.

Cam position sensors would be my guess. They don't always throw codes/put EML on.

Tony.
 
  • Like
Reactions: Lee
@t-tony what about plugs or coil packs? It literally does it only when cold and then when warm it runs really nicely. Assume it would have a constant issue if either of those ?
 
Try cleaning the throttle body and also the idle control valve.

Tony.
 
ICV was done by @Lee earlier in the year..breaking the ‘how fast can I get an ICV out” record by some margin. Rattles like a baby’s toy. Throttle body worth a look.
 
  • Haha
Reactions: Lee
Why does the rough idle only happen when the engine is cold? That's because the engine control is on open loop when the engine is cold and then goes to closed loop when the engine is hot.

The only main sensor running in open loop is the MAF. As you have checked and fixed any vacuum leaks, try unplugging the MAF and doing a cold start. See if that fixes or improves the problem.
 
rmoconnor41 said:
One other thing. The smog pump was "enthusuiastically" removed one day and the blanking plate fitted. Is there anything leak wise I may have missed from its enthusiastic removal?
Click to expand...
I think it would have shown up on the various smoke tests. We can have another go but I think you are probably air tight now.
 
rmoconnor41 said:
One other thing. The smog pump was "enthusuiastically" removed one day and the blanking plate fitted. Is there anything leak wise I may have missed from its enthusiastic removal?
Click to expand...

There would be a small vacuum pipe to the valve you removed. It needs to be blocked off or you will have a vacuum leak. IIRC it comes from the rear of the inlet manifold. If there is no vacuum draw on the pipe when the motor is running, then it is possibly already leaking.

Tony.
 
Mine is a 4 cylinder. I have the exact same problem.

Car starts first turn of the key but, to me, it feels like it's only running on 3 cylinders.

Idles rough like that for maybe 2 minutes and then suddenly it'll run smooth.

I must confess it doesn't worry me much. By the time I've closed the garage door and buckled up my seat belt it's running sweet and off I go.

I just put it down to a bad spark plug, weak spark, that will sort itself out next time I service it. If it doesn't then I'll scratch my head and think of something else.
 
rmoconnor41 said:
Afternoon,

The vehicle is a 1999. 2.8.

For some time it has had a rough idle when cold. The revs swing between 800-400 until the vehicle is warm. Then the idle is very steady.

It is always throwing trim bank error codes . P0170 and P0173 Fuel trim bank 2 and 1 control limit.

MAF is newish
No air leaks. Thoroughly tested by the shed.
VANOS rebuilt
DISA and ICV checked.
Post CAT O2 sensors replaced.
Smog pump was removed and blanked off.
It threw a thermostat code on the shed's advanced code reader so that was replaced last week.

I am running out of things to check or replace.

Any thoughts?

Thanks
Click to expand...

Are your fuel trims indicating rich or lean? Knowing this will give you the direction where to look next. Sorry to say, diagnostics are often time consuming and frustrating but ultimately satisfying when finally resolved. Remember, your engine has three simple requirements: fuel, air and spark. There's still a lot of things that need to be checked (and re-checked).

Also, running the vehicle for long periods in this condition can damage the catalyst - sorry again.
 
I have had a look online at cam sensor The price and range of brands is huge. Is the original made by Siemens?
12141703221
 
You must log in or register to reply here.
Back
Top