Hello everyone,
I have a 1998 k1500 that originally came with a 350 vortec that now has the gm replacement HT383e(has about 6,000 miles on it now and out of warranty due to time). The reason I mention both engines is because I don't remember if I had this issue with the 350 prior to getting the 383. The issue: At idle, every few seconds the engine shudders. Nothing big but enough to briefly shake the truck. Here's what's been changed and rechanged that did not fix or change the problem. This has been over the course of roughly 3 years, 3 mechanics and 1 tuner. Any help would be so appreciated as this has consumed me.
(Updated)Mpfi assembly, distributor assembly with cap and rotor, intake manifold gaskets, spark plugs, plug wires, egr valve, brake booster vacuum hose, cats deleted, heads were taken off and found some valves were not sealing correctly(not even sure how that's possible on a new engine) so that was fixed, ICM, IAC, TPS, cleaned mass air flow sensor, pcv valve, alternator, coolant temp sensor. Essentially anything that could be checked, was. I'm sure I'm leaving something out but at this point it's so far beyond my abilities. I've been on many forums looking through posts and it seems there is at least one other person that had this issue. He believed his went away after a 411 swap. One of the mechanics opened a case with GM but nothing was solved. I have inquired about the case but do not personally have the equipment to bring any new data.
Finally,
I'm not opposed to just taking it to another shop if anyone knows one in the Dallas, TX or Little Rock, AR region.
I have a 1998 k1500 that originally came with a 350 vortec that now has the gm replacement HT383e(has about 6,000 miles on it now and out of warranty due to time). The reason I mention both engines is because I don't remember if I had this issue with the 350 prior to getting the 383. The issue: At idle, every few seconds the engine shudders. Nothing big but enough to briefly shake the truck. Here's what's been changed and rechanged that did not fix or change the problem. This has been over the course of roughly 3 years, 3 mechanics and 1 tuner. Any help would be so appreciated as this has consumed me.
(Updated)Mpfi assembly, distributor assembly with cap and rotor, intake manifold gaskets, spark plugs, plug wires, egr valve, brake booster vacuum hose, cats deleted, heads were taken off and found some valves were not sealing correctly(not even sure how that's possible on a new engine) so that was fixed, ICM, IAC, TPS, cleaned mass air flow sensor, pcv valve, alternator, coolant temp sensor. Essentially anything that could be checked, was. I'm sure I'm leaving something out but at this point it's so far beyond my abilities. I've been on many forums looking through posts and it seems there is at least one other person that had this issue. He believed his went away after a 411 swap. One of the mechanics opened a case with GM but nothing was solved. I have inquired about the case but do not personally have the equipment to bring any new data.
Finally,
I'm not opposed to just taking it to another shop if anyone knows one in the Dallas, TX or Little Rock, AR region.