I hope that resolving the loose MAP clip and new MAP helps you get things resolved. You sure are staying focused on this, you deserve a break.

George

 

Before committing to the new MAP sensor you may want to check the 5v reference circuit and ground then install the retaining clip and see if the values straighten out.


George

 

George ,
well I cleaned the MAF sensor really well, and it is about unchanged at 5.75 idle and 18.25 at 2500 RPM 98 degrees ambient temp. pretty much no change from first check of 18.50

I swapped out the MAP sensor, I was unable to find a retaining clip anywhere, as it has been discontinued since 2015 by GM so I will have to hillbilly a retainer
there is a slight change in readings from the MAP I got the following with 98 degrees ambient temperature
KOEO 96
on at idle 650 RPM 38
at 1650 RPM 30

the before readings were
KOEO 97
Idle 650 RPM 34
at 1650 RPM 26
Seems to be a slight change from the old MAP

I have a load reading from my handheld, it says the load is 3.5%

I haven't installed the ECT yet, too damned hot outside Still no codes thrown or pending
I have to make a road trip tomorrow to Yakima that's 70 miles round trip so I will get an idea on fuel consumption and see if there was any change

 

George,
I think I am onto it now, from looking at things, the dealership that did the engine swap reused the intake and fuel system and exhaust, and reused all the old sensors too, as they show their age and the O2 sensors look to have never been touched. After swapping out the MAP, the air temp sensor and moving onto the ECT today, using all AC/Delco parts
Plus the fact that I also changed the air filter and PCV valve, I took it out for a ride out of town. To keep the data the same I filled up and when the nozzle shut off I pumped the gas three more times to make sure of the fuel level in tank. I put on 105.5 miles 78 highway miles using cruise control, most of the trip with a lot of climbing of hills, and 27.5 city miles, I went back to the same pump and refilled the very same way. I used 6.5 gallons of fuel for the 105.5 combined mileage and that works out to 16.8 MPG Hooray!! I hope this isn't a fluke, but will monitor it.
I feel like swapping out the MAF also, as those reading didn't change from the first reading and after a thorough cleaning. I should probably replace spark plugs as they must be sooty burning all that extra fuel. maybe this will give me a couple of extra miles. I checked the Plenum, it is a little dirty, no built up crud on the plate but something you can wipe off with a rag with solvent on it. Might be another project day once it cools down.
The rig is doing one thing that mystifies me, if you are driving above 40 mph and take your foot of the gas you can coast for a long time before it slows down. I mean if I am doing 65 on the highway and take my foot off the gas, it will take a full minute to slow down to 30 mph on a flat road The Tach drops down accordingly but I find I need to brake more with this car than my Chevy van. With it if I took my foot off the gas it pretty much stopped in it's tracks. I wonder if my tranny isn't kicking down, and how to test that. Or I may just be weird, as I haven't driven a 4x4 for 20 years.

I want to thank you and everyone else that has helped me get my rig running right again.

 

Same mileage as me - 17 mpg! Good job staying focused and putting up with my detailed diagnostic path, it's not for everyone. I am glad that you got straightened out.

Analyze, identify and repair.

George

 

George,
I am 70 years old, I remember being able to see the ground from the engine compartment and a tuneup meant points and plugs. I see now that all of these sensors are interrelated rather than stand alone, One being a tad off can have a breaking effect on the next one down the line, but that one is not the trouble point.
It is all to much for my old brain to comprehend sometimes. I am really glad that I accepted computers early in their inception and learned to use and repair them. Too many in my age group are still computer handicapped and get taken advantage for it.
Thanks again, and any ideas why my rig won't slow down in a coast situation?
DB

 

I'm not far behind, 64 here - I started filing points and cleaning plugs so that my broke **** could keep my old junkers running almost 50 years ago. We rebuilt everything back then - starters, alternators, carberators ... All you needed to know back then was 12V to the coil.

If you do a snap throttle does the rpm drop back down to idle quickly? How about at highway speed if you let off the gas and then take it out of gear does the rpm drop to idle quickly?

George