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from 810 to 560 in one night. bad idle

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Old 07-12-14, 08:48 PM   #1
grumpi300
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Default from 810 to 560 in one night. bad idle

first off, i have a 92 sc300. mostly stock.
a few nights ago I was working on my ac system. changing out the receiver drier and expansion valve to fix my a/c. I also removed my heater core. well after I got done and put everything back to how it was before, I turned my car on. instead of getting that long deep-ish rumble I used to get, I got a short and quick deep rumble, then drop to a low almost nothing note from the exhaust.
now a couple weeks ago, I checked the idle with a timing light since my cluster is not accurate. the timing light showed that on idle, each cylinder was 810. which is normal.
side note, after fixing everything I drove my car for about 3 or 4 days and I haven't gotten a single check engine light.
today, I checked the idle and it was at 560 on all cylinders according to the timing light.
next, I removed one end of number 1 spark plug wire with the engine running to see if the engine harmonics changed. then put the wire back. then number 2, then 3 etc. I did this to see if one cylinder was not contributing as much as the others, and I found number six reacted slightly less than the rest. it still reacted, just not as much. i'm about to do a compression check and see if all the cylinders are within specs. i'm also planning on buying spark plugs since I haven't changed them ever. they look pretty bad and rusted so i'm hoping that this fixes the issue. but if it doesn't, what else should I check for?
when I removed the heater core, the whole steering column had to be removed. basically everything from the seats forward. I left the ecu intact. the only wires I really had to disconnect are the power steering ecu, and the climate control. other than those, no wires had been messed with inside. is there anything inside besides the engine ecu that can cause this?
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Old 07-12-14, 09:34 PM   #2
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well compression test came out horrible. really horrible.
#1 - 142
#2 - 140
#3 - 120
#4 - 80
#5 - 100
#6 - 105
seems like I need a new engine. I guess this might be why my fuel consumption was horrid. I would fill up every 3 or 4 days.
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Old 07-14-14, 09:20 AM   #3
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leak down test determined I have a bad intake valve. so I feel I should take the head gasket off, rebuild the head, put a tt head gasket and some arp head studs. call it a day. what do you guys think?
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Old 07-14-14, 10:10 AM   #4
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Originally Posted by grumpi300 View Post
leak down test determined I have a bad intake valve. so I feel I should take the head gasket off, rebuild the head, put a tt head gasket and some arp head studs. call it a day. what do you guys think?
Sounds like a good time to build it for NA-T.....If you are doing the work yourself it wont be that much $$$....but if you have high mileage on your motor may be time to consider a swap
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Old 07-14-14, 08:56 PM   #5
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I want to go swap. I have 234 on the engine all original. from when I got the car it seems like nothing has been changed. I changed the fuel filter when I got it, it was still from Toyota. that was at 225k miles.
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Old 07-14-14, 08:59 PM   #6
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i think for now i'm gonna put it back together. drive it wherever i need but nothing extra. baby it the whole time. save up to fix my exhaust leak. then save up for a r154 swap since my fuel milage is crap. also i don't want to go 2jzgte swap without having a manual. an automatic gte sounds like a buzz kill.
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Old 07-15-14, 08:39 PM   #7
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well this is funky. i got my idle back to normal. i found out that i had accidentally tore a idle air control valve wire from the connector. so i soldered it back together and now my idle is completely normal. back to 810. so happy i got it running like normal again.
but at least now that i know i have bad cylinders, i'm gonna stick to driving it like a grandma to not condone anymore cylinder failures. save up for a gte engine.
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Old 07-15-14, 08:40 PM   #8
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feel free to close thread
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Old 07-15-14, 08:40 PM
 
 
 
 
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