1992 1500 question (s) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Stevetra · 09-10-2004, 11:18 AM

I have a 1992 Chevy 1500, ext cab short bed. 5.7L V8 (350)
Air conditioning
Auto trans.
177000 miles

I have 2 questions.
Question 1
If the truck sits for any period of time, like overnight, the first time I start it, the engine fires up ok, but then dies. If I give it some gas at startup it will stay running, after its warm, it starts without touching the throttle.

Question 1a
When I accelerate from a stop normally, there is what feels like a dead spot in the acceleration, like the engine is choking. The truck leaves the line fine, but at about midrange in first gear it looses power momentarily, and picks back up.
If I tromp on the gas…it runs like a banshee…no hesitation

Question 2
I have an automatic transmission with overdrive, if I place the truck in drive, it shifts normally through the gears. If I place the truck in Overdrive, it shifts in and out of overdrive, even on a flat road top.

What can I check??

ChevyTech · 09-10-2004, 12:02 PM

Hi and welcome to the board.

Does your IAC (idle air controll) valve seem to be working? If you don't know, try turning on the A/C while listening to the engine RPM. You should be able to here the Computer and IAC valve speed up the rpm to compensate for the load of the A/C compressor. When the engine is cold the IAC should be giving you a fast idle speed. When you do get it started, does it run at a higher idle speed when cold?

You could have a bad coolant temperature sensor. If the computer does not see it's cold the mixture and IAC will be wrong.

A dead spot on acceleration could be a fuel supply problem, a bad TPS (throttle position sensor) to much EGR(exhaust gas recirculation) or something else.
When was the last time the fuel filter was replaced?
Does your check engine light come on?

Your drivability problems could be causing the shifting in and out of overdrive.

I'm sure some other members will have more ideas. Lets us know what you find.

Stevetra · 09-10-2004, 01:23 PM

I will check to see if the IAC is working when I leave work today, and let ya know what I find out.
As for the fuel system, the Truck had a new fuel pump and filter installed 2 months before I purchased it.
No check engine lights come on
When I test drove the truck, I was sure the Truck had a carb on it, cause it felt just like a bad accelerator pump I was used to changing on the old Q-jet carbs. But when I pulled off the air cleaner...and saw wires....well...I was lost.

As far as the Transmission is concerned, are there any sensors or cables I can check in the meantime? Does the transmission use a downshift cable, vacuum hoses or is it all electronic?
What tells the transmission to shift into overdrive?

And thanks in advance...this is the first good info I have gotten on this problem.

Stevetra · 09-10-2004, 04:30 PM

Ok, I sat in the parking lot at work with the engine idling, and listened to the engine as I switched the AC on and off.
The engine dose not increase RPM to comensate for the compressor load. If anything, I loose a few RPM at idle.

ChevyTech · 09-10-2004, 05:28 PM

I believe 1992 was the first year for electronicly shifted transmissions, but I could be wrong. I know 1993's are electronic ( no down shift cable) all controled by the computer which is refered to as a PCM rather then a ECM being it controls the transmission.

Being you have no codes set it will be harder to find. Something is in a believable range to the computer, yet it is not correct. The problem you described as feeling like a bad accelerator pump is the problem I think should be focussed on first.

Someone that is EXPERIENCED and GOOD with a scan tool can quickly look at the sensor readings and see which one is out of the normal range. Just because someoen can hook up the scan tool does not mean they will be of any help, but if they are good it is worth the money to find out whats going on.

Hope I have been of some help.

Stevetra · 09-11-2004, 07:05 PM

You have been a great deal of help. I have replaced the IAC, and it now starts like a dream, thank you very much, you ROCK

I still have the shifting problem, but I have investigated it further.
I am assuming that when we say a transmission has overdrive, it means it has 1st, 2nd,3rd, and 4th or overdrive.
Here is the thing that confuses me, I place the transmission in L1, and when its time I shift to L2, then when its time I shift to D (drive).
At 65 mph the old 350 is humming along....ok...so I shift to OD (overdrive)
It shifts into overdrive...then a few seconds later...it feels like it shifts into 5th...I am like WTF....

It is in this area the shifting is happening.
Could the overdrive just be slipping?

Is it time to overhaul this puppy?

To be honest...I am scared like a little girl at the possible cost of a trans overhaul.

ChevyTech · 09-11-2004, 07:28 PM

Your welcome, I'm glad I was able to help out.

The other shift you feel is you lock up torque converter. It should feel like another gear. It sounds like everything is ok to me.

Edit - Actually the lockup torque converter is the shift you think you feel a little above 40MPH.

If you want to feel the lockup torque converter lock up and release try this. Drive down the road at a steady speed above 45MPH with the shifter in the OD position and push the brake pedal down just a little bit. Not enough to put on the brakes but just enough for the electrc switch on the brake to move. This will release the torque converter. Then take your foot off the brake pedal and the torque converter wil lockup again.

Chevytech

Stevetra · 09-13-2004, 08:22 AM

Again...you hit it right on the nose.
I did the brake check and sure enough its the converter.
Last question...
Is this normal?
It seems to engage and disengage quite a bit.

ChevyTech · 09-13-2004, 11:21 AM

It's hard to explain what is normal. If push the brake a little or completely let up on the gas pedal the converter will release. So some poeples driving habits/style cause it to lockup and release a lot.

If you drive up an incline it does not take as much throttle to get a release.

I have driven my truck into heavy wind and had the converter release.

Hope this helps

ChevyTech

Stevetra · 09-13-2004, 03:20 PM

actually it is most noticable when I have the cruse control on. But what I think I may end up doing is checking with my old boss. When I was 20 I used to work at a transmission shop in Florida called JW performance transmission. I machined valve bodies and did some R&R while I was there. I believe he might cut me a deal on a lock up converter and a new Trans, if anything, next time I visit my Dad, I will drop in and see what he thinks. Thanks for all your info...you have been a great deal of help.

09-10-2004, 11:18 AM	#1
Stevetra Registered User Join Date: Sep 2004 Posts: 96	1992 1500 question (s) I have a 1992 Chevy 1500, ext cab short bed. 5.7L V8 (350) Air conditioning Auto trans. 177000 miles I have 2 questions. Question 1 If the truck sits for any period of time, like overnight, the first time I start it, the engine fires up ok, but then dies. If I give it some gas at startup it will stay running, after its warm, it starts without touching the throttle. Question 1a When I accelerate from a stop normally, there is what feels like a dead spot in the acceleration, like the engine is choking. The truck leaves the line fine, but at about midrange in first gear it looses power momentarily, and picks back up. If I tromp on the gas…it runs like a banshee…no hesitation Question 2 I have an automatic transmission with overdrive, if I place the truck in drive, it shifts normally through the gears. If I place the truck in Overdrive, it shifts in and out of overdrive, even on a flat road top. What can I check??

09-10-2004, 01:23 PM	#3
Stevetra Registered User Join Date: Sep 2004 Posts: 96	I will check to see if the IAC is working when I leave work today, and let ya know what I find out. As for the fuel system, the Truck had a new fuel pump and filter installed 2 months before I purchased it. No check engine lights come on When I test drove the truck, I was sure the Truck had a carb on it, cause it felt just like a bad accelerator pump I was used to changing on the old Q-jet carbs. But when I pulled off the air cleaner...and saw wires....well...I was lost. As far as the Transmission is concerned, are there any sensors or cables I can check in the meantime? Does the transmission use a downshift cable, vacuum hoses or is it all electronic? What tells the transmission to shift into overdrive? And thanks in advance...this is the first good info I have gotten on this problem. Last edited by Stevetra; 09-10-2004 at 01:31 PM.

09-11-2004, 07:28 PM	#7
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Your welcome, I'm glad I was able to help out. The other shift you feel is you lock up torque converter. It should feel like another gear. It sounds like everything is ok to me. Edit - Actually the lockup torque converter is the shift you think you feel a little above 40MPH. If you want to feel the lockup torque converter lock up and release try this. Drive down the road at a steady speed above 45MPH with the shifter in the OD position and push the brake pedal down just a little bit. Not enough to put on the brakes but just enough for the electrc switch on the brake to move. This will release the torque converter. Then take your foot off the brake pedal and the torque converter wil lockup again. Chevytech Last edited by ChevyTech; 09-12-2004 at 01:15 AM.

09-10-2004, 12:02 PM	#2
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Hi and welcome to the board. Does your IAC (idle air controll) valve seem to be working? If you don't know, try turning on the A/C while listening to the engine RPM. You should be able to here the Computer and IAC valve speed up the rpm to compensate for the load of the A/C compressor. When the engine is cold the IAC should be giving you a fast idle speed. When you do get it started, does it run at a higher idle speed when cold? You could have a bad coolant temperature sensor. If the computer does not see it's cold the mixture and IAC will be wrong. A dead spot on acceleration could be a fuel supply problem, a bad TPS (throttle position sensor) to much EGR(exhaust gas recirculation) or something else. When was the last time the fuel filter was replaced? Does your check engine light come on? Your drivability problems could be causing the shifting in and out of overdrive. I'm sure some other members will have more ideas. Lets us know what you find.

09-10-2004, 04:30 PM	#4
Stevetra Registered User Join Date: Sep 2004 Posts: 96	Ok, I sat in the parking lot at work with the engine idling, and listened to the engine as I switched the AC on and off. The engine dose not increase RPM to comensate for the compressor load. If anything, I loose a few RPM at idle.

09-10-2004, 05:28 PM	#5
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	I believe 1992 was the first year for electronicly shifted transmissions, but I could be wrong. I know 1993's are electronic ( no down shift cable) all controled by the computer which is refered to as a PCM rather then a ECM being it controls the transmission. Being you have no codes set it will be harder to find. Something is in a believable range to the computer, yet it is not correct. The problem you described as feeling like a bad accelerator pump is the problem I think should be focussed on first. Someone that is EXPERIENCED and GOOD with a scan tool can quickly look at the sensor readings and see which one is out of the normal range. Just because someoen can hook up the scan tool does not mean they will be of any help, but if they are good it is worth the money to find out whats going on. Hope I have been of some help.

09-11-2004, 07:05 PM	#6
Stevetra Registered User Join Date: Sep 2004 Posts: 96	You have been a great deal of help. I have replaced the IAC, and it now starts like a dream, thank you very much, you ROCK I still have the shifting problem, but I have investigated it further. I am assuming that when we say a transmission has overdrive, it means it has 1st, 2nd,3rd, and 4th or overdrive. Here is the thing that confuses me, I place the transmission in L1, and when its time I shift to L2, then when its time I shift to D (drive). At 65 mph the old 350 is humming along....ok...so I shift to OD (overdrive) It shifts into overdrive...then a few seconds later...it feels like it shifts into 5th...I am like WTF.... It is in this area the shifting is happening. Could the overdrive just be slipping? Is it time to overhaul this puppy? To be honest...I am scared like a little girl at the possible cost of a trans overhaul.

09-13-2004, 08:22 AM	#8
Stevetra Registered User Join Date: Sep 2004 Posts: 96	Again...you hit it right on the nose. I did the brake check and sure enough its the converter. Last question... Is this normal? It seems to engage and disengage quite a bit.

09-13-2004, 11:21 AM	#9
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	It's hard to explain what is normal. If push the brake a little or completely let up on the gas pedal the converter will release. So some poeples driving habits/style cause it to lockup and release a lot. If you drive up an incline it does not take as much throttle to get a release. I have driven my truck into heavy wind and had the converter release. Hope this helps ChevyTech

09-13-2004, 03:20 PM	#10
Stevetra Registered User Join Date: Sep 2004 Posts: 96	actually it is most noticable when I have the cruse control on. But what I think I may end up doing is checking with my old boss. When I was 20 I used to work at a transmission shop in Florida called JW performance transmission. I machined valve bodies and did some R&R while I was there. I believe he might cut me a deal on a lock up converter and a new Trans, if anything, next time I visit my Dad, I will drop in and see what he thinks. Thanks for all your info...you have been a great deal of help.



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