tuning for smooth cold idle

[liquidh8]

Hey all. I fixed the high BLM issues I had, it was a combination of a few things, exhaust leaks, intake gaskets, blah blah. Got it all fixed, and I bought a TT chip from a board member for stock injectors. The car runs great, except cold idle is horrible, I have to keep it running till it warm up. ( about 157dF) and warm idle is ok. Idles open loop. The a/f is real fat, like TT says it should.

I started modding a stock bin for idle, i went off of a few things from a sheet I d/led from turbotweak. I haven't tried it yet though.

Are there anything you diy'ers did to smooth out your cold idle?

i know I can get chip vendors to burn me a chip that "works". But I would like to keep egr, and all the emissions stuff working. And I am not a fan of pulling out the prom, and sending it back and forth. When I can do it myself.

Any input guys thanks.

 

[QUIP'6']

subscribed. mine is worse warm than cold.

 

[jasjamz]

Wish I could help you more but, my translator is set to lean idle and idles smoother than when it is at the default.

 

[liquidh8]

Well, for those watching the thread.

My set-up:

Stock 100K long block, including cam and heads
Stock ported upper plenum
Stock gasket matched lower plenum
3.5 MAF pipe
green stripe injectors, 30 lb'ers
stock MAF w/1 screen
AFPR, 43 vacuum line off
big ol k&n
stock turbo, inlet bell ported, exhaust elbow hogged out
3 inch DP
dual 3 inch exhaust
TT chip 93 octane, 18 lbs boost.
new style coil packs.
other little things everyone has done.


I started to tune with tuner pro RT. With a stock bin, it runs like crap, lol. Bought the TT chip cause it was a deal, and figured I'd see how it runs with it compared to whatever tune I make.

All the vacuum lines are new, turbo pretty new on rebuild, leak free no play. (old one was junk) I replaced all the gaskets from the intake up, fixed leaky headers and crossover pipe. replaced the EGR, MAF, ECM, had to repair a ton of wiring. It runs way better then when I bought it. But, the cold idle is a problem for me.

My chevy wagon has got a large by huge cam, TBI, air gap manifold, 10.5:1 compression, and I tuned it to idle 750RPM warm, 950 cold. And it is smooth. Granted, it took like 100+ chip burns, making one change at a time.

I gather there aren't many TB owners who burn thier own chips. But if the few are reading this post, maybe we can get together and share info for the greater tune???:smile:

 

[Eric Stage I]

Just so you know, a chip for stock injectors won't work right with 30lb injectors. Some people get away with it, but idle, cold start, blm's, etc, won't be very good.

If you downloaded the cold start article off my site (by Dennis Leek), you should be able to perfect it for your car, once you get it tuned for the 30lb'ers. Most of the work is in the open loop A/F multiplier vs coolant temp table.

Not a lot of chip DIY'ers left these days!

Regards,
Eric

 

[supercomp729l]

Hello,

I have spent lots of time on Chip for 30 lb injectors along with many hours of road testing for spot on drivability. The current combination is set for 20 lbs boost and Methanol. If you want a caopy of the bin file email me @ thuard@aol.com

Tom Huard

 

[dennisL]

I can help but understand that there is not just 1 or 2 items that affect idle. During warmup, the ecm uses spark advance tables for increased advance that tapers off as the engine warms up. It also uses fuel tables for a target AFR at various coolant temps. Then you have the target rpms for various temps and lastly the IAC control parameters that are always in use.

The spark tables have little affect so let's skip them for now. The fuel tables and the target rpms will have a hugh affect on warmup idle so they definitely need to be changed. After these changes are made, the IAC controls can be tweaked to either smooth or roughen the idle depending on your preference.

I can't put everything you need in this post but let's start with the target rpm tables. The one used in P/N is located at $669. Decide on what you want the "hot" or normal operating temp rpm to be, then work backwards (or colder) from there. I happen to like the stock value of 750 rpm at 176 and 198 degrees. Going up the table (colder) from there, I changed the rpm to 850, 950, 1000. Stock these are 775, 800, 900. I left the 90 deg value of 1050 rpm alone. Next I use 1100, 1250, 1300 which were 1250, 1350, and 1400. The first 3 table entries I left alone. Maybe it will make more sense if I just list all the table hex values: 70, 70, 70, 68, 64, 58, 54, 50, 4C, 44, 3C, 3C, 3C, 3C, 3C, 40, 40. Now these rpms work good provided the target AFRs are also changed. I'll do another post on these changes but let me know if this is the type of info you are looking for.

Dennis

 

[dennisL]

OK, now let's look at open loop (O/L) fuel. The first thing to consider changing is the temp used for the O/L to C/L switch ($405). Stock is 76 degF which I believe is too low. (This might be an emissions thing.) I use 144 degF which is midway between table entries for all the fuel tables controlled by temperature. If your chip uses O/L Idle, this is the temp O/L idle starts.

Next you need to think about the AFR after the switch to either C/L or O/L Idle. The stock C/L AFR is 14.7:1. Your O/L chip will be whatever you want. I suggest you make the O/L fuel tables richer, then just before the switch point make the AFR within 0.5 of the C/L (or O/L) AFR. This makes for a smooth transition rather than a very noticeable change to the idle.

Two tables determine the warmup target AFR. I call it target because the ecm doesn't have a clue what the actual AFR is. Table $4F7 determines the initial AFR and is the equivalent of a choke in the old days. Table $521 sets the AFR after the "choke" time has expired. The stock values for both these tables are way lean starting with the 68 degF entry. This was done because this is the table entry that is used when the ecm switches from O/L to C/L at 76 degF. From here on up all the stock AFRs are lean because the ecm will be in C/L and this lowers emissions.

Table $521 definetly must be changed to improve cold idle. The values used depend on your setup and target AFR after the switch to C/L (or O/L idle). I use O/L idle at either 14:1 (in P/N) or 13.5:1 (in Drive) so I don't think my table values would the best for you. Experiment with these tables but let me know if you need help.

We have to make more changes to fix the cold idle problem but that's it for now.

Dennis

 

[liquidh8]

Dennis, Thanks for the posts. I read the papers you made. I made a bunch of changes as recommended in those papers. Raised to c/l switch point, and the o/l afrs was changed to be .5 afr from the c/l setting. I haven't tried it out yet though. With the holidays, a good friend passing away last week, just haven't got to it. I want to keep this thread alive for those trying to do the same thing as me.

Hello,

I have spent lots of time on Chip for 30 lb injectors along with many hours of road testing for spot on drivability. The current combination is set for 20 lbs boost and Methanol. If you want a caopy of the bin file email me @ thuard@aol.com

Tom Huard

Tom, I will take you up on the offer. THANKS! If my wagon runs real good with the chip, I can use the compare function to see what was changed.

Thanks for you replies guys!

Jim

 

[Low Budget]

Did you ever get your idle the way you wanted it to be?

When Eric said:

"Not a lot of chip DIY'ers left these days!"

I would have to agree. I see a whole lot of threads in the chip sections of forums asking what and whose, but very little of how and why.

I wanted to chime in to let you know I am one of those DIY'ers. If any of you other DIY'ers want to "compare notes" so to speak, I'd welcome the conversation! I don't mess with this stuff very often, but I do enjoy the challenge.

My idle preference is to force it into closed loop earlier than stock settings. I have had no problems living with the very short time it may stall if left alone. For the most part, I can start it from cold, use my left foot on the brake, right on the gas, and by the time I get backed out of the garage and into the street, it's fine without chasing it at all. I have my rpm's throughout the whole warm-up range set lower than factory too. In fact, I believe I have them all set to my target idle when warm. I always HATED how these cars would run at a higher idle when first started. Even if the engine had just been shut off warm, it would run at a higher rpm for a short time when first started. I programmed that crap out of the chip too. That required more than the basic rpm vs temp changes too, but I'd have to wrack my brain a little to remember what I had to do. I do remember it was a victory for me when I got it the way I wanted it to be. :smile:

 

[liquidh8]

you are in PA too. I haven't worked too much on the tune. This thread I started a while back, lol. But I still have the car. I had a bunch of mechanical upgrades to do, no I am doing the fuel system. Then reseal the tranny and a rear main seal. So I will be tuning, but not till the end of the summer in to fall probobly.

I would be more that willing to share notes also.

 

[Low Budget]

you are in PA too. I haven't worked too much on the tune. This thread I started a while back, lol. But I still have the car. I had a bunch of mechanical upgrades to do, no I am doing the fuel system. Then reseal the tranny and a rear main seal. So I will be tuning, but not till the end of the summer in to fall probobly.

I would be more that willing to share notes also.

Yep, I'm about 1 1/2 hours from Yardley in traffic, or 1 - 1 1/4 with a good run. My wife and I go to the Bensalem Golden Corral for supper once in a while. That's not to far from you if I remember correctly. Let me know when you get back to the chip programming stage. I'd be happy to talk further!
Jeff

 

[norbs]

What software are you guys using to mod your bins, tunerproRT? Are you modding the TT chips? You do realize the code is not the same and the way the tables are read may mean something else, than what is actually happening?

 

[Low Budget]

What software are you guys using to mod your bins, tunerproRT? Are you modding the TT chips? You do realize the code is not the same and the way the tables are read may mean something else, than what is actually happening?

Oh yeah..well aware thanks. I know there is some really different sh!t going on in his chips. I wish I knew half of what that guy knows about code manipulation! I give myself a headache just remembering how to add one little feature into an unused section of the chip. Still, I enjoy the challenge.

I use a combination of BM Computer Source T-6 Tuner, and Hex Workshop (hex editor). The basic stuff I use T-6, and what that doesn't allow, I use the Hex Workshop to dig deeper.

 

[TurboDave]

Oh yeah..well aware thanks. I know there is some really different sh!t going on in his chips. I wish I knew half of what that guy knows about code manipulation! I give myself a headache just remembering how to add one little feature into an unused section of the chip. Still, I enjoy the challenge.

I use a combination of BM Computer Source T-6 Tuner, and Hex Workshop (hex editor). The basic stuff I use T-6, and what that doesn't allow, I use the Hex Workshop to dig deeper.

good old fashion software!!! the stuff I used to use when I was hot into this stuff.

 

[Low Budget]

good old fashion software!!! the stuff I used to use when I was hot into this stuff.

"If it ain't broke", TurboDave....you can surely complete this statement yourself!

My wife and I were just down through your lovely town the second week of June for our 20th anniversary vacation.

 

[TurboDave]

"If it ain't broke", TurboDave....you can surely complete this statement yourself!

My wife and I were just down through your lovely town the second week of June for our 20th anniversary vacation.

Should'a hollered. could have had you over for a visit.

 

[liquidh8]

Oh yeah, when I get the mechanical upgrades and interior work done, I'll give you a holla!

I am using tunerpro RT, since I am not the best programmer .

I didn't ever try to do anything with a TT bin. I wish I could add a few of the features into mine, but I am not THAT good. I've been tuning TBI/TPI for years, and recently LSX and the TB. But I am not much of a code hacker to add stuff.

 

[Low Budget]

Should'a hollered. could have had you over for a visit.

I didn't know I knew anyone in the area. Technically, I didn't at the time, as I don't think we ever talked before, did we? Thanks for saying so though. I'll keep you in mind if we get back down that way!

Oh yeah, when I get the mechanical upgrades and interior work done, I'll give you a holla!

I am using tunerpro RT, since I am not the best programmer .

I didn't ever try to do anything with a TT bin. I wish I could add a few of the features into mine, but I am not THAT good. I've been tuning TBI/TPI for years, and recently LSX and the TB. But I am not much of a code hacker to add stuff.

I'm not a super code hacker either. I have trouble understanding what's been done in a chip like a TT even when someone who knows explains it to me. I do understand it eventually though!

I do not get into the massive rewrites like in one of those chips though. I've only done a couple things besides changing factory settings. I don't use a wideband O2 at all. Not for data logging or control. Not yet anyway. If I could change my "screen name" (to high budget), perhaps I'd be quicker to do more.

 

[dennisL]

Programming is not that difficult

After you spend enough time to get a general idea of what the ecm is doing, you'll realize that by only making changes via TunerPro places limits on what you can accomplish. You have to make program changes to really make a difference.

Deciphering the instruction set seems intimadating at first but we're using an 8-bit processor that is simple compared to what's in your home computer. In addition, you don't need any special compiler software to make program changes. I used a hex editor for years with excellent results.

Lastly, everything you need as reference material is readily available thanks to the Internet and when you have questions, there are people who can answer them.

If you already have the capability to make chips, get a copy of the program (downloaded from gnttype.com), get a Motorola M6800 Reference manual or instruction map then start thinking about what you would change if you could (because now you can).

Dennis