Question to those with Cam's - Coldstarts

[Mickey21]

Sorry about the long post, but I want to get it explained best I can...

I recently purchased a Holden Crewman SS 5.7 LS1 shown in my signature. It has had quite a bit of work done to the engine by a qualified shop a few hours away from here. The shop does a lot of Holden V8 racing in Australia and New Zealand so I know they are very capable of what they do, but nonetheless...

I know the cam installed is spec'ed specifically for the setup, but it has coldstart issues. Is this something that can never really be ironed out on lumpy cam setups or should is it possible to remove completely? I dont mind dealing with the issue if it comes with the territory, but being my first cam installed on an LS engine, I just want to hear advice from others that have had theirs cammed as well.

Essentially it is on a MAFless tune and I had it in to them a couple of times to look at the tune to see if there is anything they can do, but the problem persists. The first time I took it in, there was an O2 sensor out so we replaced that and chalked it up to that, but the second time they mentioned the weather changes had the effect. For the most part the engine will run fine if I wait for the fuel closed loop to set in (2 minutes). But it has still stalled on me before....

If I watch the RPM gauge, it idles around 1K, but periodically falls to 500RPM and back up. If I put the car into reverse or drive and havent waited long, the car will usually stall if I dont apply liberal fuel to propel the car forward. This causes a problem if I am just backing out a driveway of course because I dont want to rocket down the driveway. If I drive about half a mile down the road, the problem pretty much goes away. But I have also had the engine stall while in a low speed turn (also within half a mile of leaving my place of origin).

What do you guys think out there? Am I wrong to expect the engine to not stall if it isnt warmed up? Or should I consider them to back off the cam setup and probably lose a bit of power in the process? I dont mind dealing with the issue to maintain what is otherwise an awesome V8 rumble, but if it can be fixed and ironed out, of course I would try to...

I dont mind dealing with it, since essentially I purchased a great ute for the equivalent of 12 thousand US dollars total... It already had 8 thousand dollars US of work done to the engine so it was a great deal... Minus the cold starts of course... Any suggestions to what the issue might be would be great...

In case you are wondering why I dont just take it to them to have another look, it is because it is a 3 hour drive, something I have to schedule with them, something that will cost me money, and far enough away that I would have to make hotel arrangements and so forth not to mention time off work I cant afford right now... There arent a lot of reputable shops around here that know how to deal with this kind of setup in my area part of the island...


To give you an idea of changes to the engine...

Heads, Headers, MAFless Tune, Cat delete, OTRCAI, Straight exhaust, Larger TB... I have tried to gain more understanding on which Cam they used and most information I could get was 228 and 620something... Problem is they performed the install in May of 2008 so I cant talk to anyone who actually did the install... Paperwork trail is useless as they installed and performed the work under a repair invoice to avoid tax problems (vehicle was owned by a personal business prior to me)... Vehicle was sold to me as a business to business purchase... I do have an invoice for the work and money paid, but it says things like "exhaust repair" and so on... Because of that I dont know what the cam is without someone tearing into the build is my guess... No?

[camarochevy1970]

Sounds like the tune is off

[Lancer-AM]

THe tune sounds off but it could be the cam. Without knowing the specs it is hard to compare against others that had a similar cam and their experiences. Unless the tuner takes a lot of pride in their work and they are really good you might have a hard time getting it fixed.

[camarochevy1970]

I have what some consider a huge cam, and never have those issues.

Here are the steps I have followed for idle tuning an ls1 with an aggressive cam

Idle Limiters --> Idle Speed: 950

Idle Limiters --> IAC Park Position: Raise all points from 40C and up to 21

Idle Limiters --> Idle Air In Gear: All points 60C and up to 8.6

Fuel --> Main VE Table: Multiply column 400 rpm by .60. Multiply column 800 by .80. Multiply column 1200 by .90.

Ignition --> High Octane Table: Add 2 deg to all points 400 to 1000 RPM, .08 to .32 g/sec



Once done with this program, start the car and check for surging. If the car surges, unplug the IAC and see if the surging stops. If the surging stops follow below.



Idle Limiters --> Idle Air in Gear --> All points above 60C to 9.2



Take the car for a drive and check your idle. If the car goes on cruise control reduce the Idle Air in Gear Table .2 (further if necessary). If the idle holds at 2000 RPM for extended periods of time reduce the P/N Airflow Decay table for all points above 10 MPH by 5% (multiply by 95) until this stops. Be vary careful on this table.



If car keeps surging with the IAC unplugged two more things to try.

Multiply Main VE table by another .95 (which would be a total reduction of 85%). Repeat until the surging goes away, or until the car begins to hesitate when you take off.

High Octane Ignition Table. Reduce timing for all points 400 to 1000 RPM, .08 to .32 g/sec by 2. Repeat, but don't reduce it any more than 6 degrees.

[Mickey21]

Thanks for that info, I am going to have to look in on that. I might also post the tune for someone to take a look at. I have a tuning suite on its way over to me at this time with the adapter to hook my laptop up. When I do I will let you guys know what I find. Thanks again and keep the suggestions coming...

[Kjhallex]

That sounds like it's all in the tune. But with an SD tune weather does change it a little. But you still shouldn't be having the problems. Post up you tune file when you can. Did you buy hp tuners?

[MuhThugga]

I would take it to someone near by who is good at tuning and comes recommended by someone. Have them look at the tune and make adjustments as needed.

[camarochevy1970]

he's in new zealand. Not sure how many good tuners there

[Mickey21]

Yeah, not too many in my area. Kind of like living in a beach side town. I tried checking with the local Holden club members as well, but most of them are into old school Holdens and those that have modern Holden models dont really mess with them engine wise... For some weird reason, most of them are content with the power that comes stock... Huh, I know, right?

Hopefully I can get the tune up soon to get some feedback. I am just annoyed that if it is the tune, a true performance shop like the guys in Auckland who do multiple LS1 and LS2 tunes everyday and it being their speciality, could miss.... Argh!!!

[schufflerbot]

Yeah, not too many in my area. Kind of like living in a beach side town. I tried checking with the local Holden club members as well, but most of them are into old school Holdens and those that have modern Holden models dont really mess with them engine wise... For some weird reason, most of them are content with the power that comes stock... Huh, I know, right?

Hopefully I can get the tune up soon to get some feedback. I am just annoyed that if it is the tune, a true performance shop like the guys in Auckland who do multiple LS1 and LS2 tunes everyday and it being their speciality, could miss.... Argh!!!

i hate you.

i mean... awesome ride and best of luck!

;)

my car is doing the same thing right now, only it happens after my car is warmed up. it will 'seek' an idle rpm from ~250 rpm all the way up to ~1200 rpm and sometimes it just dies.

its driving me crazy, i have someone looking at the tune this week.

let us know if you find anything

[camarochevy1970]

i hate you.

i mean... awesome ride and best of luck!

;)

my car is doing the same thing right now, only it happens after my car is warmed up. it will 'seek' an idle rpm from ~250 rpm all the way up to ~1200 rpm and sometimes it just dies.

its driving me crazy, i have someone looking at the tune this week.

let us know if you find anything

RAF table

[afgun]

RAF table

Ruh-roh Raggy!

[Mickey21]

SO I picked up an engine scanner and took a quick look this morning at the live data and I am seeing some weird readings on the o2 sensors... From those in the know that can comment, I am seeing about .1v on the Bank1 sensor and about .9v on Bank 2. Should there be much variance between them. Bank 2 seems to bounce up and down quite a bit and Bank 1 seems to hover. This is all after closed loop of course.

I am guessing, but is Bank 1 left side Bank 2 right? I know I had the left one replaced about 4 months ago because it was not registering completely. Is that Bank 1 or 2? Does one of them need replacing you think?

I am going to look over it more as I learn how to use the software, but it is pissing down rain all day, I have been able to play with it much.

[afgun]

As I've learned... bank1 is driver (with LHD), bank2 is passenger (again with LHD); I don't know if RHD changes this or not. I would suspect no, but you never know with the General.

Assuming that you haven't mucked with the commanded AFR, the O2s should bounce around when you're not at WOT. Looky here.... http://www.hollandms.com/newbie/tuning_new.htm

[schufflerbot]

any update mickey?

[Mickey21]

Yeah I was viewing all four sensors. My guess is from the live data capture that in screenshot1, which was from a start of the engine, the 02 sensor starts out at full rich and goes to full lean and sits there. I believe that means that sensor B1S1 is faulty. My further question is where does S1 sit? At the collector? Just looking for confirmation from more knowledgeable people than I that this is the case. I have noticed fuel economy has taken a dive, which if I theorize correctly is because B1S1 is telling the engine it is running lean and the engine responds with throwing more fuel in there to compensate... No? Looking into replacing the part but need to get paid later this week. With my motor mount (left side) failed recently, money is tight. Here is a few screenshots of the results...

http://nzholdenclub.com/images/dyno/LiveDataScreenshot3.jpg

http://nzholdenclub.com/images/dyno/LiveDataScreenshot4.jpg

[afgun]

My further question is where does S1 sit?

S1 is the front sensor; on the GTO it's in the downpipe from the manifold to the cats. B1S1 is the left-hand forward sensor. S2 is after the catalytic converter, so B1S2 would be the left-hand rear sensor, and so-on.

Either you have a bad sensor, or a badly misfiring cylinder. Easy thing to try, if they'll come out that is, is to swap the front sensors between the banks. If you can get the sensors out...

If the problem follows the sensor, bad sensor. If the problem stays put, you have a cylinder not giving you what you expect.

[Mickey21]

That is what I suspected on the location of S1. Just need to get some time to get down there and try a swap to confirm. What leads me to believe the o2 failure is the likely culprit is fuel consumption has gone way up and there seems to be excess fuel out the tail pipe. Realise no cats at all.

[schufflerbot]

were it me, id just replace all the 02s and be done with it. if you bought it modded, there's no telling how many times those have been installed/removed and you could have more problems than you know what to do with if multiples go out.

glad youre getting the problem pinpointed, though. what happened to the motor mount?! you driving through some bush?!

[discofreak]

i hate you.

i mean... awesome ride and best of luck!

;)

my car is doing the same thing right now, only it happens after my car is warmed up. it will 'seek' an idle rpm from ~250 rpm all the way up to ~1200 rpm and sometimes it just dies.

its driving me crazy, i have someone looking at the tune this week.

let us know if you find anything

Hate to be the bearer of bad news (and sorry for the hi-jack), but last I saw this was on a 'vette I put together and it ended up being a bent valve as a result of a failed LS7 lifter. Are your knocking noises the valve hitting?

I would also get a lot of weird pops - but those weren't nearly as prevalent as the struggle to find idle on a tune that put down 599 to the wheels the day before the problem started. Even weirder, it would only do this when hot and sometimes it'd even stop for a while - it drove strong until the idle problem started again.

I would check all of your valves.

[Mickey21]

what happened to the motor mount?! you driving through some bush?!

Wish I had the money to buy all 4 sensors, but if I can tell they are good or bad, I shouldnt have to replace them all... As for the motor mount, it split where the rubber meets the steel parts. I am told by many Holden people over here that the stock ones dont hold up longer than 100,000k's typically and this ute has done 108,000k's. I dont blame it though since it has been modded for half of it's life and the extra torque couldnt have helped. I want to replace the mounts with some aftermarket upgraded strength ones so I dont have to worry about this again. I see that one of the sponsors Rocksandracing has some upgraded ones that will fit my LS1 as well. I would like to get a set for my setup, but I cant afford them this week. I hope to replace them in the next month though for both sides... I have some other upgrades that I plan on at the same time, just wish I didnt have to worry about these other issues as well.

[Robofuzz]

Any luck on this yet?

P.S. I love this kind of thread where knowledgeable members are helping each other!

[Mickey21]

Better late then never, I did find the problem...

Turns out the left side O2 sensor was in fact dead. Replaced it, but we also found some interesting problems from the previous owner. Turns out the last owner left it with 6mm plug wires (stock). Upgraded them to 10mm wires. Also, the plugs were for some reason bosch on the right, ac delco on the left AND they were gapped DIFFERENTLY. I was blown away. WTF... After changing all that and reading the left O2 sensor, the right side was a bit lazy in comparison. Cleaning didnt help. Replaced the right side O2 with a new one and BANG, no more cold start/stalling issues. Runs great now and idles so much more smooth. Idles sits at about 950RPM without issue. No more bouncing needle. SWEET!!!

[Kjhallex]

That's good to hear!

[hughes]

i know that in my old 1990 silverado (cammed of course) it had a really rough idle while it was cold. it would also stall on me when i would come to a quick stop. the fix was a stall converter. that thang ran like a champ after that. if you have an automatic tranny you shoud get a stall. if your a manual then:confused:

[69GOAT]

Just a little reminder on idles. At idle the air flow is difficult and a little problem might seem worse than it is. I pulled my throttle body off and saw soot on the intake manifold side of the throttle plate. This makes air flow around the edges somewhat inconsistant. Try cleaning this first before fooling with you tune. Mine went from nearly dieng to smooth idle again.