5.7 TBI loss power

[Schurkey]

scan test..yes..an other issue.. i have a innova 3140g...and pcm doesnt communicate at all....

The 3140 is said to be compatible with OBD-1 from '82 to '95. Perhaps yours is defective. You do have the correct connector to plug into the under-dash diagnostic port...right?

You can scan for codes by jumping two terminals on the diag port with a paper clip by reading blinks on the Check engine light.

Code reading should not be confused with a proper scan which would also include access to the data stream.

 

[efipaneltruck]

i was able to do a compression test this morning . i removed all the sparks plugs in order to do it
before spending money in randoms parts i wanted to make sure i have a good engine to start wit


here the results

#8 --151psi #7 --148psi
#6--149psi #5-- 149psi
#4--145psi #3--136psi -----added oil in cylinder and went to 157psi
#2--152psi #1--149psi


what do you guys think ? does cylinder number#3 would be the one causing the truck to no go over 50mph?

when i started this tread i did a vacumm gage test as well . and it was 21hg constant .

 

[efipaneltruck]

The 3140 is said to be compatible with OBD-1 from '82 to '95. Perhaps yours is defective. You do have the correct connector to plug into the under-dash diagnostic port...right?

Code reading should not be confused with a proper scan which would also include access to the data stream.

engine has been swap in older truck
and i find out the obd connector wiring have been cut......its why i culd not get any reading from the scanner
im actually trying to rewiring it.....( super fun!!!!!!!)

 

[Schurkey]

i was able to do a compression test this morning .

what do you guys think ? does cylinder number#3 would be the one causing the truck to no go over 50mph?

136 psi is fine. Not "perfect", but not really a problem. I think GM says "at least 100 psi, and highest within 25% of lowest". I disagree, I think they're being too generous in order to reduce warranty claims. I would prefer to see lowest within 10% of highest, but it's not hugely critical.

152 - 10% = 152 - 15.2 = 136.8. You're good to go. That is NOT the reason the thing won't go over 50 mph.

engine has been swap in older truck
and i find out the obd connector wiring have been cut......its why i culd not get any reading from the scanner
im actually trying to rewiring it.....( super fun!!!!!!!)

Once you get the proper connections, the scan tool should give you enough clues to figure out what's wrong.

 

[efipaneltruck]

i have been able to rewire the obd1 connection......
here the codes...long list........

#31
#32
#32
#34
#41
#43
#52
#54
#55

engine and transmission have been swapped in an old chevy truck 1960 apache

 

[Schurkey]

Clear the codes, drive it, see which codes come back.

Look at the data stream during the drive. The data stream ususally means more than the codes.

Interesting. I've been looking for a '60 GMC or Chevy truck. Torsion bar front end, coil spring rear end. Quite the deal back then.

 

[efipaneltruck]

also today i checked the timing .
and find out the timing light flashed but sometimes i could see a dead spot on and off..

 

[efipaneltruck]

ok
i unplug battery for 15minutes , with light on to make sure i drain everythimg

- well first with the scann tool i cant get the vin or model or anything .
i just picked 1987 and other ( other as vehicule )

- it tells me this vehicul doesnt support live data...?

now the codes

#13
#25
#34
#35
#42
#43

it has only one o2 sensor . exhaust both side goes into one exhaust. sensor on driver side . one wire o2 sensor

 

[Schurkey]

Find out what vehicle the engine computer came out of, program that info into your scan tool.

Of course the thing supports "live data". The scan tool doesn't know how to access it. With my scan tool, I need to enter various digits from the VIN number. I don't know how YOUR scan tool works, though.

 

[PlayingWithTBI]

it tells me this vehicul doesnt support live data...?

now the codes

#13
#25
#34
#35
#42
#43

it has only one o2 sensor . exhaust both side goes into one exhaust. sensor on driver side . one wire o2 sensor

All TBIs only have 1 O2 sensor and they're on the driver's side exhaust manifold. With code #13, it sounds like it isn't hooked up.

That's a lot of codes, check your ground wires on the T-Stat housing, those are for the ECM. #25 is for MAT (Manifold Air Temp) which I don't think a 92 even had one (I could be wrong)? As @Schurkey said, you need to figure out what ECM you have.

Here's a troubleshooting guide.
TBIcodes.pdf