93 Brougham still has problems
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5.0 and 5.7 Discussion, 93 Brougham still has problems in Cadillac Engine Technical Discussion; Ok so this car now has New plugs Wires Cap Rotor Air filter Breather filter O2 Sensor Air Inlet Temp ...
  1. #1
    codewize's Avatar
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    93 Brougham still has problems

    Ok so this car now has

    New plugs
    Wires
    Cap
    Rotor
    Air filter
    Breather filter
    O2 Sensor
    Air Inlet Temp Sensor
    Set timing

    And here's the result. Immediately after the work the car seemed to run great. Now a few weeks down the road I have similar symptoms of

    the car feeling like it doesn't have enough power when climbing even the smallest incline.

    The car shifts hard.

    Small hesitation off idle.

    And the O2 Sensor 00-44 Left oxygen sensor under voltages (closed loop operation) code is back

    What would cause this? What should I be looking at? Cat? Vacuum leak?

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    N0DIH's Avatar
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    Re: 93 Brougham still has problems

    All of a sudden change or gradual?

    Low O2 in Left Side? That is lean condition. Do you have a bad valve or a mis adjusted valve? How is idle quality? Any pinging? Does car run good when cold and bad when hot (>3.5 minutes from cold start) Was timing set properly? If not, it will be severly reduced. Does it start easy cold? Does it start easy hot?

    An electrical issue (High Voltage) will be a rich condition, as it will be leaving unburned fuel. A bad Cat (plugged) will cause rich condition. O2 will see it "rich" and lean it out. Is there 2 O2's? But not trigger a faults. You have a fault, that means that the cross counts were not high enough and the voltage was below 0.45v for too long. Doesn't mean the O2 is bad, it rarely ever does. I mean very rarely.

    Is it shifting hard due to higher throttle application? You have a 4L60 non E right? So you have a TV cable. This is used to determine throttle application, so if it is shifting hard it is likely more application of throttle, so the trans thinks you are stepping on it. But with lower power out, the trans feels hard.

    I am starting to wonder if you are chasing a valve leak around, likely an exhaust valve, as you aren't seeing rich mixutures coming from the intake valve. The high exhaust pressures from the other cyls may be pushing up burn gasses up the valve and diluting the cyl. And under compression, the fuel in there would leak out. (which would screw up O2 also, making it look rich, but the ECM will lean out any rich condition)

    I would do a compression test at this point, and maybe a leakdown if you can. Note on the compression test how long it takes to bleed down. Do the bank of cyls that the O2 is on. Both is ideal, as it is good comparisson data. Take a good close look at the plugs, are any different looking? They should all be nearly identical.

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    Re: 93 Brougham still has problems

    All of a sudden change or gradual?

    The degradation of performance since the tune up was gradual.

    Low O2 in Left Side? That is lean condition. Do you have a bad valve or a mis adjusted valve?

    Unknown

    How is idle quality? Any pinging?

    Idle is good. I wouldn't say it's rough. Idles about 600 RPM's but drops to 500 every 5 or 6 seconds then comes back. No pinging, no strange noises at all.

    Does car run good when cold and bad when hot (>3.5 minutes from cold start) Was timing set properly? If not, it will be severely reduced. Does it start easy cold? Does it start easy hot?

    Symptoms are less noticeable when during the first 3 - 5 minutes of operation. Car starts fine in cold and hot. Timing was set per AllData procedure and double checked.

    An electrical issue (High Voltage) will be a rich condition, as it will be leaving unburned fuel. A bad Cat (plugged) will cause rich condition. O2 will see it "rich" and lean it out. Is there 2 O2's? But not trigger a faults.

    OK are you saying that the Cat could cause a lean reading? No you're saying that the O2 would throw a rich code if anything? As far as I can tell there is only one O2 sensor.

    You have a fault, that means that the cross counts were not high enough and the voltage was below 0.45v for too long. Doesn't mean the O2 is bad, it rarely ever does. I mean very rarely.

    Is it shifting hard due to higher throttle application? You have a 4L60 non E right? So you have a TV cable. This is used to determine throttle application, so if it is shifting hard it is likely more application of throttle, so the trans thinks you are stepping on it. But with lower power out, the trans feels hard.

    4L60? I don't know. It's the LO5 engine. That's exactly what it feels like. Trans thinks your on it but with less power than expected.

    I am starting to wonder if you are chasing a valve leak around, likely an exhaust valve, as you aren't seeing rich mixtures coming from the intake valve. The high exhaust pressures from the other cyls may be pushing up burn gasses up the valve and diluting the cyl. And under compression, the fuel in there would leak out. (which would screw up O2 also, making it look rich, but the ECM will lean out any rich condition)

    OK.

    I would do a compression test at this point, and maybe a leakdown if you can. Note on the compression test how long it takes to bleed down. Do the bank of cyls that the O2 is on. Both is ideal, as it is good comparisson data.

    I'll try to do this as soon as I can.

    Take a good close look at the plugs, are any different looking? They should all be nearly identical.
    Plugs all looked the same when I took the old ones out. In addition I would like to add that from a closed throttle position there is a sort of dead spot. Many times from idle the first little bit of throttle is dead then all of a sudden it jumps like you're jerking the throttle the the current position. This is noticeable even when driving. If I'm driving 55 or so and let off the throttle the car sort of jerks almost as if the closed position were to low. Could a bad or mis adjusted TPS cause this.

    I'm certainly not ruling anything out but it seems more like a fuel / timing / ignition problem then mechanical. I should also add that the cap and rotor I pulled off were only a year old and were both severely burned.

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    Re: 93 Brougham still has problems

    ..

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    Re: 93 Brougham still has problems

    Sorry, I missed your reply....

    Silly question, any idea if the injectors are good?

    Take a timing light and shine it at the spray (be careful!! this is gasoline spraying! And timing lights are a 10-20KV sparked strobe light!) and see if it is uniform and both sides are even.

    The plugged up cat will cause it to appear to run rich, but with the computer, it will see it and start leaning it out, if it can't lean it enough, i.e., still not enough O2, it will finally declare a fault and say it can't do it.

    I would try this to try to rule out the Cat. As the Cat is in the way all the time and doens't matter if it is in open or closed loop, try this. Short the coolant sensor leads. Paper clip and some electrical tape is fine. The ECM will see this as a fault and force open loop. Then drive. Does it run better? Like close to normal?

    This isn't saying the coolant sensor is bad or good, just forces the ECM into a mode.

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    Re: 93 Brougham still has problems

    Some possible help here too:

    http://corvettefever.com/techarticles/4688/

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    Re: 93 Brougham still has problems

    Taking some time to look into these things. Used a bottle of fuel system cleaner. Anyone have a brand that works or that they like?

    Today while idling it threw the O2 code for lean again. Actually wait a second. It was code 45 which is rich not lean. Hmmmm

    Been very busy and haven't had time to do the timing light trick.

    Will keep you posted. Thanks for the help so far.

  9. #8
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    Re: 93 Brougham still has problems

    I think the only stuff I have been partial too is from Chemtool. It is in a plain can with red white and blue colors. Need to be 18 or older in a lot of states to buy it. It is pretty potent. I tend to run it in high concentration, like 2 cans in a half tank. I don't honestly know if there is any benefit or not, the old NAPA counter guy recommended it. Wonderful advice eh? But then again, in the last 500K miles on all the cars I have had, I have never had a plugged injector. But with Multec injectors, it is hard to plug them.

  10. #9
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    Re: 93 Brougham still has problems

    Ok so I looked at the spray pattern with the timing light. Although I wouldn't say they're like new they seem ok. No real globbing or sideways spraying. The spray is fanned out pretty well.

    While I was tinkering around I started looking at other things. I noticed thet when I pull the plug off of the IAC, it has no affect on the idle. No codes no nothing. At this point the car does idle kind of rough and the idle goes up and down as I mentioned before.

    Could the IAC be at fault?

  11. #10
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    Re: 93 Brougham still has problems

    No, the IAC once idle speed is stable, doesn't change much at all. Once the engine is warm, chances are it is at minimum anyway.

    I am running out of ideas other than compression or leak down.

    Has anyone messed with minimum air? Being it idles around right speed probably not. The throttle body should be just closed, not sticking, with no air passing through the blades at idle (so IAC can control it properly).

    EGR isn't operating at wrong time? You can disconnect to test. No vacuum leaks there? Exhaust gas is "inert", essentually it has no effect other than replacing some of the intake charge with something that does nothing, like adding a brick to the toilet tank. So if it gets too much, power is lost, at WOT and idle EGR should not operate, but at cruise (when warm) it should. EGR introduction reduces some of the peak charge temp so NOx emissions are reduced some. Also timing requirements tend to go up when EGR is on, so pinging may result if left off.

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    Re: 93 Brougham still has problems

    OK here are a few more facts. I'm listening to what you're saying I'm just trying to gather information. I checked the timing today just to make sure nothing has changed and it's dead on. I also pulled the cap off the distributor and found that, once again, the contacts seem to be burned / worn far more than I would expect in just a couple months. Maybe this is telling me something?

    The bit about the EGR valve, are you saying that the EGR could be bad? What's the deal with that air tube thing on the right bank? I hear people talk about cleaning it and replacing it. What's that all about?

    Oh yeah and at idle after I pull the timing bypass out the normal operation is 18 deg BTC under the cars control. 0 BTC when in bypass mode as per specs.

  13. #12
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    Re: 93 Brougham still has problems

    Not saying EGR valve is bad, possibly due to some exhaust issues, it is opening at the wrong time. So you can just unplug it to diagnose. Pretty quick and "dirty"....

    The air tubes have no effect on power, that is part of the AIR, Air Injection Reaction system. It puts air in the exhaust manifolds to help complete the burn with the super hot exhaust gas coming out the ports. If it is still rich, it will combust there. Hence the need for the Diveter Valves to direct air away when it is not needed, else it would do some backfiring at times. Often there is an additional pipe that goes to the cat converter, same deal, with it hot, the additional air helps the converter efficiency.

    Are the cap contacts all burning in the same location? Are they all way off to the edge of the contact? I found some idle drivability improvement on my 307 Cutlass (ok, I had a 350 Olds in there with the factory computer) by reindexing the cap. This involved putting a paint mark or some mark on the cap to the distributor base, then grinding the notch that indexes the cap to the base, then resinstall, and install in the direction that would more center the sparking on the contacts. Idle became smoother. I am sure there is some variation in cap design, and with ECM cars, the caps likely have not had a spec update (ok, GM probably did, but the aftermarket didn't), as the ECM cars have a very high timing, often higher than some of the older non computer cars. And it spends much more time there at the higher timing than the older cars. Again, this isn't really a "fix" than it is a tweak, and that is only to center the spark on the cap contacts. But it can't hurt....

    I am wondering if the ignition module (is it a GM one? If not, get a GM one) is bad.

    I might still have one around, PM me and I can send it to you if I can find it. I always get them at junkyards, most are good, and GM ones are the best. You can check yours by monitoring the dwell, I can check and see if I can find the proceedure. I think places like Autozone can check them too. Often aftermarket ones are dirt cheap and do not do the dwell increase/decrease properly.

    Ignition Timing sounds on. Any chances that timing chain jumped? Short of a degree wheel, I don't know another way to check it without a known good car.

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    Re: 93 Brougham still has problems

    Ok

    Not saying EGR valve is bad, possibly due to some exhaust issues, it is opening at the wrong time. So you can just unplug it to diagnose. Pretty quick and "dirty"....

    Will check that tomorrow.

    The air tubes have no effect on power, that is part of the AIR, Air Injection Reaction system. It puts air in the exhaust manifolds to help complete the burn with the super hot exhaust gas coming out the ports. If it is still rich, it will combust there. Hence the need for the Diveter Valves to direct air away when it is not needed, else it would do some backfiring at times. Often there is an additional pipe that goes to the cat converter, same deal, with it hot, the additional air helps the converter efficiency.

    Oh OK that makes sense.

    Are the cap contacts all burning in the same location? Are they all way off to the edge of the contact?

    They are in fact off to the later side of the contact. Not real bad but the leading edge of the contact is not affected.

    I found some idle drivability improvement on my 307 Cutlass (ok, I had a 350 Olds in there with the factory computer) by reindexing the cap. This involved putting a paint mark or some mark on the cap to the distributor base, then grinding the notch that indexes the cap to the base, then resinstall, and install in the direction that would more center the sparking on the contacts. Idle became smoother. I am sure there is some variation in cap design, and with ECM cars, the caps likely have not had a spec update (ok, GM probably did, but the aftermarket didn't), as the ECM cars have a very high timing, often higher than some of the older non computer cars. And it spends much more time there at the higher timing than the older cars. Again, this isn't really a "fix" than it is a tweak, and that is only to center the spark on the cap contacts. But it can't hurt....

    I don't think I could do that here because there is an opening where the electronics plug in and that's all keyed so it seals around the wiring platform (for lack of better description).

    I am wondering if the ignition module (is it a GM one? If not, get a GM one) is bad.

    GM cap and rotor. Not GM module. Will replace ASAP.

    I might still have one around, PM me and I can send it to you if I can find it. I always get them at junkyards, most are good, and GM ones are the best. You can check yours by monitoring the dwell, I can check and see if I can find the proceedure. I think places like Autozone can check them too. Often aftermarket ones are dirt cheap and do not do the dwell increase/decrease properly.

    I'll get pricing tomorrow. If it's real bad I'll PM you.

    Ignition Timing sounds on. Any chances that timing chain jumped? Short of a degree wheel, I don't know another way to check it without a known good car.

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    Re: 93 Brougham still has problems

    You know this really makes sense now. 2 years ago this all started when the car died while driving. I had just replace the ignition module but my mechanic said that it was bad. When he replaced it again it ran but right after I replaced it the first time is, I think about when this boggy loss of power thing started happening.

    It only went to a mechanic because I didn't have time to tinker with it in the middle of the week and we needed to get to work the next day. Should have just done it myself.

    GM Module is on the way. $70. Could be worse. I'll pick it up during this coming week and get it installed. Will unplug the EGR and test just prior to changing the ignition module.

    Thank you so much for your help thus far.

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    Re: 93 Brougham still has problems

    Make sure the thermal grease is applied below it. I have heard 2 schools of thought.

    1. Apply liberally. The bigger the blob the better the job. This is from a Mechanical Engineer at work, she has done testing with our grease on a 3W cell phone (OnStar) that sees some reasonably high temps (automotive grade 3, but could pass for grade 2 if we wanted to). She said no issues with a big blob. The excess just gets pushed out anyway.

    2. Apply sparingly. Too much and it will start to insulate. See above, it has test data to prove, this does not.

    You can get thermal grease any autoparts store, but it should come with module. The white thermal grease is best, if you can find it. Radio Shack has it for sure.

    The module is an expanding dwell module, the dwell actually changes at rpm, gains coil saturation at higher rpm. Not fixed. Some cheap modules are just plain fixed, so if they are done poorly, they won't function well and the coil will never put down as much power as it should. Another reason so many new cars are running multiple coils, longer dwell time, allows for higher rpm operation without losing coil efficiency. Coil Saturation is the amount of time the coil sits charged with energy, aka, the 12v applied across the primary side of the coil, the longer the better, to ensure it is fully charged. It all takes time, and the higher and higher rpm you are, the less time you have to saturate the coil. That is why MSD ignitions can only multiple spark until 3000 rpm, they run out of reasonable saturation time. (yes, if you are creative, it isn't that hard to make your own multiple spark ignition with a stock HEI)

    There are aftermarket modules, but they are not to GM specs, and with that, you never know just how good or bad they will be. Jim Hand swears up and down by the GM module. And with a handful of low 11 sec timeslips on a stock HEI, who can argue?

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