Breaking up/cutting out and bogging down

[Shawn2131]

So This problem has been occurrent for awhile now and I've been doing a lot to try to fix it and it's just getting more and more expensive. It's a 98 350 with longtubes but the problem only came up about a month ago so I don't know.

I have a P0102 P0340 I've already replaced the sensor that hasn't helped and i've also replaced the crankshaft sensor also and that hasn't fixed it.
The problem is hard to explain but it bogs its self down then I either have to left off or floor it then let off for it to clear up. Then for the cutting out problem the timing is fine but say if i tap on it it cuts out then comes back. I do have 02 sensors their brand new gm sensors but if anyone could help that would be great thank you and if you need more info to try to help then il try my best.

 

[Drunkcanuk]

So This problem has been occurrent for awhile now and I've been doing a lot to try to fix it and it's just getting more and more expensive. It's a 98 350 with longtubes but the problem only came up about a month ago so I don't know.

I have a P0102 P0340 I've already replaced the sensor that hasn't helped and i've also replaced the crankshaft sensor also and that hasn't fixed it.
The problem is hard to explain but it bogs its self down then I either have to left off or floor it then let off for it to clear up. Then for the cutting out problem the timing is fine but say if i tap on it it cuts out then comes back. I do have 02 sensors their brand new gm sensors but if anyone could help that would be great thank you and if you need more info to try to help then il try my best.

So....many have come here with issues, that's usually how we found ourselves here. And one thing I learned, is how people are going to reach, so I'll start.

You are gonna need a scanner to help diagnose what's up. One that reads live data.

What's your fuel pressure readings?

What is the state of your tune up items? Like plugs etc.

 

[Schurkey]

98 350 with longtubes

How is the EGR system plumbed?

I have a P0102 P0340

What are those codes for? It's impolite to make us look them up.

I've already replaced the sensor

WHICH "sensor"? MAF? Cam position? Something else?

i've also replaced the crankshaft sensor also and that hasn't fixed it.

Are you also getting crank position sensor code(s) you haven't listed?

it bogs its self down then I either have to left off or floor it then let off for it to clear up. Then for the cutting out problem the timing is fine but say if i tap on it it cuts out then comes back.

You are gonna need a scanner to help diagnose what's up. One that reads live data.

What's your fuel pressure readings?

What is the state of your tune up items? Like plugs etc.

Exactly right. The first things to look at are "The Usual Three".

1. Verify fuel pressure at prime, at idle, and under load. Most fuel pressure gauge assemblies have a push-button pressure release connected to crappy vinyl tubing. Route the tubing so it empties into a drain pan, then push the button while the engine is running. This simulates higher fuel demand if you can't check fuel pressure on the highway. Fuel pressure should remain steady even with fuel flowing down the pressure-relief tubing. How old is the fuel filter? Have you ever dumped a bottle of Chevron Techron Complete Fuel System Cleaner into the gas tank? (Recommended at every oil change.)
   
2. How old are the usual “tune-up” parts and procedures? Inspect/replace distributor cap, rotor, plug wires, spark plugs. Make sure the ignition coil will reliably fire a spark-tester calibrated for HEI when the coil is fully warm, and misted with water from a squirt-bottle. Cranking compression test of all cylinders while the spark plugs are removed. Verify EGR, PCV, EVAP, and Heated Air Intake (if used) systems for proper operation. Verify proper initial timing (TBI) and electronic spark advance (TBI and Vortec). Replace old O2 sensors unless you can PROVE that they're working properly—old O2 sensors get lazy, they don't provide accurate data, but they do provide “data” that fools people into thinking they're “working”.
   
3. Connect a scan tool (NOT a crappy “code reader”) and look for “codes”. More important, look at the data stream to verify EVERY sensor and computer output. Verify fuel trims during the time that the vehicle is not running properly. Look for misfire counts for each cylinder (OBD2 only.) “Codes” have official diagnostic procedures that will be found in the service manual set for your vehicle. The service manual set can be downloaded from the links in the Sticky thread section of the Engine forum on this web site.

 

[Shawn2131]

So....many have come here with issues, that's usually how we found ourselves here. And one thing I learned, is how people are going to reach, so I'll start.

You are gonna need a scanner to help diagnose what's up. One that reads live data.

What's your fuel pressure readings?

What is the state of your tune up items? Like plugs etc.

I haven't looked at fuel pressure il check when I drive the truck again but what should they be. Then for tune up I changed plugs about 3 months ago and wires about 2 and the whole distributor is also 2 months old. I was also thinking it could be the fuel filter because that hasn't been ever changed but it's rusted on there really good.

 

[Drunkcanuk]

I haven't looked at fuel pressure il check when I drive the truck again but what should they be. Then for tune up I changed plugs about 3 months ago and wires about 2 and the whole distributor is also 2 months old. I was also thinking it could be the fuel filter because that hasn't been ever changed but it's rusted on there really good.

Believe it's in the 60psi range, but I'm a TBI guy.
Ummm, ya, change the damn filter!! Lol
That would be a good place to start.

 

[Shawn2131]

How is the EGR system plumbed?


What are those codes for? It's impolite to make us look them up.


WHICH "sensor"? MAF? Cam position? Something else?


Are you also getting crank position sensor code(s) you haven't listed?



Exactly right. The first things to look at are "The Usual Three".

1. Verify fuel pressure at prime, at idle, and under load. Most fuel pressure gauge assemblies have a push-button pressure release connected to crappy vinyl tubing. Route the tubing so it empties into a drain pan, then push the button while the engine is running. This simulates higher fuel demand if you can't check fuel pressure on the highway. Fuel pressure should remain steady even with fuel flowing down the pressure-relief tubing. How old is the fuel filter? Have you ever dumped a bottle of Chevron Techron Complete Fuel System Cleaner into the gas tank? (Recommended at every oil change.)
2. How old are the usual “tune-up” parts and procedures? Inspect/replace distributor cap, rotor, plug wires, spark plugs. Make sure the ignition coil will reliably fire a spark-tester calibrated for HEI when the coil is fully warm, and misted with water from a squirt-bottle. Cranking compression test of all cylinders while the spark plugs are removed. Verify EGR, PCV, EVAP, and Heated Air Intake (if used) systems for proper operation. Verify proper initial timing (TBI) and electronic spark advance (TBI and Vortec). Replace old O2 sensors unless you can PROVE that they're working properly—old O2 sensors get lazy, they don't provide accurate data, but they do provide “data” that fools people into thinking they're “working”.
3. Connect a scan tool (NOT a crappy “code reader”) and look for “codes”. More important, look at the data stream to verify EVERY sensor and computer output. Verify fuel trims during the time that the vehicle is not running properly. Look for misfire counts for each cylinder (OBD2 only.) “Codes” have official diagnostic procedures that will be found in the service manual set for your vehicle. The service manual set can be downloaded from the links in the Sticky thread section of the Engine forum on this web site.

The p0102 is Mas or volume air flow A circuit I already changed the MAF then the P0340 is camshaft position a circuit and I just changed out the entire distributor and for the crankshaft i changed just for peace of mind. And im not getting any crank position sensor codes just changed it for peace of mind. And Egr system has been blocked off the right way but i did headers awhile ago and the problem is just not coming up.