C16XE Loss of power under load/open throttle.

[SimonTW]

I recently got my car back from having some work done on it. The head gasket needed changing and whilst it was there I had the cambelt and waterpump changed. Before I took it in the car ran perfectly with no problems. I also had a powerbox fitted whilst everything was off.

The car runs nicely and pulls fairly well but as soon as I put my foot down under load the power is cut and the car judders and then power comes back and it's fine. If I bring the revs up slowly there is no problem but as soon as I put my foot down the power drops. The car doesn't cut out. I've checked all the plug connections, stuck a set of new leads on it and a set of new plugs and the problem is still there.

Has anyone had a similar problem after fitting a powerbox or should I be looking at something else before I swap back to the standard inlet to rule it out.

[John]

Check for air leaks around the box. cambelt timing ok?

[SimonTW]

All the gaskets are new on the inlet side so I'm hoping there are no leaks. I've not checked the timing. I'd like to hope the garage who did the work have set it properly but I don't have much confidence in them so will give it a looking at.

[chrisd1986]

Im having this on my x16xe with powerbox but only when its warm

[Liam]

I had the same problem and after changing lots of bits I found out that it was the fuel filter that had clogged up. Once it was changed it ran fine again. If you haven't replaced it already I would try that first.

[SimonTW]

It was changed about 18months ago when I did the conversion. I'll get it a go though. Thanks Liam!

[Will F]

How many miles have you done with the powerbox? Could be the maf just getting used to the new airflow and the ecu having kittens...

[SimonTW]

I've done about 100 miles in it since picking it up.

I've got a few things to check over now at least.

Also doing a bit more research it seems the crank sensor pulley trigger wheel may have slipped which was mentioned as a common problem after having a cam belt change. I really hope it's not that though!

[John]

I've done about 100 miles in it since picking it up.

I've got a few things to check over now at least.

Also doing a bit more research it seems the crank sensor pulley trigger wheel may have slipped which was mentioned as a common problem after having a cam belt change. I really hope it's not that though!

I've also seen the actual crank pulley slip round the crank under load too.

[SimonTW]

:eek: Would that not cause the engine to stop running altogether though?

[chrisd1986]

Ive done 500 miles in mine

[John]

:eek: Would that not cause the engine to stop running altogether though?

Not the one I saw, the bottom pulley by hadn't been tightened correctly, the inner gear had worn the woodruff nearly almost away. Was fine at idle, higher up the rpm range it instantly became flat.

Check your bottom pulley bolt has been tightened correctly :-)

[chrisd1986]

Not the one I saw, the bottom pulley by hadn't been tightened correctly, the inner gear had worn the woodruff nearly almost away. Was fine at idle, higher up the rpm range it instantly became flat.

Check your bottom pulley bolt has been tightened correctly :-)

Had a 8v corsa like this

[SimonTW]

Today I've changed the air flow meter, coil pack, fuel filter and checked the timing marks and it still has the problem. I can't hear a blow from the exhaust but I'm going to check it over tomorrow just in case there is a blow under load.

[meritlover]

you can't tell be checking the timing marks, because the belt has not slipped. it's the crank that slips relative to the pulley. you can only see by removing the aux drive pulley and looking at the woodruff key against the timing pulley. it only needs to move a couple of degrees to make a difference, sometimes, if it gets worse you get loads of bizarre EML codes flashing which confuses the GM 'professionals'. usually because the crank and cam-sync pulses dont occur when the ECU expects them so you get 'quad-module failed', 'EGR failed' 'cam sensor failed' etc.

[meritlover]

...or you could just take it back to whoever did the work and tell them to sort it all out.

[SimonTW]

I only want to do that as a last option to save myself a load in labour charges and sensors through them and for my own piece of mind so I know they have been checked and ruled out.

I understand what you mean though about the timing on the pulleys now you have put it that way thanks. I'm now at the point where taking it back to have that looked at is only option left to check.

[scott.parker]

I had similar thing on my old xe with a chopped down sfi box, the arldite glue split the joint causing air to rush in after the maf so it couldn't work out what was going on, it then happened again as I had a split in a inlet pipe, check everything for air vacuum leaks around the new power box thoroughly, as it's possibly a simple fix..

Sorry to hear your having issues again though mate.

[SimonTW]

Cheers Scott. I've been all over it for air leaks. I had all the holes in the inlet welded up except for one small vacuum take off for the fuel pressure reg. I had the throttle body off earlier so I've checked the faces and gasket. The EGR ones have both been blanked and I tiger sealed and bolted them into place.

In hindsight I wish I had just had the head gasket stuff done and then done the powerbox at a different time so I could just rule one or the other out.

[therealnovaboy]

I would suggest lookin at the MAF sensor. Sounds like it may be funked.

try unplugging it and see if it is similar or better symptoms.

My corsa runs without a MAF untill you try accelerate hard or go up a hill then it just drops in power. However it is a 1.2 16v.

[SimonTW]

Already tried a spare one on it made and no difference to the symptoms at all.

[therealnovaboy]

have you flashed the fault codes?

[SimonTW]

Yeah just with the paper clip. Nothing at all showing.

[SimonTW]

I've decided to change the pulley I also had to order the trigger ring as the pulley design has changed from my early C16XE. I figured as it's a fairly common thing and they have to take it off to check it I may as well just have it changed anyway so it's done.

Here are the part numbers and prices for the timing belt pulley, aux drive belt pulley and the bolt for future post searches.

Aux Drive Belt Pulley: £79.20 (9129210)
Crank Timing Pulley: £43.56 (9129207)
Bolt: £3.89 (11095041)

[Edd]

hope you get it sorted, sounds like you aint had the best of luck with it

[chrisd1986]

Just a daft question but what fuel pump are you running and just check you dont have any kinks in your fuel lines

[SimonTW]

Okay. I bit the bullet and bought the new pulleys. Vauxhall told me both would need to be changed.

I just want to make sure I get the right info here. Meritlover if you can clarify please as you seemed to know about this one.

Is it this pulley that gets worn? The key between this and the crank.
http://farm6.staticflickr.com/5513/9373528993_9f6707962b_c.jpg

Or is it the trigger wheel pulley that gets worn where the notch is cut out.
http://farm8.staticflickr.com/7449/9373526413_6d603c5b45_c.jpg

I dropped it back of with the garage who said there was no movement between the crank cambelt pulley and the crankshaft itself but there was a slight amount of movement between the aux drive belt pulley and the crank pulley.

Off to pick it up later so will see if it's made any difference and hopefully someone on here can clarify to me which gets worn.

[boyd_1989]

Does it just bog down when in low revs unless you feather it on abit? Try rev it to 3k then put your foot down see what happens. on my c16xe when I put my powerbox on it doesn't like being in the low revs, until I put my superchip in anyway lol. But ive had my powerbox on the engine for about 2 years now and always been like it it picks up well after 2500rpm but doesn't really kick in till around 4500rpm. if you give me your email address I can send you a video of my car on the dyno and youll see what I mean.

I always thought maybe it could do with getting abit extra fuel in there but then people on here told me standard fuel pressure is fine, so I left that alone.

[jimbob-mcgrew]

if its the powerbox messing the ecu up, what can you do about it ?

[meritlover]

Either of the pulleys will give issues if there is scope for misalignment. its normally pretty obvious that the timing pulley has moved because the material is compressed sintered alloy, it crumbles and the key chews up.
the aux pulley will give sync and ign timing issues because the trigger wheel is not relative to crank position and the sync pulse from the cam is off too. Again, without knowing just how much 'play' there is then its hard to say.

there is absolutely no reason for the aux pulley to be replaced unless its clearly damaged.

The powerbox 'shouldnt' cause it. check all the vacuum hoses and EGR connection (if you've removed it) The engine is still able to meter the air correctly. Any low speed issues will be due to the now shortened runners and different sized plenum.

[meritlover]

particularly check the Vac hose between the plenum and the fuel pressure regulator is connected properly.

[SimonTW]

particularly check the Vac hose between the plenum and the fuel pressure regulator is connected properly.

It's one of the first things I checks but it's all okay with it.


Either of the pulleys will give issues if there is scope for misalignment. its normally pretty obvious that the timing pulley has moved because the material is compressed sintered alloy, it crumbles and the key chews up.
the aux pulley will give sync and ign timing issues because the trigger wheel is not relative to crank position and the sync pulse from the cam is off too. Again, without knowing just how much 'play' there is then its hard to say.

there is absolutely no reason for the aux pulley to be replaced unless its clearly damaged.

The powerbox 'shouldnt' cause it. check all the vacuum hoses and EGR connection (if you've removed it) The engine is still able to meter the air correctly. Any low speed issues will be due to the now shortened runners and different sized plenum.

I picked the car up last night and the old parts were fine. the play in the old outer pulley against the inner one was next to nothing and the key looks fine too. Thanks for replying with some more information. I really appreciate it! I'm just gutted it wasn't that and it didn't cure it.


Does it just bog down when in low revs unless you feather it on abit? Try rev it to 3k then put your foot down see what happens. on my c16xe when I put my powerbox on it doesn't like being in the low revs, until I put my superchip in anyway lol. But ive had my powerbox on the engine for about 2 years now and always been like it it picks up well after 2500rpm but doesn't really kick in till around 4500rpm. if you give me your email address I can send you a video of my car on the dyno and youll see what I mean.

I always thought maybe it could do with getting a bit extra fuel in there but then people on here told me standard fuel pressure is fine, so I left that alone.

It's pretty much what your describing. I'll drop you a PM with my email address. Thanks!


So to sum up it still drives as it did before with the new pulleys on. Maybe the next step is to have a tuner look at it to see if it can be mapped out. It looks like a change in driving style will be needed temporarily to work around the problem or just break and sell it as i'm sick of messing now!

[meritlover]

is there a knock sensor on these? i cant remember.

where do you have your air temp sensor fitted?

when was the last time the fuel filter was changed?

have you plugged it into a live sensor viewing tool to see what's doing what?

[SimonTW]

Yes there is a knock sensor on them. I don't think there is an air temp sensor on it though. Fuel filter was changed last week after the problem started which didn't affect it. I've not plugged it into a diagnostic. Just done a paper clip fault code test which threw up nothing.

[meritlover]

I don't think there is an air temp sensor on it though.

there should be somewhere. i forget if this is the MAP of MAF load sensing. if its MAP, it should definitely have one in the intake tubing. (reason i say this is it may have been discarded when the power box was fitted)
if its MAF, then its imbedded in the flow meter so it doesn't matter.

diagnostic codes tell you nothing. you need to find some one with a code reader that can read the live values and know what their looking at. or post a data dump and i will analyse.

[Liam]

There isn't an air temp sensor as yours is a c16xe so you've got the AFM instead.

I've got a **** load of camshaft, crankshaft and knock sensors if you want me to send you one of each? Just cover the postage or something.

They were left by the bloke who previously had my unit when he left. He used to break Tigra's and left lots of different stuff.

^^^ c16's have a MAF sensor, x16's have a MAP sensor so this one will have a MAF sensor.

[boyd_1989]

Ill send you my video in about 30 mins mate, post it up on here aswell if you like. Ill pm you once I've sent it to you.

[meritlover]

There isn't an air temp sensor as yours is a c16xe so you've got the AFM instead.

I've got a **** load of camshaft, crankshaft and knock sensors if you want me to send you one of each? Just cover the postage or something.

They were left by the bloke who previously had my unit when he left. He used to break Tigra's and left lots of different stuff.

^^^ c16's have a MAF sensor, x16's have a MAP sensor so this one will have a MAF sensor.

ye thats what i thought. i Just can never remember what one is what. Thats the first things i'd rip off and junked anyway. lol