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Discussion Starter · #1 ·
I have a 1996 MX-6 M edition V-6 that I had to rebuild the heads on. It ran great before it overheated and screwed up the heads. After doing this work, I've never been able to get it to idle correctly. I had no engine codes before I redid the heads but now I get a flashing check engine light and getting just about all error codes. The car runs great except at idle. It is especially bad with the AC on. The higher the AC is turned on the worse it idles. It actually wont idle at all on high AC and barely if at all on 1 or 2. I have done an entire tune up when redoing the heads, I did not do the O2 sensors as they were not errroring out before the work was done. The errors I get now indicate all O2 sensors are bad, MaP sensor is bad (changed that to no avail) I've also checked to make sure that I have the distributor in teh correct place but the exact procedure for timing it is a pain and hasnt seemed to help any.

could it be that I damaged the crank shaft sensor when putting it back together? I've confirmed with another mechanic that the Cam and timing bet were put back in teh right place and dont want to just start changing alll teh sensors hoping to get it right eventually. It is driving me crazy as the car otherwise runs excellently. It has 169k miles on it and still uses no oil and will still get up and go past 140 mph. IT JUST HATES TO IDLE, not that I'm a fan of sitting in traffic but sometimes its necessarry.

Please help.

'nix
 

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hm, thats interesting if its not off timing,

did you inspect your o2 sensors? have you tried to start it at first and it kept cranking? maybe you choked your sensors. not enough fuel or too much.
id inspect and clean.

but other than that, its got to be in the vaccum. im sure you rechecked everything but you got to tripple check and recheck.

im having a similar issue, when it start it i have to give it a lil gas. and thats after installing my ze intake.
 

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Discussion Starter · #3 ·
tried that

I took another MX-6 and a Mazda 626 with the same engine and setup under the hood and double checked the vacume hoses with a mechanic and they all look good. It starts fine without having to give it gas. It idles a little rough with the AC of, with the AC on it barely idles at all. If you turn the AC on high it will immediately die when you are coming to a stop or put it in neutral. It didnt have this issue before I rebuilt the heads. Maybe I got some trash in the O2 sensors or some other sensor but not sure which one thatt would be or where to start looking. It has 3 02 sensors and its expensive as hell to just start changing them one at a time. I've never seen an 02 sensor that could be cleaned. What do you do, spray it with carb cleaner? Seems like that would destroy it.

I initially thought I must have had the cam off a notch but the timing belt later jumped and I had to have that and the tensioner replaced and the mechanic that did that ( I was working too many hours to do it myself) said the cam was dead on accurate and it was in time. I did notice that the distributor has to be turned almost all the way to the end point to get it in time instead of near the middle as you would expect. I'd love to get this engine running right for the first time in three years. Its been running like this for that long, with the check engine light on or flashing but the only time it runs bad is at idle. when I put it on the sensor reader it shows all kindsof screwed up codes. I doubt that ALL the sensors went bad immediatey after rebuilding the head.....but like I said, I can take it out on the interstate and it will flat haul a$$ and top out above 140....not that I do that very often....lol

If you'll give me the steps to clean the sensors (which ones in order and the method of doing it I'll start there)

Thanks for the help. This has been a source of annoyance for a long time. No mechanic wants to touch it. The only other thing I can think of is to bring it to the dealer and let them change everything which is what they'll do in my opinion.....they will read the codes and cange each one till they get no codes left and Id bet it will still idle badly...

'nix
 

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Discussion Starter · #4 ·
tried that

It does this every time I run the car and its not just when I first start it or waiting for it to warm up, its consistent whenever I'm at idle.

I took another MX-6 and a Mazda 626 with the same engine and setup under the hood and double checked the vacume hoses with a mechanic and they all look good. It starts fine without having to give it gas. It idles a little rough with the AC of, with the AC on it barely idles at all. If you turn the AC on high it will immediately die when you are coming to a stop or put it in neutral. It didnt have this issue before I rebuilt the heads. Maybe I got some trash in the O2 sensors or some other sensor but not sure which one thatt would be or where to start looking. It has 3 02 sensors and its expensive as hell to just start changing them one at a time. I've never seen an 02 sensor that could be cleaned. What do you do, spray it with carb cleaner? Seems like that would destroy it.

I initially thought I must have had the cam off a notch but the timing belt later jumped and I had to have that and the tensioner replaced and the mechanic that did that ( I was working too many hours to do it myself) said the cam was dead on accurate and it was in time. I did notice that the distributor has to be turned almost all the way to the end point to get it in time instead of near the middle as you would expect. I'd love to get this engine running right for the first time in three years. Its been running like this for that long, with the check engine light on or flashing but the only time it runs bad is at idle. when I put it on the sensor reader it shows all kindsof screwed up codes. I doubt that ALL the sensors went bad immediatey after rebuilding the head.....but like I said, I can take it out on the interstate and it will flat haul a$$ and top out above 140....not that I do that very often....lol

If you'll give me the steps to clean the sensors (which ones in order and the method of doing it I'll start there)

Thanks for the help. This has been a source of annoyance for a long time. No mechanic wants to touch it. The only other thing I can think of is to bring it to the dealer and let them change everything which is what they'll do in my opinion.....they will read the codes and cange each one till they get no codes left and Id bet it will still idle badly...

'nix
 

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i had both my 02 sensors bad and it didnt hurt the idle. it just ran rich. what is your idle at crank? then also tell me what it is when in gear.

i got some o2 sensors real cheap off ebay like 20 each you just had to splice them in, once you get those in it will help a lot with mpgs.

my crankshaft sensor is waiting to be replaced but thats not really messing my idle up too much just BARELY, since the PCM is relying off the camshaft sensor in the disty.

all this happened after replacing heads huh? no leaks on the gaskets right?

getting a bunch of codes? which codes are you getting exactly? if its a bunch of random ones you could have a bad ground somewhere messing up all your voltages but that would probably give you problems everywhere. let us know.
 

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off topic but wtf is the ad at the bottom about lol. Just a picture of what appears to be a switch or something with some wires going into a bolt. I'm not buying whatever it is without annoying words!

The weird thing is the AC with your situation. Thats more or less just a power load when your are chaning fan speeds. The AC compressor always pumps the same amount of refridgerant. If timing is good and compression is good its def a sensor. I know you said you checked your map but that really sounds like a MAF prob. Check the plug and check the prongs. I could be wrong but that really sounds like the intake MAF.
 

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Discussion Starter · #7 ·
changed MAF

changed the MAS Air Flow sensor and that didnt help, it still shows the code for a bad MAF!! Thanks for the info about the AC, thats what I thought, if the compressor is on, its on. My GF figured out that if you keep it on low it idles better! Where could I have a voltage drain that would cause this problem?

Could it be a bad crankshaft sensor? I know they are pretty sensitive (as per Haynes) if its bad could it cause everything else to act stupid?

I cant even get a mechanic here to look at it after I tell them whats wrong and how it came to be....The reason I started doing my own mechanic work years ago was because I kept getting incompetent mechanics that did all kinds of stupid things like not tighten stuff all the way! I do better work than they do and this is the first time I have had major issues with anything I've fixed on any of my cars over the years.

Have Haynes Manual, will attempt anything! lol
 

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First, what are the codes you're getting? Reset the battery and check again to see what codes you're still getting.

Second, if your idle doesn't increase when your ac is turned on, it may be the iac that's bad, or your ecu. Does your idle go up any when you turn the steering wheel while idling? If not, then either your iac isn't moving when it's being told to, or your ecu isn't telling it to move. You can probably find a used iac from the wreckers or a fellow 6'er for less than $30.
 

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Discussion Starter · #9 ·
First, what are the codes you're getting? Reset the battery and check again to see what codes you're still getting.

Second, if your idle doesn't increase when your ac is turned on, it may be the iac that's bad, or your ecu. Does your idle go up any when you turn the steering wheel while idling? If not, then either your iac isn't moving when it's being told to, or your ecu isn't telling it to move. You can probably find a used iac from the wreckers or a fellow 6'er for less than $30.
Thanks for the reply Paul. I forgot I had another post about my problem child that I started some time ago. Here is the link to that thread.

http://www.mx6.com/forums/2g-mx6-general/218717-multiple-error-codes-after-head-rebuild.html

I need a mod to delete or end this thread to prevent futher confusion, know any???
 
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