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Old 08-21-2006, 06:37 PM   #81
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John, can you remember where those switches

Quote:
Originally Posted by john hd
odd that you mention your power steering pump.

on my last tbi vehicle i remember there was a sensor or contact that uped the rpm's when the steering was cranked to either stop. this was done to keep from killing the engine when you tried to stall the power steering pump.

possible culprit?

john
John, can you remember where those sensors or contact switches were located? If my Suburban has those, and one of them is defective or closed on, it could indeed be the culprit! I will read the Haynes book on the Power steering pages to see if there is any mention of them. Bill
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Old 08-21-2006, 07:25 PM   #82
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bill,

that's gonna be a tough one, i have not had that truck since '99. i sold the books with the truck.

perhaps you could look for a connector on the steering box and try unplugging it. that is, if there is one to begin with!

just a wild stab!

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Old 08-21-2006, 07:34 PM   #83
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Hello lebolewis ,I ran this problem to my friend who owns a shop in town here to swap thoughts .One thing we discussed is the TPS voltage ,his comments were that high or fast idle 454s have been common with the TBI ,and his
recommendations would be to adjust your TPS so that you have .50 volts
only. Then disconnect battery to clear the PCM memory (it will clear on these
vehicals ,after 96 up you need a scan tool to do it.)Drive over 45mph for 1/2 mile or more ,the IAC will be commanded all the way closed for a moment to relearn and will use the TPS also for calibration ,then go back to its position
See then if your idle speed is corrected.I had mentioned the TPS before and you had checked it ,but this is suppose to work to get the PCM to slow down
your idle.I agree that your system appears to be working right and the IAC
is working correctly.The last thought I have is that the PCM Prom
(programmable read only memory) needs to be updated or rather have a recalibration ,GM had troubles ,alot with the proms ,many updates and reflashes ,where you have the PCM rebooted to get different info input
in the Prom .The dealer can reflash the PCM .You may have to just get this done .I have never seen a power steering switch cause a fast idle ,but
at this point john hd may be right ,unplug it ,its in the power steering pressure hose ,and you have hydroboost ,thats why your pump moans when you hit the brakes ,check the fluid level first ,you can add a conditioner to
the fluid to see if it can help the whine. did you try closing off your
IAC air hole ? Last ,Put a vacuum gauge on the engine see what it says.
I still use one regularly to check the engine operation ,valves etc.It should read about 18 to 20" hg vacuum ,if it is incorrect it will cause the MAP sensor to give the PCM incorrect information .Once this gets figured out you will be an expert on this issue .Everything you have done is what I myself and any
good shop would do to resolve the problem .Good diagnostics is key to fixing
any problem .

Scott
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Old 08-21-2006, 09:49 PM   #84
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More stuff!

Scott, thanks for all the info.

1) I read all the pages on Power Steering in the Haynes book, and checked all the components on the electrical diagrams, looking for a reference to the power stering switches mentioned by John hd. I found NONE. I will look tomorrow at all the pwr steering hoses to see if there is a pressure switch somewhere. I doubt there is one on my system.

2) The TPS voltage was .78 volts, with the throttle closed. If it can be adjusted, I will set it to .5 volts, then clear the PCM memory, do the 45mph thing and see what happens. An interesting note...... on all these checks where I have disconnected the device and turned on the ignition to check the voltage from the PCM, Haynes says that a "check engine" light will be set and will have to be cleared. Well, that has not happened on my system. Don't know what that implies!

3) The Haynes book says that I can get the PCM fault codes that have been set by the PCM with a simple shorting wire. The readout will be displayed, one at a time, in the same location on the instrument panel as the "check engine" message. This is an OBD1 system (supposed to be) and a scanner is not required. See Haynes page 6-6. I'm going to try that and see what I get, BEFORE I reset the codes by disconnecting the battery.

4) Yes, I did the IAC plugged test. Engine slowed considerably, but not stalled. It's described in one of my previous posts.

5) I am familiar with computer firmware. I not at all surprised that my PCM codes would be out-dated or have flaws in them. Any idea what the dealer charges for an update? They ought to do it FREE! Crappy stuff they have sold to us unsupecting buyers!

6) If none of the above works, I'll do the vacuum gage check.

......to be continued. Bill
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Old 08-22-2006, 09:14 PM   #85
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Mistakes were made!

First thing done today, I checked the PCM fault codes, using the shorting jumper....it worked! Got a 34 and a 42. Book is in the garage, but I think I remember those were for the MAP and TPS, both of which I had unplugged and turned the ignition ON, yesterday and the day before, when I check them. THAT action set those fault codes.

Next, I looked at the TPS to see if it was adjustable. It didn't seem to be. I decided to remove it for a closer inspection.......this was a very bad and costly decision! I removed two screws and then the TPS. I heard a little "click" and felt a slight twist to the left, as I removed it. Wondered what that sound was. Looked it over very carefully and confirmed it was not intended to be adjusted, it was held in a fixed position by the two mounting screws. Attempted to re-mount it and could not get it back on the TB rod. The end of the TB rod was shaped like a thick screwdriver tip and was perfectly vertical in the idle position. Looking at the TBS fitting, there was a grove for the end of the rod to fit in, however, it was not vertical, it was offset to the left about 45 degrees. Hmmm....why is that? Inserted a screwdriver in the slot and moved the TBS back and forth....it moved freely and since it was spring driven it came to rest back at the same position.....45 degrees to the left of vertical! I thought, OK, I'll just move the TB valve rod with the accellerator control to match the 45 degree offset and then put the TPS on. Bad decision...wrong move! Moving the TB rod with the accelerator turns the rod in the wrong direction....it moves 45 degrees to the RIGHT! And that's just enough to get the TPS to fit on the end of the rod.....but in the wrong position!!..... and when you release the accellerator and it goes back to the idle position, it wipes out the TPS!!!!!! UGH!! And this thing is not cheap! One place was $39, another was $42, another was $24 but not in stock and finally I bought it for $31. Driving the Surburban to get the new part, without the TBS sensor installed is a whole nother story....I barely made it! You wouldn't believe the symptons!

Back home I surveyed the situation and concluded there were two ways to get that TPS mounted correctly. 1) Remove the TB AGAIN (UGH) so I could have open access to the side of the TB, then match the TPS to the TB rod and twist it 45 degrees to the right and put the screws in. 2) Leaving the TBI in place and using tin snips, trim the TB gasket (the NEW one I just installed) close enough to the TB sides that I could get close to the TB rod to match the slot and twist it to the right to mount the screws. I settled on the latter and was making great progress when a huge thunder cloud with wicked bolts of lightening arrived un-noticed and rained cats and dogs for about an hour. I was outside, so this project STOPPED, and is posponed til tomorrow. Not a good day. Bill
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Old 08-22-2006, 11:11 PM   #86
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Bill , so sorry to hear that you had that TPS trouble ,normally you hold the TPS in a position that when its on ,you then turn it into position and put in the screws,the click off course is the switch snapping back.I did not forsee
you removing it though or I would have made a point to explain that.Some of those are adjustable and some are not ,loosen screws enough to rotate TPS
for adjustment .once you have the TPS installed you can recheck the voltage
I had said .50 not .5 though.It would seem on this one you cannot do an
adjustment.I do have a thought though ,how about just plugging in the TPS
before you put it on and running the engine to see if it changes rpm,
rotate TPS to achieve the .50 reading see if it has an effect.Some of these
ideas do hold merit as I had a high reading TPS on a ford 5.0 v8 1993, idled fast 1000 rpm till I replaced it ,immediately idle at correct RPM .Your truck
isn't giving you a break ,thats for sure.The dealer should charge around 85
dollars for the reflash prom ,but who knows these days ,youll have to check
with your local dealer to find out .You are probably past the TPS check as I had mentioned ,by now it's probably back together . your right about those codes ,set by your testing ,the light will not stay on if you plug the parts back in .The later model vehical 95 possibly ,but for sure all 96 up vehicals
the light will remain on until it resets after many miles or cleared with a scan tool.You have tested that lower gasket for a leak ,the TBI adapter to intake
manifold? Well ,not much left to try at this point .Let us know what happens.

Scott
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Old 08-23-2006, 10:06 AM   #87
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Learning more every day!!

Scott, got your last post BEFORE I installed the TPS. So, I plugged the new TPS in, started the engine and it idled very fast, just like it did yesterday with no TPS installed at all...and the "check engine" light was still on after I plugged in the new TPS! That worried me a lot. Then I thought that with the TPS not on the TB shaft, the signal readout contact was sitting all the way toward one end and was sending the wrong voltage to the PCM, probably 0.00 volts! Connected my volt meter and I was correct 0.00 volts. Using a screw driver, I slowly turned the TPS until the signal to the TPM was .50 volts.....but no decrease in the idle RPMs what so ever! Now I'm really worried. I thought that perhaps I had really screwed things up by driving to get the part with NO TPS installed!! Now what to do?!! I decided to disconnect the battery to reset all systems and hopfully get rid of the "check engine" light. That worked....the check engine light went out and while the battery was disconnected, I installed the TPS on the TB. Started the engine and everything seemed back to normal, thank goodness. That is..... NORMAL for my engine, 1000 RPMs at idle! Nothing changed!! Took it for a drive, thinking that the PCM might need a little time to readjust to everything, drove good, all the strange symptons frome yesterday were gone. THAT was a BIG relief!! Checked the voltage to the PCM from the new TBS and it was .98 volts at idle!! Good grief!!......this is higher than the old one! But it doesn't make the idle speed any faster, it's the same! Strange.

What I'm thinking is now that everything is reset and back to normal, I will try one more thisg.......remove the TPS and adjust it to .50 volts with a screwdriver and see if that now will lower the idle speed. If it does, I will use a Dremel tool to reem out the mounting holes a bit so that I have a little "adjustment". It will only take very little movement to move it .48 volts.

What do you think? Bill

Oh, I forgot to say that there is no second gasket under the TBI on my engine. There is no mounting plate, it connects directly to the intake manifold.
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Old 08-23-2006, 10:38 AM   #88
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Unplug the battery

Before doing that, unhook the neegative battery cable for a minimum of 2 minutes. That will reset the ECM, and clear the codes it has stored. After that, it will also look for the TPS signal, and use it, which it is not doing right now.
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Old 08-23-2006, 11:19 PM   #89
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Lebowlewis , I would do exactly that with the TPS ,and you can see how that
o.oo volts caused the engine to go faster at idle .so ream out the holes
and set to .50 Clear the PCM as Terry said ,then do the 45 mph drive and see.If all else fails ,it is time for a reflash prom .you may find that GM has a
TBS on this problem (technical service bulletin) although they never want to
admit that any TSBs ever exist for anything.I don't know for sure ,possible.
finally ,you may find that the engine still wants to remain too fast ,even with the TPS adjustments ,sometimes these mods work and somtimes they have
no effect.the .78 TPS should be fine really ,but over the years we find that
fooling the PCM sometimes with said adjustments can definately help.It is
worth a try anyway.Be sure ,that no other vacuum leaks are not present ,
I know I know ,but really flood that Wd40 around the intake base area of the
TBI for good measure ,if not done already as it won't hurt anything and will dry up.Then well ,we'll see what happens .

Scott
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Old 08-23-2006, 11:21 PM   #90
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Oh by the way you did say no second gasket or plate ,you have the 94 engine,sorry about that Bill .how far open are the throttle plates ,can you check at all ,its hard to see in there somewhat i know.

Scott
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Old 08-25-2006, 11:40 AM   #91
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Defeated Warrior!!

Tried something....learned something!

Before I Dremeled the TPS mounting holes and run the risk of screwing it up and having to buy a new one, I decided I would just "test" to see if the PCM reacted by reducing the idle speed when I lowering the voltage from the TPS to the PCM from .70 volts down to .50 volts.

Since I'm single, I don't have a helper to do these things, so I have to do this stuff step-by-step, alone. I removed the TPS and got my voltmeter all setup, turned on the ignition and moved the TPS a little just to see if everything was working ok. It was, all set. Started the engine and immediately it went to high idle about 1500 RPMs. I got out of the cab and went around to my TPS/voltmeter setup and adjusted the voltage to .50 volts......no reduction in idle speed! Slowly raised the voltage up to .90 volts .....NOTHING ....no reaction from the engine! Then all kinds of strange noises came from the transmission! Shut everything down.

This is what I think happened. After I removed the TPS and just as soon as I turned the ignition ON, the PCM saw 0.00 volts coming from the TPS. It then declared a major FAULT, went into the "crazy" mode and all bets were off!! What happened? When you remove the TPS from the TB, it is spring loaded and it immediately moves the signal pickup to the extream left position which is a 0.00 volt signal fed to the PCM. The only way to avoid this situation is to have two people do this. Turn the ignition OFF and reset everything by disconnecting the battery for 5 minutes. Remove the TPS, then manually adjust the TPS approximately to the .50 volt position, hold everything in place and THEN have the 2nd person turn on the ignition and start the engine. The PCM should see everything as normal. When the idle speed settles out, then do the adjustment and see what happens.

The other more risky way would be to "Dremmel" the mounting holes, mount the TPS and try to adjust for .50 volts and see what happens.

Anyway, I put everything back together and reset everything and started the engine......everything back to normal. Bill
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Old 08-25-2006, 05:57 PM   #92
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What the H---, Tomorrow, go for it!!

Tomorrow is forecasted for 92 degrees, coolest in several days! So, tomorrow, I Dremmel the mounting holes of the TPS!! What the H---, it's only another $31.00, if I screw up!! I have sweated at least $643.65 worth of sweat over this thing, so that's a minor investment!! To be continued!! .......persistant Billy Bob
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Old 08-25-2006, 07:24 PM   #93
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Lebolewis , your desciption of how to do the TPS is correct as you noted
in your post,as the TPS adjustment with disconnecting the battery after the
setup of TPS ,then reconnection and letting the computer do its relearn road test.You can see though how the engine can race high if the TPS is wrong.It
won't idle down by turning the TPS as you found out.Anyway, hear from you
later.

Scott
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Old 08-25-2006, 08:50 PM   #94
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I've been following this thread for a while now....I think I'm back in love with my QuadraJet.

Lebo - you have the patience of a Saint
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Old 08-25-2006, 08:54 PM   #95
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Quote:
Originally Posted by swebster
I've been following this thread for a while now....I think I'm back in love with my QuadraJet.

Lebo - you have the patience of a Saint
And stubborn as a Missouri mule, to. (a good thing, in most cases)
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Old 08-26-2006, 12:25 AM   #96
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over63 and swebster,
I agree with you , trying to solve this problem over the forums is tricky and
not easy as I nor others are there to help in person .I give alot of credit
to lebowlewis for his patience and determination to fix this thing.I work on this kinda thing everyday ,but when I first started working on the 80s cars
and on up to today ,it was a challenge to fix this stuff.The fact that GM has
and had many TSBs and Prom changes to solve these drivability problems
made it tough ,because that could solve the problem when I could not .
Very frustrating sometimes .today with the advanced scan tools available
and the very helpful self diagnostic capability of OBD II ,it is easier ,but yet
still a challenge to repair problems.todays computers are vastley superior to
the 90s PCMs by a long shot ,requiring more hands on testing of sensors and
mechanical tests ,such as the throttle plate opening etc.The scan equipment
I use now allows plugging in to the vehical and retrieving huge amounts of data without opening the hood.It goes beyond the trouble codes ,the data
stream capability really gives a window into what the PCM sees ,along with all
the information of what each sensor is doing ,injectors ,pulse width ,duty
cycle ,fuel trim ,oxygen sensor readings ,on and on .Well Im rambling on here
but the point is anyone willing to take a crack at what at first appeared to be
a possibly easy fix ,(the TBI gasket) deserves some kudos for sure.

Don't get me going on the Q jet now ,love / hate relationship there.

Scott
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Old 08-26-2006, 10:17 AM   #97
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Slight Victory!

Slight Victory!......very slight.

I got up early and got in the garage, before it got so hot!

Gathered all the tools I would need and removed the air cleaner, "ONE MORE TIME" and then the TPS. Luckily, I had just the right tool part in my Dremel set to do the reeming of the mounting holes. (that Dremel is a handy too, if you don't have one, put it on your shopping list) Reemed out both holes a bit, didn't want to overdo it. Installed the TPS and hooked up my Digital Voltmeter and tried the adjustment to see how much I had. Not enough, only down to .69 volts. More reeming. Installed the TPS....not quite enough, could now adjust down to .59 volts. Trying to get down to .50 volts. Then I noticed that the washers on the Torq head mounting bolts were preventing me from getting all the adjustment that was available. When I tried to remove them, I discovered they were permanently fixed on the bolts, but they would turn! What to do?!! Then I smiled and remembered "nothing is ever easy for me!" Tried to cut a slice out of them...too hard. Turned on my trusty bench grinder and carefully ground off one side of the washer, making sure I didn't let the grinder get into the bolt threads. That worked. Installed the TPS and adjusted it the MAX amount and got .50 volts!....PERFECT!! Disconnected the battery for 5 minutes, reconnected and started the engine. Engine was cold, so had to wait for it to come up to operating temperature. Still idled at 1000 RPMs in neutral. Got in, drove down the road a ways and back and think I have gained a reduction of 50 RPMs when in gear. It now idles at 650 RPMs in gear. Not PERFECT, but close and I think that is all I am going to get from this PCM.

What have I gained from all of this? Well, let's see:

Direct Benefits-
1) I reduced the idle RPMs by 50 RPMs.
2) I now know my way around under that hood and I know a lot more
about what makes this big engine run, or NOT run, than I did before.
3) I am now very familiar with my Haynes Repair Manual
4) I have met some nice helpful people on the Forums.

Indirect Benefits-
1) Got tired of all the black grease on me, so I sprayed my engine with
de-greaser and hosed it off! It's now much cleaner and looks good!
2) Found the source of two different oil leaks - torqued the valve cover
bolts and the oil pan bolts. Stopped those leaks.
3) Disconnected that !@#$%^ alarm horn! Had to deal with that thing
every time I disconnected and re-connected the battery!

Oh,....I guess you could add this as a benefit. I have 5 daughters and when I mentioned to one of them about all the sweating I've been doing....she said, "well Dad, just think of it as a "free Detox", your body is getting a free clensing!" What can I say.......... Bill
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Old 08-27-2006, 05:20 PM   #98
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Good Job there Bill ,well done .You were able to do what you have been trying to do .Your shop manual should call for about 600 to 650 rpms in gear
I think,so sounds like your there.

Scott
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