Replaced front brakes but!

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  #1  
Old 04-16-11, 12:04 AM
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Replaced front brakes but!

Good Morning,
I have a 95 Chevy Lumina APV with the 3.8L V6 my problem was most of the time when I pushed down on the brakes she would stall plus my cruise control would kick off. I replaced the front brakes at my cousins. That night I drove her home no more check engine light or stalling at stops.
When I was getting off the highway I went to push on the brakes I noticed my head lights went dim & dash lights I looked at my volt gauge & the needle dropped but she did not stall once stopped everything was fine!. This was on Monday since then she has been ok but I get a surge at a steady 40mph.
Last year I had the MAP sensor changed & they found some bad wires going to it the mechanic said that she was alway reading 36% due to the bad wires which he just cut the bad part out & put connectors in. He said at the time that down the road I could have more. What I wanted to do is take the alternator off & have it tested but I think it could be more bad wires to the MAP sensor?. I also read but don't believe this could be the cause that it could be the EGR valve!. Today as I was just getting home the check engine light came on again!. I also read about some lock out on the tranny that could be causing it & to unplug it & see if she runs better. So needless to say I'm lost hear!.
My question is could it be the alternator? although she shows real good according to my gauge!. Does anyone sell a wiring harness for the MAP sensor? & does it go from the MAP sensor to the computer? Last does anyone have any suggestions on what it could be? as she has a steady jerk at 40mph & on hard stops at night the needle of the volt gauge drops right down but at least she does not stall!.
If anyone can help me I Thank you very much!.
Will,
 
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  #2  
Old 04-16-11, 05:08 AM
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Should be some real mechanics along with some ideas, but in the mean time I'll throw a couple of things out.

1. I would get the codes read for starters. Not sure if your '95 is OBD I or II. If it's OBD-I you can read them yourself, OBD-II will need a reader. AutoZone and some other parts houses will do it for free (they hope you'll buy the repair parts from them, of course).

2. EGR is a possibility.
3. A vacuum leak comes to mind, too.
4. Although the alternator could be going, I'm more inclined to think the engine is trying to stall and as the RPMs drop to near stalling speed the alternator output is dropping is well.
5. There wouldn't be a separate harness for the MAP circuit. You can buy pigtails for the various connectors on cars, but they only consist of the connector and a few inches of wire. If there is a bad circuit in the harness, a new wire would have to be run.
6. Are all the routine maintenance items up to snuff? Plugs, wires, cap, rotor, filters, etc?

 
  #3  
Old 04-16-11, 08:34 AM
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well, i am not a real mechanic, but brake booster operates off vacuum created by engine. it is supplied to it via a hose, running from engine intake manifold, usually.
hence, if you press on brakes, booster "requests" additional vacuum, and that adversely influences the general engine operation.
you know, the more i think about this, i start remembering general situation similar to yours, back in time with one of my cars. that was when i figured that overall engine loss of performance could be felt through brake booster operation, as engine was simply not supplying enough suction to run all the vacuum operated devices.

here's my suggestion for you.

bring her to a repair shop, real one, not just some corner guy, and have full blown diagnostics done. you might be lucky and it may be OBD2 engine. makes it easier. GM started OBD2-s on as early as some 95 models. if not, they should have proper means of diagnosing CEL causes. also, you want to do pressure test. unless your alternator belt is VERY LOOSE and causing general power supply drop down whenever demand for it comes.
check alternator belt. if it's ok - do full diagnostic. will cost you what, hundred bucks, but you'll know what the heck is wrong with it. prolly a lot. tell 'm to do diagnostics, then call you with recommendations, and DO NO REPAIRS until you approve. might be a good idea to post it here before you authorize any $$$
 
  #4  
Old 04-16-11, 11:13 AM
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I want to Thank you both for the help! & for your time. It's a stange one for sure I took her out today the diffrence is it is very cool weather wise & she ran grate!. One thing I have noticed is that my fan comes on & stays on when I put the heater on I'm not sure if this is normal. My cousin has a Monte with the 3.8L 2001 she put her heater on & the fan did not come on. So I'm not sure if the years would make a diffrence I know she is an OBD 2. Being on a fixed income it is hard but I think I might have to take her to a garage but will do as u said before I spend any money I will post what they came up with!.
Once again I want to THANK both of u very much it was a BIG help!
Will,
 
  #5  
Old 04-16-11, 12:19 PM
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if she's OBD2, then you can read codes, pro bono, at any parts store. will give you good starting point.
if she runs better in cold weather = higher density air, more oxygen. wild guess though.
you awfully start sounding like there's a leak somewhere. air or vacuum.
you have 3 bucks for a can of brake cleaner? buy one, start engine, let it warm up to norm, then start giving it shots of cleaner all over the throttle body, valve cover, air intake, etc. the very moment engine bogs - that's where the leak is.
you can check alternator belt, right? it's simple grab and pull thing. my buddy REAL mechanic twists belt. if he can see the opposite side of the belt - that belt is shot on his book.
as of fan... start with simple. check your blower settings. some cars have it set to automatically turn a/c on when in defrost mode. the fan you are hearing might be a/c fan, not coolant fan.
 
  #6  
Old 04-20-11, 04:08 PM
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If your at idle and you hit brake hard and yank the wheel at the same time and it dies. you need to clean your idle air valve/controller. It may also need to be replaced. After cleaning IAC you need to look for vacuum leaks. With the engine running spray carb or brake cleaner around the upper portion of the engine focusing on small hoses and spray around the brake booster. If your idle jumps up quite a but at any time your vacuum leak is near where you just sprayed.
 
  #7  
Old 04-21-11, 06:47 PM
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Good Evening,
The more I read about the IAC the more I think you have something so tonight I took the harness of the IAC the specs say ABCD A-B should be 40-80 as should C-D mine read 87.6 on both. Then I jumped B-C which should read infinity mine does not so I think I probably will get a new one & see what it does. I thought it might be the alternator but I never seen this before so I'm not sure!. I tied the carb spray but nothing happened!.
Thank you very much for your help!. I'll let you know what she does!.
Will
 
  #8  
Old 04-23-11, 06:37 PM
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explain what you mean read infinitity. What are you measuring across? Why did you jump it?
 
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