My car won't run or stay running for more than a few seconds with the EST disconnected. Swapped in a 383 and had a chip made for it. Did initial timing by ear. I try to use a light and disconnect the EST wire engine dies. Any ideas? With the wire connected timing light shows 4 to 10* advanced.

All help appreciated.

Jim

 

WAG is your timing is too far out to run with the est unplugged.

 

exactly what ede said. your base timing, at idle, with the est connected should read around 20* or more.

 

So I should bump the the current timing up at least 10* more and then check to see if it is able to run with the EST dissconnected? I.E. reading 20*+ with the EST currently connected. What does this connector do anyways?

Thanks,
Jim

 

try 10* base timing with the est connector disconnected.

the est connector is like your vacuum line for the vacuum advance canister on the older vacuum advance distributors.

 

What induction are you runing and what are your motor specs? "Custom chips" do not exist unless the tuner has the car in his hands with the proper equiptment. That is unless you are carbed.

 

I have a new 10.5:1 compression 383 speed density tuned port injection motor:
Prepped 350 4-bolt main block
Eagle internally balanced rotating assembly
Wisco pistons
Trick Flow aluminum heads (195)
Comp Cam hydraulic roller cam:
Comp Cam XR276HR, duration advertised in 276 ex 281 @ 0.050” in 224 ex 230, lift in 0.503 ex 0.510, lobe 112°
Comp Cam roller lifters and rockers
Accel ported intake base
AS&M intake runners
Ported plenum
Ford 30# injectors
New distributor, rotor, cap
All new sensors
Etc.

Original set-up was a 305 sd tpi all in my 1991 Trans Am.

I had a chip burnt per these specs to get me running prior to a follow up dyno tune. I got the car running by ear and it seems smooth considering the set-up. I originally hooked the timing light up and it read ~4* forgetting I needed to disconnect the EST. I adjusted to closer to 10* still with the EST connected. I then remembered I need to disconnect the EST and the motor will not start or stay running unless the EST is connected. I’m not sure what I should do about timing?

 

just give it enough throttle so it stays running with the est disconected. then try to set the timing correctly. if the engine still stalls after the timing is set with the est disconnected, go through the reset mininum idle procedure.

 

Thanks, I will hopefully give this a try Saturday. I wonder now if my timing is really that far off. The car runs and idles at ~900 rpm.

 

Keep advancing the idle timing until the engine will run at idle with the EST wire connected. The ECM adds in a bit of timing on top off static. I had this problem, my timing had to be 15* or higher with the EST wire connected for the engine to idle with the EST wire disconnected. Thats how I found out that my true staitc timing with the EST wire disconnected was way retarded.

So, advance the timing with the EST wire connected until you get to a ECM controlled timing that will allow the engine to run with the EST wire disconnected.

Then set your static timing with the EST wire disconnected.

 

Moving the distributor with the EST connected is a lost cause. The ECM adds timing to pre-set the base setting. The ECM will "limp" and change the timing if the dizzy is changed or bumped. That is why the car runs with it connected. Chances are the base "custom chip" you have is junk. You need to have the car on the dyno with a skilled tuner.

 

Well I guess at this point, all I can do is see if bumping up the timing will allow me to run with out the EST. Otherwise limp it over to get tunned. I new I'd have to get it tunned, but didn't think timing would be an issue.

 

Well, you guys where right. My timing was way off. About 10* retarded actually......yikes. Now I have it set with the EST connector "disconnected" at 8*. Runs smooth. Unfortunatly my idle is sitting at about 1500rpm when in park and neutral and about 1000 rpm in gear. Nothing was changed since I had the little old 305 in there, so I'm not sure. It is a 1991 sd tpi, so I can't adjust the set screw. Is this most probably a computer chip problem?

Thanks again,
Jim

 

Note: Idle is high when engine is warm and cold

 

just use an awl, small pick, or small screwdriver to pierce and remove the small plug covering the set idle speed screw.

follow the min idle/air procedures listed in the tech article section of this site to set minimum idle.

 

Thanks, I appreciate your help. The idle has changed because of the different set-up right? Probably most specifically the 30# vs. 19# injectors. I just want to make sure I'm not by-passing a bigger problem.

 

correct. larger displacement engine as well. different engine, heads cam etc....