1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

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Tim Martin
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Re: 1998 Chev K2500 - 7.4L Miss Under Load

Post by Tim Martin »

protraxrptr17 wrote:Exact same symptoms as before the valve job. No better,no worse. We will see. I'm doing the job right now. These rockers are not like the old style. These have shoulder bolts. No adjustment. It's all done at the lifter.
I agree with you on the rocker adjustment for the 7.4L engine.

Am really curious if lifter replacement fixed this motor issue.
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Re: 1998 Chev K2500 - 7.4L Miss Under Load

Post by protraxrptr17 »

Fixed!!!!!! Praise God!!!
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steven kiser
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by steven kiser »

glad it's fixed. what solved it................
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by protraxrptr17 »

Lifters.
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by brother bubba »

'scuse me for butting in, but I found this ordeal rather interesting to follow. The bottom line appears to be a lifter pumping up, but I'm still kind of curious about the scope trace that was posted earlier in the thread. That trace looked to me like it had a floating ground. Did you happen to capture a trace after the repair ?
Measure it with a micrometer, mark it with a piece of chalk, cut it with an axe. Sand it to fit.
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by mopwrforme »

your not butting in this is a community effort all comments or questions are welcome. and welcome to the forum glad to have you 8) 8) 8)
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by protraxrptr17 »

No I didn't. It ran good so I shipped it. Never been so glad to see a vehicle gone from my shop. Please elaborate. I want to learn as much as I can about these secondary patterns.
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by steven kiser »

i'm also wondering if a ground issue was resolved during the lifter replacement..............................
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by brother bubba »

ok let me see if I can do this .....
PARADE.JPG
PARADE.JPG (42.05 KiB) Viewed 4848 times
close enough I guess. This is what I would have expected to see as a scope trace on ths vehicle. Schematic shows this as a distributor engine so this is how a normal parade trace would look. Notice the fifth cylinder trace. Low firing voltage,ragged burn time, no distinct cut off, no coil ring. Firing order 18436572 this would be cylinder #6. Keep in mind that at 600 RPM, this trace repeats five times a second. At 3000 Rpm, 25 times per second. sometimes you gotta look through several traces to find an intermittent misfire. The image that you uploaded showed either a bad ground reference on the scope *OR* a bad ground in the ignition. Needless to say, the image you uploaded was not a viable reference. Thats why I was curious to see the "after" shot. If in the course of replacing the lifters you inadvertently fixed a bad ground in the ignition, you still wind up with problem fixed, but was it really the lifters ???
Measure it with a micrometer, mark it with a piece of chalk, cut it with an axe. Sand it to fit.
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by protraxrptr17 »

I can say with absolute confidence that there was no ground issue before or after lifter replacement. I dont see how a bad ground could only affect one cylinder in a distributor ignition. Not saying you are wrong, just dont see how.
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Re: 1998 Chev K2500 - 7.4L Miss Under Load FIXED!!!!

Post by protraxrptr17 »

The screenshot you posted is much different than mine. I would be more concerned with number 6 than 5.
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