Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: jereboam on 05 August 2010, 00:29:31

Title: Occasional surge in engine revs
Post by: jereboam on 05 August 2010, 00:29:31
Every now and then, there's a momentary jump in the engine revs.  It's most noticeable when waiting in traffic.  If I've got the handbrake on, I can feel the strain to move forward.  If I'm just holding it on the footbrake, I have to press harder to stop the car moving forward.

I'm also sometimes getting a bit of a thump when driving along.  It feels like it's coming from the rear axle, but that doesn't seem to make any sense.  I've been assuming that it was a problem with the gearbox, and I was going to get the ATF changed - I've had the car 4 years and it's never been changed. 

Now I'm beginning to wonder if the surge and the thump are related.  I had the coil pack replaced a couple of weeks ago, and I'm suspicious that they might have screwed something up.

Any suggestions?
Title: Re: Occasional surge in engine revs
Post by: feeutfo on 05 August 2010, 00:40:03
Possible air leak causing revs to rise? Did they remove the plenum to access dis PAC? Would think so. Check plenum is seated correctly and the seals to inlet manifold aren't pinched, vac pipes secure etc

Thumping defo atf related though.
Title: Re: Occasional surge in engine revs
Post by: Darth Loo-knee on 05 August 2010, 00:43:08
This may sound daft but check the gearbox breather has not being put wrongly onto the breathers on the rear of the plenum. Seen this a couple of times.  :-?
Title: Re: Occasional surge in engine revs
Post by: feeutfo on 05 August 2010, 00:56:34
Quote
Possible air leak causing revs to rise? Did they remove the plenum to access dis PAC? Would think so. Check plenum is seated correctly and the seals to inlet manifold aren't pinched, vac pipes secure etc

Thumping defo atf related though.
Also is icv seated correctly?
Title: Re: Occasional surge in engine revs
Post by: jereboam on 05 August 2010, 01:19:12
Quote
Quote
Possible air leak causing revs to rise? Did they remove the plenum to access dis PAC? Would think so. Check plenum is seated correctly and the seals to inlet manifold aren't pinched, vac pipes secure etc

Thumping defo atf related though.
Also is icv seated correctly?

Sorry - I don't even know what an "icv" is, or where it wold be found, let alone  know how to check if it is seated correctly.   :(

But thanks for the help.  I'll get another garage to check it all out, and possibly change the ATF.

(I only know that abbreviation because I read it on this forum - I'm not very good with cars.) :)
Title: Re: Occasional surge in engine revs
Post by: feeutfo on 05 August 2010, 01:29:15
Quote
Quote
Quote
Possible air leak causing revs to rise? Did they remove the plenum to access dis PAC? Would think so. Check plenum is seated correctly and the seals to inlet manifold aren't pinched, vac pipes secure etc

Thumping defo atf related though.
Also is icv seated correctly?

Sorry - I don't even know what an "icv" is, or where it wold be found, let alone  know how to check if it is seated correctly.   :(

But thanks for the help.  I'll get another garage to check it all out, and possibly change the ATF.

(I only know that abbreviation because I read it on this forum - I'm not very good with cars.) :)
Icv, idle control valve.

Silver mustard pot sized canister pass side pf plenum on top of the engine, needs no more than a visual check J. Just make sure it's seated in its rubber gronit, peazy.
Title: Re: Occasional surge in engine revs
Post by: jereboam on 05 August 2010, 18:09:23
Quote
Quote
Quote
Quote
Possible air leak causing revs to rise? Did they remove the plenum to access dis PAC? Would think so. Check plenum is seated correctly and the seals to inlet manifold aren't pinched, vac pipes secure etc

Thumping defo atf related though.
Also is icv seated correctly?

Sorry - I don't even know what an "icv" is, or where it wold be found, let alone  know how to check if it is seated correctly.   :(

But thanks for the help.  I'll get another garage to check it all out, and possibly change the ATF.

(I only know that abbreviation because I read it on this forum - I'm not very good with cars.) :)
Icv, idle control valve.

Silver mustard pot sized canister pass side pf plenum on top of the engine, needs no more than a visual check J. Just make sure it's seated in its rubber gronit, peazy.

Think it's OK - it doesn't move and seems to be tied on securely. 

I had a look at the tubes going into the back of the plenum, but it's utterly beyond my physical abilities to investigate where they come from, so I've got no way of ensuring that they are connected correctly. 

What I did notice was that the covers for the hex bolts which secure the thing in place are no longer there.  Before they did the coil pack, only one of them was missing.  I know that's not what's causing the trouble, but to me it indicates sloppy workmanship, and I'm now worried about what else they had left over after they'd finished. :( :( :(
Title: Re: Occasional surge in engine revs
Post by: duggs on 05 August 2010, 18:32:10
I had the same.  In my case the crack sensor was on its way out. Eventually, it jumped and died and wouldn't start again for 15 mins or so.

Changed the sensor, hasn't done it since.