Rob95CS Posted November 21, 2003 Report Share Posted November 21, 2003 In reference to: Rough engine idle, Surging at cruise ?? So my Cat Converter was toast. I had it replaced with a Carsound converter, and the car no longer hesitates when getting on the gas from stops. Unfortunately, that's all it fixed. Here's a rundown of my symptoms that still persist: When starting the car and sitting idle, the engine will buck and shake visibly and you can feel it from within the car. The RPMs on the tach will visibly fluctuate up or down 50-100 RPMs every time the engine bucks. When given a little gas, the shaking no longer occurs once running around 1700 RPMs. From the back end of the car, I can hear an audible 'Putt putt putt putt' coming from the exhaust. (It only became AUDIBLE after I replaced the Cat Converter. Before, I could FEEL the exhaust coming out in short bursts with my hand.) When in drive and holding the brake at a stop, the car will shake and the idle again fluctuates 50-100 RPMs. Letting off the brake but not hitting the gas will result in the car lurching forward slowly, while still shaking violently. When getting on the gas to take off, the shaking is eliminated. Once at a steady cruising speed, the engine will once again begin to buck and shake. One thing I noticed is this ONLY occurs at speeds over 40 MPH. Tapping the gas or brake will stop the bucking. Here's what I've done to the car lately: Plugs and Wires replaced about 2 months ago, all still check out fine. Cleaned the terminals of the coil packs. Changed oil & filter. Replaced EGR Valve. Cleaned throttle body, TWICE. Replaced Cat Converter w/ a Carsound. I'm out of ideas! I've never seen an SES light, so I can't even get a code. Anyone have any other ideas? Would the TPS do this? Quote Link to comment Share on other sites More sharing options...
Slade901 Posted November 22, 2003 Report Share Posted November 22, 2003 You might want to clean the (IAC) IDLE AIR CONTROL VALVE and the spot where the IAC goes in with a throttle body cleaner and try to get rid of any build up in there. If possible replace the IAC. I've got similar issue with your car before. My car used to surge above 40MPH once in a while just like your car does and now I'm having a Trouble Code 42. The book states it's a Faulty Connection or Ignition Module. I think it's my Crankshaft Position sensor and another folks here suggested as well. So, I'll replace my Crankshaft Position sensor first and see if that fixes my problem and if not then I'll check on Ignition Module or Ignition coils. Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted November 22, 2003 Report Share Posted November 22, 2003 Sounds like a faulty EGR valve too Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 22, 2003 Author Report Share Posted November 22, 2003 EGR Valve was replaced already. I've also tested it and checked the gasket, all seem well. But it almost acts like it's missing, so it could be a coil going, although all check out ok. I'll clean the IAC Valve tonight. If I can't figure this out, it's going to a GM garage for a diagnostic, although I don't want to pay for it. Thank you, I will post back after I get my IAC Valve done. EDIT: You said also the Crank Position Sensor? Doesn't that control when the spark is fired? How hard is that to get to? Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 23, 2003 Author Report Share Posted November 23, 2003 So I cleaned the IAC Valve and DAMN was that ever due for a cleaning! I got a whole rag covered in black carbon deposits that came off of it. I cleaned out the passageway it was in w/ a toothbrush also and wiped it clean with a blue rag. Performed an idle relearn, and now it idles SMOOTH! Unfortunately, the shaking problem is still there! But the idle no longer fluctuates. I'm going to replace the fuel filter tomorrow. I tried getting it off tonight, but it's rusted on REALLY badly. There's no way this can be the original fuel filter from the factory in '95?! (160,000 miles ago) :shock: :shock: :shock: I also managed to make it start leaking gas by messing with it, so it's definately gotta be replaced now. Quote Link to comment Share on other sites More sharing options...
PaPaPooh Posted November 23, 2003 Report Share Posted November 23, 2003 the shaking problem might be motor mounts hear clunks going into gear? can you see the bushings in the dog bones exsseviely moving while shaking? Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 23, 2003 Author Report Share Posted November 23, 2003 the shaking problem might be motor mountshear clunks going into gear? can you see the bushings in the dog bones exsseviely moving while shaking? Never heard any noises other than the usual lifter clatter on a cold start. Couldn't hurt to check. Will tomorrow after I fix the fuel leak I created. But wouldn't that be a constant shaking anyway? When driving, mine only seems to do it when stopped at a stop sign or at a cruising speed in 4th gear w/ very little to no load on the engine. Quote Link to comment Share on other sites More sharing options...
PaPaPooh Posted November 23, 2003 Report Share Posted November 23, 2003 nope accelerating puts torque on the mounts so the shaking goes away if no clunk may not be mounts but i would check them for sure to rule that out hell it could be normal mine doesnt do it but i have a 2.8 so i cna't say it is normal good luck and let us know Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 23, 2003 Author Report Share Posted November 23, 2003 No it's definately not normal... it never used to do it. I'll check everything out tomorrow. Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 24, 2003 Author Report Share Posted November 24, 2003 I haven't checked the mounts or anything yet, mainly because I don't know where they're all at, but I'll do a search later. Here's something I just happened to notice today: At speeds below about 35, under light acceleration, I can hear a metallic rattling sound that sounds like it's coming from near the front drivers side wheel well (right about where the tranny is at) So these questions come to mind: 1) Is there a motor mount near there that could be rattling? 2) Could this be my torque converter going bad? The car does only shake at speeds above 40 MPH under light acceleration (when the TCC is locked up?) Pushing the gas past half throttle (causing a downshift) and tapping the brake will both make it stop shaking. Both of those actions cause the lockup clutch to disengage, am I correct? Does this not make sense? But would a bad torque converter ALSO cause the car to shake at idle (both while in park and while in gear with the brake held)? And would it make this metallic rattling sound? Quote Link to comment Share on other sites More sharing options...
joey b Posted November 24, 2003 Report Share Posted November 24, 2003 I was going to say the torque convertor myself. I'm not sure of symptoms of it going bad though. What you might want to do is check the resistance on your plug wires. I would also not rule out the TPS. Also, everyone is talking about their CPS going bad lately. That is not an electrical sensor. It is simply a magnet and as the crank comes near the magnet it creates a charge (simple physics, my friend). Not sure if you all knew that. At least on the DOHC, don't know about on the 3.1. Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 24, 2003 Author Report Share Posted November 24, 2003 Do you happen to know off hand what the resistance on the wires should be? I'll go buy a multimeter tonight. I know they're handy to have around. Also, how can I diagnose the TPS? Thank you all for your help. I'd be lost without this board. Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 25, 2003 Author Report Share Posted November 25, 2003 the shaking problem might be motor mountshear clunks going into gear? can you see the bushings in the dog bones exsseviely moving while shaking? Motor mounts all check out fine. No play whatsoever. It's the engine itself that's rocking front to back when it's running. I can see the oil pan and tranny pan rocking from underneath the car. The Dog-bone rubber bushings look OK. They move with the shaking of the engine, but what is considered excessive movement? I've never seen another 3100 up close. Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 26, 2003 Author Report Share Posted November 26, 2003 I'm convinced this problem is NOT a mount. I'm certain it's mechanical because the colder it is outside, the worse it shakes on a cold start. It's dependent on the temperature of the air outside. What are the symptoms of a leaking intake gasket?? Quote Link to comment Share on other sites More sharing options...
Rob95CS Posted November 28, 2003 Author Report Share Posted November 28, 2003 OMG! I'm so fucking retarded. Here's what my problem was. As you can see, the electrode area inside the spark plug is broken COMPLETELY out of the spark plug, meaning it got compressed inside a piston, right? Luckily, no problems seem to have developed from it yet. Quote Link to comment Share on other sites More sharing options...
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