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[erubus]

Hi there guys.  I've now had my 2.0 16v X20XEV omega for 4 or 5 months and still can't get it to work.  So far the EGR, coilpack, leads and plugs, airflow meter, idle valve, ecu chip and transponder, head gasket, inlet manifold, servo pipe, coolant temperature sensor and most of the vac pipes under the bonnet have all been changed as well as the complete exhaust system and a few other things.

the symptoms are a very rough idle, backfiring into the inlet manifold, inability to hold the revs at a steady speed and cutting out.  It seems to run ok above about 2'500-3'000 rpm.

I did a compression test the other day just in case and got 180psi per cylinder.  the plugs are sooty, but with white soot at the tips.

squirting easy start around the engine bay made the revs rise when sprayed in the vicinity of the servo pipe hence the replacement, but i have run out of the spray so haven't tried it since fitting the new one, although i coated all the joints with RTV as a back-up.

nothing sems to make any difference and i'm running out of things to change! (and money)  I have had it plugged into a computer and didn't get any useful information.  was told to replace the AFM and ICV and if that didn't work wire the ICV straightto the ECU, and if that didn't work to change the ECU.  all of which i have done with absolutely no difference to the way the engine runs.

The injectors all give a strong fully atomised spray and all plugs spark.

Now question time:

If i pull the vac pipe off of the diaphragm bit of the coilpack should this do anything?  it doesn't, so i'm wondering if maybe the diaphragm has burst and isn't advancing/retarding the ignition if that's what it does??

also if i pull the vac pipe off the fuel pressure regulator, should that make any difference?  again it makes no difference.

been looking for a replacement engine, but can't seem to find any anymore.  the used to be ten a penny, but the few that i have found are going for silly money. i still have the 20SEH, but i'm still not keen to fit it, more fuel, less power and it's done 240'000 miles already!

thanks in advance for any advice.

[Marks DTM Calib]

Are ALL the vac connections made to the inlet, from memory there are 3, one for the brake servo (large), one for the small breather and a third (to the EGR?)....which I cant totaly remember where it goes.

Classic vac leak symptoms though.

Ow yes....NEVER EVER PUT EASY START NEAR ANY ENGINE.

Its the chemical of the devil and spells death to all engines

[aaronjb]

Wouldn't backfiring through the intake indicate either a serious spark/cam timing problem, or an intake valve failing to close properly?

The last time I saw that behaviour (including a nice sheet of flame!) was on a Renault that had bent a valve after cambelt failure..

[erubus]

all vac connections are present, connected and don't leak.  easy start is the chemical of the devil, but useful for locating vacuum leaks.

there had to have been a vac leak somewhere, as the easy start made the revs go up when sprayed in the general area of the servo pipe, which has now been replaced and well and truly sealed, as has the fuel tank vent valve and associated piping, and all other pipes.

The backfiring into the inlet is the thing that is confusing me.  as aaronjb says, it could be a valve timing thing, but the timing checks out. all pointers are in the right place when no 1 is at tdc.  i know it isn't bent valves as the compression test reads 180 psi on each cylinder (+/- 2 or 3 psi) which kind of leads me to think that the ignition timing is miles off, far too advanced I would think, which would also explain why it runs ok at high revs.

is the advance/retard controlled by the ecu though, or is it by the vac connection to the coilpack?  If it's the ecu i can pretty much rule that out as it's been replaced.  i have tried a new coilpack on it, but not changed the vac thing around.

cheers, gill

[Welung666]

all vac connections are present, connected and don't leak.  easy start is the chemical of the devil, but useful for locating vacuum leaks.

there had to have been a vac leak somewhere, as the easy start made the revs go up when sprayed in the general area of the servo pipe, which has now been replaced and well and truly sealed, as has the fuel tank vent valve and associated piping, and all other pipes.

The backfiring into the inlet is the thing that is confusing me.  as aaronjb says, it could be a valve timing thing, but the timing checks out. all pointers are in the right place when no 1 is at tdc.  i know it isn't bent valves as the compression test reads 180 psi on each cylinder (+/- 2 or 3 psi) which kind of leads me to think that the ignition timing is miles off, far too advanced I would think, which would also explain why it runs ok at high revs.

is the advance/retard controlled by the ecu though, or is it by the vac connection to the coilpack?  If it's the ecu i can pretty much rule that out as it's been replaced.  i have tried a new coilpack on it, but not changed the vac thing around.

cheers, gill

So is carb cleaner and it won't strip every molecule of lubrication off everything it touched unlike Easy Start! Throw it away before you really knacker your engine.

[Marks DTM Calib]

Advance retard is electronic, no mechanical parts involved

[erubus]

balls.  thought that would have been too simple.

what exactly is the vac connection to the coilpack for then?

[Abiton]

What vac connection? DIS pack just has 4 HT leads and one LT multiplug, doesn't it?

The EGR has a vac pipe to it, and if plugged into the wrong place on the thing, will make it run very badly (tried it by mistake once  ).

I can get a photo of correct vac plumbing to/around EGR when I get home if that would be helpful. 

[erubus]

it must be that i'm thinking of then.  i thought the egr was the gubbins to the right of the engine behind the ecu, or is that the AIR?

if that's the case it's not the egr that's been replaced but the AIR thing.  either way they are both connected up correctly, or at least the same way as my cavalier xev was and that ran fine.

[erubus]

sorry just saw the bit at the bottom of your post.  that would be helpful if you could post a pic. at least it would confirm if it was plumbed correctly.

trouble is with this engine in the omega is it's so tight for space at the back.  the one in my old cav was dead easy to get in about (just as well the head was off more often than a whore's knickers on that engine)

[erubus]

last question before i have to go out for a while.  if the vac pipe was disconnected from the egr (assuming that's the one right next to the coilpack) would it make the engine behave differently?  pulling the pipe from it doesn't make any difference to the runnig, and if it should would suggest something was up with th egr, at least to my  mind....

i'm clutching at straws you may be able to tell.

[Abiton]

OK, I think the vac hose you're referring to is going to the valve that either links the carbon canister to the inlet, or doesn't.  Just below and to (UK) driver's side of DIS?

I've taken some piccies of the EGR plumbing,and a few other vac connections around this general area.  Will upload and post later.

On the EGR, next to DIS on passenger side, there should be two vac hoses on the rear (hardest-to-get-at) side, the lower of which goes to a tiddly dangling filter, the upper going to the throttle body area, via a (whitish on ours) hard-plastic vac pipe.  On the front side of the EGR there's a looped pipe going from high up on the thing, to lower down.  Pics may clarify!

[Abiton]

Right, hopefully these 3 pics will help you check the vac connections relating to purge valve and EGR.

1. EGR:


2. Purge Valve:


3. Vacuum sources for both of these:


Please excuse the grotty looking throttle body! 

[Big_Roger]

Hi,
You seem to have tried just about everything I can think of.

If youv'e been trying to get it right for a few months, have you actually tried driving it?  Do the brakes work?

I ask because I just wondered if the brake servo diaphragm is leaking.

I had this problem on a Maxi many many years ago.
Roger

[2woody]

blocked exhaust ?