Dodgy Idle + Tuning - Calibra

Tican · 1 Sep 2008 at 18:57

HI all,

One thing I have noticed with my car is that it idles at around 5-600rpm, and makes the whole car shake,

What is the easiest way of making the idle around the normal 900rpm (holding the revs at around 900-1000rpm makes the dodgyness go away

)

It is the 8v engine.

On another note, how easy is the engine to tune? and what bits are needed

Lashout_UK · 1 Sep 2008 at 19:08

Got a picture of the engine bay/intake to hand? There's probably a screw which you can rotate to raise the idle RPM.

Tican · 1 Sep 2008 at 19:11

I'll go out and get one

Give me a few mins

Dogbreath · 1 Sep 2008 at 19:16

This engine has an idle control valve which is controlled purely by the ECU. An incorrect idle could be caused by numerous faults such as air leaks, gummed up idle control valve (very common), incorrect cam timing etc. You need to source the cause of the poor idle before it can be fixed.

Tuning the engine is doable but why didn't you buy a 16v if you wanted more power?

Tican · 1 Sep 2008 at 19:23

Ah right, there is some tape over the air feed, maybe that has come loose or isn't working

Might have to source a new pipe

Pictures of engine bay (first picture you can see the tape)

http://www.metalmayhem.org/ian/cally/01092008193.jpg

http://www.metalmayhem.org/ian/cally/01092008194.jpg

Dogbreath said:
This engine has an idle control valve which is controlled purely by the ECU. An incorrect idle could be caused by numerous faults such as air leaks, gummed up idle control valve (very common), incorrect cam timing etc. You need to source the cause of the poor idle before it can be fixed.

Tuning the engine is doable but why didn't you buy a 16v if you wanted more power?

Any idea's on how to check on the faults? (no engine management light etc. but I guess there won't be)

Meh, I don't know, I am not too fussed on tuning, perfectly happy with the car , but something to do in my spare time I guess!

Dogbreath · 1 Sep 2008 at 20:22

Any leaks in that convoluted pipe with the red tape on will cause problems since the engine will be drawing in unmetered air (i.e. air that hasn't been through the mass airflow meter) and the engine will be running lean.

The idle control valve is the cylindrical item connected to the right hand side of the plenum with a short pipe, and another long black pipe running back to the throttle body. Take it off and give it a good flush with carb cleaner.

penski · 1 Sep 2008 at 20:29

Tuning parts are quite plentiful; the engine was a mainstay of the autograss lot for many years.

Cam, manifold and remap will have you kissing 150bhp.

If you have the dollah, 220+ is possible.

I know a guy with a 180bhp 1600 Family II lump in his Astra rally car. Revs to 8,750 and does about 5mpg on stage.

*n

Tican · 1 Sep 2008 at 20:31

This?

Sorry I am useless with car's (well I know what I am doing to a degree once I know what something is

)

Tican · 1 Sep 2008 at 20:34

penski said:
Tuning parts are quite plentiful; the engine was a mainstay of the autograss lot for many years.

Cam, manifold and remap will have you kissing 150bhp.

*n

Any links for this (or search terms

) ? Are the engines 115 bhp standard, can't remember?

Biohazard · 1 Sep 2008 at 23:49

DJ Binks said:
This?

Sorry I am useless with car's (well I know what I am doing to a degree once I know what something is )

Yeah, thats your ISCV.

Dogbreath · 2 Sep 2008 at 00:10

DJ Binks said:
Any links for this (or search terms ) ? Are the engines 115 bhp standard, can't remember?

Calibra 8v 115bhp, 125 lbft
Calibra 16v (C20E) 150bhp, 145lbft.

Spending a chunk of cash will get it up to standard 16v performance levels. The 16v engine is good for over 200bhp without touching any internal parts (i.e. induction, fueling and exhaust changes only).

One possible route might be the 8v engine from the SRi 130 cavalier and 2.0 8v Astra GTEs (engine code 20SEH). It's the same basic engine but with a different cam, ECU and (I think) different pistons giving higher compression.

This is the very detailed website of someone who went down the 2.0L 8v tuning route with his Astra GTE, rather than getting a 16v.

http://www.clubcalibra.com/ or http://www.cavweb.com/ may be useful sources of information.

Biohazard · 2 Sep 2008 at 10:29

Dogbreath said:
Calibra 16v (C20E) 150bhp, 145lbft.

The 16v engine is good for over 200bhp without touching any internal parts (i.e. induction, fueling and exhaust changes only).

Come again?

Dogbreath · 2 Sep 2008 at 10:33

Biohazard said:
Come again?

Err, not sure how I can simplify it further to be honest, but I'll try:

You can extract over 200bhp from the C20XE by only fueling, induction and exhaust changes. The engine internals (cams, porting, valves, pistons etc.) do not need to be changed to achieve this power.

Any better?

aproctor · 2 Sep 2008 at 11:21

Dogbreath said:
Err, not sure how I can simplify it further to be honest, but I'll try:

You can extract over 200bhp from the C20XE by only fueling, induction and exhaust changes. The engine internals (cams, porting, valves, pistons etc.) do not need to be changed to achieve this power.

Any better?

i.e you do not need to fit turbos or get remaps.

Sone · 2 Sep 2008 at 12:55

aproctor said:
i.e you do not need to fit turbos or get remaps.

i thought as in not new cams or forged pistons etc :confused:

anything to do with the fueling will surley require a remap / new ecu?

Biohazard · 2 Sep 2008 at 22:00

Dogbreath said:
Err, not sure how I can simplify it further to be honest, but I'll try:

You can extract over 200bhp from the C20XE by only fueling, induction and exhaust changes. The engine internals (cams, porting, valves, pistons etc.) do not need to be changed to achieve this power.

Any better?

50 bhp on a N/A 2ltr 16 lump by which induction changes?

More fuel is pointless without more air, so how are you getting all this extra air/flow without porting? A filter change isn't going to achieve that.

Lopéz · 2 Sep 2008 at 22:08

Who mentioned a filter change?

Biohazard · 2 Sep 2008 at 23:54

Lopéz said:
Who mentioned a filter change?

That is why I am asking.

I want to know what can bring 30% odd increase in power and torque on a N/A without having to split the block.

Dogbreath · 3 Sep 2008 at 08:48

Biohazard said:
That is why I am asking.

I want to know what can bring 30% odd increase in power and torque on a N/A without having to split the block.

Throttle bodies (and and aftermarket ECU to control fueling) and a well designed exhaust manifold. And that's pretty much it. A budget installation can use bike throttle bodies and megasquirt and a pair of DCOEs can get you to around 180bhp if you prefer carbs.

SBD Taper throttle body conversion

Why do you think the 20XE has got such a name for itself?

Biohazard · 3 Sep 2008 at 10:44

Dogbreath said:
Throttle bodies (and and aftermarket ECU to control fueling) and a well designed exhaust manifold. And that's pretty much it. A budget installation can use bike throttle bodies and megasquirt and a pair of DCOEs can get you to around 180bhp if you prefer carbs.

Why do you think the 20XE has got such a name for itself?

Carbs can be just as efficient btw.

I'm not going to argue as I don't know the 20xe that well, but TB's without wilder cams is slightly half assed. Also, what are the exhaust manifold changes? Any pics of the before and after manifold? Tubular isn't always best, losing low end for high end grunt. Either which way, I'd rather have headwork first then TB's. Not the other way around.

Still a lot 30-50 bhp from a manifold and carbs without headwork imo.

edit: making up a loom to use with megasquirt just now

having just finished my headwork. with that, ported inlet, TB, and slightly worked valves I'll be lucky to gain 15% (from 140). tb manifolds hard to come by on my lump. :./