Hmmmm 1994 Ford Tempo idle problems

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Runs great, runs cool enough to touch the engine after 40 or so minutes in park.

In drive however:

Drives great 10-15 mins untill operating temp is up some then dies at braking / idle.

Checked plugs, they dont need replacing. Changed fuel filter today (GOT WORSE??? Possibly but it wasnt fully cooled when I tested it).

Exhaust is strong, clean, and cool enough again to touch at.

Any ideas anyone? Someone suggested to me that there is an exhaust sensor that could be detecting a bad fuel mixture on the block somewhere that looks like a relay or a plug but I dont know where this is.

I'm open to any ideas. The engine is in great shape but I'm stumped at this point as to why after doing routine maintence to this thing it all of the sudden runs worse (drives worse) than when I started. :banghead:

Thanks!

posted by  Blue_Frog

Might be a computer problem.

posted by  EvilPodAE

I don't know about your car, but around that time Ford had some troubles with ignition modules burning up and causes those exact symptoms. I've replaced 3-4 because of that.

posted by  DodgeRida67

What u should do FIRST is check the throttle body. Pretty sure u will find lots of black gunk in there. Clean that out if that's the case. Ford's from those years tend to stall only when hot in part due to this prob. It'ss cost u prolly 10 bucks to do this, so a def. try b4 changing anything. U will prolly need 2 people to do this as I'm sure ur engine wil stall or try to when u partially remove the intake hose to ur throttle body. Don't need to remove it completely, just enuff to squeeze in the can of throttle body cleaner.
Hope this helps. :thumbs:

posted by  Carcass

You know both of them ideas are starting to sound real logical to me. I've put off messing with it the past few days and just relied on it for short trips. Tonight I left it idling while I was getting smokes n beer but I got caught up in a conversation with a neighbor. When I got in the car (windows closed...they havent been when I've been tinkering with it) there was a distinct fuel smell in the air...like something in the fuel system was running rich. Hadnt noticed that before.

Thanks...those are real inexpensive troubleshoots I hadnt thought of yet.

posted by  Blue_Frog

Does it have a miss? If the manifold is cool enough to touch it means the cyl isn't firing. If so, check the compression and check for spark. Then if still doesn't solve anything, you've got problems.. ie.. bad injector.

Won't be the throttle body if the vehicle is running... Throttle body just supplies air to the cylinders, if one cyl is getting air, they all will be. fuel is the problem.

posted by  88GrandPrixSE

Hard to say if there is a miss...havent done compression tests cuz I havent had the money to put a deposit on 'borrowing' a compression tool from a parts store. I dont hear or feel a miss fire (and yeah I've done enuff around to know the feel and sound of them) yet it does tend to do a light backfire if I rev it at idle for a few minutes and then let off.

The plugs arent dirty, scored, or fouled and they all get fire test when I pull them and put them to the block. I dont think its a missfire but I was planning on a compression test this weekend just to make sure I dont have a weak piston driving everything down. It did sit for like 9 months after all....there could be shitty seals or rings going on (UGH!...I hope not)

posted by  Blue_Frog

haha "borrow" hahahaha. If the header is cold though, 100% gueranteed the cylinder isn't firing for one reason or another... like a head gasket that has a major hole, no compression, bad injector..

A simple way to test for fuel is to take out the plug, and turn the engine over, then go out and see if it's wet around the plug or if it reaks of fuel, or if you had a flexible pen light, jab that right into the cyl and take a look to see if you can see any badly scuffed walls, coolant, fuel, etc.

posted by  88GrandPrixSE

No major hole in the head gasket....promise that. Have taken a garden hose to the whole engine listening for any kind of pressure or vaccum leaks. That isnt it.

However I will look at your description of testing for a weak cylinder again. I see it but have never heard of it. Can you explain it better? I know I'm getting pressure (wet pressure) from the hole that the plugs go into from doing the block / fire test and putting my finger over the open hole. Explain your method a bit more.....

posted by  Blue_Frog

It's just a very quick and dirty method to check for fuel. Just take out the plug of the cyl that isn't making any heat, and turn the car over with the key and a small amount of fuel should leak out of the cyl without the plug, or you should be able to smell it. I don't really know how to explain it better than that, it'd be easy to demonstrate, hard to explain.

posted by  88GrandPrixSE

WTF? it ain't compression prob as he would be guzzling oil. If u roil level is fine, don't mess with compression checks. Wasted time. Trust me ur throttle body is dirty, I've seen it at least 20 times. Clean it out, takes 10 minutes. And i bet u that ur idle speed will climb about 1000 RPM after it's done cause the previous numbnuts that worked on ur car in it's life adjust idle speed to compensate. U shouldn't ever have to touch idle adjuster. If u do it's cause ur car has worn parts. Clean out ur throttle body and then tell me I'm wrong, I dare ya. :thumbs:

posted by  Carcass

No I'm starting to think that the water pump is 'going bad' ( :screwy: every time I've ever had a water pump go bad or diagnosed repaired one it meant the water pump was obviously shot).

See my post today:

Cooling System Questions: (http://www.car-forums.com/talk/showthread.php?t=9798)

And go from there....

BTW the throttle is fairly clean.

posted by  Blue_Frog

What are you talking about, you don't know what causes a loss of compression obviously. So don't speak of what you don't know. It would not even touch the oil in lots of cases. If it was the throttle body it would not run at all, it wouldn't die after warming up. Don't question others methods when you don't know what you're talking about. Could easily be compression.

Is the water-pump making any noise? Is the vehicle over-heating? If not, chances are it's not the water-pump. Besides, if it were, and you constantly over-heated it, chances are you're going to break something, like are rod, or weld your piston to the wall, stuff like that. Over-heating can cause a lot of different problems. Screwed up my crank when I tried to hobble my car home when it needed a motor, needless to say, i didn't really care cause it already needed a motor.

posted by  88GrandPrixSE

That diagnosis like u said n I said appears to be wrong...I think it is an UNDERPREFORMING water pump though I have never heard of such a thing....all water pumps I have ever replaced have just plain been screwed....see my post today. Banff already convinced me that its worth a try.....

posted by  Blue_Frog

If u say so numbnuts. I`ve seen ur previous post about american cars vs imports, and u got burned pretty bad. Seems u know more about cars than me. And if ur so inclined, explain to me how a loss of compression in some cases doesn`t take oil. :clap:

posted by  Carcass

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