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Intermittent lack of power to engine


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jeffreydykes
New User

Jan 27, 2006, 7:41 PM

Post #1 of 4 (2755 views)
post icon Intermittent lack of power to engine Sign In

I have a 1996 Mercury Sable in good condition. Just recently, after doing some driving about town and after driving for about twenty minutes, I discovered that my car wouldn't go past about 25 mph. It's like there was no more power. I parked it for a short time, and drove again, and it drove fine for another fifteen or twenty minutes, then repeated the problem. I continued to drive unabated, and it worsened - this time refusing to go past 10 mph. Up to the speed limit there is no engine stuttering or stalling, and when I first crank it up it runs fine for a while. Only after it's been running for a bit does this problem manifest itself. I seriously doubt it's bad gas or spark plug problems, as the engine would give me problems all the time with those. I took it to Goodyear for them to run an engine diagnostic (bad idea - they ripped me off), but they said that they found no problem.

Any ideas out there?


DanD
Veteran / Moderator
DanD profile image

Jan 28, 2006, 7:23 AM

Post #2 of 4 (2748 views)
Re: Intermittent lack of power to engine Sign In

This could be caused by a few things low fuel pump pressure, restricted exhaust, ignition primary or secondary systems or a sensor that’s going out of its parameters after it reaches operating temperature. Not enough to set a code to give you an avenue to look in but maybe enough that someone looking at scan data may see a sensor that is suspicious.
What may have to happen is to have test equipment like a scanner, fuel pressure gauge and an exhaust back pressure gauge connected to the vehicle while it’s doing its thing.
Problems like this are very frustrating for both the repair shop and the owner of the vehicle and it’s a two way street that both you and the shop have to be willing to give and take.
Dan.

Canadian "EH"






Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 28, 2006, 7:37 AM

Post #3 of 4 (2747 views)
Re: Intermittent lack of power to engine Sign In

Sounds like either an exhaust restriction or fuel pressure problem.

* To check for an exhaust restriction - put a vacuum gauge on intake manifold with a "T" so any device will still work. It should read about 18 at idle. It should read the same with no load at 2,000 rpms. Best if you can do this while you have the problem and you may see a lower # at high rpms and that is an indicator of an exhaust restriction. If you see this is could be anything in the exhaust but most common would be a converter or strange muffler problem.

* You'll need a gauge test fuel pressure which should have a hook up on the fuel rail.

Hard part here is you are going to have to catch this in the act or I think you'll just get normal readings. FYI fuel pressure should be around 40-45 psi. (some cars are more and I don't have a chart) -- You may need a buddy to hold brake and put a load on engine to observe this. PLEASE DON'T STAND IN FRONT OF THE CAR IF YOU TRY THAT! Safety first and if it doubt DON"T.

Let us know what you find - those are the areas I would look first. Good luck - T



redbull95
New User

Jan 29, 2006, 7:36 PM

Post #4 of 4 (2711 views)
Re: Intermittent lack of power to engine Sign In

I had the same problem with a 2000 ford contour. I could drive the car for 30 minutes then all the sudden it started to lose power until it stalled. If i let it sit and cool off then i could go about 30 more minutes. It happened to be a sensor that would malfunction when the car heated up. I don't remember which one it was but that might help you fix it.






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