Rough idle solutions

[shanep1987]

First off, i have replaced plugs and wires.. put a new iac on it, new air filter, cleaned maf, cleaned throttle body, checked pcv, and checked for vacuum leaks with carb cleaner. Nothing has helped. The rough idle seems to get worse with the engine/outside temp. When I first start it up it runs fine for a few minutes then the rpms drop around 7-800 and starts missing/shaking like hell and seems as if it wants to die on me. Also driving the truck runs good, intil i come to a stop. I am growing frustrated and I am just wondering if there is anything else I can check?

Thanks

 

[Insanejughead]

Throttle position sensor going bad, perhaps?

Have you pulled codes?

 

[shanep1987]

No cel....

 

[RustedRanger]

Check for codes with a volt meter like it shows in the tech section.

 

[shanep1987]

TPS is good.. also have noticed bubbling/hissing from the radiator cap. Normal?

 

[FireFighter431]

Where us your temp gauge runnin?
Try unhooking the EGR valve and see if that helps.


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[gw33gp]

TPS is good.. also have noticed bubbling/hissing from the radiator cap. Normal?

That is not normal. It is a good indicator that cylinder compression is getting into the cooling system. This is typically caused by a bad head gasket but could also be a cracked head. This can also cause a misfire at low rpm due to a reduction in compression.

 

[shanep1987]

Turns out this is the one year that didnt have an EGR from my understanding 2002 3.0. So what is my next step if it is a cracked head?

 

[PanamaExpat]

Do a search on cracked head and or blown head gasket and several of those threads will tell you how do diagnose those problems. One of them you sample the coolant for exhaust gasses and the other is a cold engine pressure test.

 

[powersmokin]

Get a simple block test kit and it will tell you if you have exhaust contaminate in your cooling system. Always good to have one on hand.

 

[fyre82]

Just put a rubber glove, large balloon or something like that on your radiator opening, start the engine and if the thing inflates its a good bet one of those is the problem.

Good luck

Rich

 

[killj0y]

That is not normal. It is a good indicator that cylinder compression is getting into the cooling system. This is typically caused by a bad head gasket but could also be a cracked head. This can also cause a misfire at low rpm due to a reduction in compression.

Yea sounds like a gasket or head, do you notice any smoke out the tail pipe? oil in the coolant? coolant in the oil? Or simply having to top off the coolant period? Overheating?

Just put a rubber glove, large balloon or something like that on your radiator opening, start the engine and if the thing inflates its a good bet one of those is the problem.

Good luck

Rich

This is a simple test that will tell you something is wrong. If this is the case you will most likely have to pull the heads one way or the other.

 

[shanep1987]

Radiator cap was bad, and coolant was dirty as hell and a bit low. Drained it; refilled seems to be fine. Engine never has overheated, nor have seen any smoke or water running from tailpipe.

I rented a fuel pressure test kit from o'reileys to rule out the fuel system. Damn thing didnt have the ford attacment.

I was thinking possibly the ECT sensor or maybe an O2 sensor, what are the chances?

 

[killj0y]

Radiator cap was bad, and coolant was dirty as hell and a bit low. Drained it; refilled seems to be fine. Engine never has overheated, nor have seen any smoke or water running from tailpipe.

I rented a fuel pressure test kit from o'reileys to rule out the fuel system. Damn thing didnt have the ford attacment.

I was thinking possibly the ECT sensor or maybe an O2 sensor, what are the chances?

Ect but sure but the o2 would likely throw a code. You said coolant was dirty? Was it low? Any oil in it?

 

[shanep1987]

No oil in it, probably 1/4 a gallon. By dirty i mean rust.