18x and 3x crank next picture is secondary ignition of #1 cylinder freeze framed.
[img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/2.jpg[/img][img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/3.jpg[/img]#1 misfire at idle or low rpm intermittently. It has a p0301 sometimes then goes away engine light does not flash just comes on sometimes and will go off by itself sometimes. The test I have performed is as follows.
1. Compression test
Cyl psi. Cyl psi
1. 188. 2. 195
3. 188. 4. 203
5. 189. 6. 194

[img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/11.jpg[/img]Pressure transducer in #1 cylinder

2. Fuel pressure is 48 psi at idle and 58 with vauum line removed from regulator. no fuel leak from regulator or gas smell on vacuum hose. Pressure was at 45 psi after car was off for 45 minutes also tested it for 10 min with engine off but key on still no change.
3. Put new plugs and wires on changed coils and icm with known good from my other buick.
4. Changed map from other buick.
5. Long term fuel trims were between -5 and -13 at idle cleaned MAF then replaced it when numbers didn't change now its positive 8 to 10 at idle when missing but near zero when not missing.
6. Swapped #1 and #3 injector all injectors are steady tapping. Wave form for injector looks good on oscope.
[img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/19.jpg[/img]7. Both crank sensor patterns look good on oscope. 3x and 18x.
8. Camshaft sensor pattern looks good on oscope.

9. Smoked intake see no leaks.
10. Pulled EGR valve it looked good pintal moves easily since I had it out I cleaned it and reinstalled it. I also pulled other buicks to compare it. Other buicks sometimes stuck if you pushed it all away in (open) so i cleaned it and got that fixed.
11. Cleaned throttle body.
12. Removed and cleaned ground under ICM and use dielectric grease on reinstallation.
13. Pressure tested coolant system even though I have had no coolant loss, it was fine.
14. Looked at secondary ignition waveforms on oscope. Hard for me to say for sure being a wast spark system looks ok for the most part but hard to sinc oscope to signal and it jumps around alot.
15 installed new LIM gaskets with metal backing along with new upper intake swapped #1 and #5 injector put new o rings on all the injectors while I was at it.
16 looked at all secondary wave forms 2 and 5 looked worst of all so changed 2&5 coil pack
Still have same p0301 comes up.


Note: sometimes it has a C1298
And a U1303 that brings on abs and brake light if you switch car off and restart usually code light and abs and brake light will go off. Codes stay in computer memory till cleared. Also another probably maybe because of these trouble codes I cannot retrieve freeze frame data.
Help notes:
A- WHITE wire.

ECM control of Ignition Control Module (after the 400 RPMs and above are achieved).

B- TAN with BLACK stripe wire.

5 Volt BYPASS from ECM for Ignition Timing Control.

C- LIGHT BLUE with BLACK stripe wire.

CRANK Position Signal to ECM.

D- PURPLE with WHITE stripe wire.

Fuel Injection Control Signal to ECM.

E- WHITE wire.

Instrument Panel Tachometer Signal.

F- BLACK wire.

CAM signal from the camshaft position (CMP) Sensor.

G- YELLOW wire.

CRANK (18X CKP) Signal from Crankshaft Position Sensor Assembly.

H- LIGHT BLUE with WHITE wire.

SYNC (3X CKP) Signal from Crankshaft Position Sensor Assembly.

J- BROWN with WHITE stripe wire.

CAM Signal from Camshaft Position (CMP) sensor.

K- BLACK with WHITE stripe wire.

Engine Ground (-).

L- BLACK with RED stripe wire.

Ground that ECM gets thru' the ignition control module.

M- RED with BLACK stripe wire.

CAM and CRANK Position Sensor Ground (-).

N- WHITE with BLACK stripe wire.

12 Volts to CAM and CRANK Position Sensors.

P- PINK wire.

Fused 12 Volts power for Ignition Control Module.


[img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/94.jpg[/img][img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/95.jpg[/img][img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/96.jpg[/img]Pressure tranducer in #1 cylinder and #1 secondary ignition on screen
[img]file:///storage/emulated/0/Android/data/com.samsung.android.app.notes/files/share/0/clipdata_191221_212407_886/98.jpg[/img]Compared to #5. #1 has slightly better running compression

Sorry it'* a 01 park Avenue 3800 I'll have to figure out how to post the puctures

Check the first "puff" on a compression test and see if it'* lower than the others. I have seen valve issues on these that will cause miss at idle and go away off idle. Just a quick thought.

Running compression test is in order.

Thanks for your very detailed information including the help notes. I have a 2001 Park Avenue vin K that I have done extensive repair work on. In the past, my vehicles included 3800 engines in four other applications. Lucerne, LaSabre, etc.
It seems that you have covered all the bases in your search for the P0301 code. I sometimes wonder if the weakest link could be the plug wire itself. Even a new wire or known good wire still has the possibility of having a flaw that could produce an intermittent problem. As you know, there is no actual wire in a spark plug wire which could mean they could be subject to a flaw. To a lesser degree, what about the spark plug? Could it be new and looking fine externally but have some type of internal flaw? I realize this seems far fetched but so many other bases have already been covered.

#1 pressure tranducer

Compared to #5 running compression looks slightly better on 1

#1 pressure tranducer

Compared to #5 running compression looks slightly better on 1



3x crank and cam sensor

Crazy secondary ignition spark may be during miss not sure how to interpret it

Also I have swapped plugs a few times along with wires and the injector twice

This is my new lower intake gaskets work

My 18x and 3x crank sensor

My current ramp on the injector

Fuel injector voltage on scope

Thanks for the additional info. This sure is a mystery as everything is checking out so well but the issue remains. Please keep us posted on any new developments..

Are we looking at cranking or running cylinder pressures? Cranking will show the timing and valves opening and closing. Need to change the time frame and stretch it out a bit. How many transducers do you have? It'* nice to compare.