Hi I have a '97 S-10 Blazer that within the last 24 hrs has started mis firing @ idle and bogs down under load. Engine cranks fine but develops a slight mis after a few seconds. Add RPM in P or N and everything smoots out and runs fine. As soon as you put the truck in gear @ idle the mis fire gets worst to the point it acts like it will stall. Then I have to baby the accelerator to accelerate. If I try to accelerate to fast the engine hesitates/bogs, same applies to climbing even a small hill or incline. It was all i could do to keep it above 50 mph climbing/accelerating (60mph downslope off accelerator) on the freeway last night. My Service Engine Soon light is on and would even flash as I was trying to accelerate/climb (first time I've ever seen that), but I have not had a chance to read the codes yet (I don't have a SCAN tool ) I have read some other threads and checked my air filter/MAF/MAP all seem fine. My cat if more less new I had it replaced a little over a year ago, and all (4) of the O2 sensors have been replaced within the last 3-5 yrs. Cap/rotor/plugs/wires about 2 yrs. Any and all feedback and ideas greatly appreciated.

Thank You,
Ryan
'97 Chevy S-10 Blazer 4.3

 

Welcome to the forum! Good job with your signature, wish everybody did that

The flashing SES light indicates a misfire that can damage the catalytic converter. It's usually caused by a fault in secondary ignition: plugs, wires, cap, rotor & ignition coil.

Get the codes and post them here. Don't let the parts store sell you a bunch of stuff you might not need, we will help you diagnose it.

Most auto parts stores rent/sell/loan fuel pressure testers, you need one

Key ON, engine OFF, fuel pump running, pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off. Post your results.

 

Will do, Thank You for the info.

Ryan
'97 Chevy S-10 Blazer 4.3

 

DTC's: P0302:P0102:P0107:P0446

I have not yet done a fuel pressure test.

Thanks again,
Ryan
'97 Chevy S-10 Blazer 4.3

 

There's a misfire on cylinder #2: front cylinder on the right, (passenger) side. Swap the spark plug with cylinder #4, (middle plug right side). Drive it until you feel it misfire, then have codes checked again and post them here.

 

I missed your last post. I posted the DTC from my phone while I was at the parts store, and I'm in a time crunch to figure this out. The Blazer is my only vehicle and I'm very dependent on it to commute to work. But to get to the point, while at the parts store I replaced the #2 Spark Plug and wire with no change in performance. I then replaced the MAP sensor in regards to the P0107 DTC, however this also did not result in any improvment. During this period I pulled the negative battery cable to clear all DTC's in order to see what the PCM would reset. My Dad has instructed me to check all sensor wiring to MAP MAF IAT, for any signs of wear. Beyond that I'm thinking 1)Pull MAF out and do a gental clean with Brake Parts Cleaner, 2)Replace Cap & Rotor, 3) Run Fuel Pressure test, 5)Replace Fuel Filter, 6)Replace Coil (Replaced within the last 2yrs have a hard time thinking is gone already but I've been suprised before). I will post new batch of DTC once PCM sets more. Please let me know what you think, I really appreciate all the help. I don't mean to jump around and beyond your advice it just like I say, I'm in a crunch to get this fixed. The Blazer did stall out on me once while I was on my way home from the parts store. At low RPM it runs really rough as if the timing were all wrong, but smooths out as RPM increase. To drive I currently put it in P or N at any stoplights so I can pick up the RPM and avoid a stall. I have to work tomorrow morning, so I won't be able to work on it until tomorrow evening and Sunday.

Thank you so much,
Ryan
'97 Chevy S-10 Blazer 4.3

 

If you are going to replace your cap and rotor make sure to get AC Delco branded parts only there IS a difference when it comes to caps and rotors for these trucks. Also I would start with the cap and rotor if it has been 2 yrs. since they have been replaced.

 

Thank you for the info. and will do. Is it the same (AC Delco) for plugs? I did an Autolite when I replaced #2 plug last night, but I only did the one since I was not sure if it was the culprit.

Thank you,
Ryan
'97 Chevy S-10 Blazer 4.3

 

Plugs should be AC Delco 41-993, (.060" gap) and yes, only use AC Delco cap & rotor. Aftermarket stuff you're lucky to get one year! MAP, MAF, IAT, IAC motor, TPS sensor, all of those sensors will affect all cylinders, not just one, save your time and money. As mentioned, start with cap & rotor and put a dab of silicone dielectric grease on each terminal, inside and out, of the cap. Then test fuel pressure and leakdown, they are critical on this engine. Key ON, engine OFF, fuel pump running: pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off. FYI: disconnecting the battery will not clear DTC's. It will shut the SES light off only if there are no hard faults present. Must use a scan tool capable of clearing memories, (not all of them are capable).

 

Solution found! Replaced cap and rotor, unfortunatly I was unable to get AC Delco this time around. Being Sunday every Parts store I called that was open did not have AC Delco in stock (I called about 6 that are resonably in my area). A few would have been able to order them but I need my Blazer to get to work tomorrow. I ended up getting Duralast Gold (Brass contacts) mostly because it had a 5 - year warranty, so I will file my receipt and if/when it goes bad I will use that warranty. Once the cap and rotor were replaced Blazer started up and ran smooth, made a couple of circuts around the parking lot with no problems. But since I was at the parts store already I rented the Fuel System Pressure Test kit just to see what I would find (partailly in regards to the P0446 which is an issue that I've been fight before these more recent problems turned up). I ran 3 tests with the following results:

Test 1: (10 min. leakdown)
Key ON, Pump running: Immediate 62psi dropped to 60psi
Pump off: Dropped to 58psi within 10:00-9:00
Gradually dropped to 50psi 9:00-4:00
Dropped to 48psi 4:00-0:00
Held 48psi +4:00

Test 2: (10 min. Leakdown)
Key ON, pump running: 60psi
Pump off: Dropped to 55psi 10:00
Rebuilt pressure to 58psi 10:00-9:30
Gradually dropped to 55psi 9:30-7:00
Held 55psi 7:00-0:00
Gradually dropped to 50psi 0:00-+3:00

Test 3: (Engine Running)
Key ON, pump running:60psi
Pump off 55psi rebuilt to 59psi
Engine Running Dropped to 52psi and held
Add RPM climbed to 55psi then reduce back to 52psi.

Blazer had not yet turned on SES light although I believe it will in regards to P0446. I will post DTC's has they come up.

Thank you again, all of the information I received was super helpful and I will, going forward, use AC Delco parts by replacing during normal preventive maintence.