92 Camaro RS - rpm's surging/loping
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Car: 1992 camaro rs 25th anniversary
Engine: 3.1 V6
92 Camaro RS - rpm's surging/loping
92 Camaro RS 3.1L V6, auto trans. When I start the car, the engines rpm's goes from 1000 to 4000 erratically. I can see this on the tach. It does not stop doing that until the engine stalls or is shut off. It backfires sometimes. I put a new gasket on the intake manifold. The battery was disconnected while it was being fixed. I did take the distributor out, and put it back in. I checked the timing. To me it appears to be ok. When I put a timing light on spark plug #1, I can see the timing mark on the scale, it bounces so I am unable to set it properly. But the timing mark is within the range it is supposed to be. Which I believe means that the distributor was put in correct. The car also has a brand new TPS and vacuum lines. Please help, thanks.
#2
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Re: 92 Camaro RS - rpm's surging/loping
Sounds like a huge vacuum leak. Is the PCV hose connected? How about the brake booster?
#4
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Re: 92 Camaro RS - rpm's surging/loping
You can check vacuum at any manifold vacuum source. It won't tell us much though with the engine surging like that. Try instead to find a large leak somewhere in the intake. You can use brake cleaner, propane, or carb cleaner for this purpose. Be sure also to double check that the MAP sensor is connected properly.
Very low fuel pressure may also cause a symptom like this. Look at your injector spray pattern. It should be a pretty good cone shape. With a snap of the throttle, the cones should touch the walls of the throttle bores. If not, you may have a broken pressure regulator spring in the throttle body.
Very low fuel pressure may also cause a symptom like this. Look at your injector spray pattern. It should be a pretty good cone shape. With a snap of the throttle, the cones should touch the walls of the throttle bores. If not, you may have a broken pressure regulator spring in the throttle body.
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Car: 1992 camaro rs 25th anniversary
Engine: 3.1 V6
Re: 92 Camaro RS - rpm's surging/loping
Unable to see any difference with spraying break clean. The vacuum line that goes from the intake to the MAP sensor has a vacuum of 5. Then jumps to 20, then back to 5 and stays there. While the map sensor vacuum is off the rpm's settle. Also, if I take off the electrical connector (and put the vacuum back on the map sensor) on the map sensor, the rpm's settle. Not loping. There is backfiring through the exhaust on the passengers side. I adjusted the distributor, with not much change after removing the vacuum line or map electrical connector. The map sensor was replaced within the last 2 years.
Unable to check the injectors, as they are under the plenum.
Unable to check the injectors, as they are under the plenum.
Last edited by MI_AMOR_2010; 03-22-2012 at 10:34 PM.
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Car: 1992 camaro rs 25th anniversary
Engine: 3.1 V6
Re: 92 Camaro RS - rpm's surging/loping, still need help after 5 posts please
oops.. still need help tho
#7
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Re: 92 Camaro RS - rpm's surging/loping, still need help after 5 posts please
Try using a vacuum pump to apply 18 inches of vacuum to the MAP sensor. See if the engine stabilizes. I want to know what integrator and block learn are doing on your car. You need a scan tool to view datastream. The exhaust firing is likely due to lean misfire.
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Car: 1992 camaro rs 25th anniversary
Engine: 3.1 V6
Re: 92 Camaro RS - rpm's surging/loping
http://www.youtube.com/watch?v=eywJZHHFkLI
Here is a video of the car. I don't have a vacuum pump... how much are they?
Here is a video of the car. I don't have a vacuum pump... how much are they?
#9
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Re: 92 Camaro RS - rpm's surging/loping
A cheap one from the parts store, like MITYVAC brand, is about $35. A scan tool like the SnapOn MT2500 is available used on craigslist for about $250 These old scan tools will always hold their value so you could always sell it for what you paid if you chose to.
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Car: 1992 camaro rs 25th anniversary
Engine: 3.1 V6
Re: 92 Camaro RS - rpm's surging/loping
Are you able to look at the video? Not sure what you mean by "integrator and block learn." ECM? And I don't have a obd 1 scanner, just an obd 2.
#11
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Re: 92 Camaro RS - rpm's surging/loping
Block learn and integrator are the ECM's fuel trims block learn is long term, integrator is short term. You can watch them with a scanner. Of course an OBDII scanner wont work on an OBDI system. I have not had a chance to watch the video yet.
#12
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Re: 92 Camaro RS - rpm's surging/loping
Just watched your video. One note on the EVAP canister vacuum, it is ported vacuum on that early system so it will not have vacuum at closed throttle. I also saw a puff of smoke from somewhere just behind the throttle body when the engine backfired. I am not convinced at all that the MAP sensor is causing your problem. I really didn't see much improvement from unplugging it. I am really thinking at this point that you have a huge unmetered air(vacuum) leak. You say that you just did the intake manifold gaskets did the engine surge like this before that? You may have a leak into the crankcase. You can test for this by removing the PCV valve from the valve cover and checking for vacuum at the open hole in the cover.
#14
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Re: 92 Camaro RS - rpm's surging/loping
There ya go. That must have been the vertical puff of smoke I saw when the engine backfired. Where to find a plenum? I would start by doing a parts request on the parts forum right here on TGO. Ive had excellent success when I used the "Parts Wanted". Option. If no luck, which would surprise me, then try a google search for used auto parts.
#15
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Re: 92 Camaro RS - rpm's surging/loping
One thing that I should mention, I see cracked plenums way too often on the 3.1 and 3.4 V6s. The cause of them cracking is over-tightening, misalignment of the gasket(the little alignment tabs need to be fully seated in the holes provided for them), or failure to follow the torque sequence.
Be sure when you tighten the fasteners that you use nothing larger than a 1/4 drive ratchet. Start with the middle bolt on either side and work your way out in a circular pattern. Turn each bolt only 1/2 turn each time. After all fasteners and the gasket is fully seated, torque the fasteners to 88in/lbs using a suitable torque wrench.
Be sure when you tighten the fasteners that you use nothing larger than a 1/4 drive ratchet. Start with the middle bolt on either side and work your way out in a circular pattern. Turn each bolt only 1/2 turn each time. After all fasteners and the gasket is fully seated, torque the fasteners to 88in/lbs using a suitable torque wrench.
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Car: 92 Camaro rs ( mostly stock for now
Engine: 3.1 v6
Transmission: 700r4 with a b&m megashifter.
Axle/Gears: whatever came stock. wanna posi tho
Re: 92 Camaro RS - rpm's surging/loping
I completely broke off the mounting tab on my plenum where the throttle body bolts up to. That was over a year ago. I JB welded the hell outta it and never looked back. If it's a small crack, it can be welded.
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