EGR, Vacuum, Trany, and Fuel - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Nazzcu · 03-18-2010, 10:06 PM

More questions about my 87. Let me preface this by saying I am not a mechanic and have very little knowledge of this drive train. So any help is appreciated.

I have still been working at getting my TBI back in order and have gotten to the EGR valve. I picked up factory vacuum lines at the pick and pull today and got everything hooked up. During this I realized there would be no vacuum line for the transmission modulator valve. So I searched, the 700r4 did not have a vacuum connection correct? I have not checked the numbers on the trans to determine what it is yet.

Question 1. What is a safe vacuum to splice so I can connect the trans back up?

Question 2. The EGR solenoid should pull a vacuum at high RPM correct? and where does the 2nd vacuum connection on the solenoid go? I tested the EGR valve by hooking it to vacuum at idle, it stalled the engine. I am assuming the valve is working? It does run slightly rough at idle and when the solenoid is unhooked and has the vacuum is open it runs smoother.

Question 3. The truck runs rich and my fuel pump runs non stop. I do not see that the wiring has been modified. To my understanding the oil switch and the fuel pump relay control this? The oil switch is not connected because it does not match the harness and it is a pain to get to to swap. What should I do to track this down.

Question 4. How much of this may be due to the wrong ECM, the truck was original 305 TBI and swapped with a 92 setup. Due to what I have seen so far, I doubt the ECM was swapped in the change.

I am about ready to pull it all and go back to a carb. The good news is I have started the body prep for repaint, which is what I am best at.

Nazzcu · 03-18-2010, 10:47 PM

I checked the trany and could not find the ID but the pan looks like a 350 or 375.

leegrady · 03-19-2010, 07:56 AM

There should be a vacuum "tree" screwed into the intake manifold to run the vacuum tube to the vacuum modulator of the transmission. The tube is steel with a short length of rubber hose at each end for attachment.

You are correct, the EGR is hooked up to ported vacuum, and the EGR needle only lifts off its seat at higher engine rpm's. And yes, the best way to test them is to apply vacuum at idle, and if the engine stalls it is working. Not sure about that second connection. Ported vacuum doesn't go straight to the EGR valve. It gos to a thermal switch first, usually screwed into the intake at a coolant passage that opens allowing vacuum to the EGR valve only when the engine is a normal operating temp. If it idles better with the EGR valve disconnected it means the valve is open a little probably because it's dirty. They should be serviced about every 60k.

Question 3: check the fuel pressure regulator. Make sure that vacuum line is good.

Confused about the ecm question. Engine size, ecm from what, 87 truck, 92....

Nazzcu · 03-19-2010, 01:04 PM

Quote:

Confused about the ecm question. Engine size, ecm from what, 87 truck, 92....

The truck was stock 87 silverado 305. The prior owner changed the engine t oa 92 350. I dont think the EMC was changed along with the engine. I know that the ECM will process differently for the 350 than the 305, what else may be effected by the different ECM's?

Nazzcu · 03-20-2010, 10:23 PM

Pulled the ECM today:

Part Number: 1227747 ADSY

I researched and i think 122747 is for 5.7 engine but I am not positive?

Nazzcu · 03-21-2010, 11:08 AM

I cant find anything on the broadcast code ADSY. I doublechecked my notes and it is ADSY. Anyone have any idea what this PROM is for?

leegrady · 03-21-2010, 01:03 PM

Remember the thread, "tbi for dummies" rfmaster had some really good information on the conversion of a 305 to a 350 tbi. Refer back to that thread. Numbers were included.

Hope your project is going well.

leegrady · 03-21-2010, 01:06 PM

Oh yeah, fyi: use the search at the top of the page to find the ole thread just que this web-site not the web, and type in the heading of the thread. (disregard this message if you're already in the know.)

leegrady · 03-21-2010, 01:32 PM

Program Read Only Memory, (PROM). It is the main micro-processor (chip) that calculates all the information coming into it (input) by the sensors, (for example: TPS) and then controls the many output devises like the injectors.

It basically, calculates the same thing over and over again, and these parameters are set in the manufacturing of the chip and never change.

There is also a "limp mode" chip in the ecm that will get you where you need to go should the main Prom chip fail.

Like rfmaster said, you can just change the main prom chip if you are running a different engine like in your situation. Youtube the proceedure to do this.

Nazzcu · 03-21-2010, 01:41 PM

Thanks, I am familiar with swapping the PROM, I am trying to figure out what this ECM and PROM came from? The 1227747 is from a light duty truck, but the broadcast code is unknown. I have searched here and the web but no mention of the ASDY code.

leegrady · 03-22-2010, 12:53 AM

Perhaps someone at a parts store could tell you what is ASDY, or a local dealership.

Nazzcu · 03-22-2010, 07:27 PM

I dont know, went by the dealership today, who called GM support. They can not pull up anything on the broadcast code. We could find replacements for other 305 and 350 broadcast codes but no record of ASDY. Lol, doesent matter I will replace it anyway, its just hard to believe there is no reference to this code anywhere.

03-18-2010, 10:06 PM	#1
Nazzcu Registered User Join Date: Feb 2010 Location: Tuscaloosa Alabama Posts: 46	EGR, Vacuum, Trany, and Fuel More questions about my 87. Let me preface this by saying I am not a mechanic and have very little knowledge of this drive train. So any help is appreciated. I have still been working at getting my TBI back in order and have gotten to the EGR valve. I picked up factory vacuum lines at the pick and pull today and got everything hooked up. During this I realized there would be no vacuum line for the transmission modulator valve. So I searched, the 700r4 did not have a vacuum connection correct? I have not checked the numbers on the trans to determine what it is yet. Question 1. What is a safe vacuum to splice so I can connect the trans back up? Question 2. The EGR solenoid should pull a vacuum at high RPM correct? and where does the 2nd vacuum connection on the solenoid go? I tested the EGR valve by hooking it to vacuum at idle, it stalled the engine. I am assuming the valve is working? It does run slightly rough at idle and when the solenoid is unhooked and has the vacuum is open it runs smoother. Question 3. The truck runs rich and my fuel pump runs non stop. I do not see that the wiring has been modified. To my understanding the oil switch and the fuel pump relay control this? The oil switch is not connected because it does not match the harness and it is a pain to get to to swap. What should I do to track this down. Question 4. How much of this may be due to the wrong ECM, the truck was original 305 TBI and swapped with a 92 setup. Due to what I have seen so far, I doubt the ECM was swapped in the change. I am about ready to pull it all and go back to a carb. The good news is I have started the body prep for repaint, which is what I am best at.

03-18-2010, 10:47 PM	#2
Nazzcu Registered User Join Date: Feb 2010 Location: Tuscaloosa Alabama Posts: 46	Re: EGR, Vacuum, Trany, and Fuel I checked the trany and could not find the ID but the pan looks like a 350 or 375.

03-19-2010, 07:56 AM	#3
leegrady Registered User Join Date: Mar 2010 Location: Lyle, MN Posts: 60	Re: EGR, Vacuum, Trany, and Fuel There should be a vacuum "tree" screwed into the intake manifold to run the vacuum tube to the vacuum modulator of the transmission. The tube is steel with a short length of rubber hose at each end for attachment. You are correct, the EGR is hooked up to ported vacuum, and the EGR needle only lifts off its seat at higher engine rpm's. And yes, the best way to test them is to apply vacuum at idle, and if the engine stalls it is working. Not sure about that second connection. Ported vacuum doesn't go straight to the EGR valve. It gos to a thermal switch first, usually screwed into the intake at a coolant passage that opens allowing vacuum to the EGR valve only when the engine is a normal operating temp. If it idles better with the EGR valve disconnected it means the valve is open a little probably because it's dirty. They should be serviced about every 60k. Question 3: check the fuel pressure regulator. Make sure that vacuum line is good. Confused about the ecm question. Engine size, ecm from what, 87 truck, 92....

03-20-2010, 10:23 PM	#5
Nazzcu Registered User Join Date: Feb 2010 Location: Tuscaloosa Alabama Posts: 46	Re: EGR, Vacuum, Trany, and Fuel Pulled the ECM today: Part Number: 1227747 ADSY I researched and i think 122747 is for 5.7 engine but I am not positive? Last edited by Nazzcu; 03-21-2010 at 12:29 AM.

03-21-2010, 11:08 AM	#6
Nazzcu Registered User Join Date: Feb 2010 Location: Tuscaloosa Alabama Posts: 46	Re: EGR, Vacuum, Trany, and Fuel I cant find anything on the broadcast code ADSY. I doublechecked my notes and it is ADSY. Anyone have any idea what this PROM is for?

03-21-2010, 01:03 PM	#7
leegrady Registered User Join Date: Mar 2010 Location: Lyle, MN Posts: 60	Re: EGR, Vacuum, Trany, and Fuel Remember the thread, "tbi for dummies" rfmaster had some really good information on the conversion of a 305 to a 350 tbi. Refer back to that thread. Numbers were included. Hope your project is going well.

03-21-2010, 01:06 PM	#8
leegrady Registered User Join Date: Mar 2010 Location: Lyle, MN Posts: 60	Re: EGR, Vacuum, Trany, and Fuel Oh yeah, fyi: use the search at the top of the page to find the ole thread just que this web-site not the web, and type in the heading of the thread. (disregard this message if you're already in the know.)

03-21-2010, 01:32 PM	#9
leegrady Registered User Join Date: Mar 2010 Location: Lyle, MN Posts: 60	Re: EGR, Vacuum, Trany, and Fuel Program Read Only Memory, (PROM). It is the main micro-processor (chip) that calculates all the information coming into it (input) by the sensors, (for example: TPS) and then controls the many output devises like the injectors. It basically, calculates the same thing over and over again, and these parameters are set in the manufacturing of the chip and never change. There is also a "limp mode" chip in the ecm that will get you where you need to go should the main Prom chip fail. Like rfmaster said, you can just change the main prom chip if you are running a different engine like in your situation. Youtube the proceedure to do this.

03-21-2010, 01:41 PM	#10
Nazzcu Registered User Join Date: Feb 2010 Location: Tuscaloosa Alabama Posts: 46	Re: EGR, Vacuum, Trany, and Fuel Thanks, I am familiar with swapping the PROM, I am trying to figure out what this ECM and PROM came from? The 1227747 is from a light duty truck, but the broadcast code is unknown. I have searched here and the web but no mention of the ASDY code.

03-22-2010, 12:53 AM	#11
leegrady Registered User Join Date: Mar 2010 Location: Lyle, MN Posts: 60	Re: EGR, Vacuum, Trany, and Fuel Perhaps someone at a parts store could tell you what is ASDY, or a local dealership.

03-22-2010, 07:27 PM	#12
Nazzcu Registered User Join Date: Feb 2010 Location: Tuscaloosa Alabama Posts: 46	Re: EGR, Vacuum, Trany, and Fuel I dont know, went by the dealership today, who called GM support. They can not pull up anything on the broadcast code. We could find replacements for other 305 and 350 broadcast codes but no record of ASDY. Lol, doesent matter I will replace it anyway, its just hard to believe there is no reference to this code anywhere.



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