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| NEVRL8T | LT1 Code 33 | ||
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Guru
 
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I have a problem that started Saturday afternoon after a 150 mile drive. Need some opinion's please. If your LT1 started running really rough. Missing badly especially at low RPM and you limped it home and got a code 33 "MAP Sensor". Would you order a new MAP sensor and try that first? I know what the FSM says but I do not have the means to test it the way the charts are laid out. Any and all help is greatly appreciated.
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Posted on: 2008/3/17 16:13
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| toptechx6 | Re: LT1 Code 33 | ||
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You should get a lot of responses to this post since it is impossible to give a "correct" reply. If we tell you no, that is the wrong way to do it we aren't being understanding to your circumstances. If we agree with throwing parts at it we are giving you bad advice, which do you prefer? Nearly anything that causes a misfire will result in lower than normal vacuum so the code may be a symptom, not the cause. At the very least before buying any parts give the engine a good visual inspection with extra attention to the vacuum lines especially the one to the map sensor, can't hurt to look at the electrical connectors either, best of luck. |
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Posted on: 2008/3/17 17:38
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| NEVRL8T | Re: LT1 Code 33 | ||
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Granted the following picture is from a Camaro LT1 but the setup is basically the same, where is there a vacuum line to the MAP sensor?
http://shbox.com/1/map.jpg Thanks for your help. |
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Posted on: 2008/3/17 18:46
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| Steve40th | Re: LT1 Code 33 | ||
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I would recommend taking a MAP sensor off of another GM car, and see if the problem goes away. Saves a few bucks that way. GM used the same MAP for many years.
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Posted on: 2008/3/17 23:46
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Ko'u ohana aia ku'a ikaika |
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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There is no vacuum line connected to the MAP.
Without telling us what module the DTC came from, not one person can verify the fact it is indeed a DTC indicating an issue with the MAP sensor. Without knowing what year model your car is, not one person can be sure with diagnostic procedure or code list to give you. There are 100 reasons the engine could be runing rough, and without knowing the above information, any advice given to you could very well be a bum steer. I wont assume anything in an effort to fill in blanks and give you a quick answer. |
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Posted on: 2008/3/18 7:22
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| toptechx6 | Re: LT1 Code 33 | ||
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My mistake, thinking of Mopar stuff I guess. A loss of vacuum from another source can still result in a MAP reading that is out of spec, as can a misfire caused by ignition, fuel or mechanical problems. |
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Posted on: 2008/3/18 8:09
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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No worries mate, that happens
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Posted on: 2008/3/19 3:38
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| NEVRL8T | Re: LT1 Code 33 | ||
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Its a 1992. Can you point me in the right direction as to how to find out what module the DTC came from? |
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Posted on: 2008/3/19 13:07
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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Refer to the PM i just sent ya mate, i replied to the one you sent me.
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Posted on: 2008/3/20 7:49
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| NEVRL8T | Re: LT1 Code 33 | ||
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I got the following info if someone can help:
Module 4 - codes H33 (Map Voltage - Low Vacuum), H34 (Map Voltage - High Vacuum), & H65 (Right Oxygen Sensor Rich) I also have some fuel coming from the rear drivers side injector (or so it appears) leaking down on to the intake. I have put some pics up of that. I am assuming this is a leaking injector. Look like that to you? [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors001.jpg[/IMG] [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors002.jpg[/IMG] [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors003.jpg[/IMG] [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors004.jpg[/IMG] [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors005.jpg[/IMG] [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors006.jpg[/IMG] [IMG]http://i55.photobucket.com/albums/g157/LeesVette/fuelinjectors007.jpg[/IMG] Any ideas? |
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Posted on: 2008/3/21 0:15
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| NEVRL8T | Re: LT1 Code 33 | ||
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I guess no one has seen anything like this before.
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Posted on: 2008/3/22 18:34
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| bogus | Re: LT1 Code 33 | ||
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a leaky multec has never happened... NOT.
you have a problem with the injectors. If it isn't a bad injector, it's a bad o-ring. as for the code: how many miles are on this car? Is the MAF original? Are the relays original? IIRC, the headlight relays are the same as the MAF. I would consider swapping relays and testing to see if the headlights work. |
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Posted on: 2008/3/22 18:39
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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Bogus, there wont be a MAF, its a 92.
The leak must be tended to IMEADIATELY, cause that is extremely dangerous. Call MAXX WRENCH and order a new set of injector o-rings at the very least. Pull the fuel rail off the manifold, turn it upside down and have a look at the injectors while the rail is pressurised, turn the key on to do that, the injectors shouldnt leak, and they certainly shouldnt leak around the o-rings where they go into the rails. The fact its rich on the right bank could be related to this leak, due to the fact the pressure at the injectors may possibly be higher on the right hand side with that leak on the left. The fact youre getting both 33 and 34 is rather unusual, they both mean the opposite of each other. For that reason, id contemplate taking that MAP sensor out, and trying another one. If you need a new one, call MAXX WRENCH (link to his website is in my sig below) and tell him what you need. Before you just the gun and replace the MAP though, and this is IF you can get another one the same to test, do that, cause there is a chance it could be in the wiring and not the MAP itself. Check all the connections to the back of the ECM, remove the battery terminals and clean them (remove neg first, and put it back on last) check the ground points, check all the wiring to be sure nothing is shorting to ground where its not meant to, especially down the right hand side of the engine where the right bank O2 circuit runs, cause if that shorts partially to ground youll probably get the rich DTC. A badly fouled O2 sensor can also give the rich DTC, but before you go and replace anything like that, pull both O2s out, put the one you removed from the left into the right bank, and the one from the right into the left bank. If the DTC then shows up on the left bank instead of the right bank, the sensor is rooted and should be replaced, if the DTC remains on the same bank and swapping the O2s makes no difference, then the sensors are probably fine another issue exsists. Some of that might sound like a waste of time, but try it ALL, cause you never know, and by the look of it any of the above could be a possibility. |
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Posted on: 2008/3/23 9:53
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| NEVRL8T | Re: LT1 Code 33 | ||
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First of all, let me take the time and say "Thank you!" for your responses.
Is 24# injectors the size I need? |
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Posted on: 2008/3/23 18:37
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| bogus | Re: LT1 Code 33 | ||
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Angel - have you done ANY of the diagnostics recommended? If not, there is a chance you are spending good money on injectors you don't need.
Casey - I missed the detail it was a 92... you are right, MAP only. |
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Posted on: 2008/3/23 18:44
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| NEVRL8T | Re: LT1 Code 33 | ||
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Quote:
I know I have needed injectors for a while. I knew I had at least one leaking injector, hard hot starts and sometimes a hesiation. I had planned on replacing the injectors since I owned the car. I tried hooking a vacuum pump to the MAP to get 10 pounds of head on it and check the voltage changes on the MAP but for some reason I cannot get a voltage reading on the MAP sensor wire (green) and common (black) wires. I can get a reading on the 5 volt reference wire. I had already ordered a MAP last week and some O2 sensors because I really just wanted to change them out. I believe this car has not had any type of work done on it before and it has 140K miles. I used the tutorial you made a while back and already have the fuel rails off and injectors out. Sounds like the connector may be bad on the MAP as well. |
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Posted on: 2008/3/23 22:38
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| bogus | Re: LT1 Code 33 | ||
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Grand Imperial Pooh-Bah
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the map connector is easy to test... put a volt meter on either end of the wire and start testing for continuity.
Do you have the Helm Manual? |
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Posted on: 2008/3/24 1:09
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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Connector on the MAP should be a very easy thing to check and just as easy to fix.
How long have you have this car? |
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Posted on: 2008/3/24 2:47
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| NEVRL8T | Re: LT1 Code 33 | ||
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Yes, I do have the helms and was trying to follow the steps on Charts. I figured the MAP should be simple but I don't know a lot about multimeters and such. I pulled the connector off of the MAP sensor and was probing inside the connector trying to get a reading. With no power I get a reading of 1 when I start the car I still get the same reading. I have the multimeter set on DC and 20 volts. I have had this car since March of 2006. I have put less than 10,000 miles on it.
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Posted on: 2008/3/24 12:01
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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Youve got the meter on the wrong setting, set it to ohms and test it that way. The resistance should change as the vacuum increases
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Posted on: 2008/3/24 12:13
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| NEVRL8T | Re: LT1 Code 33 | ||
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That would explain it, thanks! |
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Posted on: 2008/3/24 12:56
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| NEVRL8T | Re: LT1 Code 33 | ||
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I am putting my red lead on the green wire and black lead on the black wire. I am also putting my red lead on the brown wire and my black lead on the black wire. I have tried my meter set on different Ohm settings and I am not getting a reading. The car has new MAP and new injectors and still runs the same. I took it for a spin and it coughed up a code 33 again. It seems to be running rich, idling rough and runs even rougher at higher RPM's. I think its vacuum related. Once I had to almost push the brake pedal to the floor to get it to stop. First time its done that. I am not sure where to go from here. |
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Posted on: 2008/3/26 22:33
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| toptechx6 | Re: LT1 Code 33 | ||
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Take a vacuum reading with a gauge and see what you have, should be 18 to 21" at idle assuming a stock cam. For the symptoms you describe you must have a substantial leak. Inspect the larger vacuum hoses first such as the one to the PCV valve,and brake booster. You could try disconnecting the hose to the booster and plugging it, if the engine runs smooth the booster is leaking. Spraying carb cleaner around the intake gaskets can reveal a leak when you hit the right area, the engine will run differently when it ingests the cleaner at the leak point.
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Posted on: 2008/3/26 22:49
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| NEVRL8T | Re: LT1 Code 33 | ||
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First of all thanks for your help. I took of the brake booster hose and plugged it and got no change. I don't see any major problem with the PVC line. Could a plugged PVC valve cause this? I am not sure how to take a vauum reading. I have a vacuum hand pump but I am not sure I can take a reading with it. Where would I hook up a vacuum gauge to get a reading at? |
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Posted on: 2008/3/27 2:10
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| toptechx6 | Re: LT1 Code 33 | ||
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A plugged PCV would not cause a leak, but if the "guts" were completely missing from the valve that could to it. To be sure there are no leaks disconnect the hose at the manifold and plug it similar to the brake hose test just to verify that is not the culprit.
You should be able to take a vacuum reading with your hand pump on any vacuum hose coming directly off the manifold. Assuming your car is the same as mine, my suggestion would be the lower of the two small nipples on the passenger side of the engine under the fuel rail cover, it should go to a "Tee" with a check valve in it. The line to the Tee provides vacuum to the A/C controls. The top nipple goes to the fuel pressure regulator, removing that one might confuse the issue since it will run richer with the vacuum line disconnected. Also check the vacuum line to the cruise control servo, seem to recall that one is fairly large too, try to plug it at the source to eliminate it from the list of possibilities, good luck. |
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Posted on: 2008/3/27 8:39
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| NEVRL8T | Re: LT1 Code 33 | ||
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I just thought I would give you all an update. I took it in to the dealership. I know the guys there and and finally broke down and took it in to them. I lost a valve spring on the passenger side. Thanks for everyones help with this problem. I guess I can look at this way at least I got new injectors and a new MAP sensor out of this and I learned something about the car and myself. Once again thanks to everyone who lended an ear and some well appreciated advice.
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Posted on: 2008/3/28 22:11
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| toptechx6 | Re: LT1 Code 33 | ||
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Sorry we weren't able to help you sort it out yourself and save you some money, but happy to hear the dealer found the problem quickly.
Good opportunity to upgrade to LT4 valve springs from GM Performance Parts, they are not expensive and will then be in place if you decide to add roller rocker arms later on to pick up some horsepower. |
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Posted on: 2008/3/28 23:36
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| CasetheCorvetteman | Re: LT1 Code 33 | ||
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I havent been here for a few days mate sorry, ive been too busy with other things.
Sounds like youve got it sorted out now |
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Posted on: 2008/3/29 3:51
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