Got The Cat Cams Inlet Only Camshaft Fitted To My Mi Yesterday

[SweetBadger 94]

Went down to QEP yesterday and bought a Cat Cams inlet only billet camshaft jobbie, i'm well impressed!

 

With the cam advanced using #4 pulley on the inlet and #2 on the exhaust its got just as much if not more low down grunt as with the standard cam but when you hit 4500 rpm it really takes off... Power seems to tail off at approx 7000rpm which is good for standard management.

 

Only problem is my idle quality is a bag of s*ite now... Even after adjusting the AFM mixture its very spluttery on idle, similar thing happened when I used the #4 pulley on the inlet with standard camshafts although it wasn't as bad as it is now.

 

Think it might be because the compression is high due to an over enthusiastic head skim and the inlet cam is so far advanced. I'm going to try sticking a #3 pulley on the inlet and the # 4 back on the exhaust to see if that helps...

 

Got to replace the starter first though as the solenoid on my 10 month old one decided to give up the ghost on a test run today and i've lost the sodding receipt!

[welshpug 1,657]

stop faffing and get a vernier puller

 

are you sure its the solenoind and not the wiring?

[John_B 11]

It's interesting to hear that badger as I'm having the exact same problems! I've also had the catcam inlet and your experience of the power characeristics are the same as mine i.e. bloody good. But mine wont idle at all from cold- it's worse than the 8V which to say the least is a bit gutting. When it's warm it idles OK- a bit lumpy but sounds quite nice IMO. I'm reluctant to blame the cam though because other people's seem to be fine, and the engine has only had this cam after a rebuild so I can't say it was running fine before the cam.

 

We've changed the AFM and fiddled with the base settings and changed the ecu water temp sensor but it's just the same. My head also had a skim but I'm sure it wasn't to enthusiastic.

 

I'm not sure what pulleys are on it though.

 

stop faffing and get a vernier puller

 

are you sure its the solenoind and not the wiring?

 

That's exactly what I've been told as well, but I'm reluctant to spend a couple of hundred on verniers plus mapping when there's no guarantee it will change anything.

 

Also the wiring to my solenoid has broken twice recently so its definitely worth checking that out.

[d-9 0]

mine idles fine with the standard management and the catcam inlet cam. pickup is a bit lumpy, throttle is definitly on or off, and its a bugger to drive in traffic, as the power comes and goes, like an 8v really. Starts and idles fine from cold, thats with no4 inlet and no2 exhaust, i tried it with 2 2's before and it was slow as hell, still not convinced its very fast thou.

[petert 587]

Think it might be because the compression is high due to an over enthusiastic head skim and the inlet cam is so far advanced.

 

No. Both of these things will improve the idle. Advancing the cam makes the inlet valve close earlier, increasing the dynamic compression. You don't need verniers. Don't get sucked in by amatures who have no idea what they're talking about. The AFM is your problem. It can't handle the reversion pulses from the bigger inlet cam. Get rid of the AFM and fit a decent ECU and your problem will diminish. Fit TB's and it will go away entirely. #4 on the inlet and #2 on the exhaust is the right combination. It's simply a case of you can't have your cake and eat it too.

[John_B 11]

mine idles fine with the standard management and the catcam inlet cam. pickup is a bit lumpy, throttle is definitly on or off, and its a bugger to drive in traffic, as the power comes and goes, like an 8v really. Starts and idles fine from cold, thats with no4 inlet and no2 exhaust, i tried it with 2 2's before and it was slow as hell, still not convinced its very fast thou.

 

 

Hmmm.. Mine doesn't idle fine, pickup is not lumpy, throttle is nice and progressive, it's easy to drive in traffic, doesn't idle from cold and is definitely fast

[veloce200 3]

No. Both of these things will improve the idle. Advancing the cam makes the inlet valve close earlier, increasing the dynamic compression. You don't need verniers. Don't get sucked in by amatures who have no idea what they're talking about. The AFM is your problem. It can't handle the reversion pulses from the bigger inlet cam. Get rid of the AFM and fit a decent ECU and your problem will diminish. Fit TB's and it will go away entirely. #4 on the inlet and #2 on the exhaust is the right combination. It's simply a case of you can't have your cake and eat it too.

 

 

there must be more to it than that Peter as on the Alfa TS engine the inlet cam operates in a retarded position at low revs up to 3000 then advances. I understand this is to improve low end torque and emissions. Surely it's all relative to the position that the cam is advanced or retarded from and it's relative position to the exhaust cam. For example advancing the inlet will increase lift at TDC which could cause idle problems?

Edited October 15, 2006 by veloce200

[James_R 3]

Think I saw you at QEP saturday morning I was dropping off a few engines worth of bits. Car look'd clean. If the idles that bad, see if you can get the CO adjusted on it so you know it's "right".

 

good luck with it

[petert 587]

there must be more to it than that Peter

 

yes there is. Advancing the cam is also increasing the amount of overlap at TDC, which of course is what's polluting the idle. But what can you? If you retard the cam too much you'll loose the effective power range, pushing it further up the rev range. It's far more important to keep the compression up by closing the inlet early. If you want a smooth idle fit the standard cam!

[SweetBadger 94]

stop faffing and get a vernier puller

 

are you sure its the solenoind and not the wiring?

 

Haha, it'd be nice to do that and get it set up properly with some aftermarket management but funds are running seriously low!

 

Fairly sure it's not the wiring but I won't get a chance to look at it till the weekend as by the time I get back from work it's dark now... Winter sucks!

 

John - Your idle sounds worse than mine, it idles better when cold and stays at about 900rpm but is just very lumpy - could be something else contributing to the bad idle on yours... air leak?

 

d9 - What was it like with the standard cams? Mine is fine in traffic, and the throttle is progressive have you retracked the AFM its easy to do and might help...

 

James - Yeah that was me, might get the CO checked really should get it on the rollers but everywhere I've phoned down south only operate the roller during week days.

 

yes there is. Advancing the cam is also increasing the amount of overlap at TDC, which of course is what's polluting the idle. But what can you? If you retard the cam too much you'll loose the effective power range, pushing it further up the rev range. It's far more important to keep the compression up by closing the inlet early. If you want a smooth idle fit the standard cam!

 

Well the bad idle is worth the extra power imo, but it still doesn't explain why the idle was also worse with the standard cam advanced. Would it be worth advancing the exhaust cam aswell to reduce the overlap at TDC?

[Anthony 1,003]

Only problem is my idle quality is a bag of s*ite now... Even after adjusting the AFM mixture its very spluttery on idle, similar thing happened when I used the #4 pulley on the inlet with standard camshafts although it wasn't as bad as it is now.

If you were having issues with the standard cams as well then I'd say there's an underlying issue somewhere, and the new hotter cam is showing the problem up worse. The idle quality will be worse with that hotter inlet cam fitted for the reasons that Peter gives - no way around that unless you put aftermarket management on - but you should still be able to achieve an acceptable idle quality with the standard management, and it shouldn't be hunting or excessively spluttering (it will sound cammy and like it's not quite running on all four cylinders - that's normal for a cammed engine with an AFM).

 

Try a known good AFM first of all and see if that helps.

[SweetBadger 94]

If you were having issues with the standard cams as well then I'd say there's an underlying issue somewhere, and the new hotter cam is showing the problem up worse. The idle quality will be worse with that hotter inlet cam fitted for the reasons that Peter gives - no way around that unless you put aftermarket management on - but you should still be able to achieve an acceptable idle quality with the standard management, and it shouldn't be hunting or excessively spluttering (it will sound cammy and like it's not quite running on all four cylinders - that's normal for a cammed engine with an AFM).

 

Try a known good AFM first of all and see if that helps.

 

 

I've got a spare AFM and have retracked it - behaves in exactly the same way. I can live with the idle as it is now and it doesn't hunt - stays fixed at about 850rpm so as you and peter say its probably as good as its going to get on standard management.

 

The only thing that doesn't add up is that the idle was spot on using standard cams with a #2 pulley on the inlet and got slightly worse and the idle mixture needed richening with a #4 pulley on the inlet which is supposed to improve the idle quality. If the bloody starter was working I'd take a quick video of it on idle but that'll have to wait till the weekend.

 

Cheers, Alex.

[dazEmad 0]

I doubt its the cat cams inlet cam making the idle poor as mine idles perfectly hot or cold.

[Rik 0]

Sorry to go off topic but how much was the single cam and where'd you get the #4 pulley?

 

Rik

[jackherer 543]

I got my mates car going today with one of these cams, the idle is fine.

 

yours sounds like an air leak to me, maybe the breathers or oil filler hose?

[chris 417 mi 34 2 Cars]

just to confirm, when adding this cam to a standard head with jenvey throttle bodies what kind of difference does it make ??

[Alastairh 47]

Chris, all your answers are here

[Mattsav 1]

I've got a spare AFM and have retracked it - behaves in exactly the same way. I can live with the idle as it is now and it doesn't hunt - stays fixed at about 850rpm so as you and peter say its probably as good as its going to get on standard management.

 

The only thing that doesn't add up is that the idle was spot on using standard cams with a #2 pulley on the inlet and got slightly worse and the idle mixture needed richening with a #4 pulley on the inlet which is supposed to improve the idle quality. If the bloody starter was working I'd take a quick video of it on idle but that'll have to wait till the weekend.

 

Cheers, Alex.

 

If its idling at 850rpm then open the throttle stop. It will probably be much nicer at 900/950rpm.

 

The no.4 pulley advances the cam, thus opening it sooner and giving more overlap. This creates bigger pulses in the inlet tract and upsets the idle.

You'll probably need a bit more fuel on idle as more will pass through the engine unburnt (which you can see as higher HC's)