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Username Post: anyone reset the baseline idle on their TBI with plug?        (Topic#362194)
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
08-15-20 10:59 AM - Post#2801190    

Wanted to know if the instructions here are accurate for resetting base idle for TBI with the plug over the idle screw.

https://itstillruns.com/reset-baseline-idle-g m-tbi...

Also if you have a minor head gasket leak would resetting base idle be pointless?

Not sure if idle is being reduced as result of excessive vibrations caused by possible random loss of compression. Vacuum is great all around as far as I can tell.

NO oil in radiator fluid. no radiator fluid in oil. just oil dampness/wetness from fine mist, around head gasket seal, no excessive oil loss either.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25256
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
08-17-20 05:47 AM - Post#2801345    
    In response to VanLife

Remove the radiator cap. Warm it up. Do you see any excessive air bubbles in the coolant? Some head gaskets will only leak when hot. Over time, they'll constantly leak.

Idle would change due to various inputs. O2 sensor input, air temp, fuel temp, engine condition, and vacuum loss.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
08-17-20 09:27 AM - Post#2801367    
    In response to gchemist

is it possible to replace the head gasket using the replacement gasket with the liquid tube gasket sealer. Without having to have the heads surface sanded down flat?

I am trying to find out if the liquid based sealer gasket can fill in the micro pitting that lead to the head gasket leaking from sitting too long without driving.

Or is there no way around it, that engine has to be removed and completely stripped down shipped to special repair shop to have it sanded smooth/flat?

I have NOT seen any noticeable air in the coolant. before having to reset the cap or risk overflow.

Why can't dealers understand NOT to sell mechanic vehicles to homeless. even when you explain DON'T sell me a mechanic vehicle cost will be too great in the end. having to constantly repair /rebuild. :mad :

now I am stuck with this piece of garbage. Replacing will be even more expensive. And also I am seeing a massive drop in used vehicles available. Because I was considering that as option before this upgrade.

engine condition is the only one at issue I think. Everything else was either checked or replaced.

Vacuum is solid center of green bar everywhere I check it.

mechanic refuses to work on my engine. because I did almost all the current repairs myself as good or better than mechanic.

once I upgrade the electrical system I don't think I am going to be able to get any mechanic to touch my van.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


Edited by VanLife on 08-17-20 09:41 AM. Reason for edit: No reason given.

 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25256
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
08-17-20 11:02 AM - Post#2801381    
    In response to VanLife

Backyard mechanics have flattened their own heads as long as machining is not needed. If it's minor, you can do it yourself with high grit paper and straight edge. I've seen plenty of engines still run only by replacing gaskets and degreasing heads. It's hard to know until damage is assessed. Gaskets can fail before parts warp. Using new head bolts will be required for a good fit and seal.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
08-19-20 07:06 AM - Post#2801485    
    In response to gchemist

Also I was talking to autozone manager who also does repairs to used vehicles and sells them at profit.

there is a copper 700 degree spay or gel liquid gasket that I could use with new head gasket. Either the gasket failed from age or it did the pitting corrosion from sitting too long.

If I did this myself I would not be able to pull pistons to check rings etc. I would only be able to pull the manifold and heads off. I have not looked but do you need to pull the distributor out to get all that off? I can't remember if the distributor post goes through the intake manifold or right next to it so as not to have to do timing etc.

If timing needed to be doing I could not do it myself NO timing tools and lack of knowledge and It usually takes 2 people One in cab adjusting distributor the other under engine with timing light while distributor is being aligned.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
08-23-20 08:45 AM - Post#2801780    
    In response to VanLife

resolved or can not be fixed completely within my means.

careful the plug on the v6 engine is a cap soft metal. it is easy to accidentally drill too far. not realizing your through . because your expecting it to be thicker than it is. these plugs look flat.

Thankfully it was a grade 8 screw. so minimal damage by drill bit. I used a quarter inch drill bit and drilled it out right on engine. you probably can't do that on a v8 too little room. I could barely get the drill in as is on a v6. smaller the drill the better.

I was able to reset my baseline idle. I put instructions in the other TBI thread but ONLY DO AT YOUR OWN RISK. My life was on the line So I had to do something. So I gambled. it paid off for me for the time being. but it did not resolve the idle instability though. it just upped the baseline idle.

SO this thread is closed in terms of resolving my issue. I can now adjust mine anytime I need too but its an involved process of taking doghouse off to access back of engine.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
08-29-20 01:53 PM - Post#2802246    
    In response to VanLife

@gchemist

Your right about the chip controlling idle. when I was checking battery charge with multimeter I read the sticker on the fan shroud.

What I did in fact affect the idle over all. but all the idle problems remain just at a higher overall RPM. So now in park for example it is at 600-1000 600 when hot. but at times the computer manages to get it even lower. but is NOT 100 % successful all the time.

Also the idle changes did not have as quite a impact once it is in drive. and the torq. is applied.

my question for idling in park is that closed loop?
and is it open loop in drive?

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25256
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
08-30-20 09:19 AM - Post#2802299    
    In response to VanLife

O2 sensor readings should be closed loop when hot or at normal operating temperatures. My scanners show closed loops for ODBII vehicles. I assume it's the same for TBI. O2 readings control idle when hot. Have you searched thirdgen.org for information? The F body guys did a lot of work with TBI.

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


Edited by gchemist on 09-01-20 02:59 PM. Reason for edit: No reason given.

 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
09-01-20 01:40 PM - Post#2802500    
    In response to gchemist

so open loop in park idle till engine warmed up.

man its a gas hog now for a v6..... if I had to guess its burning close to about twice as much

I am tired of things being under engineered. I am damned if I do damned if I don't.
trying to solve these problems with supplying enough energy in van to run climate control and use an APAP.

under engineered for example is charging one battery from another rather than splitting the power from the alternator and making the alternator do the work.

The battery should only be used for when alternator is not actively supplying power majority to all the time. .

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
09-01-20 01:50 PM - Post#2802501    
    In response to gchemist

First time I have heard "f body guys" who are they?

I am googling and just seeing requests for help from them.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
gchemist 
Member #271 Senior Chevytalk Moderator
Posts: 25256
gchemist
Loc: Austin, TX 78748
Reg: 05-09-00
09-01-20 02:59 PM - Post#2802506    
    In response to VanLife

Go here: https://www.thirdgen.org/forums/

'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE


 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
09-02-20 06:00 PM - Post#2802575    
    In response to gchemist

it turns out the instructions I gave was the calibration of the IAC. to rest baseline idle.

what I wrote is the instructions for the GMC MH olds engines 455 and 403 that had TBI added after it left the GMC plant. Where the owner had one put on. To help the engines run better.

This explains why there was a bigger impact on park idle, than while in drive idle.

The chip you referred to still fully controls idle while warmed up and drive with the exception of a slightly higher base idle while in drive.

Most of the time it runs fine but now and then it rattles hard but evenly, while sitting at light thinking please don't blow up on me. and the ECM occasionally kicks idle down to get it to stop doing it but not every single time.

the exhaust soot is black too now. so I might have it 50 rpm too high causing rich fuel maybe , I have not dared pull plugs to see.

THe spark plugs before idle change was clean no soot what so ever or only on 1 side of spark plugs.

I just hope a go fund me that maybe set up on my behalf succeeds. It would really suck if it failed to get the funds needed.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


Edited by VanLife on 09-02-20 06:03 PM. Reason for edit: No reason given.

 
VanLife 
Contributor
Posts: 357

Reg: 03-20-18
09-02-20 06:12 PM - Post#2802577    
    In response to gchemist

thanks they have a whole section devoted to TBI in general. It might not matter what kind if vehicle its more about the TBI than anything.

when asking Questions its related to van I own: 1987 GMC 3/4 ton G2500 vandura, V6, No AC, standard length. 3speed trans(no overdrive).


 
65_Impala 
Very Senior Member
Posts: 4548

Reg: 12-29-02
09-16-20 08:41 AM - Post#2803573    
    In response to VanLife

Your issue is odd. The ECU should keep the idle rpm the same regardless of engine load. The idle should only be higher while the engine is warming up. Once it reaches the 100* to 120* range it should stabilize at the programmed idle rpm. The IAC is the likely suspect if the idle isn't stable. The idle should remain the same as you move the idle screw until you go far enough the IAC can't adjust any further.

Now, some engines were programmed with open loop idle. It seemed to be mostly big block trucks but you just might have open loop idle. In that case, the idle won't stay stable. I'm not sure how to check this without testing or reading the chip in the ECU.

There are many cars and trucks that had very similar TBI systems. Yours has a 1227747 ECU. The cars which had a 1228746 ECU are very similar in how they operate and function. You can use most of the troubleshootign and operation information from one for the other. The main physical difference is the cars had an intake air temperature sensor the trucks don't have.




 
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