Throttle body Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jpnc · 12-22-2015, 10:10 PM

I have a 1988 GMC Sierra pickup with a 305 engine. I just bought a 1991 GMC Sierra pickup with a 305 engine.

Will the throttle body from the 1991 fit the 1988?

The 91' TBI # is 17091041
C 1891 KDL

The 88' TBI # is 17087019
0778 JNL

I think they are both 220 TBI....not sure

Thanks for any help!

ChevyTech · 12-23-2015, 11:40 AM

Look at the TPS connector.

I think 1991 was the year that the style of TPS changed from a large single row 3 pin connector, to a small round 3 pin connector.

The only other difference I can think of to look for is the air cleaner stud.

Early TBI units had a single air cleaner stud. Later units had two air cleaner studs. I don't know what year the change happened for air cleaner studs.

jpnc · 12-23-2015, 07:42 PM

ChevyTech thanks for the info. I will check it tomorrow. I wonder if I could swap the ECU also?

ChevyTech · 12-23-2015, 08:28 PM

You're welcome.

Quote:

Originally Posted by jpnc

I wonder if I could swap the ECU also?

The 1988 & 1991 should both be a 127747 ECM

Unless they have the same axle ratio, transmission, vehicle weight..... you should keep the PROM (chip) inside the ECM with the vehicle it is from.

If you get me the PROM codes for both vehicles I may have them both in my charts.

jpnc · 12-23-2015, 09:06 PM

Where are the PROM codes located?

The 1991 has a bad head gasket or cracked head. The bottom end seems to be fine. How can I check and see which side of the engine is blown or cracked?

Thanks for all of your help!

ChevyTech · 12-24-2015, 09:06 AM

I see I missed a digit in the ECM number I listed. It should read 1227747.

The PROM is inside the ECM.

Electro static discharge (sparks) can damage the PROM and you should do a search and some reading before you remove a PROM from the ECM.

If the head gasket failure, or cracked head, is bad, you may be able to see which cylinder or cylinders by looking at the spark plugs.

Pressurizing the cylinders one by one with air is a method I like for looking for a cracked head or failed head gasket.

jpnc · 01-09-2016, 08:42 PM

Thanks for all of the help ChevyTech!

I have another post I wish you could read...."Need some help on engine swap"

I found me a 1993 350 Tbi engine

ChevyTech · 01-09-2016, 09:22 PM

You're welcome!

I just replied there.

12-22-2015, 10:10 PM	#1
jpnc Registered User Join Date: Nov 2015 Location: Archdale Posts: 26	Throttle body Question I have a 1988 GMC Sierra pickup with a 305 engine. I just bought a 1991 GMC Sierra pickup with a 305 engine. Will the throttle body from the 1991 fit the 1988? The 91' TBI # is 17091041 C 1891 KDL The 88' TBI # is 17087019 0778 JNL I think they are both 220 TBI....not sure Thanks for any help!

12-23-2015, 11:40 AM	#2
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Throttle body Question Look at the TPS connector. I think 1991 was the year that the style of TPS changed from a large single row 3 pin connector, to a small round 3 pin connector. The only other difference I can think of to look for is the air cleaner stud. Early TBI units had a single air cleaner stud. Later units had two air cleaner studs. I don't know what year the change happened for air cleaner studs. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

12-23-2015, 07:42 PM	#3
jpnc Registered User Join Date: Nov 2015 Location: Archdale Posts: 26	Re: Throttle body Question ChevyTech thanks for the info. I will check it tomorrow. I wonder if I could swap the ECU also?

12-23-2015, 09:06 PM	#5
jpnc Registered User Join Date: Nov 2015 Location: Archdale Posts: 26	Re: Throttle body Question Where are the PROM codes located? The 1991 has a bad head gasket or cracked head. The bottom end seems to be fine. How can I check and see which side of the engine is blown or cracked? Thanks for all of your help!

12-24-2015, 09:06 AM	#6
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Throttle body Question I see I missed a digit in the ECM number I listed. It should read 1227747. The PROM is inside the ECM. Electro static discharge (sparks) can damage the PROM and you should do a search and some reading before you remove a PROM from the ECM. If the head gasket failure, or cracked head, is bad, you may be able to see which cylinder or cylinders by looking at the spark plugs. Pressurizing the cylinders one by one with air is a method I like for looking for a cracked head or failed head gasket. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

01-09-2016, 08:42 PM	#7
jpnc Registered User Join Date: Nov 2015 Location: Archdale Posts: 26	Re: Throttle body Question Thanks for all of the help ChevyTech! I have another post I wish you could read...."Need some help on engine swap" I found me a 1993 350 Tbi engine

01-09-2016, 09:22 PM	#8
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Throttle body Question You're welcome! I just replied there. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.



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