Hooray for me, my car is finally running and drivable. I set the valve lash way too tight, which is why it didnt run. Anyway, the timing is set fine, but I experience bogging/stalling and backfiring/popping when I mash the pedal over 1/2 throttle. If I feather it then it will get up to speed, but when I slam it down it sputters and dies. Is this a tuning problem that I must take up with Brian from TBI Chips? or is this something that I need to work on? I think I'm gonna goto radioshack this weekend and build an ALDL cable and get some readings.

Anyway, there's a new problem. Of course. The ground wire that connects to the battery cable (at the battery) and runs to the body (about 10" long) fried. The car doesn't start unless I replace that wire (which gets hot). There's a short somewhere I'm guessing, but WHERE? I had to use 8awg speaker wire to re-ground it, and it gets hot fast so I remove it after it starts. I don't want to have to keep doing this every time I start my car either Any ideas?

 

Not sure on the short but the poping and stalling is a result of bad tuning. You should just bite the bullit and start doing it yourself. You will crap when you get your first prom close and your car pulls like a frieght train. A heads and cammed LO3 is a pretty fun car when tuned. It is like you have awoken the beast.

 

But like I said, I haven't the time or money I'm really interested in one of those on-the-fly tunable PROMs though...


Well I have reason to believe the wire only controls the starter's ability, Because everything else appears normal before I start the car. Loud radio, bright lights, etc. I can remove that ground wire AFTER the car is started without any ill effects. Could it be something related to the starter, possibly a loose or damaged wire touching the body?

 

Bout d@mm time bro! lol! good to hear!
:rockon: :rockon:
-G

 

Have you checked your starter to see if it might be pulling too many amps? Does it make any funny noises when you are starting the engine?

Steve

 

The starter is fairly new (6mo), but has never given me any problems before. The battery is a DieHard Silver.

 

Oh by the way I am running the stock TBI unit. Brian emailed me telling me that I'm probably not getting enough fuel when I floor it. Does this sound like the problem? I'll put the Holley 670 back on eventually I suppose, but it's a real bear trying to rig everything up to that stupid thing. I hate how incompetent Holley's design is on that crap.

 

Our mod's are about the same. I'm running the stock tbi unit and stock injectors. I heard all that bs about larger injectors and tbi units. You need the fuel pressure up some and tune the chip. The biggest adjustment to stop the bog/lag/lean backfire is more pump shot in the chip.

Oh by the way I have 55 lb and 65 lb injectors and the Holley pos that I do not use at this time on this setup. So it's not being cheap for the reason

 

I give that holley unit a big thumbs down. I hate that piece of crap. Anyway, I need an AFPR, what do I do? I don't want to modify the stock TBI (partially because I dont have a dremel to cut the slot thingy, or any time to do it). Can I buy an addon FPR? Perhaps one with a guage?

 

Sorry I got here late. If I understand correctly you just did a head and cam swap. Did you replace the rear ground strap that goes from the head to the firewall?Did you mount the negative battery cable back on the head in front? Sounds to me like all the juice from the starter is routing back threw the small ground cable instead of the negative battery cable.

 

yeah the strap is connected. should I add a ground wire just to keep others from burning?

 

After what you have done as far as mods the AFPR should be an ez mod for you to do!

You don't need to slot.https://www.thirdgen.org/techbb2/sho...hreadid=216769

You do need a 3/8-24 tap and a 3/8-24 bolt

 

the afpr mod wont take as much time as you think. i've done 2 of them the 1st one i thought would be hard, the 2nd one took me like a few minutes to disassemble it, drill it, slot it and put it back together.

DM91RS, i havent tried it that way b4, infact i never gave it a thought.

 

Yea, to echo what the others said you're going way lean. Peep that new prominator on the diy prom board, if I didnt already have a programmer and chips I woulda bought that in a heart beat, cooler than hell.

 

OKAY WTF. REASON #524 I WILL NEVER GOTO A SHOP AGAIN. I was cleaning up the mess under the hood and I found out that my coolant temp sensor was no plugged in, and the MAP sensor vac line was disconnected (harmless mistake). I started the car and it still ran like crap when I was driving... Well upon closer inspection, I noticed that the #4 spark plug wire was not snapped on to the spark plug. The wire got burned but I replaced it with some left-over piece of wire and on I went. I took out some plugs and noticed that they were kinda rusty and very bare metallic. Does this point to lean to confirm everyones thoughts?

The car drives awesome when I manually shift it. I'm not sure whats wrong when I have it in drive, but it doesn't always downshift. The TV cable is connected properly, but I have not checked the fluid level.

The car is fast. However, it has a void between 1000-2000 rpm, but after that it seems to pull really hard. But then it seems to fall on its face after 4700 rpm. I'll guess this is attributed to running lean as well?


Wow the car loves to roast the tires but it doesn't even chirp them when it shifts (or I do it manually even). Does this also point to running lean? It's probably part of my void between 1000-2000 rpm, also... I checked the timing and it's about 16-18 degrees advanced... is this odd to you? it's waaay off to the left of the tab. Oh well, it runs.

Wow I can't wait to get this car running optimally. I'm getting about 10mpg leadfooting it while running poorly tuned.

 

http://www.filteredimage.com/poo4bra.../enginebay.jpg


ttt

 

Your ful pump will cause the car to run flat on its face. You are lean and your stock pump is givin' er' all shes got.

 

Sounds like the main ground strap doesnt have good contact and the starter is pulling through the smaller grounds. Check that there isnt any paint or garbage on the head where it connects adn that the connection is clean and solid.

As for the way it runs, with the exception of the popping, thats pretty typical of how a non-stock motor will run on a near stock chip. Id get a fuel pressure gauge and check the fuel pressure to make sure it isnt dumping off under load. The plugs being clean isnt much to worry about, either unless the car was jsut under WOT before they where pulled. EFI cars tend to leave the plugs bone white.

 

I hate some of those shops...

With the throttle all the way open, depress the 'D' shaped metal tang and pull that damn cable housing toward the fire wall as hard as you dare. Release the metal tab then the cable housing. The ratcheting mechanism will take car of any overtension in the cable

 

I already adjusted the TV cable. I noticed my transmission is slipping now. Before it shifts it spikes up about 200-300 rpm and then engages. I have not checked the fluid yet. And the ground strap is located on there to the back of the clean head. I'll recheck it though.

And Shifty, you're saying I WILL need a new fuel pump? Whyyyyyy?! I dont wanna drop that friggin tank It's gonna be a pain in the ***.

 

Sounds like the transmission may jsut be worn out. Mine did that after I swapped as well. Now itll allow the motor to rev till it blows at WOT.

 

If the tranny didn't exhibit these symptoms before the swap I'd be inclined to think the TV cable still isn't right (too loose). I'd entertain the notion that the increased power of the engine has now pushed the tranny over the edge, but not until I was absolutely sure the TV is correct.

The factory method of retracting the cable and allowing the ratchet to self adjust can result in too little TV actuation. The cables ratchet mechanism can fail over time.

I'd follow dimented24x7's advise on adjusting the TV assuming you haven't tried that already. That method results in maximum TV pressure at WOT which is what you want.

Before you try his method you can check if the TV is too loose. Rotate the Throttle full open by hand and try and pull the cable out. If you can pull the cable, then the TV is adjusted too loose.

Also, the geometry of the cable bracket to the throttle lever is fairly important to proper TV operation. If you've got non stock brackets/locations you'll want to correct the geometry. Otherwise you run the risk of smoking the tranny.

 

Brent hit upon something I ahd noticed after putting on my holley. The holley only seems to work well with the other holley components and my trans didnt really shift properly untill I actually used the holley tbi and holley spacer. Before that the shifts would be a bit mushy at low speeds. I dont know why holley insists on doing everything different but they do. If you compare the holley throttle shaft assy. with the stock tbi you will see that they are different. Its pretty annoying in that my gas pedal is now half way down to the floor when the throttle is closed because of the change in geometry with the holley.

 

I dont have the holley on right now because I seriosuly hate those fxcking linkage problems.

 

Ok, jsut make sure that the tv cable is set proper and the trans fluid is up to spec.

 

Can I get away with just increasing the fuel pressure, or do I need bigger injectors?

 

You are gonna eventually need both. Your car should run a bit better with a new pump but you will max out the injectors. You can run them forwhile just as long as you are not lean up top. The fuel pump will drastically help.

 

drastically? hmm...

but adjusting FP will help me fix the voids throughout the RPM range, but have the same "redline" until I get the pump?

 

To an extent. If you have your fuel pressure set to manitian at least 15psi at WOT but your pump can only support 11 then you are in trouble. Just because the flood gates are open doesn't mean that the water is there.

 

I'm goign to make an AFPR this weekend and see what happens. I've got mixed results; some people tell me I can get away with stock injectors where others say don't even bother with them. I can't find any 350 (55#?) injectors to save my life for under $80. TurboCity has them for about that price, and it seems way overpriced IMO.

 

You can get away with them for a bit. The fuel pump is the weakest link and not the injectors. After you get the tune dialed in with the new pump see what type of fuel demands you need in the upper RPM's. Then if you have the stockers maxed you know it is time for bigger injectors. Typically these cars are impossible to tune with heads and cam and stock fueling. After the new pump goes in things will be easier and your car will feel different at all RPM's. I have witnessed a tuning attempt on a LT1 cammed and vortec headed LO3 with the stock fuel pump and injectors. It was a nightmare. A new pump was added and pretty much every bit of previous hesitation went away. The tuning has no progressed and the stock injectors are now the weak link.

 

Wow. Hmm... What do you think the time difference is in the 1/4 against these two comparisons? I know a lot of people are trying to pull me to the dark side and goto carb. They tell me the stock pump is fine for carb, and my car would be so much faster as carb... Is this true? Should I listen to these guys and turn my back on TBI? Or should I struggle with it like everyone else is?

 

Hang in there. There is a lot of weak links on these cars as you can see and you will get it worked out. The stock pump can supply enough fuel for a carb set-up because carb set-ups do not need anything higher than 6 or 7 PSI. They don't need high pressure like FI systems do to make the fuel pattern and spray. Even with the stock injectors and a new fuel pump and basic tune, you should feel your car pull really hard in the upper rpm's. You would be amazed on how different the part throttle and WOT feel of your car will change with a better pump. The next heads and cam LO3 that I make will have a high flow pump before I start.

 

FPG001 - $83 a.k.a. GCA701
http://www.autoperformanceengineering.com/

is this the part number I want?

 

That one will work fine and avoid any problems with too much pressure for the regulator to handle. Although I have yet to see that but have heard about it. That is a good price as well.

 

Awesome, I think I'll get it when I get a job. I'm really not looking forward to dropping the pan.

 

You mean tank? It is not to bad but it does get frustrating depending on how rusty everything is down there.

 

tank tank tank my bad

yeah I live in michigan, so you can only imagine
stupid rust.

 

There is another way , but thats all I'm gona say.

 

I assume your refering to hacking up the floor pan?

You can drop the tank w/o dropping the rear. The only parts that need to come off is the trackbar and shocks/springs so you can get the rear down far enough. Also the exaust has to come down as well.

 

Token, you mentioned above that you cannot find 350 injectors. Look on ebay for used TBI units, get an entire unit off a 350. I looked almost every day and just recently found a 350 TBI unit off a 9C1 Caprice and the guy didn't know what he had so I did a "Buy it Now" for $20. So I got a solid TBI unit with 65# injectors for super cheap, they're out there just keep your eyes open.

 

good plan, I'll keep my eyes open