https://ls1tech.com/forums/16315948-post63.html
hoping some graph savvy people can tell me if this is all ok or if theres a problem

 

I'm not sure what those 02 readings are even saying....but I would get it scanned with an OBDII....see how the 02 sensors are switching with the engine idling.

Its just about the biggest culprit with our cars to KILL gas mileage. I've seen many guys with a bad sensor thats just in the failing stages (AND NO CODE WILL POP) and they get around 150 miles per tank.

Bad MAF won't effect gas mileage. I had mine unplugged for two years and had zero change in mileage, power idle, nothing changed. MAF's are unnecessary, at least in my car....lol.

Other than that:
Leaky fuel injector(s).....but you will usually have a misfire at idle or low rpms.

Fuel leak somewhere....easy to find.

.

 

Oh, also in the 1998's....a failing coolant temp sensor will cause the engine to run like amazing ****. My engine literally will not run for more than 5-10 seconds with a bad one. Thats why I carry a spare with me....lol A failed one is enough to get me stuck in the boonies.

Not sure about the 2001 PCM's........

.

 

i pulled all that data with my obd2 scanner. no codes. new o2s less than 1k on both. (could be a dud) the scanned showed them switching but im not sure what proper switching looks like.

i have a 98 ls1 in my car. i dont have a misfire. there is a slight stumble at idle every now and then. seafoam cause it to not be as noticeable.

 

Might have a leaky injector if you have a stumble at idle. Put a pressure tester on it, prime it, see how fast the pressure falls off.

I put new 02 sensors in in January. Brand new Densos. One was a complete dud.

.

 

I could had a dud as mine have less than 1k. As for leaky Injectors, I have a very small stumble at idle only in drive. Even then it happens every now and then.

 

Could be the leaky injector.

Also, make sure none of the spark plug wires are touching any part of the metal exhaust manifolds.....that will cause misfires at all different rpms. But at idle it'll happen almost always.

.

 

Ok I'll check that here in a bit.

 

No plug wires touching headers

 

the o2's should be a drastic change at idle...

something like say 80-100 milliamps to 600+ milliamps.. then back down...

 

So there's nothing out of place in the graphs? Why does the o2 output just stay flat?