LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Problems after GM847 install

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Old Aug 8, 2008 | 07:15 PM
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Default Problems after GM847 install

So the car has been running fine since the install was finished last week, but last night i opened her up a little bit and the car didn't want to hold idle afterwards. So i kept the revs up to get it home. Today i cranked the car up to see if it still was acting up and it ran fine. So i pulled it in the garage and checked all the fluids, looked for leaks, and found no problems. So i went to drive the car around the block and it did fine until i began to bring it back. It would struggle to hold idle if i had my manual fan switch on high so i turned off the manual override and it would idle fine. So i pulled it in my driveway then let it idle and it held fine with the fan off but the oil pressure was low enough to make the "check guages" light come on. So i shut the car off. Then after a few minutes tried to restart it to see if the pressure was back up. The car turned over very slowly like the battery was almost dead or like something was in a bind, but i finally restarted it by giving it a little throttle while turning it over. Still had low oil pressure at idle and the light came on again.

im at a loss the car runs great when off idle all the problems happen when its sitting at idle.

all thoughts and opinions are appreciated

Last edited by MadMike 97 Z28; Aug 9, 2008 at 12:13 PM.
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Old Aug 8, 2008 | 10:55 PM
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is the engine knocking when its running? What's Batt voltage when the car is at idle? Is the car tuned?
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Old Aug 8, 2008 | 11:45 PM
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No knocking, but im not sure about the battery volts exactly but i believe it was slightly on the high side i think the battery is on its last string. that still wouldn't explain the low oil pressure.
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Old Aug 9, 2008 | 12:48 AM
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When batt voltage gets low the gauges go crazy. My alternator broke and i had to drive the car you should have seen all the weird **** going on in my dash. It could be the engine starting to spin a bearing also. My oil pressure got lower and lower untill it read 0 check gauges came on car started knocking. The next morning i could start it and have 40 psi oil pressure at idle with no knock but if i bliped the throttle it would knock.
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Old Aug 9, 2008 | 01:14 AM
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ya i have seen the guages go nuts in my moms car when the batt was dead but i don't really have anything crazy going on it the camaro it just seems to get low oil pressure once its warmed up but other than the guage and the light it idles fine with the fan off.

I hope to god its not a bearing going ill be PISSED!!!

also to answer one of your questions the car is tuned its a mail order by Madz28

Last edited by MadMike 97 Z28; Aug 9, 2008 at 01:19 AM.
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Old Aug 9, 2008 | 08:47 AM
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Did you wire up the switch or did you buy the slp one. cause if you wired it up then did you make sure you put a diode in place of were the B+ hooks into the wire going from the pcm to the fan. If not that could explain the idle issue because now your back feeding 12 volts into the pcm when its not commanding it every time you run that fan.
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Old Aug 9, 2008 | 11:07 AM
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Originally Posted by Jditlfm
Did you wire up the switch or did you buy the slp one. cause if you wired it up then did you make sure you put a diode in place of were the B+ hooks into the wire going from the pcm to the fan. If not that could explain the idle issue because now your back feeding 12 volts into the pcm when its not commanding it every time you run that fan.
no its the slp one.
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Old Aug 9, 2008 | 11:13 AM
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I noticed you said you opened her up a little bit. How many rpms did you take your motor to? Also how many miles are on your motor? I did a cam install last february and had 100k on the engine. It lasted for 2 days before a rod bearing went.... leaving me with barely any oil pressure and check engine lights, my car also wouldnt hold an idle without dying. All this happened after I banged through the gears a little bit one night. It could be something else but it doesnt sound good.
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Old Aug 9, 2008 | 11:59 AM
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Originally Posted by LT1forever
I noticed you said you opened her up a little bit. How many rpms did you take your motor to? Also how many miles are on your motor? I did a cam install last february and had 100k on the engine. It lasted for 2 days before a rod bearing went.... leaving me with barely any oil pressure and check engine lights, my car also wouldnt hold an idle without dying. All this happened after I banged through the gears a little bit one night. It could be something else but it doesnt sound good.
maybe 4500 or 5000 and a i didn't shift hard i just let it wind out a little. and i have 113k on the engine.

if it was bearings wouldn't it make noise?
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Old Aug 9, 2008 | 12:49 PM
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Originally Posted by MadMike 97 Z28
maybe 4500 or 5000 and a i didn't shift hard i just let it wind out a little. and i have 113k on the engine.

if it was bearings wouldn't it make noise?
It would, but it would be a small noise or a big noise depending on how bad the bearing is.
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Old Aug 9, 2008 | 12:51 PM
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it could be many things..did you check oil for any metal shavings/
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Old Aug 9, 2008 | 12:59 PM
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Originally Posted by ******
it could be many things..did you check oil for any metal shavings/
yes i did and i think there is a little but im not 100% sure

is there anything else that i could fix that would cause these same symptoms?

Last edited by MadMike 97 Z28; Aug 9, 2008 at 01:12 PM.
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Old Aug 9, 2008 | 02:20 PM
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just started the car up to see how if it has gotten worse.

ignore the rpm gauge saying 1100 it is off by 200 rpms i have verified this with a scan tool.





this is the lowest i could get the oil pressure to go i had the car all the way warmed up then turned the fan on high to bring the temp back to 180 and it went to about 15 but i didn't drive the car just let it idle in the garage.

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Old Aug 9, 2008 | 04:18 PM
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Mine started getting doggy and died 3 times before I could get it home. If its a bearing it will progressively get worse in a hurry. It might seem like you have ok power now but if you put your foot in it again you will spin the bearing even more and probably put a groove in the block. I'm just stating your worst possible scenario. I honestly didnt hear anything out of the ordinary when my bearing spun, I just noticed I had way too low of oil pressure. I'd just get your car checked out to be safe.
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Old Aug 9, 2008 | 10:03 PM
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Originally Posted by LT1forever
Mine started getting doggy and died 3 times before I could get it home. If its a bearing it will progressively get worse in a hurry. It might seem like you have ok power now but if you put your foot in it again you will spin the bearing even more and probably put a groove in the block. I'm just stating your worst possible scenario. I honestly didnt hear anything out of the ordinary when my bearing spun, I just noticed I had way too low of oil pressure. I'd just get your car checked out to be safe.
im thinking that i have a problem with either the pump or the bearings the only thing is i would hate to replace the pump and find out it was the bearings but if i don't have to i don't want to do the bearings.
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Old Aug 11, 2008 | 06:56 AM
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Put a mech gauge on there just in case. I dont trust sensors.
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Old Aug 11, 2008 | 12:35 PM
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im not worried about the pressure anymore i found metal in the oil so its coming out of the car for new bearings and probably a new pump.
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Old Aug 11, 2008 | 04:08 PM
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wow that sucks you were in the same boat i was. Well actually i still am in the boat. LOL
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Old Aug 11, 2008 | 05:35 PM
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my oil pressure is low at at a idle too, but my motor was rebuilt like 4 weeks ago...
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Old Aug 11, 2008 | 06:14 PM
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Originally Posted by MadMike 97 Z28
im not worried about the pressure anymore i found metal in the oil so its coming out of the car for new bearings and probably a new pump.
Eh dont worry, there are alot of other LT1 owners who have spun a bearing at one time or another. It just gave me an exscuse to get a 383!
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