HKS camshaft stall problems

[mrdsukautos]

So i fitted 256 inlet and 264 exhaust cams
no real idle problems other than ever so slightly lumpy on start up but car settles down quite quickly
Main problem is this- when slowing down to a stop or near stop car loses idle and stalls. this does not happen all the time and certainly doesnt happen same way everytime
Is this something i have to live with ?

[Ian C]

Nope, it shouldn't do that at all. Manual or auto?

[Chris Wilson]

UK or J-Spec engine?

[Bob]

I would say it's less likely to be the cams, more likely to be a loose connection to one of the sensors from when the cams were installed. Have you got an aftermarket ecu / piggyback tuned for the cams?

[Cadburys Purple]

I've got this same problem and so has another lad on here. It doesn't happen everytime with us but it does occur quite often. Were on standard cams but we've been told that its the O2 sensors?:search:

[Ian C]

If your car overfuels then it can have a tendency to stall or try to stall when you pull up to a junction. You can sit stationary and give it a brief bit of wide open throttle to rev it up, let the revs drop, and if it tries to stall when the revs get back to idle then it's probably overfuelling. Which may well indicate an O2 sensor issue.

-Ian

[grahamc]

I have a jspec, I am running 264/264 cams, and have no issues with my idle or coming to a stop like that. Definitely not something you should have to live with.

[Muffleman]

What ecu ? And who mapped it ?

[Bob]

Just a thought, but are you sure that all the timing marks are lined up exactly?

[Chris Wilson]

Did you or whoever just fit the cams, but didn't re shim the clearances? Tight clearances will cause this. J-Spec engines adapt to changes in duration and lift less well than UK engines which have an air flow meter. Are the cams timed up properly?

[Wez]

Mine was doing this with 264/264 as it was overfueling, after pulling a load of fuel out on the AEM in that area of the map its fine.

[Chris Wilson]

Goes to show how even a mild set of cams changes the fuelling (and almost certainly the timing) needs.

[TLicense]

Mine was the same. Massive overfuelling when changing the cams to 264's.

[mrdsukautos]

ok thanks for all the replies guys and sorry for my late reply
its a j spec auto
no piggyback or standalone
just installed cams as starting to finally do the car now and get this big single install done bit by bit
timing is perfect
didnt reshim the clearances chris :(

[Ian C]

I'll be the first to say that a single conversion doesn't happen bit by bit :) It's all or pretty much nothing I'm afraid, otherwise you end up in a situation where you've changed parts and buggered up how the stock ECU runs it. Er, kinda like this :)

Also the stock cams choke up the top end so not as much fuel for a given boost pressure is thrown in by the stock ECU. You can clear that breathing out by putting in wider cams - the engine ingests more air but the boost pressure remains the same in the plenum so the stock ECU thinks it's still as it was. The mix will be leaning off, question is, how much?

-Ian

[Chris Wilson]

ok thanks for all the replies guys and sorry for my late reply
its a j spec auto
no piggyback or standalone
just installed cams as starting to finally do the car now and get this big single install done bit by bit
timing is perfect
didnt reshim the clearances chris :(

But you DID check them after fitting the cams, and they were all correct...?:innocent:

[mrdsukautos]

But you DID check them after fitting the cams, and they were all correct...?:innocent:

lol chris
no i didnt car runs perfect except for this stall problem on stopping sometimes
I kinda had to leave it as it was damn late chris and it was just one of those things that i meant to go back and check and didnt


Ian i know its an all or nothing but you know how it is bud never got the damn time always working on everyone else's cars so wanted to start at least getting some bits done

[uk-rich]

i have just changed from hks 256 to 264 and some of them need to be re-shimed, which has pissed me off no end

[Chris Wilson]

It's entirely to be expected.

[Ian C]

I installed my 256/264 cams a few years back and didn't realise, back then, that reshimming was required :) Imagine my surprise when I found they were all in tolerance a while later :D :nana:

[Sharpie]

Mine was doing this with 264/264 as it was overfueling, after pulling a load of fuel out on the AEM in that area of the map its fine.

So, you HAVE to have a fuel computer when installing aftermarket cams.....I have never read this before.

As a temporary measure, could you not up the min idle speed to 1000 rpm to avoid the stalling or does this have other side effects to consider also ???

[stupra]

I have 264/264 cam's fitted and i'm only running on a base map on the EMU, but I don't have this problem. The cam's were re-shimmed by Mark at Phoenix when they were fitted though.

[Wez]

The stock ECU uses closed loop in that area to try and correct the fueling but to take advantage of cams you should correct the fueling.

I am not sure about stock turbos but when running my PHR Stage 1 on the dyno we had to add loads of fuel to the map compared to stock cams, in the non vac area.

To give you some idea, with only the cams changed I made 552hp at 1.1bar where stock cams made 510hp at 1.4bar.

[Sharpie]

If people are overfuelling at idle, when does borewash come into play ?