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Old 07-16-2012, 07:58 PM   #1
mfencl
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87 350 tbi timing

I got my truck to finally run after like 3 month truck won't idle two things I could think of time which I do not have access to a timing gun or my butterflies aren't opening enough to let it idle but friend did say that the butterflie were completly closed when I let off the throttle the butterflies r completly closed anyone know how to adjust that?
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Old 07-16-2012, 11:56 PM   #2
wyattglock
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Re: 87 350 tbi timing

That is controlled by the idle air control valve. If it is stuck closed the truck won't crack the blades open far enough to get air flow and idle properly. I ran into the same thing on my tbi 454.
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Old 07-17-2012, 12:20 AM   #3
Desert1957
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Re: 87 350 tbi timing

you CANNOT time a "TBI" engine without a timing light, Beg, Borrow, or Steal one . Disconnect the little brown wire, and set it the right way. trust me I have seen it tried and some of the attempts were 40-50 off.

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Old 07-17-2012, 10:04 AM   #4
rfmaster
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Re: 87 350 tbi timing

Quote:
Originally Posted by mfencl View Post
I got my truck to finally run after like 3 month truck won't idle two things I could think of time which I do not have access to a timing gun or my butterflies aren't opening enough to let it idle but friend did say that the butterflie were completly closed when I let off the throttle the butterflies r completly closed anyone know how to adjust that?
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You must have timing light - sorry no if's, but's or whatever's - got to have this piece of TE to work on EFI equipped cars / trucks!
Unlike classic, non-ECM carburetor equipped engines the ECM in TBI system controls timing advance (and other things as well). For ECM to carry out its duties, the base timing should be set to 0deg, with EST connector open. When you open EST connector (single brown-white wire just under brake booster) the SES will lite (this normal) and idle will drop down to 600 RPM. Once set reconnect and shut engine down. Clear SES code by disconnecting battery for 30 seconds (engine off!!!!). After engine restart check timing at idle - it will be bouncing between 16 and 20 deg - this normal as ECM continuously varies SA timing. You are done with timing.

It is normal (in TBI ) for throttle blades to be closed at idle. The IAC controls amount of idle air getting into engine during idle. IAC should be reset - use search function I have posted this procedure on several occasions.

All of the above assumes that you've mechanically sound engine, there are no vacuum or exhaust leaks, ignition system is in working order and there are no fuel pressure issues.

//RF
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