kgfrombeelo

So here's my deal, since I know this forum is the best place for TBI info:


I have an '85 Monte Carlo base couple. Was a 4.3 TBI car, swapped it over to a Chevy Performance 350. Vortec heads, all iron, rated at 330hp. Have gmpp aluminum intake, machined 46mm TBI with 65 lb flow matched inectors, FPR with gauge reads about 12-13 psi, ceramic coated long tubes, high flow cats, 2.5 exhaust with x pipe, flowmaster super 44's, a PCM from a 1993 Chevy 1500 pickup with the 350(don't have the part # handy). Air pump delete, EGR delete. Custom dynontune.


Problem I run into is the car runs like crap when it gets cold out. The colder the worse. The reason I kept fuel injection was to have that consistency and have a computer make the adjustments so I wouldn't have to. For example, tonight it was in the upper 40's, rare for upstate new york and so its great time to pull the car out, get it warm and the wheels moving. The snow is long gone and so is 99.5% of the salt to I took it out for a short ride. Last time it ran it was colder out, and the PCM takes forever to adjust. I let the car idle in the driveway about 2 minutes and there was just tons of unburnt fuel spew out the tailpipes. Started driving(which is the only thing that helps resolve it) and the car ran rich as hell for about mile and slowly improved. Now also when it's cold I do hear what sounds like a vacuum leak coming from behind the HVAC controls. I know these are vacuum controls and I know the hoses do eventually dry rot. Not sure if that's a contributing factor but I'm sure it's not helping. Another thought, I know this PCM has pathetic computing power and the car was tuned on an 84 degree day. The tuner said the car can only increase or reduce fuel by 25%. Another note, it's been said by more than 1 person my o2 sensor is slightly further downstream than an ideal position. Could be a factor.


So my point is going forward with the car I am doing upgrades. I still have the stock 2.41 rear end(yes you read that correct) so this spring that getting ripped out and a GM 12 bolt with 3:73's is going in. Next I want a new fuel system. Between GM performance and Edelbrock, this can easily cost between $2,200 and 4 grand. I won't quite have the cash for that this season, but I was wondering if upgrading to a more powerfull computer like a Megasquirt would be worth while. For hundreds, not thousands I could add exponentially more computing power than what I have now. Maybe that could stabilize my system and make it more adaptable? Because in the warm weather I'm quite happy with how the car runs. It eats up pavement and just wants to go when it's in its range. I've tried to give you guys all the details I can on what I have. Any thoughts or advice on where to steer this thing would be appreciated.

RBob

iTrader: (1)

The ECM/PCM needs to be tuned for cold running, simple as that.

Until the engine is warmed up and the O2 sensor is active (hot) the ECM/PCM won't make any fueling corrections.

RBob.

kgfrombeelo

Yeah I don't think that would be worthwhile for me. I only take the car our so rarely in really cold weather. Also in upstate new York it can be in the 70's and then in the upper 30's the same day. Not to mention the chips in these pcm's are a seriously pain in the a** to get at. I was just looking at your website though and it seems your product might actually be the solution I'm looking for.

MrWillys

I would send the ECM to Moates.net and have a 28 pin socket installed so you can use 27SF512 flash chips. Download Tunerpro RT and find the appropriate ADX and XDF files and make sure to build a history table.


https://www.thirdgen.org/forums/diy-...xcel-tool.html


Log the vehicle and play back the file allowing the history table to populate. This will give you your BLM averages so you can modify your VE tables. I'm of the opinion that all speed density applications that are not stock should be tuned in this manner. Who better to do it than yourself.

Tuned Performance

iTrader: (92)

you should have a 16168625 witch uses a memcal.
You can unsolder the stock chip and install a dip socket and flash prom.
If you need help on this feel free to pm me. I don't mind helping if you cover shipping. It's easier than using a piggy back board. You can use a moates hdr1 and burn2 to make changes. You might want to invest in a wb o2 gauge if this is happening in open loop. Sounds like the tune is close just cold conditions.
If this was tuned live you might want to take it back to your tuner and get what you paid for.
You will need tunerpro rt
http://tunerpro.net/downloadApp.htm


http://www.gearhead-efi.com/Fuel-Inj...Information-E6

hpete

Would a 3 wire (heated) o2 sensor help with this?

Tuned Performance

iTrader: (92)

Sounds like the complaint was not in closed loop.
A heated o2 would speed up cl operation and help keep from going into ol.