line to fuel regulator blade58 [ View ] [ Email ] [ Blogs ] [ Car Ads ] apopka, Florida   Posted by housrace  -  08/10/2008 12:28 PM yes, check the fuel pressure regulator housrace [ View ] [ Email ] [ Blogs ] [ Car Ads ] Spfld., Illinois

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