150PS engine installed in 102PS van

[paesy23]

Long, story short I’ve had to replace the engine in my T6 102 highline as the old engine killed itself (44k miles, and out of warranty). Anyway, I sourced a new engine a very low mileage CXG model and my mechanic has just fitted it. I made a slight mistake though, as it turns out the new engine is a 150 bhp model and as a result this has resulted in a fault (flashing glow plug light along with an engine management light on the dash and code P008800 fuel rail / system pressure too high from the OBD reader).

My mechanic thinks that the fuel regulator on the new engine is providing the injectors with too high pressure and that the regulator is picking it up as a fault and telling the ecu, hence the warning lights. We’ve come up with 2 solutions which may or may not work. Refit the original regulator off my old engine - hopefully reducing the pressure to the engine, or remap the ECU, my mechanic isn’t sure if this will cure the issue (when they remap the ecu, do they adjust the pressure of fuel, or the duration of fuel at the injectors ?).

I’ve spent a fair amount of money to get to this stage and now I seem to be back to square one, although at least my engine is now running on 4 (rather than 3) cylinders.

Any help, advice or experience would be very much appreciated.

 

[Spaghetti]

Crikey. How did your original engine give up?

 

[DaveyB]

Oh man, that sucks. Can’t help i’m afraid, but I sure do hope you get it fixed.
Now tell us how the hell it blew up with just 44k on the clock.

 

[czmate1999]

hmmm, haven't a clue who would be best to help you, @Dellmassive @Pauly @Salty Spuds @Loz - any ideas who might have an answer on this one?

 

[Loz]

You didn’t mention if you had the ECU with the new engine or using your old ecu?

 

[mmi]

CXG model and my mechanic has just fitted it. I made a slight mistake though, as it turns out the new engine is a 150 bhp model

Hmmm... this is confusing. I have thought 150PS engines would be only CXH(A) and CXF(A).
CXG(A) would be 62kW(84PS), CXG(B) 75kW(102PS).

 

[paesy23]

Hmmm... this is confusing. I have thought 150PS engines would be only CXH(A) and CXF(A).
CXG(A) would be 62kW(84PS), CXG(B) 75kW(102PS).

Judging by the stamp on the timing belt cover both engines are definitely CXG, you’re definitely correct in saying that the CXGB version is the 102 as that’s what mine was. This is the code for the new engine

 

[paesy23]

You didn’t mention if you had the ECU with the new engine or using your old ecu?

Thanks, old ecu with the new engine. Ecu wasn’t available with the new engine

 

[paesy23]

Crikey. How did your original engine give up?

Not sure exactly what caused what, but basically on a trip back from Cornwall over Christmas the engine started misfiring, originally thought it might be an injector, but when we checked we found a hole in the inlet manifold. We removed the manifold and the port (in line with cylinder 2 had melted itself - see pic), not sure if the egr cooler failed and caused it to overheat, melting the port and putting plastic into the engine, or there was some kind of blowback from the cylinder (sorry I’m not a mechanic ) that caused the hole. A compression test revealed absolutely no compression in cylinder 2

 

[paesy23]

Inlet manifold - look closely at melted port 3rd from the right.

 

[Spaghetti]

Not sure exactly what caused what, but basically on a trip back from Cornwall over Christmas the engine started misfiring, originally thought it might be an injector, but when we checked we found a hole in the inlet manifold. We removed the manifold and the port (in line with cylinder 2 had melted itself - see pic), not sure if the egr cooler failed and caused it to overheat, melting the port and putting plastic into the engine, or there was some kind of blowback from the cylinder (sorry I’m not a mechanic ) that caused the hole. A compression test revealed absolutely no compression in cylinder 2

Wow. Doesn’t bode well for the rest of us! Is that glass reinforced plastic?

 

[mmi]

Judging by the stamp on the timing belt cover both engines are definitely CXG, you’re definitely correct in saying that the CXGB version is the 102 as that’s what mine was. This is the code for the new engine

View attachment 58489

Yes, that's the sticker I was thinking. Now I'm a bit guessing (but informed guessing) - but it seems that you have correct "hardware" so the old ECU should do the job.

Can you read what the ECU thinks the fuel pressure in the rail is? I would expect it to be approx. 30...32MPa (300..320 bar) on tick-over at 830 rpm - based on how it is on both 150ps and 204ps T6 engines.

What kind of OBD reader you were using? The general ones don't necessarily reveal VW specific faults?

 

[paesy23]

Mmi, thanks for your response. My mechanic originally used a snap on solus obd reader, which did struggle to read the engine type, however he then took it to a friend who specialises in vw’s and used his obd reader, which gave the daily code.

He has swapped over the fuel rail, sensor & regulator this morning and the problem still exists. Van is running perfectly well, but has the engine management light on and flashing glow plug light too.

We are now thinking the only cure would be a remap to update the ecu and fuel map

 

[Robert]

Mmi, thanks for your response. My mechanic originally used a snap on solus obd reader, which did struggle to read the engine type, however he then took it to a friend who specialises in vw’s and used his obd reader, which gave the daily code.

He has swapped over the fuel rail, sensor & regulator this morning and the problem still exists. Van is running perfectly well, but has the engine management light on and flashing glow plug light too.

We are now thinking the only cure would be a remap to update the ecu and fuel map

I would try VCDS first to see what faults you have stored and then I would preform number of VCDS measurements(fuel pressure, etc.).
Have a look on the forum map, maybe there is someone local willing to help you.

 

[Loz]

Is there no chance you can swap your ECU with the engine seller?

 

[paesy23]

My mechanic originally tried a snap on

Is there no chance you can swap your ECU with the engine seller?

loz, I’m not sure, I can check with them (I bought the engine from t5 Cotswold parts), I kind of just assumed that if I did swap the ecu it might throw up all sorts of other problems / faults. I was hoping a remap may solve the problem, but I’m still not sure and it’s another £3/400. I’ve spoken to my mechanic again and he said he took it to someone that had Vcds software and the fault code was P008800 and the fuel line was registering 31 (or 31000) mpa at idle which kind of lines up with what mmi said above. The question from me now is will a remap be able to tell the ecu that the pressure is ok and not produce a fault or am I going to be wasting more money ?

 

[Robert]

If you swap engine control unit, you will have to pair it with your instrument cluster(immobiliser is integrated part of it).
And if you swap IC as well you will have to sort out component protection.
I don't think this is right direction for you to fix your problem.
Again, I would concentrate on proper diagnosis.
You have to get VCDS and do it the right way .

 

[mmi]

I'm afraid there are a few adaptations you need to carry out as many of the components have been changed from the point of view of ECU.

One of them is adapting the injectors. This can be done through VCDS adaptations. The calibration codes are engraved on each of them. However, can't tell if this is the root cause.

Yes, it's the two lines of characters without any spaces! See attached adaptation map (injector 3).

Another one might be adapting the EGR even though engine seems to run some kind of process even without initiating it. I suppose many of the processes are found under "Basic settings" of VCDS. However, not sure if this is such a critical here.

Meanwhile to exclude faulty sensors/wiring attached all measurement blocks and adaptation values of an 150PS CXFA engine (DSG, 4Motion) to give an idea what's in there.

I'd pull out the same from your ECU and compare if yours is missing values or having some extreme values (possibly indicating wiring problem?). However, certainly would be better to have the same from exactly same type of engine (CXGB).

 

[Chris1]

Have you checked to make sure the fuel return pipe is not damaged / pinched or even blocked. (Possible when fitting engine) Fuel pressure should be around 300 bar at idle when running pressure will range from 1200 - 2000 bar.

 

[Dellmassive]

Over 1400 data PIDs there @mmi block map from the engine ECU?

Wanna post your how to.....

So we can get/compare ECU blockmaps.


Are you saying the ONLY fault code is.... ?

OBD fault code P0088 is defined as “Fuel Rail/System Pressure – Too High”,

What happens when the rail pressure sensor is un plugged.?

Have you tried simulating the rail pressure sensor signal back to the ECM?

Does the engine run smooth?

Have you thought about retaking it to VW for a look?.... they can do the programming for a cost.