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Discussion Starter · #1 ·
When I stop suddenly at lights etc. The rpm drops between 590-670 (hot engine) and stays there down go up. and oil light comes on, flickers? when I am making high rpm there is no problem. but when i stop and hold the break engine acts like it is gonna die and then comes back on and off. I checked oil replaced it with synthetic etc. But when I stop slowly the rpm stays between 740-820 (hot). It happened long time ago after i put a new engine in it. the oil light was flickering and after 2 days it broke down i had to replace piston heads. there is no electrical problem on the car. alternator is new starter is new. any idea?

thanks.
 

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Discussion Starter · #3 ·
Where did you move it? I can not find it? title of the chat is "Threads in Forum : Ford Focus & General Car Chat" then why did you move it? and where?

Where did you move it? I can not find it? title of the chat is "Threads in Forum : Ford Focus & General Car Chat" then why did you move it? and where? thanks.
 

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It was moved to General Technical Chat because you're describing a mechanical or electrical problem.

First off, it would be good if we knew what engine your vehicle came with. For now I'll assume that it is a Zetec because those are the most common. This will be written on the valve cover. If you have a Duratec, the plastic intake manifold is in the front of the engine compartment between the radiator and the engine, it has coil on plug ignition, and there is nothing written on the valve cover. If your spark plugs go into the side of the engine and not through the valve cover, then you have an SPI.

Zetecs have issues with the PCV valve vacuum line, and Ford has a fix for it. Purchase a new PCV vacuum line from a Ford dealer and it will come with heat protection. That causes idle issues, but there are other causes. This should always be checked because it is so common in Zetecs. Replace the PCV valve at the same time if you find a damaged PCV vacuum line. Typically vacuum lines cause high idle, but in the case of this line it can cause low idle issues when the line collapses due to heat damage to the rubber.

The idle air control valve could also be your problem. I never suggest replacing it first. I think the best way to diagnose if you have an IAC problem is by cleaning the part. This fixes it most of the time. I would also recommend going through what is considered a tune-up on this car= plugs, wires, clean the MAF, replace the air filter, replace the fuel filter. If you need help with these items, don't hesitate to ask.

Once finished with your repairs or tune-up, reset the A/F ratio by unplugging the negative battery terminal for 10 mins. Then start the engine without touching the accelerator. If you have a tachometer, you'll notice that the engine speed is around 1k rpm. It will remain around 1k rpm until the test finishes. This is a timed test, and the test begins when the idle settles down to 1k rpm. I do this on a warm engine. It should take approximately 6 minutes unless you touch the accelerator. If you do, the test will restart. When the test is finished, the idle will drop to normal which is about 800 rpm.
 

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Discussion Starter · #5 ·
Sorry forgot to mention I have an 2.0 SPI single head cam. I cleaned up throttle body. replaced the oil with 5-20 synthectic oil. reset the computer. no hope. it is ok when it starts cold. when i stop at the red light suddenly it drops to 620-680. I park it idles around 710. PCV is good too. any idea?
 

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You checked to make sure that the PCV vacuum line wasn't collapsed at idle? It will do that on SPI also. The reset won't work if you haven't found a problem, sorry, I forgot to mention that.

When was the last time you changed your fuel filter? It has a 20k mile or 1 year lifetime.

Air filter?

Have you located and cleaned the IAC?

Has anyone messed with the throttle plate adjustment screws on the TB?

Mileage on the car?
 

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C2H5OH
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About 100rpm disparity between idle in Park and idle in Gear, sounds correct to me.

To me it sounds like this is something best left to a professional.
 

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Discussion Starter · #8 ·
Thanks for the comments guys,
Another thing I guess i forgot to mention. The engine had dropped valve problem.
I put a remanifactured engine on it. This flickring light problem came up. Oil light
flashing on and off. I heard a bad noise from passenger side. And it broke down again
this time replaced cylinder heads. Mechanic told problem was bad timing belt idler(cannot remember maybe tensioner)
But now it started happening again. I am afraid it will cost another engine to me.
I replaced fuel filter long time ago. pcv valve is new. I havent checked IAC yet. Cleaned up
throttle body. Air filter is all good. i took it to a professional I do not know why he said he does not
want to bump the idler up or something like that. Since it is a new engine I do not
know the answer for throttle body adjustment etc. milage is not even 2000 miles.
well right 100 rpm disparity seems ok but it is not steady it goes down a lot between 590 and 620 with hot
engine when i make sudden breaks. or stop at the red lights. the oil light is flashing. and engine acts like it is gonna
die and then comes back to normal.
 

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C2H5OH
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Well, the oil light is not designed to "flash".

And being none of us know what parts were reused from the old engine, we have no idea if one or more of those parts was/is also bad.
Which is why it's going to be easiest to bring the car back to whomever installed the engine for further diagnosis.

And a reman engine with only 3,000 miles, I'd sure think there's still warranty on it.
 

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Discussion Starter · #10 ·
Absolutely, It is designed to flash. But not when the oil level is good and only when I stop at lights. And almost all parts new only egr valve and air filter box maf etc is old.
 

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C2H5OH
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Absolutely, It is designed to flash. But not when the oil level is good and only when I stop at lights.


NO IT IS NOT.


The oil light is designed so that it lights up when oil pressure falls below about 6psi.

If the light flashes, that would mean the oil pressure falls below and rises above cyclically. That may indicate a problem with the pickup or pump.


The light has very little to do with oil level.
 

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As said the light does not flash, it only appears to. If cold engine doesn't do it and only hot does then you are looking at an oil pressure issue most likely and engine troubles. Could be idle is low enough to simply flicker the light. You cannot adjust the idle speed up, it is electronically controlled and why your guy didn't touch it. He knows that. The throttle blade can be cracked open more but the computer simply readjusts back to the same speed as before.
 
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