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1995 Lumina APV, 3.1L quit running,
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Proa42
User
Nov 20, 2009, 4:20 PM
Post #1 of 5
(4545 views)
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1995 Lumina APV, 3.1L quit running,
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95 lumina apv, 3.1L, 177K miles:
It started running poorly about a month ago. It would not run smoothly at speed and bucked when trying to cruise and backfired when decelerating. I read the troubleshooting section of my manual and decided it was a bad gas filter, because the trouble started immediately after filling the near empty tank. I thought it was bad gas, and added injector cleaner -- in case. It seemd to clear up the problem.
Yesterday, it started again (160 miles after apparent fix), and me 55 miles from home. So, I took a chance.
This is my observation of what happened along the way:
Vehicle would idle at lights and accelerate well enough, but sluggishly. Once I reached speed I relaxed the accelerator and the vehicle began to buck with a backfire when the pedal was released. I discovered I could keep it from "bucking" by accelerating and allowing it to decelerate, and repeat the process. I let the speed drop to 60, then accelerate back to 65+. Somtimes I could get it to run well enough at 65 to use the cruise.
Eventually it changed. about 10 miles from home it began to buck and slow. I could keep it running by holding the pedal to the floor. Gradually top speed went from 65, to 35, and then held at 25 for about 4 miles. Then all I could get was between 10 and 15 mph for the duration of the trip.
Pedal to the floor, the engine barely ran. I could hear it hear sucking air, and it was shaking. It stopped, but restarted -- barely. I got home.
Changed fuel filter again today.
Fuel at Throttle body and coming through injectors.
Won't start. Fires, but will not stay running when key is released. Will only fire when pedal is held to the floor -- like in the good ol days of carbs and points.
(You think I could put a carb and distributor in this pig?)
The engine has a new distributor, coil, plugs and wires, and is getting gas.
It's got me beat.
I finally got a "Check Engine" light this morning while trying to start it. Didn't have one all the way home.
HELP!
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Loren Champlain Sr
Veteran
/ Moderator
Nov 20, 2009, 6:13 PM
Post #2 of 5
(4532 views)
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Re: 1995 Lumina APV, 3.1L quit running,
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Proa; What I'm reading, smacks of an overfueling condition. Hopefully, the catalytic converter isn't plugged, but from the symptoms, it may well be. The converter plugging will be a result rather than the cause. There are a multitude of possible causes. TPS, fuel pressure, pressure regulator, secondary misfires, MAF or MAP sensors, ect. Now that the CEL is illuminated, the computer, hopefully, will have set a trouble code that will help in diagnosing the original cause. You need to get to the bottom of this so, if the cat is plugged, you don't ruin the new one. We can help you with the diagnostics. Let's start with getting fuel pump pressure.
Loren
SW Washington
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Proa42
User
Nov 21, 2009, 8:19 PM
Post #3 of 5
(4521 views)
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Re: 1995 Lumina APV, 3.1L quit running,
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First off a BIG 10-Q.
Fuel pressure at 10 psi, which is right in spec -- 9 - 13 psi.
Ok: Found out my O'Reilly"s Auto PArts store has a loaner diagnostic machine. I had no "codes" to read. Back to the manual.
So, I tested the MAP. Got 5.132 volts as per spec., but when I pulled a vacuum there was no voltage drop. According to the manual, I should replace it. So I did.
The engine Idles now. And it runs well enough to get send a "check engine" warning, so I'm back to O'Reilly's for the computer.
But, it still only idles. Depress the throttle and it "dogs" down and dies. Now, there is a soot stain on the driveway so I know she was running rich last night while I was try to get it run. The exhaust looks clean now, at idle. Idles nicely, though.
Going to check TPS voltage tomorrow.
I can see the EGR actuate, so it's not stuck. Is it possible it is opening when it's not supposed to open?
Tomorrow I'll know more -- maybe.
Do you any sites that have a more detailed explanation of how the components of the Emission Control System interact and maybe "fault-tree" diagnostics?
Thanks again
(This post was edited by Proa42 on Nov 21, 2009, 8:21 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 22, 2009, 5:20 AM
Post #4 of 5
(4510 views)
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Re: 1995 Lumina APV, 3.1L quit running,
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Mke sure you were testing the right wire on that MAP sensor and not just the 5v reference signal input. If it's reallly reading 5v all the time, that would be your problem. Make sure it's getting a good vacuum supply also.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Proa42
User
Nov 22, 2009, 5:13 PM
Post #5 of 5
(4498 views)
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Re: 1995 Lumina APV, 3.1L quit running,
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Replaced MAP, and it idles OK. Still dogged down, so it's back to the diagnostic.
. It has
Then got TPS code. Checked voltage. Was in in spec until throttle was rotated. Instead of going up, it dropped. So, in went the new TPS.
Back to the diagnostic. Cleared codes. Now I get a speedsensor code, showing 100% voltage. I'm guessing a short.
I actually drove it, but it still behaves like a Rolls-Kinardly. Rolls down hill -- Kinardly roll up the next.
Tested VSS (Vehicle Speed Sensor). Voltage less than the 10 volts minimum. Book says, "Take it to the dealer to check the ECM/PROM."
Y'all agree??
Any good supplier of used ECMs?
(This post was edited by Proa42 on Nov 23, 2009, 3:22 PM)
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