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  #31 (permalink)  
Old 03-25-2013, 07:12 PM
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Don't know if this will help or make things more confusing. A while back I replaced a suspect MAP sensor on my 4.3l. Have what sounds like pinging around 1500rpm. Well the MAP seal seemed to be leaking as you could here the noise when it was wiggled a little. Installed a new MAP and gave it a test drive.
I knew something was up before I got on the brakes the first time. Almost ran a stop sign. The engine was idleing pretty fast as I was mashing the brakes pretty hard. Drove about a mile at about 45mph to the next stop sign(with almost no throttle input), and it was doing the same thing as far as high idle speed and mashing the brakes pretty hard. Drove another 3 miles at around 60mph and it seemed to be getting alot better at the next stop sign like the computer was learning something. Another couple of miles and everything seemed to be back to normal.
Just saying that it might take the computer some time under load at speed to fine tune. I know that there is a certain proceedure to getting the computer to "relearn" after parts have been replaced/adjusted.
For instance mine has a "Crankshaft Variation" relearn proceedure where you drive 55mph for 8 minutes, decelerate to 45mph with no brakes for 1 minute, perform 4 deceleration cycles of 25 seconds,and so forth.
You might do a google search for relearn proceedures for your engine. Then again it may just pertain to newer vehicles with ODB II. I can't say for sure.
ssmonty

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  #32 (permalink)  
Old 04-10-2013, 09:22 PM
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It turns out that there was some EGR action at idle,making the engine run like crap. The VSS in my 700R4 won't work with the FI systerm unless you harvest the speed buffer from the donor vehicle but no one at Painless bothered to mention that in their documentation so my TCC was engaging as soon as the vehicle moved even the slightest bit. I had to order a calibration unit from Dakota Digital and that should correct the problem. I'm still having a problem finding an idle speed that feels smooth enough when the transmission is engaged and it turns out that my newly built 700R4 has some problems... It won't shift from 1st to 2nd until the truck is doing well over 30 mph and the shift is harsh and it will not shift into 3rd at all. I have reviewed my setting of the TV cable with the shop that built the trans and they have verified that it's set correctly and told me to bring the truck in and they would look at it but the shop is like 13 miles away so it looks like I need to flatbed it down there but all in all, there is progress but I can't promise that my next project won't have points, condenser, a 4bbl and a 4 speed!
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  #33 (permalink)  
Old 04-11-2013, 09:24 AM
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Quote:
Originally Posted by 1great40 View Post
It turns out that there was some EGR action at idle,making the engine run like crap. The VSS in my 700R4 won't work with the FI systerm unless you harvest the speed buffer from the donor vehicle but no one at Painless bothered to mention that in their documentation so my TCC was engaging as soon as the vehicle moved even the slightest bit. I had to order a calibration unit from Dakota Digital and that should correct the problem. I'm still having a problem finding an idle speed that feels smooth enough when the transmission is engaged and it turns out that my newly built 700R4 has some problems... It won't shift from 1st to 2nd until the truck is doing well over 30 mph and the shift is harsh and it will not shift into 3rd at all. I have reviewed my setting of the TV cable with the shop that built the trans and they have verified that it's set correctly and told me to bring the truck in and they would look at it but the shop is like 13 miles away so it looks like I need to flatbed it down there but all in all, there is progress but I can't promise that my next project won't have points, condenser, a 4bbl and a 4 speed!
You cant drive her 13 miles in 2nd gear?

peace
Hog
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  #34 (permalink)  
Old 04-12-2013, 04:24 PM
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I may do just that. I need to talk to the transmission guy again though. And I want to get my VSS issue straightened out so that when it is at the transmission shop, we can verify that the lockup is working correctly as well. I'm kinda stoked right now since the truck is at the point where I can just reach through the window, turn the key and it starts up and runs well. I think the Idle speed problem may be a worn throttle body since I can now feel the throttle plates sticking in the body when I go to actuate the throttle and the idle speed is still not as slow as I would like, its over 800 RPM right now. I chose the best throttle body out of the 3 that I had but that doesn't mean it's in good shape. I'm trying to locate just the body without the injectors and maybe I can save a few bucks but who knows. Can anyone comment on a worm throttle body making the engine idle too fast? my assumption is since I have set the idle with the GM procedure and the throttle plates appear to be completely closed and are actually sticking in the throttle bores, there is air being admitted around the throttle shaft or somewhere, limiting how slow the idle can be set.
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Old 04-12-2013, 07:08 PM
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On my 2000 4.3 the IAC(Idle Air Control) valve does all the work if I'm not mistaken. My throttle body butterfly closes off the air flow completely and the IAC provides the air I believe, but my injectors are in the ports unlike your TBI set-up.
Mine will idle high when its cold, and its around 800 rpm. Thats also about what it is after normal driving when I first put it in "Park", then while watching the tach, it will gradually drop to around 650 ish as the IAC closes a bit, or so it seems.
Do you think you could remove the IAC, make it move to its max/min limits, then mount it without the electrical connection, to see if it will make a difference? Just to see if can actually drop the rpm to a lower level by itself, or if there is something else admiting air into the intake? Just a thought.
As far as the trans, you might try to set the TV cable "Long" or extending the cable a little further than you would when doing the normal TV cable adjustment, so that the trans thinks your not giving it as much throttle if you know what I mean. Just for the trip to the shop mind you. I don't think you'll damage it for a short trip. I could have it backwards, but I think it will shift sooner because of less pressure. Note where the cable "ratchet" is in relation to its housing(counting teeth) then extendit a couple of teeth more. Worth a try. Note that it doesn't take much of a change in TV adjustment to make a difference in shift.
I did some playing around with my 2004r to get it to shift "right" hooked up to a Holley. Ground a slot into the throttle lever so that I could move the TV cable attachment closer or farther away from the throttle shaft for custom adjustment. I've since made an adapter to bolt on my next project. The adapters I've purchased didn't work very well IMO.
FWIW
ssmonty
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  #36 (permalink)  
Old 04-12-2013, 07:30 PM
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A couple of questions that I didn't see anyone ask earlier in the thread:

Is your IAC working properly (how did you set it)?

What is your timing doing? What did you set the base timing to?


Regarding the IAC, there are a couple of ways to check this that are relatively antiquated, but work. Based on your previous posts it sounds like your idle is still too high when it warmed up. If that is the case, then improper IAC function could be the cause. Mix that with the timing not being right and it might be something.

Ignore this if you've already set these properly.
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  #37 (permalink)  
Old 04-12-2013, 08:04 PM
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Quote:
Originally Posted by ssmonty View Post
On my 2000 4.3 the IAC(Idle Air Control) valve does all the work if I'm not mistaken. My throttle body butterfly closes off the air flow completely and the IAC provides the air I believe, but my injectors are in the ports unlike your TBI set-up.
Mine will idle high when its cold, and its around 800 rpm. Thats also about what it is after normal driving when I first put it in "Park", then while watching the tach, it will gradually drop to around 650 ish as the IAC closes a bit, or so it seems.
Do you think you could remove the IAC, make it move to its max/min limits, then mount it without the electrical connection, to see if it will make a difference? Just to see if can actually drop the rpm to a lower level by itself, or if there is something else admiting air into the intake? Just a thought.
As far as the trans, you might try to set the TV cable "Long" or extending the cable a little further than you would when doing the normal TV cable adjustment, so that the trans thinks your not giving it as much throttle if you know what I mean. Just for the trip to the shop mind you. I don't think you'll damage it for a short trip. I could have it backwards, but I think it will shift sooner because of less pressure. Note where the cable "ratchet" is in relation to its housing(counting teeth) then extendit a couple of teeth more. Worth a try. Note that it doesn't take much of a change in TV adjustment to make a difference in shift.
I did some playing around with my 2004r to get it to shift "right" hooked up to a Holley. Ground a slot into the throttle lever so that I could move the TV cable attachment closer or farther away from the throttle shaft for custom adjustment. I've since made an adapter to bolt on my next project. The adapters I've purchased didn't work very well IMO.
FWIW
ssmonty
We were posting at the same time. It does sound like a bad or improperly setup IAC.
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  #38 (permalink)  
Old 04-12-2013, 11:31 PM
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Thanks for the additional information and a BIG thanks to everyone who has suggested stuff for me to try.

I may have stated that I built a lot of this truck in the wee hours of the morning over many years...not a great way to do it. Tonight, I was staring at the TBI stuff and started playing with the throttle shaft because I'm feeling the sticking of the throttle plates as I mentioned. Well, was I in for a shock! The throttle shaft is very sloppy in the throttle body. I'm thinking now that I may have swapped my throttle lever from the donor truck onto the wrong throttle body. I went back to my junk and found 2 other TBI units. One is the original from the donor truck and the other is from a newer 4.3 but it still looks like a model 220. The newer unit had a nice snug throttle shaft so I'm cleaning it up and I'm going to swap the fuel metering unit that's currently in the truck onto this throttle body. I have myself pretty much convinced that the sloppy throttle shaft is contributing to my idle setting problem. The throttle body is soaking in cleaner right now and I'll build it back up tomorrow and see how it runs.
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Old 04-13-2013, 02:06 PM
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I assembled the "new" throttle body today and when I installed it, that engine would idle so slow you could hear the individual injector clicks! I set the minimum air and idle speed according to the GM procedure and since this is an OLD (1989) pre-Vortec, pre-balance shaft engine, I had to find a sweet spot where the idle was as smooth as it was gonna get without just plain running it too fast. I know there weren't the smoothest idling engines in the world but I think it doesn't make much difference when the truck is parked at a cruise night . I still need to put the scanner back on there and look at my IAC count but I'm confident that it is in the correct range now.
I just received a Dakota Digital SGI-5 Universal signal interface unit to get the right pulse rate from the VSS in the transmission to the ECM. My Painless Performance manual did not say that the ECM wouldn't work with the stock VSS built into the transmission unless you used the factory speed buffer, which went to the big swap meet in the sky with the donor truck. Once I get that set up, I should be able to reconnect the VSS and not have the scanner tell me I'm doing 244 MPH crawling up my driveway and the instant TCC lockup should go away too. Then I need to get it to the guy who did the transmission to see why it wont shift correctly despite having set the TV cable according to the GM procedure.
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  #40 (permalink)  
Old 04-14-2013, 12:00 AM
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Congrats. Did your vacuum increase? I ask because you mentioned previously that you had about 12 at idle and that seems somewhat low for a stock cam.

Good luck with the transmission. Hopefully the guy that built it for you will make it right.
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Old 04-17-2013, 08:58 PM
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Not much progress since I last posted. I have managed to log some data and I'm including a frame of it here. What I'm noticing is that no matter what I do withthe minimum air setting as far as ROM with the IAC disconnected, the idle keeps going back to 1000RPM. Everyone is telling me I have a vacuum leak, but I cant find one. Also, if there's a vacuum leak, then there's too much air getting into the engine. Why then would the computer call for more air (IAC counts in the 70's) Here's the data

1989 Astro/Safari
Z=4.3L TBI

Diagnostic Codes

Current Code 24
Vehicle Speed
Sensor (VSS) Short
Circuit


Vehicle Data List


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL NORM
AIR SW SOL CONV
BATTERY(V) 13.9
BLM 153
CLEAR FLOOD OFF
COOLANT(F) 191
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 77
INTEGRATOR 132
LOOP STATUS CLSD
MAP(V) 0.98
O2S(mV) 466
O2S CROSSCNTS 66
P/N SWITCH P/N
PROM ID 3051
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.45
VEHSPEED(MPH) 0
Frame:-5 Time:-5.7
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Old 04-18-2013, 11:39 AM
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Originally Posted by 1great40 View Post
Not much progress since I last posted. I have managed to log some data and I'm including a frame of it here. What I'm noticing is that no matter what I do withthe minimum air setting as far as ROM with the IAC disconnected, the idle keeps going back to 1000RPM. Everyone is telling me I have a vacuum leak, but I cant find one. Also, if there's a vacuum leak, then there's too much air getting into the engine. Why then would the computer call for more air (IAC counts in the 70's) Here's the data

1989 Astro/Safari
Z=4.3L TBI

Diagnostic Codes

Current Code 24
Vehicle Speed
Sensor (VSS) Short
Circuit


Vehicle Data List


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL NORM
AIR SW SOL CONV
BATTERY(V) 13.9
BLM 153
CLEAR FLOOD OFF
COOLANT(F) 191
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 77
INTEGRATOR 132
LOOP STATUS CLSD
MAP(V) 0.98
O2S(mV) 466
O2S CROSSCNTS 66
P/N SWITCH P/N
PROM ID 3051
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.45
VEHSPEED(MPH) 0
Frame:-5 Time:-5.7
I re-read this whole thing and a couple things come to mind beyond the original cal pack and memprom problems; these are the air leak around the throttle shaft, how you get to idle speed and operating temp, as well as other problems related to low but steady vacuum readings beside air leaks.

1) Worn throttle shaft bores do allow an air leak which affects manifold vacuum. Either the throttle body needs to be replaced or the throttle shaft bores need to be bushed.

2) Idle speed is set by the IAC, the throttle plates should be tightly closed untill the system is powered up.

3) I see two entries of engine temp from the CTS sensor of 160 and 167 degrees. If this is a fully warmed up-engine that temp is too cold unless you have a custom chip with the low temp modification in the program, otherwise the chip is operating the engine in cold start, rich mixture mode all the time.

4) A steady low idle vacuum can also be caused by retarded ignition or camshaft timing. Both of these can be the result of a worn timing gears and chain among other possibilities.

Bogie
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Old 04-18-2013, 04:57 PM
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Originally Posted by oldbogie View Post
I re-read this whole thing and a couple things come to mind beyond the original cal pack and memprom problems; these are the air leak around the throttle shaft, how you get to idle speed and operating temp, as well as other problems related to low but steady vacuum readings beside air leaks.

1) Worn throttle shaft bores do allow an air leak which affects manifold vacuum. Either the throttle body needs to be replaced or the throttle shaft bores need to be bushed.

2) Idle speed is set by the IAC, the throttle plates should be tightly closed untill the system is powered up.

3) I see two entries of engine temp from the CTS sensor of 160 and 167 degrees. If this is a fully warmed up-engine that temp is too cold unless you have a custom chip with the low temp modification in the program, otherwise the chip is operating the engine in cold start, rich mixture mode all the time.

4) A steady low idle vacuum can also be caused by retarded ignition or camshaft timing. Both of these can be the result of a worn timing gears and chain among other possibilities.

Bogie
I'm pretty confident that the throttle body is in good shape w/ respect to the throttle shaft, The engine vacuum is 22 inches at 1000 rpm. The throttle plate opening is set per GM procedure and the plates look basically closed.

You were reading temperature data in frame information provided by SSMONTY.. . If you look at the data that I posted you will find the coolant temp at 191 degrees F. The ignition timing was set to 0 degrees with the timing connector disconnected. The enginehas 54K on it but I have not verified the condition of the timing chain.
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Old 04-18-2013, 07:11 PM
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Have you tried hooking the vacuum pump to the MAP while the engine is in closed loop, and varying the vacuum and observing the levels indicated on your scanner to see if they correlate? Can you increase it enough to get the idle down?
FWIW
ssmonty
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Old 04-18-2013, 07:29 PM
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Quote:
Originally Posted by 1great40 View Post
Not much progress since I last posted. I have managed to log some data and I'm including a frame of it here. What I'm noticing is that no matter what I do withthe minimum air setting as far as ROM with the IAC disconnected, the idle keeps going back to 1000RPM. Everyone is telling me I have a vacuum leak, but I cant find one. Also, if there's a vacuum leak, then there's too much air getting into the engine. Why then would the computer call for more air (IAC counts in the 70's) Here's the data

1989 Astro/Safari
Z=4.3L TBI

Diagnostic Codes

Current Code 24
Vehicle Speed
Sensor (VSS) Short
Circuit


Vehicle Data List


CODES PRESENT NO
3RD GEAR SW ON
AC REQUEST OFF
AIR DIVRT SOL NORM
AIR SW SOL CONV
BATTERY(V) 13.9
BLM 153
CLEAR FLOOD OFF
COOLANT(F) 191
ENGINE RPM 1000
EXHAUST 02 LEAN
HIGH BATTERY NO
IAC POSITION 77
INTEGRATOR 132
LOOP STATUS CLSD
MAP(V) 0.98
O2S(mV) 466
O2S CROSSCNTS 66
P/N SWITCH P/N
PROM ID 3051
TCC LOCKUP NO
TCC SOLENOID OFF
TPS SENSOR(V) 0.45
VEHSPEED(MPH) 0
Frame:-5 Time:-5.7
Coolant is 191 degrees, engine is fully warmed up.
TPS looks a tad low
Idle speed is 1000
IAC is way too high, should be around 20 with idle speed at spec.
That is a good indicator of an intake leak.

Easy to check.
Pull PCV valve ,plug hole.Pull tube on other valve cover that allows fresh air in. Put a vacuum gauge in the hole and run the engine.If it builds a small amount of pressure...then youre normal. If it build vacuum...then you have an intake leak inside the valley area under the intake.
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