Timing jumping around with EST disconnected?
#1
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Timing jumping around with EST disconnected?
Last night, I was doing the IAC reset procedure and thought it was a good opportunity to check the base timing since I already had the est disconnected.
while setting it... I noticed a previous owner had marked 0* with a white mark and it was pretty close to this. while adjusting, checking, and adjusting... it seemed the timing jumped and so did the RPM. I was under the impression only the EST would shift it off base timing. Is there something else controlling base timing?
I am fighting idle and off idle stumble issues. When I used WINALDL previously I saw my IAC counts at 160 and still not a steady idle so I replaced it and did the rest. Not much changed. Oh... the IAC I took out was broken so.. there is that. I don't feel it is a complete waste of time at this point.
while setting it... I noticed a previous owner had marked 0* with a white mark and it was pretty close to this. while adjusting, checking, and adjusting... it seemed the timing jumped and so did the RPM. I was under the impression only the EST would shift it off base timing. Is there something else controlling base timing?
I am fighting idle and off idle stumble issues. When I used WINALDL previously I saw my IAC counts at 160 and still not a steady idle so I replaced it and did the rest. Not much changed. Oh... the IAC I took out was broken so.. there is that. I don't feel it is a complete waste of time at this point.
#2
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Car: 88GTA
Engine: 5.7TPI
Transmission: Auto
Axle/Gears: 3.27
Re: Timing jumping around with EST disconnected?
Kyle,
A couple things you cane check,
1) Take your dizzy cap of and watch it as you move the crank with a socket and wrench. If the crank moves before the rotor, in either direction, they'res slop in the Timing chain.
2)The harmonic balancer may be shot; look at the rubber ring, or
3) With the new mark on balancer, the chain MAY have jumped a tooth. I doubt that.
Good luck!!
Bob
A couple things you cane check,
1) Take your dizzy cap of and watch it as you move the crank with a socket and wrench. If the crank moves before the rotor, in either direction, they'res slop in the Timing chain.
2)The harmonic balancer may be shot; look at the rubber ring, or
3) With the new mark on balancer, the chain MAY have jumped a tooth. I doubt that.
Good luck!!
Bob
#3
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Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: Timing jumping around with EST disconnected?
the icm has a built in 'limp home' timing advance BUT the timing should still show pretty rock steady with a step jump in timing advance at around 1500 rpm (reportedly varies with different models/icms.).
I agree that your problem may be mechanical
I agree that your problem may be mechanical
#4
Senior Member
Re: Timing jumping around with EST disconnected?
Did you reset the ecm (assumes its the stock ecm)...id go ahead and reset it. Tpi ecms should ALWAYS be rest when making -ANY- electronic or bolt on change.
Most ppl don't get this and thats why they fight issues in the dark-
Most ppl don't get this and thats why they fight issues in the dark-
#5
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Re: Timing jumping around with EST disconnected?
No I did not reset the computer, yet. If anyone has seen my other threads there is an underlying code 34 and a stumbling idle. I have only had this car for a short time and it runs pretty good overall just some issues.
Anyway, knowing I would have that code plus the 42 for disconnecting the EST while setting the timing, I just followed the procedure. Install the IAC, Plug it in, Ground A&B, Turn on, wait, unplug, turn off, unground, disconnect IAC, start up, warm up, set RPM... just happened to decide to also re-check the timing. It was at 2* advance.
It was only jumping 2* or so and the RPM would come up with it.
The car has not been beat that I can tell and only has 60K miles. Would be a very early timing chain failure.
On a positive not, the IAC counts are not at 160 solid anymore by down in the 10-20 range.
Just to cover all bases, it has a code 34 and new relay/maf that I did not install. Had a reman ECM in it, got another... neither fixes the problem.
Found IAC counts very high while looking into the idle issue.
last night first time I noticed the dash temp gauge not working, and after driving I was sitting in the driveway and the car overheated. Was odd... both fans on and temp kept climbing.
I have also looked into any potential vacuum leaks, but haven't found any and pulling 15" Hg at 600RPM and if I am in D and at speed near 20".
Anyway, knowing I would have that code plus the 42 for disconnecting the EST while setting the timing, I just followed the procedure. Install the IAC, Plug it in, Ground A&B, Turn on, wait, unplug, turn off, unground, disconnect IAC, start up, warm up, set RPM... just happened to decide to also re-check the timing. It was at 2* advance.
It was only jumping 2* or so and the RPM would come up with it.
The car has not been beat that I can tell and only has 60K miles. Would be a very early timing chain failure.
On a positive not, the IAC counts are not at 160 solid anymore by down in the 10-20 range.
Just to cover all bases, it has a code 34 and new relay/maf that I did not install. Had a reman ECM in it, got another... neither fixes the problem.
Found IAC counts very high while looking into the idle issue.
last night first time I noticed the dash temp gauge not working, and after driving I was sitting in the driveway and the car overheated. Was odd... both fans on and temp kept climbing.
I have also looked into any potential vacuum leaks, but haven't found any and pulling 15" Hg at 600RPM and if I am in D and at speed near 20".
#6
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Car: 1987 SC/1985 TA
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Re: Timing jumping around with EST disconnected?
try a new rad cap before additional worrying about the overheating. I've had good luck with the AC Delco cap from Rock Auto, bad luck with some others.
#7
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Re: Timing jumping around with EST disconnected?
Do understand I have had this car a limited time and there are mods done to it by the previous owner(s). The air dam is in tact and the front of the radiator is clean... but the dual fans have no shroud. Upgraded aluminum radiator too... but I think it is a directed air flow issue.
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#8
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Car: 1987 SC/1985 TA
Engine: 350/vortec/fitech
Transmission: T56
Axle/Gears: 3.27 9-bolt
Re: Timing jumping around with EST disconnected?
the factory electric fans did not have a shroud. and they should be able to cool down a well tuned motor indefinitely.
you may have some motor control issues that are causing it to run hotter than it should. timing and fuel delivery off, pretty much anything that is not allowing the motor to convert the heat energy of combustion into usable torque as efficiently as possible, will generate excess heat.
you may have some motor control issues that are causing it to run hotter than it should. timing and fuel delivery off, pretty much anything that is not allowing the motor to convert the heat energy of combustion into usable torque as efficiently as possible, will generate excess heat.
#9
Supreme Member
Re: Timing jumping around with EST disconnected?
My timing mark runs around like a rat on crack, even with the ESC disconnected.
Distributor is new, but timing chain and balancer ar 30 years old.
I set the distributor to #1 TDC, and then twist the the distributor until the idle sounds the least worst.
Distributor is new, but timing chain and balancer ar 30 years old.
I set the distributor to #1 TDC, and then twist the the distributor until the idle sounds the least worst.
#10
Supreme Member
Re: Timing jumping around with EST disconnected?
Last night, I was doing the IAC reset procedure and thought it was a good opportunity to check the base timing since I already had the est disconnected.
while setting it... I noticed a previous owner had marked 0* with a white mark and it was pretty close to this. while adjusting, checking, and adjusting... it seemed the timing jumped and so did the RPM. I was under the impression only the EST would shift it off base timing. Is there something else controlling base timing?
I am fighting idle and off idle stumble issues. When I used WINALDL previously I saw my IAC counts at 160 and still not a steady idle so I replaced it and did the rest. Not much changed. Oh... the IAC I took out was broken so.. there is that. I don't feel it is a complete waste of time at this point.
while setting it... I noticed a previous owner had marked 0* with a white mark and it was pretty close to this. while adjusting, checking, and adjusting... it seemed the timing jumped and so did the RPM. I was under the impression only the EST would shift it off base timing. Is there something else controlling base timing?
I am fighting idle and off idle stumble issues. When I used WINALDL previously I saw my IAC counts at 160 and still not a steady idle so I replaced it and did the rest. Not much changed. Oh... the IAC I took out was broken so.. there is that. I don't feel it is a complete waste of time at this point.
Do this. I did what this guy did before he rebuilt his fairmont, to my truck and the slack was horrible. After throwing on a new chain, it's as steady as it can be. And it shouldnt take you more than 10-15 minutes to do a quick test.
#11
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Thread Starter
Re: Timing jumping around with EST disconnected?
Do this. I did what this guy did before he rebuilt his fairmont, to my truck and the slack was horrible. After throwing on a new chain, it's as steady as it can be. And it shouldnt take you more than 10-15 minutes to do a quick test.
https://www.youtube.com/watch?v=4_f5ukZVri8
https://www.youtube.com/watch?v=4_f5ukZVri8
On my list of "Planned Mods", yes I am one of those people who sit an write out a plan, putting a Wide Band O2 sensor is on my list. Unfortunately it only has a narrow band guage on it right now and I am not sure if I should believe anything I see on it. All it does it dance around. Could be lean cause the overheating?
#12
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Thread Starter
Re: Timing jumping around with EST disconnected?
Well, last night I went to pull the car out so I could clean it up some, then get back to working on it. No Start.... found a fuel leak down near the rails.
So here we are... upper intake is off. Tonight I will look for the leak.
So here we are... upper intake is off. Tonight I will look for the leak.
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