Camshaft instalation probs! HELP!

[bbenny]

Ok i installed some GTR camshafts in my RB20 today. also fitted a new timing belt.

so here are my probs.

when i installed the cams i noticed the inlet cam was much harder to turn than the exhaust cam when making small adjustments to align the cam gear marks for no.1 TDC

after thinking maybe the new cam was bent i pulled it and installed the standard cam, but it felt just as stiff to adjust, so back in went the GTR cam.

Now my problem is the car cannot hold idle without droping rpm and then dies

now when i try to start the car it pretty much dies immediately.

is this due to the "lumpy" camshaft or something else?

any advice or help would be much appreciated.

Ben.

[Jay95R33]

A bit of a stupid question (I'm not sure how the cam is mounted etc..), but did you put the cam mounts/craddles back in the same position??

I replaced a cam on an old car years ago and it did the same thing, found out that the mounts/craddles that hold the cam in place were put on in the wrong order (my bad !!) which put a fair bit of load on the motor cause they were slightly out of wack.... I ended up needing to get them line bored to fix it...

Not sure if this is your problem, maybe someone else can confirm.

J

[bbenny]

thanks, but i am positive i put them back in the right order, they are numbered which makes it very easy.

[Jay95R33]

Ahh cool. Well it's not that then

Apart from that, the only other thing I can think of is the timing belt being a tooth out of alignment. Not much else can go wrong

J

[bbenny]

well i checked all the alignment marks and they were spot on, i even turned the motor a couple of times manually and double checked to see they came back in the right spot...

[Jay95R33]

Hmmm... You've probably done this already, but is the CAS set OK? Not making any wierd noises like it's rubbing on anything?

Other than that, I'm lost for ideas

[sidewaymambo]

Will increasing the idle rpm help? what ecu ?

[yogi000]

I would say, if your belt is on right, marks match up, all hoses back in the right spot (eg. Crank Reciculation Thingi) and CAS on the right mark(by eye), reset the ecu and try starting it and holding the idle up for a couple of mins and see if it help but other than that i'm stumped.

dunno if that is any good tho

[Roy]

Other dodgy trick that may get you to where you need to go is to grab a screw driver and adjust the idle control valve, i did this when i had a leak/slit in an IC hose until i could replace it...as it would stall at idle otherwise.

[jnr32r]

are you sure youre not out a few teeth out. triple check cam pulleys and cranck

[Craved]

ecu would be good, might running lean on idle if the camshaft holding open longer than the injectors are programed to pulse! just an idea...

[bbenny]

yeah i have tried everything everyone has mentioned here.

the only thing i think could be causing it is the fact the inlet cam felt much stiffer to adjust than the exhaust. it was noticably harder to adjust, i think the engine is having trouble turning it over at idle and hence stalling.

the only thing is, when i noticed this problem when fitting the GTR cam i decided to throw the standard item back in position to check there was nothing wrong with the GTR cam. But the standard one felt just as stiff...

[KamikazeR33]

didnt happen to drop anything inside perhaps? ive seen this done before...

[bbenny]

i dont think i dropped anything in, i was pretty meticulous doing this job.

there are no strange noises to suggest there is a spanner in the works (literally).

I only can think of a few things that are causing this.

- either the fact the in.cam was difficult to turn is causing the problem.

- the timing belt has jumped a tooth or so on start up (i doubt this)

Considering they are a very mild cam upgrade compared to the standard items the ECU should be able to handle them.

so im stumped here.

i think ill pull the whole lot out and go back the the drawing board.

[jnr32r]

Place Your Bets Here:

1_ $50, its the timming belt out of alignment .....

[JasonO]

Have you checked the timing ?

There's no gaurantee that the CAS pickup on the RB20 / RB26 cams is in the exact same location.

Get yourself a timing lamp.

[ylwgtr2]

sounds to me like youve may have bent the valves....if your inlet valves were open and you turned the ex cam...you may have pushed the ex valve iinto and open inlet valve....

[Sydneykid]

Hi bbenny, check the clearances (feeler gauges) between the cam lobes and the buckets, if there is a bent valve you should see large clearances that the hydraulics can't take up. If it is not missing, then I doubt this is an issue.

You really need a timing light to confirm the ignition timing. Have you tried advancing the CAS and seeing what effect it has on the idle? We usually have to run a bit more advanced igntion timing at low rpm with aftermarket cams.

[bbenny]

hey sydneykid

i invested in a timing lamp today, i did adjust the CAS and it was a little better when advanced but still wouldnt hold idle

it doesnt backfire or sound bad at all, when i drove the car around the block (taking it easy) it was extremely sluggish, i found that response was really poor at low rpm, even if i fully opened the throttle nothing would happen for some time till it reached 3000rpm but even after that point it was very slow.

ylwgtr: i dont think ihave bent any valves because at no time did i rotate any of the cam shafts - i only noticed the stiffness of the in. cam when making a minor adjustment to align the pully marks.

thanks for all the advice here guys, keep it comming, i will begin to pull it all apart again tonight and try see if i have missed anything. if it still doesnt work after rebuild no.2 i will throw the standard cams back in and see if i still have the problem.

sydneykid: did all your installations have good idle or did you have similar problems??

[mabru]

Hi Benny,

I just finished my cam swap as well this past week and the car has been down since with the exact same problem you are describing.

The timing marks are dead on, all 6 plugs are getting spark, and there's PLENTY of fuel, I know this because the plugs almost instantly foul after a couple attempts at idle. I have noticed that when it is colder outside the car will idle until it warms up a bit, my ECU is now pointing the finger at the coolant temp sensor. I have also performed a comp check of all 6 cylinders and they all read the same value, I am under the assumption that if there are bent valves then the comp gauge should not hold pressure (I could be wrong, it's happened before). Of course if I have valves bent in one cylinder then somehow I have valves bent in all six and I think I would've noticed something, a noise perhaps. I have checked everything I can think of at this point and have been using my wife's S14 as a taxi lately. I have ohmed out the harnesses to the AFM, swapped AFM's, CAS's, and ignitors with a friend's known good parts.

But I am so glad someone else has performed this swap and seen the exact same problem as I have. You are not alone...

I'm going to replace my coolant temp sensor tonight after work and see if it makes it better, my car has idled exactly 3 times since the swap and everytime its been after it was a chilly rainy evening.

I'll re-post after I check out this temp sensor issue, hopefully with some positive results.

Of course any other ideas/suggestions are appreciated

-Matt