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setting base idle and timing.

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Old Feb 26, 2013 | 10:12 PM
  #1  
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Car: 89 trans am GTA
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setting base idle and timing.

So im finally at the point of getting all my sensors adjusted but im at a snag.

I need to set base timing

I need to set base idle. (Adjustment plug was tampered with by the PO

I need to adjust the tps.

In what order should i do these?
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Old Feb 26, 2013 | 10:21 PM
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Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: setting base idle and timing.

http://www.chevythunder.com/do_it_yo...0minimum%20air
https://www.thirdgen.org/forums/tpi/...-i-adjust.html
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Old Feb 26, 2013 | 10:54 PM
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Car: 89 trans am GTA
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Axle/Gears: 3.27
Re: setting base idle and timing.

ok the links help alot but should i try and set timing once i get it running somewhat?
i just installed a new distributor and new tps. and about to put a new iac probably tomorrow
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Old Feb 27, 2013 | 01:48 AM
  #4  
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From: Aloha, Oregon
Car: 1991 Christine Z28
Engine: RV Cam and Intake 350 SBC
Transmission: 5speed
Axle/Gears: 3.08 ls Posi
Re: setting base idle and timing.

If your crank, cam, and distributor are lined up, there is nothing left to time unless the engine is running. When it's running use a timing light to dial in the timing. Do this with the distributor unplugged from the computer so the computer doesn't adjust it.
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Old Feb 27, 2013 | 07:09 AM
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: setting base idle and timing.

Originally Posted by Dakota W.
When it's running use a timing light to dial in the timing.
And after you have set the timing set the idle
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Old Mar 1, 2013 | 09:34 PM
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Car: 89 trans am GTA
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Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

HELP!!!!!! after breaking two starters i finally got it to fire up.. but im having a huge problem.

it will only fire up if i give it a little throttle. then it wont stay running unless i blip the throttle. and its misfirin or backfiring. feel/sounds like popcorn in the intake. i can feel it popping into the intake.


so heres what all i've done to the car.
hooker 2055's
edlebrock runners.
tpi spacer
1.52 roller tip rocker arms and new pushrods.
new timing set.
new egr valve
new tps/iac/maf/cts/knock sensor/iat.

i can get the the timing set in with it barely running as close to 6* as i can. i've tried to set base idle but have no idea where to start at.
i do have the aldl jumpered.

Last edited by 92crimsonRS; Mar 1, 2013 at 09:35 PM. Reason: bad keystroke.
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Old Mar 1, 2013 | 10:37 PM
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: setting base idle and timing.

Originally Posted by 92crimsonRS
its misfirin or backfiring. feel/sounds like popcorn in the intake. i can feel it popping into the intake.

1.52 roller tip rocker arms
new timing set.
Where to start.
Are you sure the timing chain was installed correctly ?
Are the rockers adjusted correctly?
The fact it appears to have "kicked back" and destroyed 2 starters worries me
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Old Mar 1, 2013 | 11:01 PM
  #8  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

yes the chain was installed correctly. i made sure of that 6 times before i even tq'd the bolts down.
yes the rockers are installed correctly. and valve lash set per what i've read here on the forum. aka tighten until. the up/down movement was gone then the preload is at 3/4 turn.

the starters were my fault mainly. the ring gear has a few teeth missing due to the p.o. every now and then it gets in the dead spot.

one thing i forgot to mention. the backfiring seems to be coming from the pass side bank only. i've tripple checked the wires are going to the right plugs and terminals. also using accel shorty plugs 276s not sure if i was supposed to gap them or if they came pre gapped

firing order 1-8-4-3-6-5-7-2 right? its not backfiring like stopping the motor or kicking back just more of missfiring and popping alot.

Last edited by 92crimsonRS; Mar 1, 2013 at 11:07 PM.
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Old Mar 2, 2013 | 01:20 AM
  #9  
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From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: setting base idle and timing.

Originally Posted by 92crimsonRS
using accel shorty plugs 276s not sure if i was supposed to gap them or if they came pre gapped.
I always like to check the gaps anyway
Is the dist set correctly to #1 TDC on the compression stroke?
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Old Mar 2, 2013 | 11:38 AM
  #10  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

Yes i set it at #1 tdc compression before i even put the valve covers on. It seems to only backfire from the pass side of the block.

Im going to pull the plugs and check gap. Any idea what i should gap the shorty plugs at?
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Old Mar 2, 2013 | 12:08 PM
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: setting base idle and timing.

Triple check your rocker adj.
Quad check your firing order.
Make sure your not 180* out of time with the dizzy.
check your plugs for proper gap.
make sure your wires are not laying on the header tubes and arc n thru.
You can set the TPS cloose without runing the motor.
once its running an timing is set you can tweak the min air rate. (I do things a bit diff than some peeps)
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Old Mar 2, 2013 | 04:16 PM
  #12  
92crimsonRS's Avatar
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

I checked everything except gap last night.

Any recommendations for gap?
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Old Mar 5, 2013 | 12:43 AM
  #13  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

well i checked the gap today. all but one or two were at .35 so i set them all at .35.

and i might have figured it out. somehow when i was turninging the dizzy to tighten the coil down i managed to unclip the coil wire. so the boot was on but the wire inside was barely touching.
seems to want to run a little more. still wont idle. i have the a&b jumpered and the idle screw adjusted out just so it might want to stay. tps is set at .55 ~ .54 back probing blue wire and using the neg battery terminal as ground.
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Old Mar 10, 2013 | 10:54 PM
  #14  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

ok well something new something old.

i've got it to where it will run for a few seconds before dying. i still have a random misfire. as i tried unplugging injectors to try and find where my popcorn sound was coming from. it doesnt seem to misfire on the same cylinder every time.

i noticed today the fan kicked on....? it was stone cold and the a&b was not jumped. so i changed the CTS thinking maybe it went bad. (under warranty) now it will run better but still misfire.

my thoughts are
1. the ecm is going bad.
2. loose missing ground that i cant locate.
3.ignition control module
4. electronic spark control module ( how often do these go bad? and where are they located?)
the fact the fan comes on and the engine isnt even warm has me thinking ecm.

Last edited by 92crimsonRS; Mar 10, 2013 at 10:56 PM. Reason: forgot....
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Old Mar 11, 2013 | 02:15 PM
  #15  
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From: San Antonio TX
Car: 1990 G92 IROC Z Miniram
Engine: 388cu 6.4 Liters
Transmission: G-Force T5
Axle/Gears: 3.73 Gears
Re: setting base idle and timing.

Make sure the ground wires in back of the heads are hook up. Disconnect the tan wire to set the timing. Make sure the rotor is pointing to the #1 cylinder before setting the timing setting the idle is usually done in the chip.. You may have to turn the distributor while the engine is running to get the engine to speed up so it could stay running.
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Old Mar 11, 2013 | 02:18 PM
  #16  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

I can get the timing just about on 6* as it will run just very poorly with random misfires. I'll check the grounds today. As well and have the icm tested.
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Old Mar 11, 2013 | 03:27 PM
  #17  
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Re: setting base idle and timing.

It may sound dumb ,but make sure the timing mark and balancer are correct. It is possible that the timing mark could be off. Make sure the motor is at t.d.c. (look in the #1 cylinder). Than see if the marks match.
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Old Mar 11, 2013 | 05:50 PM
  #18  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

I made sure the mark was correct when i had the balancer off.

One thing i just noticed. The power feed wire to the ecm is hot. Like really warm to the touch after me trying to keep the car running.

And one last thing. There is a wire coming from the alt. Going to a connector just like the ecm power wire.....is it possible i got them backwards? I have the ecm wire going to the plug that leads to the 20a fuse in the little case. And the alt running to the other plug straight into the harness.

so here's another thing.....i remember reading that the service engine light should come on then go off for a second then stay on when the key is switched into the "on" position. mine stays illuminated. does not flash flicker of anything.
i pulled the ecm out last night and noticed the prom wasnt seated fully. so i pulled and fully seated it.

Last edited by 92crimsonRS; Mar 11, 2013 at 07:39 PM. Reason: another issue
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Old Mar 11, 2013 | 08:24 PM
  #19  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

just got my aldl cabe working again so hopefully after dinner i can go see what in the world the ecm is thinking.

anything i should look for that would cause this strange misfiring?
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Old Mar 12, 2013 | 03:16 PM
  #20  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

Had a thought. The icm has to be grounded right? I remember pulling the dist and it didnt have a gasket. Yet the gasket set came with a mounting gasket. Maybe the gasket is preventing the icm from getting a good ground?
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Old Mar 22, 2013 | 12:32 AM
  #21  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

so what would happen if the distibutor wasnt grounded?
would it be the cause of my problems?
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Old Mar 22, 2013 | 10:18 PM
  #22  
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Car: 89 trans am GTA
Engine: 355
Transmission: T56
Axle/Gears: 3.27
Re: setting base idle and timing.

ok so here's the update. i added extra grounds. checked all engine to frame grounds. none are loose or missing.

i ran winaldl and noticed the CTS was reading 107*F which i know is not accurate. (i just replaced the sensor.) and its been 65*F outside all day.

so i wanted to double check so i unplugged the CTS sensor and now the ecm is reading -38*F does that sound right?
im leaning more and more towards a bad ecm. seeing as i dont see knock counts on my readings.
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