C20XE Early Engine Block With Late Valve Head

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You are using an out of date browser. It may not display this or other websites correctly.You should upgrade or use an alternative browser. C20XE early engine block with late valve head

• Thread starter Varnis9
• Start date Feb 18, 2019

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Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus Hello guys My C20XE has an early bottom end, merged with a late cylinder head (Motronic 2.8 ecu and wiring loom with all sensors). The engine has never run properly during idle. When on cruise though it works sweet, The symptoms I have are:

1. Sometimes the engine starts on second crank
2. Rough idle
3. When it starts it sticks at around 3000 rpm then drops to 1000 ish after a few minutes
4. Smells fuel at exhaust

I have replaced almost all sensors, took ecu wiring out and checked all good, no ecu fault codes, checked timing and fuel pressure at 2.5bar as it should.. I have started thinking maybe it is an incompatibility between old bottom end and late cylinder head? Can anyone share some light on this? Thanks

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales I doubt very much it’s anything to do with incompatibility between the head and block. Unless someone has made a real bodge job of matching it up.... it sounds more likely to be an electronic/ECU issue. If the engine had a distributor initially, your problem may lie in the loom conversion from M2.5 to M2.8. There are many different types of sensors between the 2 My Fast Road/Track build Instagram

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus It looks like the 2.8 was transferred as a whole, cylinder head and sensors, to the early bottom end. Wiring has been sliced open checked for shorts, broken wires all good, replaced connectors and pins. Still to no avail.. Loosing my mind with the car now.. Not sure if it is something to do with timing difference between early crank and late camshafts?

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales Round or square tooth belt/pulleys? I assume you are running an M2.8 ECU ? Have you tried changing your MAF/Lambda sensor ? My Fast Road/Track build Instagram

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus

AndyB-Redtop said: Round or square tooth belt/pulleys? I assume you are running an M2.8 ECU ? Have you tried changing your MAF/Lambda sensor ? Click to expand...

It s got round teeth pulleys. Changed lambda and afm with genuine still no luck. Yeah running 2.8 ecu.. You got any suggestion pal?

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales It’s difficult to determine really. Having an earlier block with a later head and running M2.8 shouldn’t give any issues really, unless you have something else going on. ICV needs attention maybe? My Fast Road/Track build Instagram

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus Replaced 3 of those fuckers, also checked wiring all good. Also checked voltage with engine off gives a solid 12v.

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales There is a difference between the early/late camshafts, well, only that the exhaust cam isn't as long on late than early to drive the distributor. The later has a different profile on the end for the coil/ignition sensor. Doubt that is your problem though because if the head was just bolted on, you already have the right cams on the engine because it runs. The cam lobe profiles should be exactly the same "Standard". Are you running non standard cams, i.e. higher profile/lift cams? If so, these might need tweaking/retarding slightly...…. But then you say it runs sweet when cruising...… Have you tried a compression test on your cylinders? Thinking of your 3000rpm on idle, what's your "blow-by" Crankcase pressure like going back to the inlet manifold through the 2 breathers from the head? My Fast Road/Track build Instagram

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus Done both compression test and engine air leak test all good within specs. The engine runs standard cams. Not sure about that blow-by pressure through the breathers. Can I measure that?

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales If your compression/air test came back good, then there should be no worry for blow by from the crank, through the breathers to the inlet. That can be ruled out. I just thought if you had poor compression, you’d have a lot of blowby going back to inlet, thus causing rough and high idling. My Fast Road/Track build Instagram

**GSI-16V**

Joined Sep 24, 2009 Messages 515 Best answers 0 Reaction score 50 Location bucks Think later ones had blue injectors rather than cream and cars with traction control had a black coolant temperature sensor and the rest are blue. Not sure if there compatible with each setup but worth looking into.

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales

**GSI-16V** said: Think later ones had blue injectors rather than cream and cars with traction control had a black coolant temperature sensor and the rest are blue. Not sure if there compatible with each setup but worth looking into. Click to expand...

Yes, I agree with this My Fast Road/Track build Instagram

TomF

Joined Jul 30, 2006 Messages 2,521 Best answers 0 Reaction score 99 Location Liverpool RE Idle control valve, have you read this: Massive improvement in idle C20XE ICV readjustment Mk2 GTE C20LET Mk3 GSi C20LET Mk4 SRi Z20LET Corsa B C20LET Mk3 Track C20LET Mk5 VXR Z20LEH​

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales

TomF said: RE Idle control valve, have you read this: Massive improvement in idle C20XE ICV readjustment Click to expand...

Excellent find that mate . Something I’ve learned today. My Fast Road/Track build Instagram

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus According to my ecu part number its off an astra 1993-94 not sure if that's "late" or early!

AndyB-Redtop

Joined Sep 20, 2017 Messages 570 Best answers 0 Reaction score 91 Location Llanberis North Wales

Varnis9 said: According to my ecu part number its off an astra 1993-94 not sure if that's "late" or early! Click to expand...

That's right on the crossover to the later C20XE (LN) "Low noise". It should state M2.5 or M2.8 on the ECU I suddenly remembered having a chat with you regarding your engine On this Thread My Fast Road/Track build Instagram

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus So the ecu I have is correct? Here is a photo of my ecu if that helps..

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**GSI-16V**

Joined Sep 24, 2009 Messages 515 Best answers 0 Reaction score 50 Location bucks Ive checked the part number in the picture and it is a 2.8.

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus Going to try the icv adjustment hopefully it will make a difference

Varnis9

Club Member Joined Jun 29, 2015 Messages 299 Best answers 0 Reaction score 21 Location Cyprus Any suggestions on the second crank engine start issue? I have checked on the pressure regulator and the pressure does not pick up during first crank... Last edited: Feb 20, 2019

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