well this weekend me and DuronClocker tried to get the base timing right on my car with the new tpi setup. we made sure we were on the compression stroke of the #1 cylinder. then we dropped the dist. in so that the rotor pointed to the #1 plug. when we tried to start it it would not start unless I gave it gas, and then it would only run if I kept my foot on the gas. the engine would run best with the dist. turned as far CCW as you could push it which I believe is advancing it right? you can also smell that it is running really rich too. no black smoke comming out the rear like there used to be before I changed the injector constant (I am running the larger LS1 injectors on my 305 with the fuel pressure turned down to 42psi). funny thing is that when I first put this thing together I missed getting the dist. in right by like a tooth or so and the inductive timing light was showing that I was waaaaaaay advanced (about an inch and a half past the farthest mark which is 10 degrees) but it would start and idle with no help. the engine shaked a whole lot like the timing was wrong but it would run on it's own. I tried to turn the timing back when I got to about 9 degrees advanced it would stall out. the way I see it the engine wants all that advance because it is running so rich and now with the dist. in right I can't give it enough advance to idle on its own so I have to give it throttle to advance the timing more correct? now the big question is why do I have too much fuel? I set the injector constant to 24.5 lb/hr because I am @ 42 psi fuel pressure. they originally are rated for 28.5lb/hr @ 58 psi. now making this change to the otherwise stock bin file should make the ecm correct for the amount of fuel it puts in. so why am I running rich? I should add that when I ran it up to 2500 rpm with the dist. in correctly there was no miss firing at all, so it is not a problem with a plug not firing or something like that. I can send a copy of the bin file if anyone has any ideas on what might be wrong.

 

Timing first, then fuel.

Did you disconnect the timing wire when you were checking your timing with the gun? If the computer is still throwing in it's advance you'll be up around 25* advanced when then true initial is actually around 5-8*. Disconnect the timing wire and you'll get your true base timing.

Did you check your plug wire routing? Getting 6&8 or 5&7 backwards is easy to do, and it will definitely run with a bad miss like that, even if the initial timing is set correctly.

Vacuum leaks, misrouted vacuum lines? That can play havoc with start-and-idle conditions, too.

There's no basis to say that you're running rich just yet. If you have a miss or the timing just isn't right it will ALWAYS smell like gas to your nose- because there's unburnt gas making it into the exhaust that should have been burned properly inside the engine. Don't use your nose to determine your A/F ratio- it'll be wrong just about every time.

 

plug wires were triple checked, esc wire is unplugged, no vaccum leaks that we could find.

 

Sounds like you need to quadruple check and start with the basics and procede outwards.

Verify good cylinders

Use propane to check for vacuum leaks.

Your motor is a hobble cobble of parts and years does the timing cover match the motor?(they are 2-3 different covers)

What tune is your engine running.

later
Jeremy

ill post more when i get a chance too

 

thing is that before I put the tpi on it was a bone stock LO3 that ran as good as the day it came off the line. nothing but the injection method has changed.

 

First thing I checked for was vacuum leaks because mine did this with a bad vacuum leak...til I noticed that my brake booster vacuum line was disconnected still

Then we checked the plug wires on distributor and plugs, and all looked well.

When we backed the fuel pressure down a bit it seemed to run a bit better, but still couldn't come close to running on its own, especially if I didn't hold the distributor as far advanced as possible.

Also, it seemed very smooth at 2000-2500RPM. Though I do say the plugs could be in better shape. Probably wouldn't be a bad idea to replace all of them and see where that leaves ya I guess. Might as well do plugs, cap, and rotor too. If nothing else, its maintenence that should get done anyways.

I was hugely suspect of the wiring and the conversion harness for the TPI setup, but if you say it was running at some point, I'd assume that was all okay.

 

One thing my uncle said as a possible test...unplug the electrical connector on the MAP sensor and see if anything changes.

 

The timing sounds like you are off by 1 tooth. When dropping it in it turns quite bit when the gear engages. Double check that at TDC you are actually pointing to #1. (I've done this before so really I'm not doubting you, just suggesting)
You may notice you are running very hot on the exhaust as a side effect. Have the "spark bypass" disconnected when checking with the light (and check the advance **** on the timing light is at 0)
I've really goofed on that before
The lines for the PCV should be rechecked to insure you have air in the opposite side from a breather or air tube from the FRONT of the throttle blade (this is the top connection on the trottle body)
The PCV valve line should come from the valve cover PCV and go into the second connection on the side of the TB.
When I first put mine together I had the canister connected to the plenum side of the throttle blades (second connection down) and could not get it to run without giving it gas. It makes for a huge air leak around the IAC.
Hope this helps you find the problem.
Good luck.
Jp

edit: Rather than pulling the dizzy, just turn it back to where you started and move all the wire 1 post over, just to see if that is the case.

 

That could be it. He just has a breather on the passenger side instead of the stock hose from vc to tb. Fix it and see if that helps a bit.

 

That should be ok as long as the port on the TB is plugged.
By putting just a breather in the valve cover he made the system "open" rather than a "closed" system.
Air enters the crankcase through the air cleaner at the front of the TB and goes into the crankcase, then the exiting air is "throttled" by the PCV valve back into the engine behind the throttle blades or directly into the manifold in some cases.

 

Ah true, the tb is plugged.

 

so any more ideas here?

 

Are you working with the same distributor as the old setup?
Is the ground strap hooked up to the intake?
Is the Egr hooked up, and if so are you getting vacuum at idle?

 

you could try setting the base timing with a vaccuum gage. this method will get it pretty close to were it needs to be.
to do this you turn the distributer till you get the highest amount of vac you can get then back it off 1 lb of pressure then tighten it.

 

but how can I set timing when I have to give it throttle just to keep it running

 

is it speed density or MAF

 

Check that you have a good ground strap from the motor to the body/battery??
Try adding a jumper cable if your not sure how good it is.
Maybe its just a power problem... or,

Go back to the basics (yes again ).
Set TPS to proper volts,
Set idle air (mechanical screw) to allow more air, Then
Set TPS to proper volts again for idle 0.45 V
Check timing (bring back to TDC)
Remove cap and confirm the rotor to #1 is where it should be.
Confirm #1 wire is on #1.
Check that IAC is closed by putting the jumper in the A & B, wait 30 seconds and turn off the key. Pull out jumper.
Unplug the IAC. (run without it ??)
Try to start it and see if you can make it idle.

This should give some kinds of indications what is going on, Also check the connectors to the distributor and or module to see if they are shaking loose connections.
Hope that helps give ideas.

 

Those injectors are 28 lbs per hour. Search for my post in the DIY PROM section slp "#25" injectors.

 

ok now I am all sorts of confused. I am not sure what the part number on my injectors is but I am pretty sure they are the larger injector. I thought that LS1 fuel pressure was 58 psi and the first ls1's had the larger 28 lb injectors, then they went to the 25 or 26 lb injectors and then they went back to the 28 lb units. all of these being rated at 58 psi. now racetronix is saying here that at 58 psi it is really a 32 lb injector and at 43.5 it is a 28 lb. so now here is the question. if I had my injector constant set at 24.5 @ 42 psi instead of 28@ 43.5 would I get my current condition where is smells rich and wants a lot of advance just to idle?
here is the link to what I am talking about.

http://www.racetronix.com/12561462RFM.html

 

this is may sound really really stupid.. but do this..

unplug the CTS.. coolant temp sensor.. and start the car..

i have the same problem as you.. and for some reason if i unplug this sensor.. the car starts up without holding the gas..

 

KiLLJ0Y, I'd say your CTS is bad then

As for the LS1 injectors, I know the '98's came with 28# and then they dropped down to 26# for '99, and I thought they stayed that way til the end of the F-body. As for how things work out with the pressures I don't know. I thought they were rated @58psi as well.

 

no its not.. there is an issue in the chip where it will only hold idle if the temp reads 100*.. if the car is warmed up.. it runs fine..

so what we did was warm up the car.. then unplug the CTS and plug in a cold one.. car dies.. both CTS's are brand new..


as far as the LS1 injectors.. i had them too.. never worked right and always gave me a rich condition.. plus they never fit right.. so i switched to LT1 injectors.. problem solved..

the ones SLP sells are take outs.. so you could possibly get 28# or 25# from the trucks.. i was told this by a rep there..

 

did you put the #1 wire directly over the rotor.


the rotor doesnt have to point to the #1 cyl, it can be anywhere as long as the #1 wire is above it and the rest follow in the correct order.

 

the rotor pointed to the post that the #1 plug wire goes to. the injectors I didn't get from SLP, I got them from a bulk seller on ebay.

 

Make sure its on top dead center and not 180 off. Both the #1 and 6# pistons are up at the same time.

 

Only other thing I can think of for the timing would be if you changed the distributor gear (or had it off) and the "dot" is not lined up with the notch the rotor goes on.
May index slightly one way or the other but should still work.

 

I doubt it is out 180 as I pulled the #1 plug and cranked the car over till I got it to blow my finger out of the hole. at this point the mark on the balancer was at 2 degrees retarded mark. so it would have to be on the compression stroke of #1 correct? and when I dropped the dist. in the rotor was pointing right where it should be, just a hair or two before from being right under the #1 plug post on the cap.

 

Soooo, did you get the #'s off those injectors yet? The LS1 and truck injectors have different part #'s.

 

I'm not that far from you, maybe a1/2 hr or 45 minutes, let me see whats up this weekend and if u have a warm or heated place to work on it I can try and stop by. Been sick with sinus garbage so no heat = no go.

U need to go BACK TO BASICS

I hear people saying whats broke and how to fix it over the internet but I see no verifiable proof anyone has done anything.

You swapped injectors out and now the car doesnt run right.

Your first clue should be CHECK THE ORIGINAL AREA OF REPAIR.

How did anyone check for vacuum leaks? Did you try using propane like I said in my earlier reply.

Slap a vacuum guage on it and test it? That cam you should pull 17-20 inches or merc.

Is it wavering or fluterring like mad? Is it steady and low?(mostl likely not).....

Lot of what u r saying points directly to a vacuum leak as my first gut feeling. Its possible your timing is way retarded still, but I doubt it at first glance...............

Having the Inj Con. off by 2 points can drive your blm down to 108-112 range at idle and could definitely contribute to your problem , especaily if the timing is off or you have a vacuum leak.

couple things to check and I'm still thinking vacuum leak somewhere at first guess, but I cant see the car.

later
Jeremy

 

I am currently back at school right now so I haven't gotten a chance to try any of the new suggestions prob. be a couple weekends before I get to play with it. just trying to get as many schools of thought as I can. so that I don't waste what little time I have to work on it and being left saying "well what now" and having to wait for another weekend to come back and try out some other thoughts. If I can't get it going when I get back I prob. take you up on your offer 3.8 cause your prob. the only one that can help me get it right before thirdgen fest.

 

I accually had to set my constant to 28 to get a 128 reading on my 383. With a 25 constant I was pig rich and 108blm's everywhere.

 

so I guess the concensus here, regardless of the fact that it may not be the cause of my problem, is that I should bump my injector constant up to 28 cause that is most likely what they are flowing in reality right?

 

If they are the same part #'s as the ones in the link and your running 42-44 psi fuel pressure, yes.

 

here is a thought after reading another thread. could the knock sensor have anything to do with my problem? I replaced the original one with supposedly the correct one to work with the 730 ecm. if I had put it in too tightly that would cause it to pick up knocking and retard my timing right? GM#10456549 is the part number for the one I used

 

anybody? thoughts on this?

 

That is a 5.7L (350 for us Americans) knock sensor.
I don't have the 305 # handy but I can confirm the number you posted is for the 350.
They are different.

 

It should be torqued to either 14 or 15 ft lbs and that is all :-)

Cant find the specs right now.

Overtightening them does increase the sensitivity.

later
Jeremy

 

hmmmmmmmmmm now I wonder if this is my problem. I torqued it to what ever the haynes manual said. for some reason I think it said more than 15. maybe I am wrong. how much difference would it make if I used the 350 sensor on the 305? can I make any changes in the bin file to work with it. like copy a few values out of the 350 bin and copy them to the 305 bin?

 

No, U simply run the knock sensor that is the most closest to your natural application.

later
Jeremy

 

What exactly did u do to make it not run?

If I have your story straight, u converted to SD TPI from TB and all was fine and car ran properly.

Then you did what exactly and everything to not make it run properly.

Be descriptive.

later
Jeremy

 

I had this same problem with my 89 IROC and it turned out to be the positioning of the distributor. May car ran perfect but would not idle. I found out the dude who had it before me had the distributor off a tooth. The ignition module was pointing straight towards the driver's side fender and the #1 plug terminal was in the wrong spot. I reset the distributor so the module pointed diagonally toward the driver's side firewall and the car has run perfect ever since. Not sure why, that is just what happened to me.

Also be careful with the harmonic balancer. If it is and old one, chances are the outer ring could have spun on the inner one and that would make your timing off. Turn the engine over until you have your TDC and if your damper is right, the mark should point right at 0 on the timing tab. If not you can try a strip of timing tape wrapped around the damper. You can get it at just about any auto parts store. Good luck