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[Omegafantasy]

Good evening all 

My Omega is finally on the road again, it sure took some time to get things done, but well worth it.

I have checked with the thread and pictures in http://www.omegaowners.com/forum/YaBB.pl?num=1152565204, but I have one question: The smaller hose that is molded onto the larger hose to the IAC, what should it be connected to? I think I have mixed up something hehe.. As it is now, it's connected to the rear multi-ram valve, which I think is wrong. Maybe it's for the fuel pressure regulator?

If anyone can clear this up I'd be pretty happy, the car lack some power..

Besides this, the X25XE to Y26SE conversion went without much trouble. I did not change the rocker covers (=exposed plug holes which filled up with water when the car sat for some weeks without the scuttle fitted).. A pain to drain :p

[JamesV6CDX]

Hiya,

The idle control valve smaller pipe, goes to the fuel pressure reg on the inlet manifold

[Omegafantasy]

Aha!
Thanks for the prompt response and clearing that up 

A quick dinner and I'm off doing some plumbing.. Cheers

[Omegafantasy]

Well, plumbing is done and the multi-ram system is working perfectly. I even think the FPR is happy.
On the other hand, I have one more case, which suddenly became more evident as the engine changed response; it's hesitating when pulling from low end to about 4000 rpm. I can't describe it in great detail, but the closer I get to 4000 the more it is stuttering. At 4000 it's like flicking a switch (almost like my modified C30SE in the old Omega A (Carlton) when the dual-ram opens). It's pretty powerless in the bottom (won't even let my wheels slip a bit in roundabouts when wet).

Some things I can think of:
- HT leads
- DIS pack
- Fuel pressure? (Filter?)
- Some other dubious electrical connection

What puzzles me is that it really comes to life at 4000 and it idles and drives very smooth unless I floor it. And no, no fault codes stored.

If it was an older car with distributor I'd say it was ignition timing, but that can't be the case on this system (at least you can't adjust it).

[Omegafantasy]

A little update regarding the poor response/misfire:

Today I've checked 3 of the spark plugs (just for the easy access and steaming hot engine). All three looked very nice, hvite and clean insulator with a tiny brown ring at the end. Electrodes looked flawless. Must be changed quite recently.

I tried disconnecting the knock sensors (as described in another thread) and took her for a spin. EML light right away and completely undrivable. That rules out DIS pack, or? I still have a feeling it's the DIS-pack or leads, I just don't want it to be that expensive (we're talking £250 for the DIS and £130 for the leads here in Norway)!
Also, while driving, I have some kind of vibration/resonance from the engine from about 2000 to 4500 rpm, which again points towards ignition.

Does anyone have any clue where to look for fault? I don't like being outrun by old volvos :p

[Andy H]

Is your multi-ram set up operating correctly?

The control flaps are meant to open/close as the revs change to give a variable length inlet tract. The the natural frequency of the inlet pipework is intended to match the frequency of the inlet pulses to aid filling the cylinders with air.

IIRC the flap in the H shaped piece behind the radiator should be closed up until about 1500rpm and the flap in the back of the plenum should be closed up until 4000rpm.

If they both stayed closed at higher revs then I imagine there would be an audible resonance and loss of power  :-/

[Omegafantasy]

I have checked those and they do work as they should. You feel it really good at 4000 rpm also, but still, there's not enough power. It's comparable to a four-banger as it is now

I've also been thinking about fuel supply, but then I wouldn't be able get more power in the top-end?

The FPR; it's connected to the hose from the intake duct going to the IAC (as in pre throttle). To me it sounds wrong :s I won't have much vacuum there when the IAC or throttle is nearly closed. Opening the throttle would cause more suction in the intake, but still wouldn't put a lot of vacuum on the FPR. Am I right here?
I have built this assuming the Y26SE and X25XE FPR works the same way.

[Andy H]

The position of the take off for the FPR seems wrong to me too but that is the way that GM designed it apparently.

I am sure you must have checked it already but I would check the cambelt / camshaft timing again.

[Omegafantasy]

Well, I haven't checked the timing yet. I really really should do! I got the engine nearly fresh from service though. About 1500 miles since full service with cambelt (although no evidence if tensioners was changed too). Gotta be sad for the previous owner getting rear-ended right after big service  :-? Sigh.. Dismantling the cambelt cover is a several beer job, but better do it anyways.

I'm thinking about trying two things:
1) Block vacuum hose to FPR and see how it acts.
2) Apply constant vacuum to FPR for comparison.

EDIT: Have now tried option 1, blocking the vacuum. Made no difference at all at any load or rpm. This can't be right? Gonna hook up my fuel pressure gauge tomorrow and have a closer look.

[Omegafantasy]

Update:
Have checked all six plugs now and they look ok. Evenly worn (well, they look new) and slightly white ground electrodes (which you can rub blank with your finger).

I have now connected the fuel pressure regulator vacuum to true manifold pressure and that actually helped a bit,  but it doesn't change the fact that it's gutless.

On light throttle it's ok, acting normal. On WOT from 1000 rpm in second gear it is still hestitating a lot, worse the closer I get to 4000 rpm until the back multi ram flap opens. Getting a decent kick from that one, but still only accellerating like a four-banger.

The exhaust is hot, really hot. I cannot touch the tail pipe when idling and if I rev it it's too hot to even get near. My friend burned his hand  It also smells a bit funny, but nothing like bad eggs as a blown catalytic converter.

One more thing left to do: Check timing.. Awh, not looking forward to dismantle that 

Still looking for clues or hints if anyone has the same experience?
Just FYI; this is a Y26SE with X25XE sensors and intake to fit 95 Omega. EGR valve is blocked with blanking plate right at the plenum. Injectors, fuel rail and FPR from Y26SE, DIS pack from X25XE.

I'm about to order a megasquirt or something... :s

[Omegafantasy]

Update again:
I got a bit upset about the whole thing so I did things a bit faster :p

Removed the intake ducts, aux belt and everything then took off the cambelt cover. Everything is lined up correctly according to markings on the cams and crankshaft. Although, there are two markings on each cam, one on each was marked red, I used those as a reference. Everything seems fine :s
Did not have a chance to look at the tensioner as the cover won't go completely off unless I remove the aux tensioner, tricky tricky. No excessive wear and tear to be seen, just a tiny tiny bit of belt dust on the waterpump, but nothing alarming.

Guess I put it back together then...

[manny]

Sounds to me like its being starved of air. Mine was the same when cold air feed got blocked by a rag. ( its a long story ).

[Omegafantasy]

Hehe, that sounds like a nice story 
Well, I'm almost certain mine isn't blocked. If I put my hand over the intake behind the grille it can suck my hand in if I rev it. You also get the "open air filter" sound if you jump it hard.

I still believe it's fuel problems. I just can't diagnose it. If I only had "My Naff Code Reader" or tech2 I could look at the parameters.

[manny]

But if it was a fuel problem why would it run ok after 4000 rpm ? Could it be a multi ram problem ?

[Omegafantasy]

It doesn't run fine over 4k, it's just a bit better when the flap opens. Would still get outrun by a four-pot auto 
I think the multi ram is fine, everything opens as it should now.

Also, not sure if I mentioned it: below 4k and WOT, it starts to vibrate a bit at the same time as it hesitates. Hmm, maybe try some higher octane fuel just to see if it retards ignition way too much.