Speed Density Tune + Cold Weather
 

I'm having issues with my truck running right when its cold. I have a speed density tune from allen tuned in San Antonio right now. I have driven this truck to West Virginia for work, and now I drove it all the way up to Wyoming. Zero problems on both trips. I was using my truck for work while im waiting on a company truck. It was starting great for 5 days or so. One morning I started it and it ran great in -10 weather, went to location and parked it. Started it at 5:15 to leave and it was warmer and it was idling like crap. The a/f was real rich and the idle was rough. I let it idle for a few minutes and it died. Started it back up and it idled a little better so I walked inside and 5 mins later its dead again and wont start at all. Ended up having to get to towed to Rock Springs to a dealership. They parked it inside over the weekend and started it monday and it started right up. All this went down last friday by the way. So they added some fuel addative thinking there was water in the fuel somewhere and it froze. I had the coolent changed to the stuff needed for the weather up here. The tech said he drove it all around town and it ran great, idled great and everything. I went to go pick it up yesterday and started it up when it was 6* outside and back to the idling like crap and idling rich. Let it warm up a little and leave and its way rich while driving. Around 10.0- 11.0, I was hoping it would warm up and get out of the closed loop and be alright. Anyway, I gave it a little gas to go through a light and the a/f would go lean when stepping on it instead of rich. It would go up to 13-14. I was in the process of turning around and heading back to the dealership when it died at a light and wouldn't start again. Had to get a tow with my tow strap to the dealer. They were closed already so I didnt get to talk to anybody. Called them this morning and let them know what went down. They don't even know how to diagnose the problem since it doesnt have a maf sensor. Seems it runs fine when its a little warmer in the day and like shit when its cold as hell. It was -22 here this morning. My question is, is this a problem with the speed density tune since it was tuned in San Antonio, Texas at a low elevation and now the trucks at 7000ft and ALOT colder. I called Allen and hes gonna call me back about it when he gets a chance. If anybody has any input on this it would be appreciated. I just need to get it running good enough to get it home when I go on days off. Sorry to be so long winded but I wanted to explain it well. Trucks mods are in the sig by the way.

Thanks,
Sam

With the changing of the weather and the SD mine would do the same thing. Weird random idle surges, died sometimes at the light. This is just me thinking but possibly since there is no MAF its not able to adjust for extreme temperature changes.

Base running air flow idle tuning will fix that problem. You have to be scaning the truck at those low temps to get the right info.

Or just run a larger MAF and be done with it. There are plenty of builders making well over 900 HP with a MAF :)

Iv seen alot of draw thru maf's boosted apps working well but not to many blow thru over 6psi.

I'm running 12-13 #'s blown through my stock MAF.The MAF is at it's limit at 4800 rpm's, then the PE tune keeps it safe until my shift points [6000 rpm's].

That way works but itS not fueling for your real airflow. Its rpm based so if you ever see more boost at say 5900 your going to go lean since the VE table flatlined at 105kpa and is now X rpm=X fuel and will not account for more or less fuel at that rpm under boost. It dose work so I'm not saying itS wrong as long as your happy at the end of the day it's just not for me.

If I was to get a re-tune to get the truck home, then I could go from there. Would that work? If I woulda known speed density was gonna do this I wouldn't have done it. Then again I didnt know I was gonna be taking my truck across half the US.

Do you sell the larger mafs blownchevy?

HA...I was having the same probs with my retune from BlackBear. Since I know nothing about tuning I have no idea what he did, but I did some data logging at idle and WOT and he sent me a reflash and its pretty much cured...give him a call and he'll answer the question I'm sure. R/

i have no problems in the cold/hot/lukewarm. clsd. Are you guys Open Loop?

I have no idea man. Just kinda strange it was working good until it got cold as hell.

This is not an SD vs MAF nor an OL vs CL problem.

This is an idle problem. Allen can't tune your idle for cold temps properly -- nothing wrong with his skills, but the SA temps don't go low enough... All you need to do to fix this is scan it as already mentioned.

just curious, how cold does it get in norcal?

here it gets low 30's. Last year when i went from Reno over the pass into Tahoe a bit colder ;)

I've driven in snow country and high altitude without issue but I could definitely feel a huge power loss at altitude.

SD for a couple years now. Temps range from 0 to 100. No issues. I agree its not SD it's probably in the Idle airflow tables and being wrong for the lower temps.

Yeah, im not dogging his tuning skills. I had no idea I would ever have this truck in temps like this. What do I need to scan this? I dont have a data logger or scan tool or anything.

Get in contact with kbracing96 he lives in WY he can tune your idle problems

Humm.. I've now driven mine in 90+ temps and below zero without the MAF AFR is fine. Your tune must not be setup properly.

have them check your fuel pressure.i seen this symtoms before and was the fuel pump and or the the fuel pump hose sucking air.making it load up at idle and then leaning out at wot.

Ok, ill try to get ahold of KBracing. I'll call the dealer and have them check the fuel pressure as well.

Man I wish you where closer, I'd fix you up! Rock Springs is clear on the other side of the state about 4.5 hours from me. :( And it is DAMN cold here! :lol:

If I can help you, let me know! More then happy too :)

Do you think a whole new tune for up here would help? If thats what I need to do then thats not a problem.

Also is NorCal with SD tune. Driven with it from the low 20's to over a 100 degrees. It always seems to run fine.

Rick

Went SD about 4 years ago now on the Denali. The tune was done by Nolan at Campbell Automotive here in Edmonton. Has worked great all the way from -40C to +40C.

I certainly wouldn't go putting a maf back on it. Aftermarket maf or stock the pcm limit is the same for airflow calibration. From there you can only alter the p.e. which puts fueling great if you only drive in vacuum and full boost. Anything in between will be richer than needed. Most likely the problem is in the injector calibration. Minimum idle air could be a problem as well as a few others, but I usually find this problem to be in the injector calibration.

Hope you've found your trouble. My truck was acting exactly like yours after a spark plug change. Thought it was a bad plug. Changed plugs and the same thing. Pig rich at idle. Rough idle. Runs better if you can get it up to speed.

Decided to look for other issues under the hood. I noticed the boost was low under moderate acceleration. HMMM. Usually see 4 to 6psi. Not seeing much boost, but the truck ran pretty good at speed. Decided to check vacuum lines. Found a split "T" (pretty good vacuum leak) where the boost guage tied in. Haven't fixed it yet, but I bet there lies the problem. Butt freezing cold temps have to be pretty tough on lines under the hood. Might be good to check yours.

Tuned mine OLSD in 85 degree weather this summer, its been down to 20 now and its doing just fine.

I'll check the lines when I get back down to the dealership again.

Fixed it this afternoon and that's exactly what my problem was. We must have jerked the line around too much during the spark plug change. It doesn't take much of a vacuum leak to make it run like shit. I took the T loose completely with the engine running and it died immediately. Hope yours is that easy and cheap to fix:cheers:

Same here man. I gotta go down to town for a class on thursday so hopefully I can check it out then.

its been colder than shit here too. Mine still has the MAF and its been idling alittle lower than normal when its was really cold. Other than idling alittle low it hasn't died on me driving around.

They called me today and said it only had 10 psi of fuel pressure. They also said they checked it when they had it running and it was 58 or 60 where it should be. Would the low fuel pressure cause it to run rich? I also told them to look at the vaccum lines. I wanna get down there and check it out myself.

Now the dealer just called me back and said it started right up and is running great with plenty of fuel pressure and the idle is 14.7-14.8 not running rough or like shit either. I'm at a loss to what the hells going on. They checked all the vaccum hoses and they said its running with plenty of vaccum.

what is your fuel setup besides 60lbhr injectors? if its stock then the regulator is in the tank. shouldn't make it run rich with low psi but it would make it die for sure. maybe i mised something but if they added fuel at idle but no where else then that why it was rich at idle and not while driving. it more than likely didn't need the added fuel but it looked like it due to low fuel pressure. i would say take the added amount of fuel back out and fix the fuel pressure issue and it will be good. if your running stock pump at 10psi it may have just worn it out having to run full out while in boost. i know mine use to drop pressure during a good run. it would not g

again i don't know if you have stock fuel system but if you do the regulator does not have a vacuum line to it. sounds to me like it don't like the cold temps. i'd have them putin a new pump. if it has 10psione minute and 58 the next hmmmm tells me its not happy.

Its got a Walbro in tank as well. The only that came with the radix I had back in the day. Yeah man everything else is stock.

there HAVE been a lot of walbro dieing here lately. lol i would inspect the stuff inside there anyway and maybe get a new one. maybe something cracked there is no telling.

I'm damn sure not letting a dealership do that job for me. Would rather not get poked for $500 bucks for a 45 min job.

I'd have to say with what you told me and reading all of this, this is not a tune related issue and you most likely a fuel pump issue. Just put a new one in and see where that gets you. Running good one minute and not the next is not a tuning issue. :)