Any of you guys familiar with the Vauxhall Z20LET engine?

[TankRizzo]

Chaps,

I finally got the VX220 remapped today by Reidy Remaps in Yeovil (excellent service and cheap for a bespoke map). However, the dyno session has highlighted a problem with the engine which I suspected had been there for a while.

The car seems to boost fine and makes good power (~240bhp now) until around 4.2k where it drops right off - the torque drops right down to around 175lb/ft from 240lb/ft. After 1k RPM or so, the power and torque picks up and climbs again towards the redline. Makes for a very annoying flatspot in the rev range, more pronounced now I am running more grunt. The boost seems to be dropping off in the midrange.

The ECU is throwing a P1106 code which is a MAP sensor boost pressure issue, but on reading around it seems this code is a little generic and can be any number of things.

I'll swap the MAP sensor and the MAF meter while I'm at it, but can anyone give me any more hints?

Cheers
Vaughan

Edited by TankRizzo on Thursday 8th April 23:11

[SimonV8ster]

How about talk to Thorney Motorsport - they specialise in tuning VX220's.

[ecain63]

Sounds like MAP sensor to me mate. The ecu is getting the wrong atmostphere signal somewhere down the line and this is where you are getting the flat spot. Take the sensor off (still plugged in) and see what reading it gives. It should be pretty near the air pressure of atmosphere (check the weather). Then refit it, give it some throttle and see if it changes under load. The MAF change will also help as these are about as reliable as Gordon Browns Economic Recovery Plan. I know its a different car, but i get my MAF's changed at every service interval. They go out of tolerance very quickly.

Other than that, the block and ancillaries are pretty strong on the Vaux engine.

[TankRizzo]

Thanks Eddie. I'll swap the MAP sensor and see what happens.

Simon, thanks for the suggestion about Thorney.

[TankRizzo]

Just to put this to bed, after swapping a few parts out I got my final dyno reading done today, 227bhp & 273lb/ft torque. Pretty happy tbh, pulls like a train now.

[LukeBird]

Good to hear it was sorted in the end.
That must shift with that much power and torque!!

[crisisjez]

TankRizzo said:

Just to put this to bed, after swapping a few parts out I got my final dyno reading done today, 227bhp & 273lb/ft torque. Pretty happy tbh, pulls like a train now.

Somethings still not right there. Those lines are way too wiggly IMO (My OH has an Astra VXR and we have dynod that loads of times as the power increased and it never looked like yours)
Have you got afr's as well?
I'll post Sophie's latest run.
Don't take any notice of the numbers, have a look at how smooth the power is delivered.

Edited by crisisjez on Sunday 23 May 23:15

[y2blade]

Callyman is pretty clued up on these engines

[callyman]

y2blade said:

Callyman is pretty clued up on these engines

Thanks Y2, but I've got the C20LET.

I cant see the dyno graph (stupid work restrictions) but did you have the fuel pressure incresed to match the increased boost? That flat spot could be it's running a bit lean, and lean is not good.

I dont know about the Z20, but in the C20 RS turbo plugs work well with higher boost.

Edited by callyman on Monday 24th May 13:30

[y2blade]

callyman said:

y2blade said:

Callyman is pretty clued up on these engines

Thanks Y2, but I've got the C20LET.

I cant see the dyno graph (stupid work restrictions) but did you have the fuel pressure incresed to match the increased boost? That flat spot could be it's running a bit lean, and lean is not good.

I dont know about the Z20, but in the C20 RS turbo plugs work well with higher boost.

Edited by callyman on Monday 24th May 13:30

ah sorry buddy, I knew it was something like that

[TankRizzo]

Thanks for the replies guys. The AFR is between 11 and 12 for 99% of the way, it leans very slightly above 12 for a second or two but ok apart from that.

Might be a boost leak perhaps. Overboost was 19psi and dropped to 13psi held. I guess I could have a pinhole leak in one of the pipes which is causing a bit of a wobble.

[callyman]

TankRizzo said:

Thanks for the replies guys. The AFR is between 11 and 12 for 99% of the way, it leans very slightly above 12 for a second or two but ok apart from that.

Might be a boost leak perhaps. Overboost was 19psi and dropped to 13psi held. I guess I could have a pinhole leak in one of the pipes which is causing a bit of a wobble.

Could be a sticking actuator?

[TankRizzo]

callyman said:

TankRizzo said:

Thanks for the replies guys. The AFR is between 11 and 12 for 99% of the way, it leans very slightly above 12 for a second or two but ok apart from that.

Might be a boost leak perhaps. Overboost was 19psi and dropped to 13psi held. I guess I could have a pinhole leak in one of the pipes which is causing a bit of a wobble.

Could be a sticking actuator?

Possibly. Or the actuator is weak and leaking boost perhaps. I'll have to datalog it and see what the ECU is commanding for boost and what the actual is according to the TMAP sensor, and also compare that with a mechanical boost gauge to double-check the sensor.