For you guys that remember my problem that seemed to have no answer, just wanted to let you know I figured it out.

Turns out it was a combination of two wierd things.

I finally decided my voltage was too low on the crank input to the ECM so I looked up and down seeing what fed that. It basically comes off the ignition switch, to a starter enable relay, through the park/neutral switch, and to the starter (branches off to the ECM too via fuse box)

I discovered that some idiot previous owner basically hot wired the car under the dash from the ignition switch directly to the starter wire. He basically shoved the exposed wire into the back of the ignition switch terminal and then twisted and taped it to the big ppl wire to the solenoid in the engine compartment. It lasted for awhile but i guess it finally rattled loose enough to cause considerable resistance, enough to where the voltage on the crank wire was extremely low.

I fixed that and viola, gained an SES light during crank, but still no crank fuel, traced it down to a shoddy ground on the ecm


So now I'm back into the F.I. scene after a long sabbatical. Drove the car on my old chip this time with the WBo2 to see what I had in there and WHOA, I actually turned around and parked it, way lean under low rpm load, no wonder it would buck and surge (RBob nailed it in a post awhile back when i asked about it)

moral of the story, dont buy crappy ghetto rigged cars

 

Wow, that's some crazy stuff. Gotta love crap work

Looks like your lil 305 is running good. That's about what my 406 traps right now(stock).:rockon:


Tim

 

i cant win!!! I drive it around for awhile, start and restart it a few times after a few chip reburns (amazing how quickly you can get it close with a WB) park, and then its back to doing the same ****! all my connections for my repairs are good wtf!?!??!?!?! when it was dead cold it started up like a champ

 

The fuel pump shutoff switch might be going bad. You can bypass it and see. The fuel pressure, do you check it while this problem occurs? Bad ecm? loose ground could have messed it up. What does it do exactly?? maybe faulty pump. Have you checked the injectors(at the connectors) to see if they are getting a signal?

 

the injectors arent getting signal, i have an injector test light and it acts just like the injectors do... ugh.. back to the drawing board

 

pablo, i had the exact same problem that you are having a few years ago. I mean, the problem is the same to a tee. Here is what i did to fix it. There is a red wire under the hood with a tan connector on it. It is a single wire about 12-10 gauage. Mine was left unpluged after the engine rebuild and it took about a year to finally find it. It is barried in the engine harness along the firewall up by the blower motor for the heater. I hope this is your problem also. I think that this wire was a main ground for the ignition stuff including injectors.

 

ok this time its official, its fixed.

I broke down and moved the battery back to the front and the problem is 100% gone

I kept saying to myself that wasnt it. Oh well, live and learn.

I have now officially rejoined the F.I. world.

The throttle response compared to the carb is unbelievable, being able to punch it from any rpm is real nice too.


Its just a matter of time before I'm able to do a direct comparison between the carb and TBI. The carb was as dialed in as it was going to get and it takes me probably 20 minutes to swap between both. Wide band data captured also for both.

One thing i know right off the bat, its gonna be able to come out of the hole much harder with TBI, low end torque has increased ten fold over the carb.

 

Sounds very interesting. I would love to know the results. So, no prelim g-tech comparisons?

 

its gonna be a little while, I need to tune the TBI setup big time.

Im not able to Gtech the car here, no good roads anywhere near, too hilly and too crowded All my perf. data comes from the track.

 

That's some good track times for a 305. Looks like you still need some real tires though. With that MPH you should et around 12.9. I have ran 13.1 so far and my car mphs about 104...

 

traction isnt the problem, low end torque is. I never had enough pump shot with the carb, It really needed a double pumper. I got the AFR spot on otherwise though.

It would hook hard and then lug till the fuel caught up with the air and then take off.

Best 60 foot I ever managed was a 2.1 and that was with a dead hook.


Strange, you are now the third person to think the times in my sig are Gtech times.. maybe ill just put my scanned timeslips in the sig

 

Carb vs TBI?.
Was posted years ago at DIY-EFI, for a LG4/TBI, 84 FBird.
Bottom line, was the only defining difference in performance and drivibility, was the carb suffered from fuel slosh in extreme heavy braking. Cold starting was better with the TBI.

 

well I think on my particular combo the differences are going to be more pronounced what with the small displacment, relatively large cam, and single plane manifold.

I shouldnt say going to be, they are, i mean just driving it today its a huge difference. With an automatic and a high stall I would guess that the kinds of differences that a combo like this has are less noticeable and masked by the light loads they place at low rpm.

and years ago you didnt have access to the tables and tuning tools we have today.

 

At least I have good reason. You told me you was getting a g-tech, about a year ago....

 

It's soundling like maybe your carb tuning may have been suffering. If you were using say a Holley, then how much time did you spend in tuning the emulsion tubes/transistional fueling?.

The tables are the same, and plug reading ain't changed.

For a Carb to TBI evaluation to be as accurate as possible means both setups have to be fully optimised. If using a Holley and just changing main jets, then the comparo is going to tilted since the carb just isn't fully tuned as what can be with a TBI.

 

You know what happens when you make assumptions.

I think I did say I was using an afb and several times in the past and I have said that I had the AFR nailed with the exception of the pump shot. If you doubt it I can send you plenty of wb data logs which, incidentally I have posted. You can see the WB data log of my 13.65@103.67 run at carlsbad raceway on these boards if you do a search. If my carb tuning was hurting that bad then my ET is doing a good job of fooling people about it. If im not mistaken your 350 wasnt even turning ETs or mph's that quick

The pump shot was as far as it was going to go, its just not possible to easily change your pump shot fuel curve. As far as transitional systems I reworked the secondary aux fuel system by closing its airbleed and enlarging its feed tube from .035 to 045 inch. I even went so far as to make my own custom metering rods at one point, and quite a few more things. I could have probably changed a few more things but taking a relatively new carb and drilling holes for trial and error tuning is not my cup of tea. Especially when going too far leaves me with figuring out a way to fill back in and redrill.

My goal isnt to prove anything to anyone, I just wanted to be able to stomp on it from any rpm and have more control over the WOT afr. Getting part throttle and idle perfect are of little concern to me. The fact that they are easily tuned with F.I. is but an added benefit.

To even comeclose to matching tuning wise Id have to have one of those new DP carbs with the adjustable airbleeds, etc and for that you are looking at 400+ dollars and im still looking at leaking fuel onto my intake anytime i take off the bowls and still less precision than FI.
I could go on, but its pointless, no matter what I post, you post a counterpoint, I could say the sky is blue and youd find a way to argue that one.

 

I didn't, you might reread what I did post.

Counterpoint is about discussion, the more various items are discussed, the more thought goes into a particular subject, and once in a while, things get productive.

BTW, the sky just gives the illusion of being blue. Viewed from space the earth is not surrounded by a blue sky.
It's not arguing when all your doing is discussing things. If you want to argue, that's just what your wanting to do.

 

Are you sure about that? All the pictures I have seen from space shows a "blue ball". I though the content of the atmoshere causes it to look blue from any angle.. Not joking, I'm curious

 

ok fair enough, I'm open to discussion any time. Thanks for adding some thoughts to the post.


Btw I think it looks like a blue ball because the earth is like 70% ocean or some number like that