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-   -   2.5L Idling Rough and Stalling (http://www.fordrangerforum.com/4-cylinder-tech/88728-2-5l-idling-rough-stalling.html)

servant2thekng 04-06-2013 01:46 PM

2.5L Idling Rough and Stalling
 
My 99 2.5L Ranger will run fine above idle but at idle it runs very rough. Sometimes when coming down to idle it will sputter badly and stall. It always starts back up but sometimes takes a few tries.

The ecu threw codes for bank 1 lean and bank 1 misfire.

So far I have replace the plugs and wires, swapped the coil packs, replaced the injector in bank 1, cleaned and tested the IAC valve, and cleaned the MAF.

I cleared the codes but haven't given it a chance to see if the code comes back.

I am not really sure what else could cause these symptoms. Bad EGR Valve?

Thanks for any help or suggestions you can offer.

Offy 04-06-2013 03:11 PM

Re: 2.5L Idling Rough and Stalling
 
bad egr should throw a code. check your intake gaskets and throttle body gasket. I don't know if a vacuum leak could cause this.

servant2thekng 04-06-2013 04:07 PM

Re: 2.5L Idling Rough and Stalling
 
I have checked for a vacuum leak using starter fluid. Could that same test check the gaskets?

I just put a vacuum tester on the EGR valve and it won't hold any pressure. I think I should replace it. Even if it doesn't solve the problem it probably isn't working.

Offy 04-06-2013 04:19 PM

Re: 2.5L Idling Rough and Stalling
 
Same method will work for gaskets. I'm not familiar with this test for the egr. Could you elaborate on this?

servant2thekng 04-06-2013 05:41 PM

Re: 2.5L Idling Rough and Stalling
 
The EGR valve should hold a vacuum when applied by a handheld pump.

Example

This is the pump I used

I just put on a new EGR valve. I tested the old one after I took it off the truck. The valve wouldn't move when a vacuum was applied and it was stuck partially open. Unfortunately the truck still idle's badly but the other tests on that first link now work correctly.

I forgot to mention earlier that the fuel pressure tested good.

I did my best to spray around the head gasket but didn't notice any difference. If the gasket was leaking, how noticeable would the change in RPM be?

What else could I try?

servant2thekng 04-06-2013 07:52 PM

Re: 2.5L Idling Rough and Stalling
 
Using my scan tool I noticed that the O2 sensor after the cat doesn't register any volts until after the engine is warmed up and even then the values are way lower than the sensor in the exhaust manifold. Could it be bad? I tried to get it out to replace it but its rusted in there pretty well.

96_4x4_XLT 04-06-2013 08:33 PM

Quote:

Originally Posted by servant2thekng (Post 1347100)
Using my scan tool I noticed that the O2 sensor after the cat doesn't register any volts until after the engine is warmed up and even then the values are way lower than the sensor in the exhaust manifold. Could it be bad? I tried to get it out to replace it but its rusted in there pretty well.

Proly but it would make your engine stall or run rough if a o2 sensor is bad the engines computer will put the truck in a pre set mode for the engine to run

stateranger 04-06-2013 08:59 PM

Re: 2.5L Idling Rough and Stalling
 
Quote:

Originally Posted by servant2thekng (Post 1347100)
Using my scan tool I noticed that the O2 sensor after the cat doesn't register any volts until after the engine is warmed up and even then the values are way lower than the sensor in the exhaust manifold. Could it be bad? I tried to get it out to replace it but its rusted in there pretty well.

Thats how that o2 sensor is suppose to function. The only purpose it serves is to monitor your catalytic converter.

Offy 04-07-2013 05:53 AM

Re: 2.5L Idling Rough and Stalling
 
Above statement is correct. 2nd O2 sensor should only register after the cat is heated up and functioning. The signal should be different because the stream should chemically change after the cat.

When you said head gasket you meant the intake gaskets right? that is why I specified because that would lead to excess air into combustion chamber that MAF did not account for.

servant2thekng 04-09-2013 06:51 PM

Re: 2.5L Idling Rough and Stalling
 
Sorry I haven't responded sooner, I work long hours during the week.

Yeah, I was spraying around the head gasket, which doesn't make sense now that I think about it. I will try to do as you recommend, probably tomorrow after work.

I coworker who had similar problems on his 2.3 ranger said he fixed it by disabling the IAC and setting the idle manually. Is there any merit to that?

----------

Oh another thing, since I changed the fuel injector on bank 1 the running lean code has not returned. Looks like I have (Had?) multiple problems.

stateranger 04-09-2013 07:20 PM

Re: 2.5L Idling Rough and Stalling
 
I would say your maf is not working properly.

This will cause all the all the issues you are having.

servant2thekng 04-09-2013 08:20 PM

Re: 2.5L Idling Rough and Stalling
 
No it does not ping. I have noticed that when I first start the engine it idles very smoothly. It only runs rough after returning to idle after driving or revving the engine.

stateranger 04-09-2013 10:03 PM

Re: 2.5L Idling Rough and Stalling
 
Quote:

Originally Posted by servant2thekng (Post 1353968)
No it does not ping. I have noticed that when I first start the engine it idles very smoothly. It only runs rough after returning to idle after driving or revving the engine.

The ping i had was caused by tape blocking the maf which also caused one of elements on the maf to burn out..... What happens is the maf is sending the ecu an incorrect airflow reading at idle and while driving, sometimes you will get a lean code, if you have a scanner with a live data readout you will see fuel trim readings at +10 to +18 when normally they should be + or - 5. Also when the rough idle starts the O2 voltage will read .01 to 10 then jump up.

servant2thekng 04-10-2013 04:44 PM

Re: 2.5L Idling Rough and Stalling
 
So I just went out and sprayed starter fluid on the lower intake gasket. When I hit a certain spot the RPM's went down and it struggled to run a bit. Isn't that counter intuitive? Does that mean I need to replace the intake gasket? I think I am going to test it again as I ran out of what little starter fluid I had and couldn't do a through test.

Also, I got a cylinder 2 misfire code today.

Thank you all for your help so far.

adamhos 04-11-2013 07:01 AM

Check plug wires


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