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Check Engine - Low Compression

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Old 01-12-2022, 02:09 PM
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Default Check Engine - Low Compression

I had an issue before Thanksgiving. Check engine light flashing. Had code pulled and misfire in cylinder 1. So I changed plugs, wires, and coil.

seemed to work great. Light went away. Took a 12 hour trip over Christmas with no issues.

Fast forward to this past weekend. Light came back on and flashing. Went down the road and light went off and vehicle started running fine again.

next day, cranked Jeep in garage. Light back on, flashing, and running horribly.

why would light come on, go off, and then come back on if there was simply a seal broken or something else inside the cylinder? Seems it would be constant and light wouldn’t go away if seal or spring was broke.

it’s at a dealership now and I fear they are going to start throwing expensive parts at it to try and find the issue.

really stinks seeing Jeep just went over 100k miles and now I’m having issues. I baby this thing and now this. All I see is dollar signs!!!

any thoughts?

Last edited by RMucho; 01-12-2022 at 03:00 PM.
Old 01-12-2022, 06:17 PM
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I agree with the dealer bit about throwing parts at it. Many decades ago a workmate had a 86 Z28 Camaro that gave trouble. Went back the day after it was repaired and had asked for all the components they replaced to be given back to him. His bill was $2200 way back then. They replaced ECU, a module and some sensors. He went home and started plugging all the old stuff back in until he hit the problem child which was an $80 sensor. Long story short the dealer refunded all but the sensor cost and time to replace and told him to keep the new items that he did not have to pay for. Food for thought for those that still go to the dealers.
Old 01-13-2022, 04:26 AM
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Typically if the compression goes low it stays low. If you have low compression in a cylinder that needs to be resolved first.
Old 01-13-2022, 05:15 AM
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Could be cyl head. Check fluids for contamination. Once it heats up air could seal and expand some areas. I got to 100k and had tons of problems. Replaced heads,coils, plugs, gaskets, injectors, oil cooler, and then full wiring harness. Turned out to need new pcm. Got rid of it after that. Welcome to Chrysler ownership.
my saga is here nomadsjku.blogspot.com
Old 01-18-2022, 07:12 PM
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Default Found it ** broken valve spring **

Found it to be a broken valve spring.
All fixed and back on the road!! OIIIIIIIO
Old 01-19-2022, 05:22 AM
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Great to hear!
Old 03-01-2023, 09:54 AM
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Default I have same issue

Originally Posted by RMucho;[url=tel:4390204
4390204[/url]]Found it to be a broken valve spring.
All fixed and back on the road!! OIIIIIIIO

mind if i ask how much they charged you? I have the same problem! I replaced the rocker arms and lifters and put everything back together. I got a misfire and replaced coils spark plugs did some electrical work for on the connectors that had the red tab (secondary lock) for the coil pack (2x) that broke off. And had a leakdown test(came back good) but a 105 compression test on cylinder 2 while the rest were at 150ish. I have the same symptoms as yours. Misfires at cold start but goes away once it warms up. Drives fine after.



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