Weird problem ... Any help appreciated !

[Ali123]

Right basically the c2 is running ph3 newman camshafts and pulls/pulled nice after 4.5k / 5k until over the past few weeks where it just feels flat....
It'll pull as it usually does upto 4.5/5k but once you get there it doesn't seem to pull like it used to !

But every now and then it seems to go like fuck again for a while then it'll go all flat and boring!:(

Anyone got any ideas?

Cheers!

[bender]

Sounds like a coilpack issue, maybe swap one in and see if it helps?

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[welshpug]

cam timing, also has it been mapped?

[Ali123]

Coilpack is fine mate as there is no misfire or any hesitation etc plus it's a brand new Delphie one about a month old!

Also it has been mapped yes and also as for it being a cam issue, if it was it would be flat all the time, where as its flat majority of the time but then at times it goes like fuck

[welshpug]

still FBW throttle?

[Ali123]

Yeah mate

[bender]

Don't think it's a cam issue, sounds like an intermittent electrical fault. I had a similar issue on an audi s3, turned out to be the MAF sensor. Could try disconnecting it and taking it for a spin. The ECU should run on its Base values with no MAF

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[Ali123]

Fuck knows man! Nothing comes up on our code reader at work either!
To put it into perspective of how much of a difference there is....there is a dual carriage way by mine which I go up and down daily,
When it seems to be running flat-ish I can get about 85/86 3/4 of way up the hill before it starts to level off...

The other day when It went like fuck the car did a ton + by 3/4 of the way up!

[welshpug]

there's no maf on these.

get it on Lexia and view the live data.

[bender]

there's no maf on these.

get it on Lexia and view the live data.
How does the ECU measure the air flow then?

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[Chipwizards]

Sounds like fuel pressure dropping off to me, has it had a pump in recent years?

Also, is the fuel fresh and decent quality? The knock control is perhaps over-zealous and pulls timing out rather too readily which is what makes them feel flat much of the time (and not the DBW throttle like every 'expert' seems to say)

[Chipwizards]

How does the ECU measure the air flow then?

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It doesn't, it's 'speed-density' load measurement system.

[Ali123]

Sounds like fuel pressure dropping off to me, has it had a pump in recent years?

Also, is the fuel fresh and decent quality? The knock control is perhaps over-zealous and pulls timing out rather too readily which is what makes them feel flat much of the time (and not the DBW throttle like every 'expert' seems to say)

Yeah man put a new delphie one in a couple of month ago now? And always run it on shell vpower... well 99% of the time !

And you reckoning possibly knock sensor then mate?

[welshpug]

throttle issues are common on them, so much so that its a service item for the R2 rally cars and included in the spares kit.

without getting it on Lexia you wont know what's happening when it isn't running right, probably a few other systems that'll read the data but a knock off copy of the o.e system is the best to use

[Chipwizards]

Yeah man put a new delphie one in a couple of month ago now?


A proper one or a shit knock-off?

I was more thinking fuel pressure dropping not knock sensing. Knock just makes them feel a bit numb and flat.

Throttle issues usually have it shut down to fast idle, well when I've had issues that's what they have done.

C2R2s vibrate the bejesus out of them so they don't last long on them.

[Ali123]

Genuine one mate, £125 quid!

[stevo67]

Has the fuel filter been changed?

[Ali123]

Fuel filter is part of the fuel pump!:(
And also I've changed the knock sensor, if anything it made it even slower!

[stevo67]

Just a suggestion go back to the place where you had it mapped,that way you'll get to see live data with the car running.Any faults with sensors will show and adjustments can also be made to map.

[Ali123]

Not a bad suggestion actually!

[Chipwizards]

Not a bad suggestion actually!

Assuming it has really been MAPPED, and not just flashed like most Joke-Shop tuners do....

There are tables in the ECU that are used to analyse throttle position vs MAP in order to check that the MAP reading is plausible. There's a table for Upper MAP value for a given throttle position at various engine speeds, and there's the same sort of thing but for Lower MAP values. If you've got cams fitted the manifold vacuum isn't as strong at low engine speeds, so the Upper MAP limit usually needs raising, so if that hasn't been done it may be running in default mode that is an 'Alpha-N' strategy (for this 'fault' condition).

There's another table that is the assumed manifold pressure from throttle angle vs rpm. This is what the ECU refers to to calculate 'relative filling' when it thinks it can no longer rely on manifold pressure for the load measurement (and thus relative filling). This 'manifold pressure model' can no longer be relied upon to give accurate relative filling values if they haven't been changed to reflect the change in pressure brought about fitting cams.

SO....

If your engine is on the verge of being in default it may sometimes be running using measured ACTUAL MAP values for relative filling, and sometimes ASSUMED manifold pressure which won't be correct due to the cams. The variation between the two measurement strategies will cause the ECU to look at different 'load' values depending which strategy it happens to be running on at the time.

If you follow me?

[Ali123]

Aye it has been properly mapped , tbh the camshafts and the mapping was done by the previous owner at gr performance , I do have the rolling road printout like, also while the camshafts went in etc the c2 vts inlet manifold and Injectors were fitted too , but the map sensor has never been connected since , but like
I said it pulled well etc until recently....

But also another thing to point out, when you get near the Rev limit it cuts out at like 6.5k and proper jolts if that makes sense? Where as when it pulls well it'll reach all the way to the limiter with no issues !

Hope that makes sense?

[Chipwizards]

but the map sensor has never been connected since ,

Why ever not? Unless it hasn't had the above mentioned tables set properly?
Have GR even got an emulator? When I last went there they were into Scoobs and Evos but with customer software that you don't really need to emulate with. To do a proper mapping job on a C2 you really need to emulate them, and I don't think Gaz and Jason have one.


But also another thing to point out, when you get near the Rev limit it cuts out at like 6.5k and proper jolts if that makes sense? Where as when it pulls well it'll reach all the way to the limiter with no issues !

Hope that makes sense?

There are two rev limiters in a C2. Sometimes they are at the same rpm, so both at 6500 for VTR and GT and 7000 for VTS, but occasionally there are different limits in the same ECU. One limit is for the 'normal' condition and the other is for the 'default' condition. Sometimes the default limit is lower than the normal limit.

Sound to me like it needs looking at properly.

Is everything else working? ABS, dash etc etc?

[Ali123]

I really don't know man, but as for everything else working properly , everything is all good!

Only thing is abs light comes on every now n then if doing high speed but then soon disappears , never bothered me enough to get it on computer at work to have look, but that's the only thing really ?!

[Ali123]

Is this something you could look at mate?

[Chipwizards]

If the ECU isn't getting a speed signal from the ABS then it runs on different maps. There are different calibrations for neutral to the other gears in particular, throttle maps are the biggest difference, but the rev limiter too. This feature can actually be used for launch control but that's another story...

Yes I can have a look, I'm in Warrington so not too far from Hudd's.

[Ali123]

Hmmmm launch control ey! But the abs thing only happens once in a while and it hasn't happened in a while like, didn't realise that could affect it though !
And yeah man just googled
Mapped Warrington, 53 minutes away!
are you free on weekends like or Monday to Friday only dude?

[Chipwizards]

Just Monday to Friday, often late though if you wanted to leave it one eve and collect it another. Train stations are local so it's easy to get back to Hudds via Manchester, or maybe some other route I haven't looked...

[Ali123]

Right I'm sure we can sort something out, I go away on holiday next week so when I get back we'll arrange a day to drop it off with you mate

[Chipwizards]

What's a holiday?

[Ali123]

What's a holiday?

You know..... ! Abit of
Sun shine and warm weather won't go amiss!