1996 Buick Regal Custom w/3.1 liter-No Spark

possible causes for code P0300
you've already change coil and plug....

P0300 could be bad #3 plug or coil... switch those also and see if code change..

if it persist try the next thing..

I would try trading fuel injector 4 to 5 and putting 5 into 4 and see which code you get.....

• Faulty spark plug (s)
• Faulty ignition coil (s)
• Clogged or faulty fuel injector (s)
• Intake air leak
• Fuel injectors harness is open or shorted
• Fuel Injectors circuit poor electrical connection
• Ignition coils harness is open or shorted
• Ignition coils circuit poor electrical connection
• Insufficient cylinders compression
• Incorrect fuel pressure

code P0305 is simmilar....

• Faulty spark plug 5
• Clogged or faulty fuel injector 5
• Faulty ignition coil 5
• Fuel injector 5 harness is open or shorted
• Fuel injector 5 circuit poor electrical connection
• Ignition coil 5 harness is open or shorted
• Ignition coil 5 circuit poor electrical connection
• Insufficient cylinder 5 compression
• Incorrect fuel pressure
• Intake air leak

code p 0307 is misfiring on no 7 cylinder ====causes --- engine mechanical fault ---wiring---ignition/ fuel system--injector --ECT/MAF sensor---ECM
look for low fuel pressure or ignition control module

Hi Fred:
I;d be checking the cps.

P1189 Buick - Engine Oil Pressure Switch Fault PO301
Possible causes
- Faulty spark plug 1
- Clogged or faulty fuel injector 1
- Faulty ignition coil 1
- Fuel injector 1 harness is open or shorted
- Fuel injector 1 circuit poor electrical connection
- Ignition coil 1 harness is open or shorted
- Ignition coil 1 circuit poor electrical connection
- Insufficient cylinder 1 compression
- Incorrect fuel pressure
- Intake air leak
PO300 is just telling you that you had a misfire.

Check these items. - Clogged or faulty fuel injector (s)
- Intake air leak
- Fuel injectors harness is open or shorted
- Fuel Injectors circuit poor electrical connection
- Ignition coils harness is open or shorted
- Ignition coils circuit poor electrical connection
- Insufficient cylinders compression
- Incorrect fuel pressure

Your engine needs basically four things in order to start:

> Volumetric efficiency (V)
> Air/fuel ratio (A)
> Compression (C)
> Ignition (I)
V + A + C + I = POWER

When there is no POWER (engine will not start), it is because one (or more) parts of the equation is missing. PRELIMINARY diagnosis is to determine which parts of the equation are present and which are missing. Then PINPOINT diagnosis is to determine WHY the missing parts are missing.

Until preliminary and pinpoint diagnosis is completed, nobody can do much more than GUESS what could be causing your problem.

With that said, you need to find out whether it is fuel or spark, or BOTH at the same time. The actual location of the problem can be narrowed down considerably by knowing this.

EXAMPLE: If there is fuel PRESSURE (verified by using a fuel pressure gauge) but there is no injector pulse or spark at the spark plugs, the cause would most likely be a cranshaft position sensor problem, because this will affect BOTH. This scenario would also completely rule out a fuel pump malfunction. However, if there is fuel pressure and injector pulse, but no spark, the problem would be more likely caused by an ignition control module, because this has nothing to do with your injectors or your fuel pump.

- proper diagnosis required.

Before I went too much further throwing parts at it, I'd have fuel pressure tested. Not uncommon for low fuel pressure to starve a cylinder or 2 and have a misfire code come up. Should only take mechanic about 5-10 minutes to verify low or o.k. , then you can eliminate that possibility.

Hello
Here is what to check let me know if you need help checking this out
most common misfire causes on the cars I've worked on have been:

1. Spark plugs
2. Spark plug wires
3. Ignition coil
4. Fuel injector
5. Wiring to fuel injector
6. Timing Belt
7. Vacuum leak or stuck open EGR
8. Contaminated fuel or bad fuel pump
9. Weak compression
10. Blown head gasket

if it runs on starting fluid its a fuel problem.. check fuel pressure even if its a couple of pounds off, the vehicle will not run. but using starting fluid may give you the extra poundage you need to make it run . also check vacuum hose at pressure regulator on fuel rail

sounds like an ignition module