Engine Idle and 3k rpm

  • Thread starter Thread starter Ricardo
  • Start date Start date
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Ricardo

Hi all,

and happy new year!

Took the Volvo 740 Estate 2ltr 1990 (G reg in the UK)for it's MOT last
weekend. Suffice to say, it sailed through with no problems at all.

The day before the MOT the engine idle was a bit rough to the extent that it
would drop to around 300rpm(ish) and then stall. A quick squirt of carb
cleaner and a cloud of smoke later, the idle leveled at 750-800rpm(ish), the
power came back and the white smoke that was coming out of the exhaust
cleared.

Now I have been left with an interesting problem. If I keep the revs below
3000rpm the engine will return to an idle of 750-800rpm. If I go above
3000rpm the engine will idle at 1500 rpm and stay the same until I turn the
engine off. This is making breaking very interesting indeed.

I've tried resetting the ECU by disconnecting the battery for an hour or so
but this hasn't helped.

Could any one offer any advice?

Many thanks,

Richard
 
Ricardo said:
Hi all,

and happy new year!

Took the Volvo 740 Estate 2ltr 1990 (G reg in the UK)for it's MOT last
weekend. Suffice to say, it sailed through with no problems at all.

The day before the MOT the engine idle was a bit rough to the extent that it
would drop to around 300rpm(ish) and then stall. A quick squirt of carb
cleaner and a cloud of smoke later, the idle leveled at 750-800rpm(ish), the
power came back and the white smoke that was coming out of the exhaust
cleared.

Now I have been left with an interesting problem. If I keep the revs below
3000rpm the engine will return to an idle of 750-800rpm. If I go above
3000rpm the engine will idle at 1500 rpm and stay the same until I turn the
engine off. This is making breaking very interesting indeed.

I've tried resetting the ECU by disconnecting the battery for an hour or so
but this hasn't helped.
Click to expand...

Throttle switch is knackered?

Tim..
 
IRT "Throttle switch is knackered?"

Oh! Is that going to be expensive?
Also, could a reletive amature fix it?

Thanks,

Richard
 
Ricardo said:
IRT "Throttle switch is knackered?"

Oh! Is that going to be expensive?
Also, could a reletive amature fix it?
Click to expand...

You dont mention which engine you have, we ought to start there, but yes,
the TPS is a bolt-on + wiring plug job.

However, i would want to test it first to make sure that is the culprit.

tim..
 
The engine is a B200F

Thanks for the tip. I'll let you know how I get on.

Richard
 
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