Misfire and rough running 98 k2500 5.7

[jaxcob]

I’ve been having almost the same exact problem with my 98 k2500 5.7. Started out as a miss just at idle and slowly got to a very bad miss all the time and spits and sputters when you try to speed up. Just did the MPFI a couple months ago and ran awesome. I just put a new distributor in with no change. Have 58 psi of fuel pressure with engine off and 52 psi with it on. Cleaned the MAF too with no change. No codes at all either. What would be the next thing to check?

Check the reading on the maf. Mine wasn't shot but was original and slow to react. Check for which cylinders are misfiring, see if there's any codes being thrown, watch your pids on torque pro or a scanner. Just because the ses light isn't on doesn't mean codes aren't being thrown. Check your sparkplug wires and sparkplugs, I chased my tail on a Dakota for 3 days and it turned out to be just sparkplug wires.

 

[stutaeng]

I’ve been having almost the same exact problem with my 98 k2500 5.7. Started out as a miss just at idle and slowly got to a very bad miss all the time and spits and sputters when you try to speed up. Just did the MPFI a couple months ago and ran awesome. I just put a new distributor in with no change. Have 58 psi of fuel pressure with engine off and 52 psi with it on. Cleaned the MAF too with no change. No codes at all either. What would be the next thing to check?

Maybe start a new thread? Unfortunately, seems like misfires are not uncommon on these engines and intermittent misfires are challenging to diagnose. It could be many things. A scanner with live data is going to be your best tool (along with some basic diagnosis knowledge) on finding the problem, especially if you don't have any codes. Also, always cover your basics and never trust new parts.

With the information you provided, I'd probably rule out fuel delivery problems, after making sure your fuel pressure is maintained while driving around (under load when the problem happens.)

 

[75lemans]

Will check MAF reading. Checked for codes with a scanner and nothing came up. Plug wires are new accel ones. Will check fp while driving. I’ll start a new thread next time. Thanks!

 

[jaxcob]

Will check MAF reading. Checked for codes with a scanner and nothing came up. Plug wires are new accel ones. Will check fp while driving. I’ll start a new thread next time. Thanks!

Best of luck!! Sometimes its things we don't think about in a chain reaction but usually its something nearby or something on what we've recently done.