Fast idle speed 1996 K1500 5.0

[corsair-pilot]

Hi all.
I have a strange problem with my 1996 K1500 5.0.
Intermittently the idle speed will raise to 1500 rpm and stay their.
This has been ongoing for some time. Items done after this started.
Converted to mfi, had leaking regulator.
egr valve replaced. had pintle position code.
intake gaskets replaced due to leaking at rear.
swapped iac, tps, crank sensor, has no intake leaks. has new plugs, wires, cap, rotor, fuel pressure per s.m. 58 psi at idle. koeo pressure is 65 psi.
driving pressure is between 58 to 63.
Any one seen this problem?
Thanks
Dale
p/s throttle is not sticking, throttle plate is fully closed.

[j cAT]

<P>

Originally Posted by corsair-pilot

Hi all.</P>
<P>I have a strange problem with my 1996 K1500 5.0.</P>
<P>Intermittently the idle speed will raise to 1500 rpm and stay their.</P>
<P>This has been ongoing for some time. Items done after this started.</P>
<P>Converted to mfi, had leaking regulator.</P>
<P>egr valve replaced. had pintle position code.</P>
<P>intake gaskets replaced due to leaking at rear.</P>
<P>swapped iac, tps, crank sensor, has no intake leaks. has new plugs, wires, cap, rotor, fuel pressure per s.m. 58 psi at idle. koeo pressure is 65 psi.</P>
<P>driving pressure is between 58 to 63.</P>
<P>Any one seen this problem?</P>
<P>Thanks</P>
<P>Dale</P>
throttle is not sticking, throttle plate is fully closed.

with the ignition off after engine was running does the fuel pressure hold ? if not injectors leaking most likely..too much fuel the engine should increase in rpm to maintain fuel air ratio by way of the IAC..
what is idle rpm ? what is vacuum ? what about PCV and the hoses ?

vacuum leak will also mess up the idle speed..

[corsair-pilot]

Hi.
Yes, fuel pressure holds after shutting down. It starts right up cold also.
Thanks for the reply.
Dale

[tblake]

Hey Dale, inspect the MAF sensor for dirt. If its dark and carboned up, get some MAF sensor cleaner and use a que tip to clean it. Also remove the IAC motor. Clean all the carbon off it and out of its bore with Carb cleaner. Then back probe the TPS signal wire. Voltage should range from 0.01 volts to 5 volts as you open and close the throttle with key on engine off. If you see any voltage drop offs or spikes as you sweep the accellerator, the TPS is shot.

[corsair-pilot]

Hi.
Thanks for the reply.

Yes I already checked and cleaned the maf. code reader shows tps working good. swaped a known good tps with no help.
I already cleaned the iac ports, it was clean. swaped iac with known good one.
I completed the iac relearn and disconnected iac and drove for a day and the idle speed stayed the same. this shows I do not have an air leak below the throttle plate.
I need to read manual some more and find out all inputs that can control iac output. Do know coolant temp and map sensor input is used.
Again thanks for your time
Dale

[tblake]

Clamp off the vacuum booster hose in case the booster is leaky.

Also have a look at the vacuum lines that go to the "soup can" that is near the radiator on the drivers side.

Is there any change if you unplug the MAP sensor on the Upper Intake Manifold?

[corsair-pilot]

Hi all.

Well its fixed. Located service bulletin for egr and other problems. Had dealer reflash pcm to latest software. no more intermittent egr code. idles normal and no more surging...
Dale

[j cAT]

Originally Posted by corsair-pilot

Hi all.

Well its fixed. Located service bulletin for egr and other problems. Had dealer reflash pcm to latest software. no more intermittent egr code. idles normal and no more surging...
Dale

so some how the pcm flash was corrupted. If this fix lasts I will be surprised.

[corsair-pilot]

Hi.

I never said my pcm was corrupt, nor does the bulletin. It updates the system and engine files to fix issues that come up due to many things.

GM and all mfgr. do updates to fix issues.

Pcm files do not go corrupt like pc do.

Dale

[j cAT]

Originally Posted by corsair-pilot

Hi.

I never said my pcm was corrupt, nor does the bulletin. It updates the system and engine files to fix issues that come up due to many things.

GM and all mfgr. do updates to fix issues.

Pcm files do not go corrupt like pc do.

Dale

I said your PCM was corrupt ! this is because when a vehicle is 14years old , GM does not care about PCM flash updates.

this was built back in 1996 and I"m sure it ran perfectly when new.

something changed ! It is possible that a prior owner replaced the PCM.

I would carefully check your grounds,also the battery connections and cables for security and corrosion.

[corsair-pilot]

J cat thanks for your input.

I am the original owner, has original pcm.
Here is GM SI doc..
See #3 and #7
thanks
Dale
Document ID # 224444
MALFUNCTION INDICATOR LIGHT (MIL) ON, POOR DRIVEABILITY #76-65-04

SUBJECT: MALFUNCTION INDICATOR LIGHT (MIL) ON, POOR DRIVEABILITY CONDITIONS (PERFORM FLASH CALIBRATION)

MODELS: 1996-97 CHEVROLET AND GMC LIGHT DUTY TRUCKS 1996-97 CHEVROLET TILTMASTER AND GMC FORWARD W4 MODELS 1996-97 OLDSMOBILE BRAVADA WITH 4.3L, 5.0L, 5.7L ENGINES (VINS X, W, M, R - RPOS LF6, L35, L30, L31)

CONDITION:

AN OWNER MAY REPORT THAT THE MALFUNCTION INDICATOR LIGHT (MIL) IS ON AND/OR THE VEHICLE HAS ONE OR MORE OF THE FOLLOWING DRIVEABILITY CONDITIONS.
1. 5.7L (L31) ONLY: SURGE OR CHUGGLE AT SPEEDS OF 42 TO 65 MPH WHILE AT STEADY SPEED OR UNDER LIGHT TO MODERATE ACCELERATION WITH THE TCC APPLIED.
2. MIL ON WITH DTC P0172 OR P0175 STORED BUT NO REPORTED DRIVEABILITY SYMPTOMS.
3. MIL ON WITH DTC P1406 STORED AND ROUGH ENGINE OR POOR DRIVEABILITY SYMPTOMS.
4. WHEN OPERATING AT ALTITUDES ABOVE 5,000 FEET, AN AUDIBLE SPARK KNOCK NOISE IS HEARD.
5. HESITATION AND/OR MISFIRE DURING LIGHT CRUISE CONDITIONS DUE TO IGNITION CROSS-FIRE WITH NO DTC STORED. THIS WILL ONLY OCCUR ON V-6 ENGINES WITH CAM RETARD OFFSET IN EXCESS OF 26 DEGREES AND V-8'S WITH CAM RETARD OFFSET IN EXCESS OF 15 DEGREES.
6. THE MIL MAY BE ON AND A DTC STORED FOR AN ENGINE MISFIRE BUT NO MISFIRE OCCURRED.
7. ENGINE EXHIBITS AN IDLE SPEED SURGE OR ROLL.
1996 MODELS ONLY
8. MIL ON WITH DTC P0102 STORED BUT NO REPORTED DRIVEABILITY SYMPTOMS.
9. 5.0L (L30) + 5.7L (L31) ONLY: DIFFICULT STARTING IN EXTREME COLD (BELOW 0 DEGREES F) CONDITIONS.
10. 5.7L (L31) ONLY: POORER THAN EXPECTED FUEL ECONOMY WHEN HEAVILY LOADED.
1997 MODELS ONLY
11. MIL ON WITH DTC P0121 STORED BUT NO REPORTED DRIVEABILITY SYMPTOMS.
12. C/K + S/T MODELS WITH EITHER V-6 ENGINE AND MANUAL TRANSMISSION: AN EXHAUST BACKFIRE MAY OCCUR WHILE SHIFTING WITH MODERATE THROTTLE AT ENGINE SPEEDS ABOVE 3500 RPM.
13. EITHER V-6 ENGINE AND MANUAL TRANSMISSION: AN ENGINE FLARE BETWEEN SHIFTS MAY BE NOTED WHEN THE ENGINE IS COLD.
14. C/K, S/T AND M/L MODELS EQUIPPED WITH L35 V-6 ENGINE, AN IMPROVEMENT TO THE VAPOR CANISTER PURGE DIAGNOSTICS IS INCORPORATED INTO THE NEW CALIBRATIONS SO THAT THE TECH II CAN TURN ON CANISTER PURGE AT IDLE SPEED.
CORRECTION:

FOLLOW THE STRATEGY BASED DIAGNOSTIC STEPS FOR THE CUSTOMER'S REPORTED SYMPTOMS. IF DIAGNOSIS DOES NOT REVEAL A CAUSE, REFER TO THE TABLES BELOW FOR THE APPLICABLE CALIBRATION CHANGE. PERFORM PROGRAMMING PER THE LATEST TECHLINE INFORMATION FOR PROGRAMMING PROCEDURES.
IMPORTANT: THE CALIBRATIONS LISTED ARE FLASH CALIBRATIONS AND ARE NOT AVAILABLE FROM GMSPO. THEY ARE AVAILABLE ON 1997 TECHLINE CD DISC 5 AND LATER.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:
LABOR OPERATION LABOR TIME J-6355 USE PUBLISHED LABOR OPERATION TIME
1996 MODEL YEAR
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
T-UTILITY 4.3L L35 AUTO NF2/NB6 -Z49 16232320 16235814 T-UTILITY 4.3L L35 AUTO NF2/NB6 +Z49 16232321 16235815 T-UTILITY 4.3L L35 AUTO NN8 -NA7/NA3 16232322 16235816 T-UTILITY 4.3L L35 AUTO NN8 + NA7/NA3 16232323 16235817 S/T-ALL 4.3L L35 MANUAL NF2/NB6 -Z49 16232324 16235818 S/T-ALL 4.3L L35 MANUAL NF2/NB6 +Z49 16232325 16235819 S/T-ALL 4.3L L35 MANUAL NN8 16232326 16235820
S/T-PICKUP 4.3L L35 AUTO NF2/NB6 -Z49 16232327 16235821 AND, S-UTILITY
S/T-PICKUP 4.3L L35 AUTO NF2/NB6 +Z49 16232328 16235822 AND, S-UTILITY
S/T-PICKUP 4.3L L35 AUTO NN8 -NA7/NA3 16232329 16235823 AND, S-UTILITY
S-PICKUP 4.3L LF6 AUTO NF2/NB6 -Z49 16232330 16235824 S-PICKUP 4.3L LF6 AUTO NF2/NB6 +Z49 16232331 16235825 T-PICKUP 4.3L LF6 AUTO NF2/NB6 -Z49 16232332 16235826 T-PICKUP 4.3L LF6 AUTO NF2/NB6 +Z49 16232333 16235827 S-PICKUP 4.3L LF6 MANUAL NF2/NB6 -Z49 16232334 16235828 S-PICKUP 4.3L LF6 MANUAL NF2/NB6 +Z49 16232335 16235829 T-PICKUP 4.3L LF6 MANUAL NF2/NB6 -Z49 16232336 16235830 T-PICKUP 4.3L LF6 MANUAL NF2/NB6 +Z49 16232337 16235831 S/T-ALL 4.3L L35 AUTO NM8 16232424 16232426 S/T-ALL 4.3L L35 MANUAL NM8 16232425 16232427 M-VAN 4.3L L35 AUTO NF2/NB6 -Z49 16232385 16235846 M-VAN 4.3L L35 AUTO NF2/NB6 +Z49 16232386 16235847 M-VAN 4.3L L35 AUTO NN8 16232387 16235848 L-VAN 4.3L L35 AUTO NF2/NB6 -Z49 16232388 16235849 L-VAN 4.3L L35 AUTO NF2/NB6 +Z49 16232389 16235850 L-VAN 4.3L L35 AUTO NN8 16232390 16235851 M-VAN 4.3L L35 AUTO NM8 16232391 16232428 L-VAN 4.3L L35 AUTO NM8 16232392 16232429
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
C/K-10/20 TRUCK 4.3L L35 MANUAL NA5/NB6 -Z49 16232310 16235832 C/K-10/20 TRUCK 4.3L L35 MANUAL NA5/NB6 +Z49 16232311 16235833 C/K-10/20 TRUCK 4.3L L35 MANUAL NN8 16232312 16235834
C/K-10/20 TRUCK 4.3L L35 AUTO NA5/NB6 -Z49 16232313 16235835 EXCEPT EXT. CAB STEP SIDE
C/K-10/20 TRUCK 4.3L L35 AUTO NA5/NB6 +Z49 16232314 16235836 EXCEPT EXT. CAB STEP SIDE
C/K-10/20 TRUCK 4.3L L35 AUTO NN8 16232315 16235837 EXCEPT EXT. CAB STEP SIDE
C/K-10/20 TRUCK 4.3L L35 AUTO NA5/NB6 -Z49 16232342 16235843 WITH EXT. CAB STEP SIDE
C/K-10/20 TRUCK 4.3L L35 AUTO NA5/NB6 +Z49 16232343 16235844 WITH EXT. CAB STEP SIDE
C/K-10/20 TRUCK 4.3L L35 AUTO NN8 16232344 16235845 WITH EXT. CAB STEP SIDE
C/K-10/20 TRUCK 5.0L L30 AUTO NA5 -Z49 16232345 16235853 C/K-10/20 TRUCK 5.0L L30 AUTO NA5 +Z49 16232346 16235854 C/K-10/20 TRUCK 5.0L L30 AUTO NN8 16232347 16235855 C/K-10/20 TRUCK 5.0L L30 AUTO NF2/NB6 -Z49 16232348 16235856 C/K-10/20 TRUCK 5.0L L30 MANUAL NA5 -Z49 16232349 16235857 C/K-10/20 TRUCK 5.0L L30 MANUAL NA5 +Z49 16232350 16235858 C/K-10/20 TRUCK 5.0L L30 MANUAL NN8 16232351 16235859 C/K-20/30 TRUCK 5.7L L31 MANUAL NA4/NA5/NM8 16232422 16256096
C/K-20/30 TRUCK 5.7L L31 MANUAL NA4/NA5 16232355 16235864 -NM8/Z49
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
C/K-ALL 20/30 5.7L L31 AUTO NA4/NB6 -Z49 16232356 16235865
C/K-ALL 20/30 5.7L L31 AUTO NA4/NA5 16232357 16235866 -NM8/Z49
C/K-ALL 20/30 5.7L L31 AUTO NA4/NA5/NM8 16232423 16256097 C-10 TRUCK 5.7L L31 MANUAL NA1/NA5 16232362 16235872 -NM8/Z49
C-10 TRUCK 5.7L L31 MANUAL NA1/NA5/Z49 16232363 16235873 C-10 TRUCK 5.7L L31 MANUAL NN8 16232364 16235874
C-10 TRUCK 5.7L L31 AUTO NA1/NA5/NB6/NF2 16232365 16235875 -NM8/Z49
C-10 TRUCK 5.7L L31 AUTO NA1/NA5/Z49 16232366 16235876 C-10 TRUCK 5.7L L31 AUTO NN8 16232367 16235877
C-10 TRUCK 5.7L L31 MANUAL NA1/NB6 16232368 16235878 -NM8/Z49
K-10 TRUCK 5.7L L31 AUTO NA1/NA5/NB6/NF2 16232369 16235879 C/K-20 TRUCK -NM8/Z49
K-10 TRUCK 5.7L L31 AUTO NA1/NA5/Z49 16232370 16235880 C/K-20 TRUCK
K-10 TRUCK 5.7L L31 AUTO NN8 16232371 16235881 C/K-20 TRUCK
C/K-10 UTILITY 5.7L L31 AUTO NA5/NB6/NF2 16232372 16235882 -NM8/Z49
C/K-10 UTILITY 5.7L L31 AUTO NA5/Z49 16232373 16235883 C/K-10 UTILITY 5.7L L31 AUTO NN8 16232374 16235884
K-10 TRUCK 5.7L L31 MANUAL NA1/NA5 16232375 16235885 C/K-20 TRUCK -NM8/Z49
K-10 TRUCK 5.7L L31 MANUAL NA1/NA5/Z49 16232376 16235886 C/K-20 TRUCK
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
K 10/20 TRUCK 5.7L L31 MANUAL NA1/NB6 16232378 16235888 C/K 20 TRUCK -NM8/Z49
K-10 TRUCK 5.7L L31 MANUAL NN8 16232377 16235887 C/K-20 TRUCK
C/K 10/20 ALL 5.7L L31 AUTO NM8 16232383 16256102 C/K 10/20 TRUCK 5.7L L31 MANUAL NM8 16232384 16256103 G-VAN 10/20 4.3L L35 AUTO NB6 -Z49 16232316 16235838 G-VAN 10/20 4.3L L35 AUTO NA5 +Z49 16232317 16235839 G-VAN 10 4.3L L35 AUTO CV4/NN8 16232318 16235840 G-VAN 10/20 4.3L L35 AUTO NA5 -Z49-EXP 16232319 16235841 G-VAN 20 4.3L L35 AUTO NA5 16232338 16235842 G-VAN ALL 5.0L L30 AUTO NA5 -Z49 16232352 16235860 G-VAN ALL 5.0L L30 AUTO NA5 +Z49 16232353 16235861 G-VAN ALL 5.0L L30 AUTO NF2/NB6 -Z49 16232354 16235862 G-VAN 10/20 5.7L L31 AUTO NA5 -Z49 16232379 16235889 G-VAN 10/20 5.7L L31 AUTO NA5/Z49 16232380 16235890 G-VAN 10/20 5.7L L31 AUTO NA5/NM8 16232301 16256101 G-VAN 10/20 5.7L L31 AUTO NA5/NN8 16232381 16235891 G-VAN 10/20 5.7L L31 AUTO NB6 -Z49 16232382 16235892 G-VAN 20/30 5.7L L31 AUTO NB6 -Z49 16232358 16235867 G-VAN 20 5.7L L31 AUTO NA5/NM8 16227552 16256098 G-VAN 20 5.7L L31 AUTO NA5 -NM8/Z49 16232359 16235868 G-VAN 30 5.7L L31 AUTO NB6 -Z49 16232360 16235869 G-VAN 30 5.7L L31 AUTO NA5/Z49 16232361 16235870 P-CHASSIS 4.3L L35 AUTO NA5 16227523 16235852 P-CHASSIS 5.7L L31 AUTO NA5/NM8 16235811 16256099 P-CHASSIS 5.7L L31 MANUAL NA5/NM8 16235812 16256100 P-CHASSIS 5.7L L31 AUTO NB6 -Z49 16187756 16235871 P-CHASSIS 5.7L L31 MANUAL NA5 -NM8/Z49 16187887 16235895 P-CHASSIS 5.7L L31 AUTO NA5/NB2 -NM8/Z49 16187888 16235896 W4 5.7L L31 AUTO NB6 -Z49 16235809 16235893 W4 5.7L L31 AUTO NA5/Z49 16235808 16235894
1997 MODEL YEAR
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
T-UTILITY FOUR 4.3L L35 AUTO NF2/NA3/NB6 -Z49 16243498 16256222 DOOR
T-UTILITY FOUR 4.3L L35 AUTO NF2/NB6/Z49 16243499 16256223 DOOR
T-UTILITY FOUR 4.3L L35 AUTO NN8 -NA7 16243532 16256224 DOOR
T-UTILITY FOUR 4.3L L35 AUTO NN8/NA7 16243533 16256225 DOOR
S-UTILITY FOUR 4.3L L35 AUTO NF2/NB6 -Z49 16243502 16256230 DOOR
S-UTILITY FOUR 4.3L L35 AUTO NF2/NB6/Z49 16243503 16256231 DOOR
S-UTILITY FOUR 4.3L L35 AUTO NN8 -NA7 16243536 16256232 DOOR
S-UTILITY TWO 4.3L L35 AUTO NF2/NB6 -Z49 16243504 16256233 DOOR
S-UTILITY TWO 4.3L L35 AUTO NF2/NB6/Z49 16243505 16256234 DOOR
S-UTILITY TWO 4.3L L35 AUTO NN8 -NA7 16243537 16256235 DOOR
T-UTILITY TWO 4.3L L35 AUTO NF2/NB6 -Z49 16243500 16256226 DOOR
T-UTILITY TWO 4.3L L35 AUTO NF2/NB6 +Z49 16243501 16256227 DOOR
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STLYE
T-UTILITY TWO 4.3L L35 AUTO NN8 16243534 16256228 DOOR
T-UTILITY TWO 4.3L L35 AUTO NN8/NA3/NA7 16243535 16256229 DOOR
S/T UTILITY TWO 4.3L L35 MANUAL NF2/NB6 -Z49 16243510 16256243 DOOR
S/T UTILITY TWO 4.3L L35 MANUAL NF2/NB6 +Z49 16243511 16256244 DOOR
S/T PICKUP 4.3L L35 AUTO NF2/NB6 -Z49 16243506 16256236 S/T PICKUP 4.3L L35 AUTO NF2/NB6 +Z49 16243507 16256237 S/T PICKUP 4.3L L35 AUTO NN8 16243538 16256238 S/T PICKUP 4.3L L35 MANUAL NF2/NB6/NA3 -Z49 16243508 16256239 S/T PICKUP 4.3L L35 MANUAL NF2/NB6 +Z49 16243509 16256240 S/T PICKUP 4.3L L35 MANUAL NN8 -NA7 16243539 16256241 S/T PICKUP 4.3L L35 MANUAL NN8/NA7 16243580 16256242 S/T PICKUP 4.3L LF6 AUTO NF2/NB6 -Z49 16243512 16256245 S/T PICKUP 4.3L LF6 AUTO NF2/NB6 +Z49 16243513 16256246 S/T PICKUP 4.3L LF6 MANUAL NF2/NB6 -Z49 16243514 16256247 S/T PICKUP 4.3L LF6 MANUAL NF2/NB6 +Z49 16243515 16256248 S/T ALL 4.3L L35 AUTO NM8 16251340 16256249 S/T ALL 4.3L L35 MANUAL NM8 16251341 16256250
M-VAN 4.3L L35 AUTO NF2/NA3 16243516 16256251 -Z49/NN8/NM8
M-VAN 4.3L L35 AUTO NB7/NC1 16243517 16256252 M-VAN 4.3L L35 AUTO NF2/Z49 16243518 16256253 M-VAN 4.3L L35 AUTO NN8/NA7 16243581 16256254 M-VAN 4.3L L35 AUTO NM8 16251342 16256259
L-VAN 4.3L L35 AUTO NF2/NA3 16243519 16256255 -Z49/NN8/NM8
L-VAN 4.3L L35 AUTO NB7/NC1 16243520 16256256 L-VAN 4.3L L35 AUTO NF2/Z49 16243521 16256257
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
L-VAN 4.3L L35 AUTO NN8/NA7 16243582 16256258 L-VAN 4.3L L35 AUTO NM8 16251343 16256260
C/K TRUCK REG 4.3L L35 AUTO -Z49 16243522 16256261 CAB STEP SIDE
C/K TRUCK REG 4.3L L35 AUTO Z49 16243523 16256262 CAB STEP SIDE
C/K TRUCK REG 4.3L L35 AUTO NN8 16243583 16256263 CAB STEP SIDE
C/K TRUCK 10/20 4.3L L35 AUTO -Z49/NN8 16243524 16256264 C/K TRUCK 10/20 4.3L L35 AUTO Z49 16243525 16256265 C/K TRUCK 10/20 4.3L L35 AUTO NN8 16243584 16256266 C/K TRUCK 10/20 4.3L L35 AUTO -Z49/NN8 16243526 16256267 C/K TRUCK 10/20 4.3L L35 AUTO Z49 16243527 16256268 C/K TRUCK 10/20 4.3L L35 AUTO NN8 16243585 16256269 C/K TRUCK 10/20 4.3L L35 MANUAL -Z49/NN8 16243528 16256270 C/K TRUCK 10/20 4.3L L35 MANUAL Z49 16243529 16256271 C/K TRUCK 10/20 4.3L L35 MANUAL NN8 16243586 16256272 C/K TRUCK 10/20 4.3L L35 MANUAL -Z49/NN8 16243530 16256273 C/K TRUCK 10/20 4.3L L35 MANUAL Z49 16243531 16256274 C/K TRUCK 10/20 4.3L L35 MANUAL NN8 16243587 16256275
C-TRUCK 10/20 5.0L L30 AUTO NB6 16243419 16256281 K-TRUCK 10
C-TRUCK 10/20 5.0L L30 AUTO NF2/NN8 16243420 16256282 K-TRUCK 10
C-TRUCK 10/20 K-5.0L L30 AUTO NF2/Z49 16204232 16256283 K-TRUCK 10
C-TRUCK 10/20 K-5.0L L30 MANUAL NF2 -Z49/NN8 16251347 16256284 K-TRUCK 10
C-TRUCK 10/20 K-5.0L L30 MANUAL NF2/Z49 16251348 16256285 K-TRUCK 10
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
C-TRUCK 10/20 K-5.0L L30 AUTO NF2 -NN8/Z49 16243422 162562866 K-TRUCK 10
C-TRUCK 10/20 K-5.0L L30 MANUAL NF2/NN8 16251349 16256287 K-TRUCK 10
C/K TRUCK 20/30 5.7L L31 MANUAL NA4/NA5/NM8 16204188 16256291 C/K TRUCK 20/30 5.7L L31 MANUAL NA4/NA5 -NM8 16243425 16256292 C/K 20/30 ALL 5.7L L31 AUTO NA4/NB6 -KL6 16243426 16256293
C/K 20/30 ALL 5.7L L31 AUTO NA4/NA5 16243427 16256294 -NM8/KL6
C/K 20/30 ALL 5.7L L31 AUTO NA4/NA5/NM8 -KL6 16204191 16256295 C-TRUCK 20/30 5.7L L31 AUTO ZW9 16232516 16256296
C/K TRUCK 10/20 5.7L L31 MANUAL NA1/NB6/NF2 16243431 16256304 -NM8/NN8
C/K TRUCK 10/20 5.7L L31 MANUAL NA1/NF2/Z49 16204196 16256305 C/K TRUCK 10/20 5.7L L31 MANUAL NA1/NF2/NN8 16232484 16256306 C/K 10/20 ALL 5.7L L31 AUTO NA1 -NM8/Z49 16243432 16256307 C/K 10/20 ALL 5.7L L31 AUTO NA1/Z49 16204197 16256308 C/K 10/20 ALL 5.7L L31 AUTO NA1/NN8 16232487 16256309
C 10/20 ALL 5.7L L31 AUTO NM8 16251344 16256310 K 10 ALL
C 10/20 TRUCK 5.7L L31 MANUAL NM8 16251345 16256311 K 20 TRUCK
G-VAN 10/20 4.3L L35 AUTO NF2/NB6 16243417 16256276 -Z49/EXP
G-VAN 10/20 4.3L L35 AUTO NF2/Z49 16204133 16256277 G-VAN 10 4.3L L35 AUTO CV4/NN8 16204134 16256278 G-VAN 20 4.3L L35 AUTO NA5 16243418 16256279 G-VAN 10/20 5.0L L30 AUTO NB6 -Z49 16243423 16256288
MODEL-BODY ENGINE TRANS EMISSION/USAGE OLD CAL NEW CAL STYLE
G-VAN 10/20 5.0L L30 AUTO NA5 -Z49 16243424 16256289 G-VAN 10/20 5.0L L30 AUTO NA5/Z49 16204135 16256290 G-VAN 20/30 5.7L L31 AUTO NB6 -NM8/Z49 16243428 16256297 G-VAN 20 5.7L L31 AUTO NA5/NM8 16204143 16256298 G-VAN 20/30 5.7L L31 AUTO NA5/Z49 -NM8 16243429 16256299 G-VAN 30 5.7L L31 AUTO NB6 -Z49 16243430 16256300
G-VAN 10/20 5.7L L31 AUTO NA1/NF2/NB6 16243433 16256312 -NM8/Z49
G-VAN 10/20 5.7L L31 AUTO NA5/Z49 16204136 16256313 G-VAN 10/20 5.7L L31 AUTO NA5/NM8 16204130 16256314 G-VAN 10/20 5.7L L31 AUTO NA5/NN8 16243434 16256315
P-CHASSIS 4.3L L35 AUTO NA5 16226705 16256280 P-CHASSIS 5.7L L31 AUTO NA5/NM8 16204158 16256301 P-CHASSIS 5.7L L31 MANUAL NA5/NM8 16204157 16256302 P-CHASSIS 5.7L L31 AUTO NB6 16243457 16256303 P-CHASSIS 5.7L L31 MANUAL NA5 -NM8/Z49 16204162 16256318
P-CHASSIS 5.7L L31 AUTO NA5/NB2 16204163 16256319 -NM8/Z49
W4 5.7L L31 AUTO NB6/-Z49 16235809 16235893 W4 5.7L L31 AUTO NA5/Z49 16235808 16235894
FIGURES: 0
GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.
COPYRIGHT 1997 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.

© Copyright General Motors Corporation. All Rights Reserved.

Document ID # 224444

[j cAT]

GM Tech Bulletin #76-65-04 was issued in march of 1997. so you and many others have suffered from these many issues over many years.

this PCM flash was created because as these engines age the engine noise increased to a level first set in the software too low . as a result all the issues with these engines//pcm were felt by the owners.