High idle

Hi
This is my first post. I bought a 97 Jimmy 4wd A/T 4 door with a burnt engine. I just changed the engine for one that I purchased from a 70 year old auto enthusiast that, purchased it new from a GM dealer 13 years ago. It was sitting on the engine stand all that time full of oil everywhere. He bought it for a project that never realized. We dismantled the heads and you could see that this thing did not have any mileage on it. Anyway, upon start up, the idle went right up to 3000+ rpm. After a few minutes, it settled down to 2500. I checked the throttle cable for binding but all OK. I disconnected the cable from the throttle body and idle went down to normal. I adjusted the cruise cable as per recommendations and now, idle is between 1000 and 1200 rpm. This is the same intake and fuel injection system that was on the other engine. Aside from the fact that the bad engine had a few spun crank bearings, it ran good. Nothing was changed besides new gaskets for the intake and the usual tune up items: fuel, air & oil filters and platinum plugs. Rotor, distributor cap and wires looked new and are AC Del co so decided to leave them on. All vacuum hoses seem fine and no vacuum leaks were detected. The MIL is flashing continuously after about 10 seconds that the truck is started. My code reader does not register any codes. I unplugged a few sensors to see if the pcm would register a code and it does so, I guess this means it is OK. I decided to take it out for a spin but, as soon as I put it in gear, it rattles and shakes from everywhere and eventually dies. I managed to drive it to access my back yard. It feels like it is working only on 5 cyl. I remember when I put the distributor back in, I could not get the rotor to align exactly with the #6 cast in the body but ,only a few degrees before it. My timing light shows 17 degrees advanced at 1000rpm and 20 deg @ 1200rpm. Is this normal or am I a tooth off on the distributor? Just for my sanity, could someone tell me which of the 2 marks on the damper is the tdc. Some say first, others the second while rotating in normal direction? I pulled a few wires while it was running and pulling #3 does not affect anything. I am not sure about #5. Seems like sometimes it affects the rpm's and sometimes it does not. Weird! Another thing. A friend gave me 2 O2 sensors that come from another, more recent 4.3 vehicle, of which I have no info. I had to cut the wires so I could refit my original O2 plugs. When I searched on line, I found that the Denso part # was not the same as what the 97 Jimmy would use. So I disconnected them. The tuck must stay in open loop cause the pcm still does not register a code. Too sum it up, high idle with no power and what seemingly looks like misfire and no DTC's. I know it is a lengthy first post but, I wanted to give the more info possible. Thanks for the help.
Don

The timing is not adjustable.
Computer controled.

http://files.automotiveforums.com/gallery/showphoto.php?photo=51302

If you have a cylinder miss work on that end.

Always check egr valve plunger for stuck open or a carbon ball.

Does the missing cylinder/cylinders have good spark and good compression?
Dist cap and rotor and wires good.
Ac Delco cap and rotor.

How is the fuel pressure?

Is this normal or am I a tooth off on the distributor?

http://www.automotiveforums.com/vbulletin/attachment.php?attachmentid=40985&stc=1&d=1289070076

Always check egr valve plunger for stuck open or a carbon ball.



This has been removed and cleaned as well as IAC valve.

Does the missing cylinder/cylinders have good spark and good compression?

Spark seems nil as I remove the wire. Compression should be OK as the engine is new. #3 cyl. is a pain to remove plug for compression check.

Dist cap and rotor and wires good.
Ac Delco cap and rotor.


Refer to original post.

How is the fuel pressure?
63 pounds with key on engine off and 55 pounds after about 3 minutes with key off.

All this has been going on for a period of 3 weeks since the engine has been installed. Right now, I am trying to diagnose what has been done and what is left to do as I had an eye operation yesterday and can not go out to work on the truck for a while. But if I have enough info to help, I will send a friend to do the footwork for me. Thanks
Don

The dist needs to be set as shown in picture.
And then camshaft retard setting checked on a scanner after start up.

If just One cylinder missing check spark and wire and cap and spark plug.
If OK better check compression.

Before I have the #3 plug removed to check compression, I would like to know if dist. was off by 1 tooth, could this cause my MIL light to flash all the time?(Not on solid)
Don

Yes dist not set right can cause missfire.
Set it per picture I posted.
Flashing check engine light is cylinder miss firing.

Thank you. Will try and have someone competent do that early this week.
Don

get rid of the platinum plugs... these engines don't do well with them, especially when cold/first started. standard ac delcos well get the best performance.

also, the last time i had my dist off by a tooth it was similar. revved high until the comp could adjust, once it calmed down, the MIL would start blinking. Also, make sure the cap is seated well. pull it and check for any uneven burn.

Thank you. Will try and have someone competent do that early this week.
Don

When setting dist make sure it is on top dead center compression stroke.
To find the right TDC on ones with 2 timing marks always pull plug and feel top of pistion for true TDC and compression stroke.
Some rebuilt dist and replacement engines I have had to remove and turn dist gear 190 degrees.

Besides spark to plugs and compression and spark plugs.
Low fuel pressure and injector pulse and lean running engine can cause engine miss.
A steady miss on just one cylinder work on compression and spark and plug and injector.
Is the plug plug on the mising cylinder dry or wet on the end?
Make sure the injector plug in on top of engine is plugged in good.
And do not rule out a bad new plug or wire or cap.
You can switch plug and wire with another good cylinder to check that end.
On the fuel pressure check it with engine running.
You need 63-65 lbs engine running.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

Thank you. I will post an update of what has been done so far shortly. In the meantime,the fact that the Mil is flashing steady , the O2 sensors unplugged and no codes stored got me thinking and curious. After checking under the hood, the emission label states "Conforms to the Canadian emission act" and does not show anywhere that it is obdll compliant. My Inova 3100 code reader does not read any codes although if I disconnect certain sensors, it will register a code. I just got my ElmScan 5 today and tried it. Here are the results. I asked on another forum and was told that 96+ are compliant. But in Canada, I beleive it was mandatory starting in 98. In any event, my scan tool's freeze frame data is not available. Could this have anything to do with the DLC? BTW, I called 3 GM dealers and no one could give me a definite answer short of putting it on the Tech2. The truck is in the yard with no plates on therefore, I can't go on the road to test it. At $325.00 for plates over here, I don't want to plate it and let it sit any longer than needed. If anyone needs the VIN to check, here it is: 1GKDT13W0V2565346 Thank's
Don

anybody think the ECU might be shot? I would assume, that even though it's canadian, it would still have been fitted with an OBDII system in 97.

when you bought the engine, did it come with an ecu? if not, yours may need to be re-programmed for it.

No, it did not come with an ECU. But seeing that all the emission components except the crank sensor are original to the previous motor, I don't see why it would need reprogramming. I removed the I/P sound insulator so I could get a look at the DLC.All the pins that are part of the obdll standard are populated. I managed to find a diagram of the connector and will be probing the #2 serial data signal wire for either a short or open today.
Don

Well, I tested the #4, 5 ground points and #2 serial data link for open or shorts. Everything seems fine. Tried different scan tools (borowed from frends) and same thing. They either state not compliant or does not conform to any standard and I can read some, but not many pid's. I wonder if the fact that my O2 sensors are not plugged could have an impact on this. Will try again tomorow and if it is still the same, will try to find support on the GM website to get an answer. And also, I did try the scan tools and decoders on other cars and they work perfectly.
Don

Just for the sake of saying not sure if it pertains to your problem but, my 93 Blazer started and idled very high and I had no code for that. it turned out to be two things. An IAC valve, which I had already previously cleaned but didn't do the trick. A junkyard one, DID do the trick. And a new intake plenim gasket, which I'm sure you already did. I'd recheck the IAC and other things like the EGR, and MAP sensors. They reek havoc with the idle.

Yes I did replace the gaskets. I might have found something but I don't know how to decypher this. Can someone help?
Don

November 25 2010
Gmc Jimmy 4 door 4wd A/T.

This is to document all the steps taken to find the cause to a flashing MIL with misfire and no codes.

Fuel pressure was verified a few times over a period of a few hours. Results are:
key on engine off: 58 psi max. Tried cycling on and of but did not go any higher.
key on eng. run: 58 to 58 psi. Jerking the throttle open, pressure builds to approx. 64 psi.
key off engine off: after 5 min bleed time 55psi
after 10 min bleed time 52 after 30 min bleed time 48psi after 60 min bleed time 42psi
I realise that pressure is a few pounds below what it should be but, upon quick acceleration, it builds up to spec or very near so I don't think this is the cause of the misfire, or why the truck shakes and wants to die when put in gear,especially at idle which holds @ 1200rpm BTW.
Here is the link to a video I made to check fuel pressure:http://s1142.photobucket.com/albums/n615/pappyam/?action=view&current=100_0099.mp4

Checked the health of engine with vacuum gauge. 19"Hg @ 1200rpm idle. Needle very steady. Snapping the throttle brings it close to 0 and around 23 to 26 "Hg upon deceleration. Does not look like anything leaking or sticking or burnt valves or even ignition miss.Another link to video:http://s1142.photobucket.com/albums/n615/pappyam/?action=view&current=100_0099.mp4#!oZZ1QQcurrentZZhttp%3A%2F%2F s1142.photobucket.com%2Falbums%2Fn615%2Fpappyam%2F %3Faction%3Dview%26current%3D100_0083.mp4 (http://s1142.photobucket.com/albums/n615/pappyam/?action=view&current=100_0099.mp4#%21oZZ1QQcurrentZZhttp%3A%2F% 2Fs1142.photobucket.com%2Falbums%2Fn615%2Fpappyam% 2F%3Faction%3Dview%26current%3D100_0083.mp4)

Today, I performed a compression test that revealed cyl. #4 and 6 to be low (155psi) compared to others that are between 176 to 180psi. A second test with oil in the cyl. showed and improvement to 180 psi. Cyl. leak test confirmed that piston rings were at fault because air was coming out of the dipstick and leakage was around 25% on gauge. No air coming out of radiator or out of adjacent cyl so, no blown head gasket or cracked block. No air out of TB or tail pipe.
As stated earlier, this was suppose to be a new engine. Cosmetically, it did not show any signs of wear when I bought it although it had been sitting bolted to an engine stand in an unheated shed for the last 13 years. The PO took care to bathe it in oil. I was wondering if the rings could be stuck after sitting for so long!! I sure don't want to pull it out again. I poured about 4 ounces of a mix I made (30% PB blaster with 70% transmission oil) into each of the 2 low cyl. and will let it sit for a day or so to see if it helps. Anyone have another recipe to free stuck rings, if that is what it is? If someone has another idea of what the problem could be, I am interested in hearing it but, I am a little scared of how it looks right now.
Don

I watched the video and saw the rough idle. If it were me on my blazer, I'd think two things with that idle;

1) vacuum leak, IAC(port in plenim get's clogged not allowing IAC to seal, IAC also must have oring around it to seal properly), EGR, fuel filter, stuck PCV valve. Everything in the vicinity of the upper plenim.

2) misfire=ignition usually. plugs, wires, coil(s), battery wires, check voltage output of alternator.

Of course, you may have already checked/done these. Or they may have nothing to do with your specific problem so take it for what it's worth. One more thing too. I've never been a fan of engine additives or crap like that, but maybe if you do have some stuck rings, an engine flush would work. Not sure if engine flush is worth doing or not, maybe someone else can weigh in on using that stuff. I'd think the tranny fluid would accomplish the same thing. But if I knew I had a stuck valve, I might try it.

Hope this helps.

Thanks 82Stang
Well, I am really at a lost here. Zipped everything back together and started the truck. Real nice smoke show. The mixture I put in seems to have helped loosen 4 and 6 but, I still have that f*****g misfire. I narrowed it down to #3. Pull the wire and nothing changes. Idle's at 1000rpm now. Changed plugs this morning. Switched wiring from #5 to #3. Same thing. I have 178 psi in that cylinder and I know for a fact that the plug is firing. I have been at this for 1 month now and I need to get this on the road for next week. I don't know where to go from here. Please HELP!!!!
Don

Here's a good read, maybe point you in the right direction...

http://www.aa1car.com/library/misfire.htm

It could be as simple as an EGR valve or valve seals. But then again, you never know...

Good luck.

At this point, I think I might have a plugged injector. I guess there is no way to test or clean them without taking the intake apart. Today, it snowed so, this is making it kinda hard to work on the truck outside. I hope I find the problem soon because I am tired of putting $$ and time and it still is not working.
Don

At this point, I think I might have a plugged injector. I guess there is no way to test or clean them without taking the intake apart. Today, it snowed so, this is making it kinda hard to work on the truck outside. I hope I find the problem soon because I am tired of putting $$ and time and it still is not working.
Don

As to putting money in it and no fix proper testing will take care of that problem.
First confirm that you have the dist set to within - or + 1 or 2 degrees of of 0 degrees camshaft retard.
Also confirm good fuel pressure and good hot blue spark to missing cylinder.
A bad or dirty MAF sensor can also cause miss fire.
Check and make sure 02 sensors are working good.
Confirm good engine vacumn.
As to testing injectors yes there is a injector balance test in a good engine capable scanner that will test each injector.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

As explained above as far as fuel pressure this is what has been done but, since it is not plated yet, I can't take it on the road for a spin.
Fuel pressure was verified a few times over a period of a few hours. Results are:
key on engine off: 58 psi max. Tried cycling on and of but did not go any higher.
key on eng. run: 56 to 58 psi. Jerking the throttle open, pressure builds to approx. 64 psi.
key off engine off: after 5 min bleed time 55psi
after 10 min bleed time 52 after 30 min bleed time 48psi after 60 min bleed time 42psi
I realize that pressure is a few pounds below what it should be but, upon quick acceleration, it builds up to spec or very near so I don't think this is the cause of the misfire, or why the truck shakes and wants to die when put in gear,especially at idle which holds @ 1200rpm BTW.I have located the misfire on cyl. #3 and it holds 178 psi pressure. I let it run with another spark plug in the #3 boot and there is a nice powerful spark. I starts easily hot or cold with no problem but I can feel the misfire as soon as I give it gas and of course, the MIL is flashing steady.As soon as I put it in gear, the truck shakes badly and you can really feel it under load.
I purchased a laptop and a cheap scanner (Elmscan5) but it does not give cam retard. On the other hand, the dist. has no means to move because the hold down bracket hole is only large enough to fit the bolt.
The vacuum holds steady @ 19psi.
I cleaned the MAF, IAC and EGR valves to the best of my knowledge. As for the O2 sensors, I presently have the wrong ones in and they are not connected. Could this cause a misfire always on the same cyl? I received the new ones yesterday and will be putting them in next. This misfire has been happening since day 1, when I started this new engine. I was not positive before that it was #3 but, now I am. That is why I was thinking of a plugged poppet I wanted this car for the winter but, it has to be plated by the end of the month and, I do not want to do so if it will not be reliable. So, after all that has been done, is it logical to think of a bad or plugged injector? I don't have the equipment to test it at home,short of taking the spider out and clean it.
Don.

As explained above as far as fuel pressure this is what has been done but, since it is not plated yet, I can't take it on the road for a spin.
I have located the misfire on cyl. #3 and it holds 178 psi pressure. I let it run with another spark plug in the #3 boot and there is a nice powerful spark. I starts easily hot or cold with no problem but I can feel the misfire as soon as I give it gas and of course, the MIL is flashing steady.As soon as I put it in gear, the truck shakes badly and you can really feel it under load.
I purchased a laptop and a cheap scanner (Elmscan5) but it does not give cam retard. On the other hand, the dist. has no means to move because the hold down bracket hole is only large enough to fit the bolt.
The vacuum holds steady @ 19psi.
I cleaned the MAF, IAC and EGR valves to the best of my knowledge. As for the O2 sensors, I presently have the wrong ones in and they are not connected. Could this cause a misfire always on the same cyl? I received the new ones yesterday and will be putting them in next. This misfire has been happening since day 1, when I started this new engine. I was not positive before that it was #3 but, now I am. That is why I was thinking of a plugged poppet I wanted this car for the winter but, it has to be plated by the end of the month and, I do not want to do so if it will not be reliable. So, after all that has been done, is it logical to think of a bad or plugged injector? I don't have the equipment to test it at home,short of taking the spider out and clean it.
Don.
On fuel pressure you have to have pressure up to specs for a injector to squirt on a cold start or cold.
Does the miss get better or stay the same cold or hot?
If you have good spark and compression and plug and fuel pressure and injector pulse to that cylinder and no vacumn leaks on it then go for a injector.
I have never had any luck cleaning them or poppet.
On you engine you can replace just one at a time.
before replacing injector I would check injector plug in wiring for locked in good and for injector pulse to that injector.

On 02 sensors causing engine miss I have had some problems with the 02 sensor wiring shorting out from corrision in it and knocking out no 4 injector.
That is a good reason to check for injector pulse to injector.
Good Luck and let us know how it goes.

MT 2500
Compression, spark etc all good. As for misfire, there is no difference hot or cold.
That is a good reason to check for injector pulse to injector
Is that something a DIY mechanic can do at home and how is this done. I do have a fair assortment of tools if you explain how this is done.
Don

MT 2500
Compression, spark etc all good. As for misfire, there is no difference hot or cold.

Is that something a DIY mechanic can do at home and how is this done. I do have a fair assortment of tools if you explain how this is done.
Don

You can check injector pulse with a injector tester noid light.
Most parts places have them.

Find the two injector wires or pulse wire to the missing cylinder and hook the noid light to them or pulse.
Watch the light for a good steady blink.
If so you have good injector pulse.
Let us know how it goes.
Good Luck

I was checking the pulse from the vcm with a noïd light in the injector module connector as suggested by MT2500, when I noticed the pin for #3 cyl. was bent. Straightened and wisfire disapeared. Now truck runs like a champ except for the idle issue. All that time and $$ for such a simple fix!! I went for a 50 mile ride yesterday to get it nice and hot. When I put it in gear, idle goes from 1100 rpm and jumps to between 1500 to 1800 rpm. The truck is acting like a thouroughbred and it does make it hard to keep on the line. I am sure it is something stupid and I am missing it. Like I mentioned in my first post, it ran good with the old motor. I can't find any vacum leaks. It could be like 82Stang mentioned, the Iac valve. But I don't want to throw anymore $$ on parts till I am sure that they are shot. BTW, I put in new O2's so that eliminates a potential problem. As far as computer controlled equipment, the only non original part is the cranck sensor. It was already attached to the timing cover of this engine.
I will take a ride with my scanner plugged in and report back my findings. Thanks everyone for your help. We found the misfire and I am positive that the idle issue will be settled shortly.
Don

I was checking the pulse from the vcm with a noïd light in the injector module connector as suggested by MT2500, when I noticed the pin for #3 cyl. was bent. Straightened and misfire disapeared. Now truck runs like a champ except for the idle issue. All that time and $$ for such a simple fix!! I went for a 50 mile ride yesterday to get it nice and hot. When I put it in gear, idle goes from 1100 rpm and jumps to between 1500 to 1800 rpm. The truck is acting like a thouroughbred and it does make it hard to keep on the line. I am sure it is something stupid and I am missing it. Like I mentioned in my first post, it ran good with the old motor. I can't find any vacum leaks. It could be like 82Stang mentioned, the Iac valve. But I don't want to throw anymore $$ on parts till I am sure that they are shot. BTW, I put in new O2's so that eliminates a potential problem. As far as computer controlled equipment, the only non original part is the cranck sensor. It was already attached to the timing cover of this engine.
I will take a ride with my scanner plugged in and report back my findings. Thanks everyone for your help. We found the misfire and I am positive that the idle issue will be settled shortly.
Don

Good find there pappyam:lol2:

I have also found the injector plug-in on top of engine not plugged in good.
Always make sure it snaps down good.

On the idle control problem watch and check your tps voltage real close.
Let us know how it goes.
Good Luck

I went for a ride with the scanner plugged in. I got code P0507 which is related to the IAC I believe. I don't know if this is relevant but, I remembered that when I cleaned the IAC,I plugged it in whitout installing it. By the time I got to turn the key on and get back under the hood to see if anything would happen, the pintle and spring had already flown inside the engine compartment. I found the parts and reassembled the valve but, it was difficult to put it back in. Is it possible that upon reassembly, the toothed shaft would not be sitting at the original place? The computer would activate the pintle but, it would not be where it should be or, would the computer adjust it where it should go anyway?
Don

I went for a ride with the scanner plugged in. I got code P0507 which is related to the IAC I believe. I don't know if this is relevant but, I remembered that when I cleaned the IAC,I plugged it in whitout installing it. By the time I got to turn the key on and get back under the hood to see if anything would happen, the pintle and spring had already flown inside the engine compartment. I found the parts and reassembled the valve but, it was difficult to put it back in. Is it possible that upon reassembly, the toothed shaft would not be sitting at the original place? The computer would activate the pintle but, it would not be where it should be or, would the computer adjust it where it should go anyway?
Don
You may have damaged it.

If the computer can adjust it and the IAC valve is working right yes it will go to the correct idle or where were it should.
Also clean throttle valve butterfly with carb cleaner and tooth brush.
And make sure return spring is closing butterfly good.

Does you scanner read iac counts and desire IAC valve counts?
If so they should match.
If not PCM has lost IAC valve control.
Bad PCM or IAC.

Does your scanner have a idle speed control/adjust test where you can control iac valve to different idle speed?

I am by no means a mechanic, more of a tinkerer. So I have a small pc compatible scanner that is just slightly better than a code reader.
It was suggesteed on another forum that my throttle cabble might be to short and, I have to admit that I was thinking the same thing the first time I started the truck with the new engine. But this cable is not adjustable, not twisted in anyway. It is the same one that was on the truck before. I looked undeneat the dash and there is a small pellet on the cable that act's as a stopper. The throttle is approx. 3/16" from the throttle stop screw. If I disconnect the cable, the truck barely stays at idle (600 rpm). I was hesitant to remove it and try to bring the pellet up closer to the pedal since, it was OK on the former engine and I don't want to screw up the electronics. What do you guys think?

I am by no means a mechanic, more of a tinkerer. So I have a small pc compatible scanner that is just slightly better than a code reader.
It was suggesteed on another forum that my throttle cabble might be to short and, I have to admit that I was thinking the same thing the first time I started the truck with the new engine. But this cable is not adjustable, not twisted in anyway. It is the same one that was on the truck before. I looked undeneat the dash and there is a small pellet on the cable that act's as a stopper. The throttle is approx. 3/16" from the throttle stop screw. If I disconnect the cable, the truck barely stays at idle (600 rpm). I was hesitant to remove it and try to bring the pellet up closer to the pedal since, it was OK on the former engine and I don't want to screw up the electronics. What do you guys think?

Does your scanner give any sensor readings?
Like IAC counts?

Yes it sounds like your gas cable is to short.

It needs to be set or adjusted so that it lets the throttle body close and come back again the stop.

If it does not do that the PCM computer can not adjust or control idle.

It needs to be set or adjusted so that it lets the throttle body close and come back again the stop.
Good. So I have been looking and, closing the throttle by hand does bring it back to correct idle. But I can't find how I can adjust this cable!!! The pellet or lug that is close to the pedal side and acts as a stopper against the sheath seems to be welded in that position on the cable! Is it just crimped in place? Can it be slid up and down that cable?
Don

Good. So I have been looking and, closing the throttle by hand does bring it back to correct idle. But I can't find how I can adjust this cable!!! The pellet or lug that is close to the pedal side and acts as a stopper against the sheath seems to be welded in that position on the cable! Is it just crimped in place? Can it be slid up and down that cable?
Don
If you are referring to the pellet on cable.
The pellet or lug or slug that is on the end of cable can not be moved.
See if anything on gas pedal bracket is keeping it from returning all the way.

Also .
If you have a cruise control cable make sure it is not holding throttle body open.

If it is not i am lost on it without seeing it.
Let us know how it does.

Let us know how it does.
When I was dismantling the old engine, I put back as many nuts and bolts in their original place so I would not lose them. Photo 004 is how I had put the throttle bracket and, photo 005 is after you put me on track. Now the Jimmy runs like it was just out of the showroom. Only the thickness ot the nut was keeping it from idling properly.Thank's guys.
Don

When I was dismantling the old engine, I put back as many nuts and bolts in their original place so I would not lose them. Photo 004 is how I had put the throttle bracket and, photo 005 is after you put me on track. Now the Jimmy runs like it was just out of the showroom. Only the thickness ot the nut was keeping it from idling properly.Thank's guys.
Don

You are welcome.
Gald you got it figured out.

In the pictures I see what the problem was.
Another good find and a fix for/by you.
And thanks for posting back how it went and what you found and fixed.
Good Luck