RPM Surging
12-02-2011, 05:53 PM
#1
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RPM Surging
What would cause the rpm's to surge? While driving, the car surges enough to jerk the car and at idle the rpm's are erratic. I'm taking it to O'riellys tomorrow to get codes scanned and I will post later. Haven't got the car tuned yet after rebuild and cam. Car has been in shop for head gasket leak. I have true duals with no X-pipe and I have been told that this could cause some back pressure problems, is this a option for the problem? Check engine light is on.
Last edited by camz28ryan; 12-02-2011 at 05:56 PM. Reason: More info
12-02-2011, 09:07 PM
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Re: RPM Surging
Found the problem. The main ground cable was very loose, tightened it up, all is good. Finally, something was simple to fix on the car. Gotta schedule the tune. Was just going to get a idle tune done locally from a guy that has tuned it before and was thinking of getting it dyno tuned. How much difference in performance will it make to get a dyno tune. My tuner said the dyno tune is for the top end.
12-03-2011, 10:37 AM
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12-21-2011, 01:57 PM
#6
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Re: RPM Surging
Looks like I celebrated to early. The problem is back. Ran fine since last post but now it rev's while driving, it's jerking pretty bad. I'm going to get codes scanned today and hopefully that will lead me in a direction to solve the problem.
12-21-2011, 04:03 PM
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Re: RPM Surging
Driving after installing a bigger cam is just going to kill the o2s. The LT fuel corrections are certain to be bottomed or topped out and can no lo get control fueling. O2 sensors will go lazy after much driving in that condition. If there is cats on it those can get burned out also or melt and clog up.
Get a scan tool and learn to use it and check the o2 x-counts. Should cycle from 0-255 at idle hot in less than 90 seconds. If not replace them when you get a tune. A good dyno tuner will tune it for all loads thru all rpms, if they don't you are wasting your money with them. You can't run your car wot all the time it must run well at all ranges.
Get a scan tool and learn to use it and check the o2 x-counts. Should cycle from 0-255 at idle hot in less than 90 seconds. If not replace them when you get a tune. A good dyno tuner will tune it for all loads thru all rpms, if they don't you are wasting your money with them. You can't run your car wot all the time it must run well at all ranges.
12-21-2011, 11:10 PM
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Re: RPM Surging
Took it by O'riellys today code was "Po117 Engine coolant circuit low input". What does this mean and could it have anything to do with the rpm surging. Were planning to have a tune done but haven't had any luck on finding anyone around here that comes recomended. And no I do not have cats.
Also noticed the wires that goes to the knock sensor is a bare wire and only has a couple of strands of wire left on the harness. Would this cause any problems like I'm having if they get wet or not enough wires to carry the amps?
Also noticed the wires that goes to the knock sensor is a bare wire and only has a couple of strands of wire left on the harness. Would this cause any problems like I'm having if they get wet or not enough wires to carry the amps?
Last edited by camz28ryan; 12-21-2011 at 11:19 PM.
12-22-2011, 05:22 AM
#9
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Re: RPM Surging
That's telling you the coolant temp sensor in the water pump housing is not working, or the wires are shorted together. It's telling the PCM the engine is extremly hot. Use this guide:
Courtesy of Shoebox:
4th Gen LT1 F-body Tech Articles
There are not "wires" (plural) going to the knock sensor. There is a single wire. If there was a problem that resulted from the wire being faulty, shorted or broken, you would have a code (P0332) for the knock sensor circuit. Since you mention "wires" are you sure you are looking at the knock sensor - bottom of the engine next to the motor mount on the passenger side? Or is it possible the wire problem is on the coolant temp sensor?
Courtesy of Shoebox:
4th Gen LT1 F-body Tech Articles
There are not "wires" (plural) going to the knock sensor. There is a single wire. If there was a problem that resulted from the wire being faulty, shorted or broken, you would have a code (P0332) for the knock sensor circuit. Since you mention "wires" are you sure you are looking at the knock sensor - bottom of the engine next to the motor mount on the passenger side? Or is it possible the wire problem is on the coolant temp sensor?
12-22-2011, 10:15 AM
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12-22-2011, 03:56 PM
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Re: RPM Surging
Injuneer, sorry I meant one wire. Yes I was referring to the knock sensor, since it's not throwing a code like you suggested I'm assuming it's ok. There are bare wires on the knock sensor harness, if water splashes up on the bare wires could it cause problems.
As far as the coolant sensor, i have tested it and it a bad so I'm replacing it as we speak.
I called the tuner in Tulsa you referred to me, he no longer does dyno but can mail order tunes. He charges $350 bucks.
Money is tight right now and cannot get together $350 bucks. My question is; With my mods will it hurt the car to drive it without a tune. I know it's gonna run like crap but will it damage anything? The cats, have already been tuned out from previous mod but I'm not sure if we tuned out the rear 02's. Currentley the car is tuned for a hot cam. Since the last tune we have rebuilt 355, CC503, headers, match ported intake and heads, blocked off egr ports, and true dual exhaust.
Should I park the car untill tune or can I continue driving it untill I get the cash for a tune?
As far as the coolant sensor, i have tested it and it a bad so I'm replacing it as we speak.
I called the tuner in Tulsa you referred to me, he no longer does dyno but can mail order tunes. He charges $350 bucks.
Money is tight right now and cannot get together $350 bucks. My question is; With my mods will it hurt the car to drive it without a tune. I know it's gonna run like crap but will it damage anything? The cats, have already been tuned out from previous mod but I'm not sure if we tuned out the rear 02's. Currentley the car is tuned for a hot cam. Since the last tune we have rebuilt 355, CC503, headers, match ported intake and heads, blocked off egr ports, and true dual exhaust.
Should I park the car untill tune or can I continue driving it untill I get the cash for a tune?
Last edited by camz28ryan; 12-22-2011 at 04:00 PM.
12-22-2011, 08:27 PM
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Re: RPM Surging
The front o2s will be toast if you have driven it much...say a tank full of gas if its running real rich or lean..like the BLM's / LT integrators are maxxed out, but without a scan tool you won't know that. Anyone modding any EFI car really needs to have a scan tool of some sort, its a necessity with a computer controlled engine. $350 for a mail order tune is too much IMO no matter who you are, every motor will run differently so a mail order will be off...hell mine changes with the weather and wear/tear, I retune mine about every summer it seems just to get the LT integrators back in line.
But for a tune to work, every other issues needs to be fixed on the car also..no electrical problems. The bare wire will be an issue if the bare part is touching anything metalic or can get wet and indirectly touch metal, ground thru the water.
Ruin both o2s and your probably looking at about $200 unless you have converted to OBD1, then a little cheaper.
But for a tune to work, every other issues needs to be fixed on the car also..no electrical problems. The bare wire will be an issue if the bare part is touching anything metalic or can get wet and indirectly touch metal, ground thru the water.
Ruin both o2s and your probably looking at about $200 unless you have converted to OBD1, then a little cheaper.
12-23-2011, 12:40 AM
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Re: RPM Surging
Ok thanks 2quik, can you recommend a tuner? I wasn't going to mail order I was going to drive the car to tulsa, the tuner said it would be better than a mail order.
Can someone send me a link to test the 02's? Wouldn't it throw a code if the 02's were bad?? Hopefully their still good, were gonna park the car untill tuned.
Also I replaced the coolant sensor and tested the wires, they were reading ok. We unhooked the battery to erase the code but after the fix the code came back... WTF
Can someone send me a link to test the 02's? Wouldn't it throw a code if the 02's were bad?? Hopefully their still good, were gonna park the car untill tuned.
Also I replaced the coolant sensor and tested the wires, they were reading ok. We unhooked the battery to erase the code but after the fix the code came back... WTF