Hello everyone, on my 2004 blazer I recently changed plugs and wires, ran okay for about a week then it started to run rough. I inspected the distributor cap and rotor and the distributor base well the rear screw hole on my distributor was broke and the front one was cracked so I ordered a new one of line, no it wasn't an ac Delco but it had great reviews and it had an aluminum base and brass fittings in the cap. When I pulled the old distributor out I didn't note where it was pointing or where it stopped turning when I pulled it all the way out. Rookie mistake but this was my first time pulling a whole distributor out so be nice. Well after reading a bunch of posts on here I did everything that they said but i couldn't get it to start. After two days of it sitting in the driveway i decided to change out the camshaft sensor on the new distributor with the old cam shaft sensor and bam she started up but was running really rough. I figured the distributor was a tooth off so I took it back out and did a little adjustment and dropped her back it well she started and was running better than the first time so I was okay with that until I could get a chance to look everything over again well it codes for cylinder 5 misfire and I can't figure it out. They are new plugs and wires, I even went and bought an extra spark plug to try to diagnose what's going on I've swapped plugs from cylinder 1&5 to see if that made cylinder 1 misfire but it still said cylinder 5 misfire so I swapped wires and still cylinder 5 misfire. If you guys can help me try to figure this headache out it would be much appreciated. Thank you.

 

Pull the plug wire for #5 and watch the live misfire counters - make sure misfire is being correctly matched to the cylinder in question before using misfire counters as gospel. Do you still have a felt misfire?

You need to check cam sensor retard and set to 0° ± 2.0°. Cam sensor retard has a direct relationship with where the rotor is pointing when the coil fires. You can get a misfire inside the cap if it is not pointing where it should be. If distributor is in a tooth off, it would immediately set a P1345 code. Does it have this code? If so, you will need to reinstall the distributor, or turn it significantly if you have replaced the hold down clamp with one that does not lock the distributor in place.

Do the stuff I said and report back please, or ask if you don't understand something.

 

When I pull the plug 5 wire the way the engine runs does not change but when I pull any other plug wire there's noticeable change in the way it runs. It does not have the p1345 code I have remove the distributor installed it multiple times just to make sure that I wasn't a tooth off and I have not replaced the hold down clamp on a distributor. What app do you recommend using to watch live misfire and to read CMP timing? I have paid for the full version of dash command and paid for the extended parameters for my vehicle but it still won't read CMP time. I messaged Palmer performance about it because I have read the other people with the same style Blazer are able to read their CMP timing they responded telling me that whenever I go to add the PID to live data screen if the bubbles read they're not able to read that data that was all they said.

 

So from what you have told me I can say that your misfire is real and it is on #5. I can also say that if your distributor is not in right (off a tooth) the P1345 code would definitely be set. So your distributor is in on the right tooth and you don't need to worry about that. You still need to worry about the Cam Sensor Retard being off - but first, regarding the misfire...……..

Double check firing order. The cylinder each wire goes to should be labeled on the cap. There are two cylinders that are out of order on the driver's side of the cap and that would include #5 IIRC.

Will spark jump from distributor to plug wire if you hold the wire in the vicinity of the terminal?
if so, do a compression check on #5 cylinder.
Report please

Now back to the OBD2 software

I have Dash Command (among many others) and I can confirm that it will read the cam sensor retard (CMPRET PID in Dash Command) on your vehicle. Since you already have the Bluetooth OBD2 dongle - if you just can't get Dash Command to work - then for under $10 you can try Car Gauge Pro which also will read the CMP Retard (use the PID with the single asterick). Car Gauge Pro does not require you to pay for any enhanced GM PIDs, but you do have to go into the setup and turn the GM ones on. Know that PIDs in Car Gauge Pro are not filtered for your individual vehicle and many modules and PIDs appear that you will not be able to use (so don't get upset with it). It is worth using for what it CAN do! Among other things including limited bidirectional control, it can read/clear codes for all systems on the data bus (Powertrain, BCM, HVAC, TCCM, ABS, SIR, etc.). Car Gauge Pro is unfiltered and raw and definitely not intuitive - but works really well once you get used to it.

 

Les is doing a fine job guiding you so follow his instructions.

By way of education for you and others, you in essence performed a drop cylinder test on #5 and since there was no change in engine rpm then that tells you that #5 is a dead cylinder because it is not contributing. The misfire count is derived by sensing a slight change in crankshaft rotation when that cylinder is firing which can be spark, fuel, air, compression, mechanical. Once you determine the category then it’s on to root cause. Example - if it’s compression then either rings, valves or head gasket, etc. Nice to see proper diagnosis and not more parts swapping. Keep up the good work.


George

 

I pulled the wire from the distributor and I get spark there, I get spark from the wire to the plug as well. Could you give me some advice on how to get the car gauge pro app to connect to my vehicle? I've tried a couple different times and haven't been able to get it to work. Is there any way to diagnose the other reasons why just cylinder 5 would be misfiring? Thank you guys for all of the assistance so far it's much appreciated.

 

And could it be because I replaced the new CMP sensor with the old one?

 

Follow Les' advice and do compression next. Also when you pull the plug report its condition. Les will get you up and running with your software

George

 

We are in process of diagnosing other reasons why just cylinder 5 is misfiring. Please do the firing order check, the compression test, and report.

For the software issues I'll see if I can dig up a link to my old Car Gauge Pro instructions. Almost sounds like a problem with the OBD2 adapter, since both Dash Command and Car Gauge Pro are not functioning properly. What Bluetooth OBD2 adapter do you have?

Here it is - hopefully you can find the things you need to know about Car Gauge Pro and Dash Command there. If not, let me know.
https://blazerforum.com/forum/2nd-ge...d-90496/page8/

 

Cam sensor will not cause a misfire. You can unplug it completely and SES light will come on, but no actual misfire. It is just used for misfire detection and timing for sequential port fuel injection. If you unplug it, it simply reverts from sequential operation to pulsing two banks of injectors and turns on the light. I really don't think the cam sensor itself previously caused your no-start condition - must have been something else in the distributor. After you check the firing order and compression, we will be going back there next.