v10viper04

what I'm wondering is i was told when i swapped my motor to run the 305 tbi comp in my car instead on the truck 350 ECM i got with the motor.... is that keeping my engine from performing at its top? cause it has a lot more torque but doesn't seem like it accelerates that much faster than my stock L03 did.... (L03 to L05 swap)

titchener

Did you do any tuning or swap the chip on the ECM when you put in the 350?

Paul T.

v10viper04

no its running on the stock 305 ECM.... i had the 350 one in but someone told me not to use it and that the 305 was better....

85irocz355tpi

You should swap the computers or atleast the chip since the computers themselves are the same and the chip is the only difference. Also you lose the 115MPH governer with the chip from the truck. You will get more power from the chip replacement since the one you have is trying to feed a 350 like a 305. You'll get the fuel that the 350 needs. You should do it to help avoid a lean condition which could lead to detonation and a blown motor. wouldn't want that. The comp is easy to change. Just pull the bottom panel off on the passenger side. take two screws out that hold the comp in place. Then unplug the comp and plug the new comp in. Or undo the two screws in the cover and pull the cover and pull old chip and install new chip and put back together.

titchener

Wow, if you didn't change the chip or bump the fuel pressure, that engine has to be running very lean as the ECM thinks its running a 305 and is only injecting enough fuel for that. During part throttle the ECM will compensate for this by watching the 02 sensor, but during full throttle its open loop and you're running very lean, which is probably why you don't have much power.

Your best fix is to scrounge a laptop, go to moates.net to get a basic chip tuning/burning setup and tune your ECM correctly for this engine. If money is flowing free and you want the slickest setup, go to dynamicefi.com and get yourself and EBL system, its not only powerful its easier for new users.

Next best in line is probably just to bump the fuel pressure, assuming your stock pressure is around 12 psi, to compensate for the increase in engine size you need to bump it to around 16 psi. This is going to take a new fuel pump (a lot of people swap in a TPI pump) and either modifying your current regulator to be adjustable with a kit from Jet, TurboCity or xtremefi or doing it yourself following instructions you can find in these forums.

You could also buy a new chip from a commercial chip tuner, this is frowned upon on this forum because its a compromise over doing it yourself. However, if $ is tight and you are in a hurry this might be an approach to consider. When I first got into TBI tuning as a first start I bought a chip from tbichips.com and it worked pretty well for me, in my case it was a stock L03 with California smog tuning which made it run like a 4 cyl. Pinto wagon. The tbichips.com chip really helped improve the driveability of the car and in my case was worth it.

Paul T.

Ronny

iTrader: (1)

The truck chip is just that. it thinks you have a 4000 lb truck and the trans that was in the truck. I would guess the importtant differences are in the spark table. I would start with a datalog. you will need an aldl cable and a laptop. software is free.

DM91RS

The only thing that held me back for years was an affordable laptop. Now that is all I use.........

v10viper04

I just swapped the ECM to the Blazer's ECM and all i can tell is that it runs smoother and quieter but it seems a lot slower.... I don't understand it..... also i tried just changing the chip and the check engine soon light kept flashing, the car ran like **** and stalled so i didn't try again and just tried swapping the whole unit....any ideas?

Ronny

iTrader: (1)

So you have in car a truck ECU. You ran the chip from truck ECU. now you swapped in a chip from ? what vehicle is that chip from? I dont believe you can swap chips from ECU to ECU unless the same ECU part #. What is the ECU part #? A truck ECU such as a 1227747(TBI) has dozens of differing chips for differing engines trans vehicle weights and some California specific.

Travis odell

i think a carb would fix it all up

titchener

Like Ronny said, swapping chips between different ECMs generally won't work, what happened was the ECM couldn't read the other chip correctly and went into "limp home" mode, which allows it to run but pretty crummy.

Generally you also can't just swap different ECM's in either, at least not without making chip and/or pin wiring changes.

I'd stay with the ECM that was originally in the car, and as I stated before either make or buy a chip correctly adjusted for your engine size increase, or bump the fuel pressure up to 16psi, at least as a starting point, with the higher pressure it should run a lot better than it does now.

Paul T.

v10viper04

it has a tpi fuel pump in it.... i installed it over the winter.....

titchener

Well, you're pretty close then. Get an adjustable regulator kit and a gauge and set your pressure to 16 psi and it should run pretty good, at least a lot better than it does now.

Paul T.

v10viper04

i swapped the 350 TBI pod thing with my
305 TBI pod thing and all i did was change the injectors.... does that mean that my fuel regulator is too low?

DM91RS

X

Travis odell

its the same fuel regulator 305 350

v10viper04

o ok... whats the stock fuel pressure around? and if my car has open element, headers, 3" cat back what should i be able to run in a 0-60? (asuming the car is running good)

also i have drove it around today and now she seems like shes running the same as the 305 ECM but a little bit smoother.

Travis odell

how many miles does your tbi 350 have on her? if its had the hell run out of it and its stock dont expect it two be way better than your 305.

titchener

So do understand correctly that you put 350 injectors in?

If so the 305 ECM tuning will not be that far off, my recommendation to bump your fuel pressure up was based on thinking you were still using the 305 injectors.

An L05 makes around 25 or so more HP than an L03, so its not going to roll your socks down but you should be able to feel the difference.

Doing some tuning or trying an aftermarket chip (not the best way to go but in this case where the engine is mostly stock it will probably help) can help you get a little more power.

Paul T.

v10viper04

it has around 60,000 miles on a rebuilt motor.... pplus i changed the oil like a week ago and its just starting to turn darker... its clean as hell on the inside apparently.

camshaftxe

With proper fueling and tune you could expect 7.8-8.0 0-60mph.

v10viper04

i just realized today that if i'm on the throttle about 1/2 it seems to pull alot nicer than full out... but when i was driving it today i started off and out of no where the motor cleared up and pulled good for a sec then (like a plug wire dieing off) it went back to the way it was.... it was wierd like it ran good for a second.....

v10viper04

Would anyone know why it does that? I had the throttle about halfway down and it was accelerating and out of no where there was two short blurps of power (like i had a fouled spark plug and it fired a couple times and made the car pull then died again) ANy idea why i'm getting little spots of power randomly through the rpm range?? could it be fuel? ignition? plugs? Wires? (the wires are mismatched... Splitfire/AC-Delcos) any ideas?

DM91RS

Can you get a laptop to use? With winaldl you could at least get an idea of what the fueling is doing up to a certain point. [not full throttle]

How fast were you going when the engine died?

v10viper04

died? it never "died" it'll just have short spots where it seems like it runs better.

DM91RS

[/QUOTE]

(like i had a fouled spark plug and it fired a couple times and made the car pull then died again)
[/QUOTE]

??

Travis odell

He's talking about like his spark is going in and out.

v10viper04

yea exactly.... i'm not sure if thats what it could be or not.... the plugs are brand new.... the wires are not new but were at the end of last summer.... i have the wires mismatched... there are some AC-Delcos and some Splitfires... Any ideas?

v10viper04

could it possibly be my coil? heating up and crapping out?

v10viper04

no one has any idea?

v10viper04

Seriously no one knows? find that hard to believe........ come on ppl i need help....

Travis odell

ok sence no one can give you any info on your set up, i will tell you the truth! you should get a carb if tbi is giving you this much trouble man? Because a stock 350 can olny do so much, and if the fuel is so lean then get you a 650 carb and a holly high rise intake! also if you wanna keep tbi you should change everything you listed.... "the wires mismatched... there are some AC-Delcos and some Splitfires... Any ideas?" if your spark plug wires are mismatched it will back fire and not start this is what will happen if mismatched!! so its eaither your fuel or your emaignation.

v10viper04

yea and i deff don't have the money to buy a carb... so i want to stick with TBI.... and what i meant by mismatched was they are different brand wires, they are all in the right places and the car runs fine.... just doesn't seem to have as much power as i think an L05 with headers should have.....

camshaftxe

So you dont have aldl, or a laptop? Its going to be almost impossable to get it to run good without a personal tune. Lo5 aint going to just down right scare you, Im not sure what your expecting, but most l05s made 180hp, without proper tune not even that.

v10viper04

My L05 specs said 210 in the blazer..... and 190 in a truck, and 180 in the caprice.....

Travis odell

Sence you want to keep the Tbi and can't get a laptop have Chevy two tune it for you, im sure it would still cost you however eaither way, or you could borrow a laptop and do it for free yourself mabie. Because i know what you mean when you say your lo5 should have more than your old lo3, my dads truck has the lo5 and you can feel a pretty good difference in the two. However my lo3 can still take the lo5 350 in his gmc however his lo5 in my car you would feel a night and day difference. I was thinking about trading him once my l03 for his l05, and your situation is exactly why i didnt.

Ronny

iTrader: (1)

I have an old laptop that would work fine for datalogging. It is sitting on shelf with bad batteries. All you need is to find such an animal(free?) at a used puter store and go ebay and buy a 12V convertor cheap and you are up and running. winALDL is free software. the cable is not that hard to build and instructions are on winALDL site. Radio shack I bet has the parts $12.

Quote: With winaldl you could at least get an idea of what the fueling is doing up to a certain point. [not full throttle]

I bet if you get your BLMs in line and have enought injector or adequate pressure the WOT will be as commanded(12.5) or close to it.

v10viper04

I think i figured it out.... it seems to be ALOT more jumpy now i figure out the Dist hold down bolt was really loose and i think it was allowing the dist to spin around and thats why it was good one day and not good the next... but it was around 4 degrees retarded and i put it at 1 degree advanced and it runs good... revs up to 5500 before she shifts even though the engine is dead over 5k... and i adjusted the TV cable and now she down shifts when i floor it... before she hardly ever did.... Thanks guys now i just need my shift kit installed and my 3.73's