Misfire

[GavinJansma]

It's me again... My 5.7 was misfiring and blinking the engine light, put plugs in it and now it pops a bit, not like plug wires are not right as it runs "ok" feels sluggish and hard to start, dies sometimes when going into gear. The plugs now make it pop all the time but not as loud as a backfire....pulled the cap off and it looks a bit crusty not too much so I took sand paper to it for a few minutes and it didn't change nothing. Seeing what I should try before I fire the parts cannon

 

[HotWheelsBurban]

What do the cap and rotor look like? If they're crusty, "time for a change"....
Vortecs are notorious for misfire on the two cylinders that cross terminals in the cap. Also, are all your plug wires tight on all 16 terminals (both ends)? I had a misfire last year on the Burb, #6 wire was barely on the plug. Correcting that, and a new brass terminal cap and rotor, fixed that issue.

 

[GavinJansma]

What do the cap and rotor look like? If they're crusty, "time for a change"....
Vortecs are notorious for misfire on the two cylinders that cross terminals in the cap. Also, are all your plug wires tight on all 16 terminals (both ends)? I had a misfire last year on the Burb, #6 wire was barely on the plug. Correcting that, and a new brass terminal cap and rotor, fixed that issue.

Alright I'll go out and look right now

 

[GavinJansma]

Alright I'll go out and look right now

All wires are snug, I'll replace the cap and rotor tomorrow and see if that helps

 

[GavinJansma]

Alright I put a brand new cap,rotor,and distributor in and pointed it at number 1 at tdc and it still pops there goes 90$ what now?

 

[Schurkey]

pointed it at number 1 at tdc and it still pops

WHICH "TDC"? TDC Exhaust, or TDC Compression?

How do you know?

If this were me, I'd put the engine at TDC Compression. If this is a Vortec engine, follow the service-manual procedure for aligning the distributor. You'll need to be aware of the "6" and the "8" cast-into the distributor body. Disregard the "6" when working on a V8. That "should" get the engine running, if timing was the original problem. Getting the distributor perfectly aligned within spec will require a scan tool.

If this is a TBI, line-up the rotor with the #1 plug wire terminal of the cap, and then verify that the pickup coil inner and outer teeth are aligned. Fine-tune the ignition timing with a timing light.

If distributor alignment/cap/rotor/etc. wasn't the original reason the engine quit running right, you'll still need to figure that out. Fuel pressure, computer sensors, timing chain...whatever.

 

[GavinJansma]

WHICH "TDC"? TDC Exhaust, or TDC Compression?

How do you know?

If this were me, I'd put the engine at TDC Compression. If this is a Vortec engine, follow the service-manual procedure for aligning the distributor. You'll need to be aware of the "6" and the "8" cast-into the distributor body. Disregard the "6" when working on a V8. That "should" get the engine running, if timing was the original problem. Getting the distributor perfectly aligned within spec will require a scan tool.

If this is a TBI, line-up the rotor with the #1 plug wire terminal of the cap, and then verify that the pickup coil inner and outer teeth are aligned. Fine-tune the ignition timing with a timing light.

If distributor alignment/cap/rotor/etc. wasn't the original reason the engine quit running right, you'll still need to figure that out. Fuel pressure, computer sensors, timing chain...whatever.

Another update I put it in and now the engine light doesn't blink now just pops... Also I put a new temp sensor in in the thermostat area and now it starts and idles like a dream

 

[Jeepwalker]

Didn't we already list off a bunch of "to-do's" on this issue in another thread?

You gotta start with the basics. Narrow it down to if it's a fuel issue, or timing/spark issue.

Fuel: Can you hear the fuel pump operate when the key is turned on? Does it fire if you pour a little gas down the TBI? What's yer fuel pressure?

Timing: Is the engine in 'time' at the #1 cyl at top of compression stroke -- and rotor pointing at #1 on the dist cap)? If not then the timing chain might have skipped a tooth or Dist is off. Then, what's the compression for each cylinder? Might pull off the valve covers, make sure all the rockers and push rods are in place and moving like they should (the right amount). Then pull your distributor, knock off the gear and pull out the shaft. Look inside the timing components. They could be shot, or the Ignition Module could be shot.

Do you have a troubleshooting tree?

You might be better off (in terms of your time) to enlist a 'car guy' you know, to come over and take a look at it. Not some high-school hooo-dag, but someone who REALLY knows their troubleshooting. Or take it to a good mechanic who'll work with your and understand your budget. It might be really simple like inside the distributor, or something else that a good mechanic might find quickly. (or not... lol).

 

[ralmo94]

Another update I put it in and now the engine light doesn't blink now just pops... Also I put a new temp sensor in in the thermostat area and now it starts and idles like a dream

Bad temp sensor can make it run terrible, but should produce a code for that, have you read the codes?

A bad plug wire also can cause a lot of problems, I would check the resistance with a multimeter before I assume they are good, rare, but they CAN be bad out of the box.