Cats plugged up?

[White96k2500]

The wiring to the starter is the problem for the starting issue, that doesn't mean the cats are good though. You can do what SAATR recommended, he's absolutely correct, but the easier route is one of the following.

A: with an infrared thermometer check the inlet and outlet temperature of the catalytic converter. Outlet temperature should be higher than the inlet by 20* or more (higher is better in this case with how old the truck is).

B: less scientific, but more fun. Unscrew the O2 sensor(s) and see if your idle improves. Maybe take it for a test drive and see if your throttle response improves as well. You can also get a good indication of how your cats look by seeing if your O2 sensor is fouled up. Make sure you unplug the O2 sensor as well or you'll end up in closed loop with sensor telling the engine you're running way lean and up running rich with the ECM trying to compensate.

C: run a scanner and look at your upstream and downstream O2 sensor readings. IIRC under 80% pops a code, but anywhere south of 90% will give you noticeable symptoms.

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Thank you for all of the info! I do have a question though, how would unplugging the 02 sensors make a difference?

 

[b454rat]

It would have to be running like **** for a long time to plug up the cats. I had a Tahoe with 257k on the original cats. EGR can make it idle like crap too, maybe pull it and clean or try a new one. Misfire could be cap/rotor, plugs, injectors.

 

[RawbDidIt]

Thank you for all of the info! I do have a question though, how would unplugging the 02 sensors make a difference?

An exhaust leak upstream of the cat will bypass the cat. If the cat is plugged, the hole will isolate the downstream exhaust. If it's a problem, performance will increase.

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[RawbDidIt]

Just the upstream ones, downstream will do nothing for that test

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[White96k2500]

It would have to be running like **** for a long time to plug up the cats. I had a Tahoe with 257k on the original cats. EGR can make it idle like crap too, maybe pull it and clean or try a new one. Misfire could be cap/rotor, plugs, injectors.

Im over 310k, the injectors would be my guess as everything else is brand new. Wouldn’t the EGR throw a code?

An exhaust leak upstream of the cat will bypass the cat. If the cat is plugged, the hole will isolate the downstream exhaust. If it's a problem, performance will increase.

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That makes sense, im gonna have to park it for a couple days while i work and ill Start messing with it this week. Thank you for the info and tips.

 

[RawbDidIt]

EGR may their a code, may not. Depends how it fails. If the diaphragm fails I believe it causes issues with no EGR code, instead it will present a vacuum leak IIRC. Injectors are usually pretty easy to diagnose by reading the plugs. And confirming no vacuum leaks.

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[White96k2500]

EGR may their a code, may not. Depends how it fails. If the diaphragm fails I believe it causes issues with no EGR code, instead it will present a vacuum leak IIRC. Injectors are usually pretty easy to diagnose by reading the plugs. And confirming no vacuum leaks.

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You know I’ve been getting a p0507 code for a while. It stayed off for a good 6 months, then came maybe 2-3 weeks ago and i cleared it and it hasn’t came back yet. Could that have something to do with the EGR? It said IAC revolutions per minute higher than expected.

 

[RawbDidIt]

P0507 tends to present with a vacuum leak, have you done a vacuum test? If you can't find it in the usual spots, it may be the EGR valve

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[Hipster]

Just toss this out. I thought most of these trucks call for a group 78 750-800cca battery and we're working with 426 of 600cca sized battery. Using roundish numbers the 600 @426 is down almost 30% but almost 50% down from 800 and what should be there. ?? This is a red flag for me. It's also really hard on starters and alternators if the cranking amps /load capacity are not where they should be and has no relation to 12.6v across the posts. below 12v the ignition and injection has trouble getting going.

 

[White96k2500]

P0507 tends to present with a vacuum leak, have you done a vacuum test? If you can't find it in the usual spots, it may be the EGR valve

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How can you do a vacuum leak test?

Just toss this out. I thought most of these trucks call for a group 78 750-800cca battery and we're working with 426 of 600cca sized battery. Using roundish numbers the 600 @426 is down almost 30% but almost 50% down from 800 and what should be there. ?? This is a red flag for me. It's also really hard on starters and alternators if the cranking amps /load capacity are not where they should be and has no relation to 12.6v across the posts. below 12v the ignition and injection has trouble getting going.

Mhm I didn’t know it was supposed to have 800 cca. What would be the best battery to get? A lot of people seem to think the everstart max is pretty good.