RPM and MPH gauges jumping around!! wtf?
08-20-2009, 09:52 AM
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RPM and MPH gauges jumping around!! wtf? So this morning as i was driving to work i realized my guages for the MPH and RPM were bouncing around. they were not accurate when i was driving and when i was at a red light it would hold onto 20 mph for a bit then calm down. the RPM would also be normal after sitting at the light for a sec. non of my other gauges were acting up and the car drove fine? any ideas of what it could be? 
dang i fix one problem only to find another
dang i fix one problem only to find another 
08-20-2009, 12:30 PM
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battery is fully charged and has not given me any problems. i replaced the alternator about 10k miles ago, not like that says much though_gm's charging system isn't really top notch but better that than a crappy motor lol.
im going to reset my computer...i have been told that my computer doesnt respond when plugged up to the obd2. Fastchip reprogramed it a few years ago. well lets see what happens. if it was the alternator shouldnt the gage reflect some kind of resistance?
im going to reset my computer...i have been told that my computer doesnt respond when plugged up to the obd2. Fastchip reprogramed it a few years ago. well lets see what happens. if it was the alternator shouldnt the gage reflect some kind of resistance?
08-20-2009, 09:29 PM
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I was thinking possible voltage spikes, you could disconnect the serpantine belt and drive it on battery voltage only, see if it makes a difference. That would confirm or rule out a bad alternator. A bad ground can cause high output voltage as well. You could check the negative ground at the right engine mount.
08-21-2009, 12:19 AM
#6
Mine did the same exact thing with a bad(loose) ground at the battery. Cruising along at maybe 10mph the gauges were going wild, from 0-40mph and all sorts of rpms on the tach.
08-21-2009, 07:13 AM
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Okay ill try the grounds, i know a year and a half ago i replaced the cables running off from the battery. both neg and pos. its weird it doesn't like when i down throttle or hold a certain rpm. the rpm can say 6,000 rpm when im only at 2,000 sometimes. mph varies by 30 mph usually. i woont be able to look into it hardcore till sat. i need to drive like 200 miles sat. so it needs to shape up because if it leaves me stranded again im buying a honda.....JK lol i would never buy a honda!!
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08-21-2009, 07:25 AM
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Mine did that once and it turned out to be the Opti?? Go figure. I would come to a stop and my tach and mph would be bouncing around, later that week it started to run like crap and it finally threw the resolutions codes. Replaced the opti and all was fine....Weird or coincidence...
08-21-2009, 02:53 PM
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if that is the problem i would be a bit upset as i replaced that about 20k ago...not cheap and not fun to put in. i mean i had to take everything off. i unplugged my battery terminals and left them off for a bit and it didn't seem to do it. so well see if it acts up again. tomorrow i can check my grounds and make sure there is no corrosion and that they are snug. i have an oil leak and it seems to leak right above my optispark that i have been meaning to fix. it doesn't leak much maybe half a quart over 4,000 miles. it might play a part in this?
08-21-2009, 03:05 PM
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if that is the problem i would be a bit upset as i replaced that about 20k ago...not cheap and not fun to put in. i mean i had to take everything off. i unplugged my battery terminals and left them off for a bit and it didn't seem to do it. so well see if it acts up again. tomorrow i can check my grounds and make sure there is no corrosion and that they are snug. i have an oil leak and it seems to leak right above my optispark that i have been meaning to fix. it doesn't leak much maybe half a quart over 4,000 miles. it might play a part in this?
After replacing my opti, I popped open the old one just for the fun of it and took the distributor to little bits, and it was soaked in oil. The whole optical sensor was brown and sludgy.
Did you not install new seals with the new opti? May I suggest a complete timing cover gasket replacement to keep your new opti safe
08-22-2009, 07:36 AM
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I pretty sure that i did do the timing cover gasket as i remeber seeing my timing chain. i always wanted to see what it looked like (weird like that). is there a water pump bearing or seal. i think it is coming from above the timing cover. little bit of squeaking but not sure if its the ac compressor that took a dump or the tensioner. i know i have a lot of problems with this car but as long as it make it back and forth to work i'm cool with the other crap as i am still trying to finish my bravada engine replacement. to top it off i was suppose to be at my shop alone so i could work on it and get paid but my office manager came in_damn it! looks like i have to wait untill she leaves.
