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Discussion Starter · #1 ·
I installed the Paxton SN89 blower on my 93 5.0 Coupe. Only engine mods to the coupe are a Typhoon intake. Well the install went well and the car runs fine, but after it idles for about 20-30 seconds then the idle drops down to around 700rpm and it has a lot of lope to it. Sounds almost like an F-cam. The car still has a stock cam and had no lope to it before. Driveability is still great and it doesn't have any miss or skip to it about idle. What could be causing this?
thanks
Mark
 

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you may have your timing to slow, you might want to use a timing light and check it out, too slow timing will cause overheating and can also lead to detonation, it could be various different things I would check this first
 

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Discussion Starter · #3 ·
2wld4u said:
you may have your timing to slow, you might want to use a timing light and check it out, too slow timing will cause overheating and can also lead to detonation, it could be various different things I would check this first
The timing is set at 14 degrees initial, same as it was before the blower. I pull timing under boost with the BTM.
 

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It sounds like your MAF. What type of MAF do you have? Try reclocking it and see if it helps. An extremely rich idle causes the engine to lope like that.
 

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The timing is set at 14 degrees initial, same as it was before the blower. I pull timing under boost with the BTM

ok that rules out the timing issues

It sounds like your MAF. What type of MAF do you have? Try reclocking it and see if it helps. An extremely rich idle causes the engine to lope like that.


thats sounds reasonable also, I would check the MAF and also check the O2 sensors as well..

1 more question, are you using a FMU and what is your fuel pressure set at?
 

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Discussion Starter · #6 ·
2wld4u said:
The timing is set at 14 degrees initial, same as it was before the blower. I pull timing under boost with the BTM

ok that rules out the timing issues

It sounds like your MAF. What type of MAF do you have? Try reclocking it and see if it helps. An extremely rich idle causes the engine to lope like that.


thats sounds reasonable also, I would check the MAF and also check the O2 sensors as well..

1 more question, are you using a FMU and what is your fuel pressure set at?
The MAF meter is stock, the sensor is at the 12 o'clock position, but I could clock it to see if that helps. The o2 sensors are brand new and it doesn't have an O2 trouble code in it. I'm running 38lbs of fuel pressure measured with the vacuum off and plugged. The FMU is 12:1, but something is wrong with the FMU, it doesn't spike the pressure like it should, however this shouldn't have an effect on idle.
 

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Id check your plugs and check the oil, if you can smell gas in the oil you may have an injector(s) bad, Im not sure about clocking the sensor as its seemingly related to fuel at the moment..

it seems the fuel pressure is ok, (actualy a little low for my taste) if it was carb'ed Id tell you your needle valve was stuck allowing gas to bleed off at idle, and this is simular to what I think it is, but I cant be for sure untill you check a few things..
 

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How is the MAF NOT related to fuel??? the MAF is what tells the EEC how much air is coming into the motor and how much fuel it needs to compensate... 99% of the time, the MAF is the reason a mustang surges or doesnt idle properly. It is probably the single most important function/sensor in the entire system.

FYI- the clocking of the MAF is very important in a blown application because the air is pulled in by the blower and not just lightly drawn in by intake vacumn.
 

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well, ok wise guy you figure it out, and by any chance did you install that ATI Procharger? maybe thats the reason you couldnt keep it togther, spanky.....and actualy your wrong....most of the time its related to the TPS, Ill just bite my tounge on this one...have at it spanky..
 

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I rest my case!

2wld4U- chill out man! I have tuned stangs for quite awhile now and I wasnt trying to be a "wise guy".. I was merely trying to help the guy out. I had many problems with my blower when it was first installed and had to figure them out myself cause I couldnt pay someone else to do it. The TPS is a simple piece, it is nothing more than a potentiometer that ranges from .9v- to 5v and if its set below 1.0v at idle then its fine...

How long have you tuned? how many stangs have you built? I bet I have more time in these cars than your age...
 

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i have a question.... what exactly is clocking your MAF and how do you do it?
 

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I rest my case!

2wld4U- chill out man! I have tuned stangs for quite awhile now and I wasnt trying to be a "wise guy".. I was merely trying to help the guy out. I had many problems with my blower when it was first installed and had to figure them out myself cause I couldnt pay someone else to do it. The TPS is a simple piece, it is nothing more than a potentiometer that ranges from .9v- to 5v and if its set below 1.0v at idle then its fine...

How long have you tuned? how many stangs have you built? I bet I have more time in these cars than your age...


well, I have tuned on race race cars for 10 years now, and have build 5 no 6 race cars myself, Im currently building a pure street ride and also have a SSO car in the works for possibly next year, but not a expert on forced induction to be honest, Im more into nitrous because it was always cheaper..and FYI im 29 and can kick your azz....lol
 

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PUR PONY said:
i have a question.... what exactly is clocking your MAF and how do you do it?
can someone answer his ?? I'm interested too, I just got my car running today and it's rich as hell at idle and the idle sucks.... prob my maf also,,,, it's in the fender the sensor is about 6 o clock,, (upside down) Bad? good?
 

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By clocking the sensor, you are just turning your MAF (black electronics on top) to different positions. What this does is changes how the air flows across the sensor. MAF's do not like "noise" which is caused by turbulence in the incoming air, thats why cold air kits with sharp bends before the MAF can cause idle problems. This is especially important with a blower because you are pulling much more air through the MAF than what you would N/A. I usually just spin the meter about a 1/4 turn at a time until I get the best idle.

2wld- where you from in WV?? I used to live near Martinsburg in a little town called Inwood... where do you race at?
 

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2wld- where you from in WV?? I used to live near Martinsburg in a little town called Inwood... where do you race at?

well thats a good question, since both my local tracks have closed and now I have to race abroad, I have heard of martinisburg but never heard of inwood, so I suppose I have never been there, other than to maybe a couple Nascar races, is that the martinsburg your speaking of? Ill proboly head to richmond for test and tune this year, either there or Kanawa valley (whitch is about 100 miles from here) if everything works out I may not even have to race in WV at all this year..unless I hit the lottery and can build my own track WV doesnt offer a ton of tracks to race at...and Im in greenbrier county, WV, I used to likve in Arkansas and did do some dirt traking there..If all this falls through I might decide to run in Pro Cup later on, but Im a drag racer at heart...2wld4u


P>S> and I was kidding about kicking your but, I really dont like being insulted for no reason though, and here is my advice, if im wrong, whitch I am alot at times, correct me, Ill be happy but dont try to make out like somebody's fool, thats no way to be, I am here for the sole purpose of well, I like this place and feel confortable helping fellow mustangers and that's what it should pretain to, if you want to get personal PM me and we'll go from there...
 

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I didnt intend to insult anyone with my post, thats the bad thing about trying to type what you are meaning to say... I have started so many arguments with my fiancee when I talk to her at work via instant messenger, so I must be pretty bad at typing with the wrong meaning. No reason to think I was making you out as a fool or anyone else for that matter.

PS. you are thinking of Martinsville VA, thats where the NASCAR track is. I was referring to Martinsburg WV, about 2.5 hours north of D.C. You are so right, there are no damn dragstrips in WV!! I have to drive all the way into Hagerstown MD just to race, or we make a weekend of it and drive to MIR, about 3+ hours....
 
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