Jump to content
SAU Community

Recommended Posts

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.

Link to comment
https://www.sau.com.au/forums/topic/42478-camshaft-instalation-probs-help/
Share on other sites

  • Replies 88
  • Created
  • Last Reply

Top Posters In This Topic

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

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

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...

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.

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.

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??

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 :rofl:

-Matt

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...