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Installed PI intake...now have bad miss

  • Thread starter Thread starter cobra2798
  • Start date Start date Feb 7, 2009
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cobra2798

New Member
Mar 30, 2005
303
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Clermont, Florida
Feb 7, 2009
#1
  • Feb 7, 2009
  • #1
Installed my PI intake from my old motor onto the new one and now the car has a bad miss at idle, sounds like it has some big cams in it. changed plugs, wires, coil packs also and no difference. What are some other things I could check? the new Motor was running fine with the NPI intake but it had a crack in it. Any help would be great. thanks.
 

02nightmaregt

To hell with your Mustang, I want to see your HOG!
Jul 1, 2007
513
4
19
Southern Indiana
Feb 7, 2009
#2
  • Feb 7, 2009
  • #2
all vacume lines connected?
 

CobraRed_96_GT

Active Member
May 20, 2006
1,421
4
39
UCSD/La Jolla
Feb 7, 2009
#3
  • Feb 7, 2009
  • #3
Sure the right wires are going to the right places?
 

cobra2798

New Member
Mar 30, 2005
303
2
0
Clermont, Florida
Feb 7, 2009
#4
  • Feb 7, 2009
  • #4
Do believe everything is right. Im lost
 

bhuff30

Founding Member
Dec 11, 2001
6,037
35
129
Olathe KS
Feb 7, 2009
#5
  • Feb 7, 2009
  • #5
I'd guess it is related to a vacuum leak. At higher rpms or under load, the miss goes away? Look for a vacuum leaks around where the lower and upper intake meet. You can use starter fluid to find the leak. The engine will rev a little faster if you spray starter fluid in the area of the vacuum leak.
 

98COBRA281

10 Year Member
Nov 24, 2007
1,348
30
59
Port St. Lucie, Florida
Feb 7, 2009
#6
  • Feb 7, 2009
  • #6
i was having a horrible miss, and backfires, i had the to 2 back wires on the passenger side in the wrong place....
 

lazerred02

New Member
Nov 19, 2004
190
1
0
FT Stewart, GA
Feb 7, 2009
#7
  • Feb 7, 2009
  • #7
Did you try unpluging each injector one at a time to see if it runs differently or stays the same? Do the same with the spark plugs, just make sure that you use some well insulated spark plug wire pliers so you don't get knocked on your tail.
 

Winters98GT

Whoop...whoop-whoop-whoop-whoop...GANGNAM STYLE!!!
Founding Member
Nov 29, 1999
5,520
1,291
224
H Town
Feb 8, 2009
#8
  • Feb 8, 2009
  • #8
did you take pictures? That always helps me.

Take it apart, minus the intake, and do it again.
 

screamin gt

5 Year Member
Apr 9, 2007
393
6
28
central CT
Feb 8, 2009
#9
  • Feb 8, 2009
  • #9
lazerred02 said:
Did you try unpluging each injector one at a time to see if it runs differently or stays the same? Do the same with the spark plugs, just make sure that you use some well insulated spark plug wire pliers so you don't get knocked on your tail.
Click to expand...

but its not throwing any codes at all??
 

lazerred02

New Member
Nov 19, 2004
190
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FT Stewart, GA
Feb 8, 2009
#10
  • Feb 8, 2009
  • #10
screamin gt said:
but its not throwing any codes at all??
Click to expand...

I have seen stranger things happen, once it is driven it may start to throw some codes.
 

cobra2798

New Member
Mar 30, 2005
303
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0
Clermont, Florida
Feb 8, 2009
#11
  • Feb 8, 2009
  • #11
I have no CEL showing and the car has not left the driveway yet. After the install should I have disconnected the battery to reset the ECU? Plugs, wires, and ciol packs are new.
 

cobra2798

New Member
Mar 30, 2005
303
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Clermont, Florida
Feb 8, 2009
#12
  • Feb 8, 2009
  • #12
98COBRA281 said:
i was having a horrible miss, and backfires, i had the to 2 back wires on the passenger side in the wrong place....
Click to expand...

Can you go into more detail on this? Which wires? Got a pic?
 

98COBRA281

10 Year Member
Nov 24, 2007
1,348
30
59
Port St. Lucie, Florida
Feb 8, 2009
#13
  • Feb 8, 2009
  • #13
cobra2798 said:
Can you go into more detail on this? Which wires? Got a pic?
Click to expand...

sorry no pic, but on my car those 2 back wires on the passenger side were the same lenght, so i could not tell exactly where they went, and i accidently reversed them, it drove me CRAZY trying to figure out such a stupid problem....
 

cobra2798

New Member
Mar 30, 2005
303
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Clermont, Florida
Feb 8, 2009
#14
  • Feb 8, 2009
  • #14
98COBRA281 said:
sorry no pic, but on my car those 2 back wires on the passenger side were the same lenght, so i could not tell exactly where they went, and i accidently reversed them, it drove me CRAZY trying to figure out such a stupid problem....
Click to expand...

Im gonna check that out. Now the wires you speak of are coming of the passenger side back of the intake? Plenum?, TB?
 

bhuff30

Founding Member
Dec 11, 2001
6,037
35
129
Olathe KS
Feb 8, 2009
#15
  • Feb 8, 2009
  • #15
You don't have a CEL yet because you haven't given the car a full heat cycle. After driving the car for a while, the computer will do some tests and diagnostics and most likely throw the CEL on after that. The same reason why clearning the codes and going to the emissions check station doesn't work.
 

Greenscobie86

Member
May 14, 2008
132
0
17
The Island NY
Feb 9, 2009
#16
  • Feb 9, 2009
  • #16
I just did this swap this weekend...

One question for you: Did you make ABSOLUTELY CERTAIN that there are no remnants of water/coolant/carb cleaner in the plug holes. It took me a good 10 minutes to blow all eight of them clean with an air hose after which I got in there with a rag and my finger.

I'm sure it is something very simple... One thing I'll tell you though, you will have a nice grin on your face when you take it out and romp on it for the first time with the PI intake....
 

cobra2798

New Member
Mar 30, 2005
303
2
0
Clermont, Florida
Feb 9, 2009
#17
  • Feb 9, 2009
  • #17
Greenscobie86 said:
I just did this swap this weekend...

One question for you: Did you make ABSOLUTELY CERTAIN that there are no remnants of water/coolant/carb cleaner in the plug holes. It took me a good 10 minutes to blow all eight of them clean with an air hose after which I got in there with a rag and my finger.

I'm sure it is something very simple... One thing I'll tell you though, you will have a nice grin on your face when you take it out and romp on it for the first time with the PI intake....
Click to expand...

You hit the nail on the head. We did the swap on friday and there was water/coolant in some plug wells that we used the air hose on to clean out, however that did not seem to work. Today I went out and started it and she is purring perfect! I think it just needed some extra time to dry out. I know the fealing of the PI intake, this intake is off my old motor that I blew up, used motor I bought had a cracked NPI intake but I got the motor for next to nothing so I had to do it. Anyway she is up and running.

One more thing, I notice the car has a little deeper, smoother exhaust note. Car has the same exhaust setup but the motor is a 98, do they sound any different? I heard the 98 motors had different exhaust manifolds?
 

badstang02

New Member
Feb 9, 2009
1
0
0
Texarkana Tx
Feb 9, 2009
#18
  • Feb 9, 2009
  • #18
Hey,dude..i just wanted to ask if you put the pi heads on your car,i didnt see it on you rmod list,and if you didnt i would suggest you get those cause,the car wont run right without them.and I know its head swap and can be a pain in the ass,but you'll probably pick up a few extra horsepower to,because it will bump up the comression on your older short block,i did the same thing on a customer of mine's car and that was the problem...its worth a shot,man..latter
 

mustangman9812

10 Year Member
Jan 14, 2004
661
6
49
Mars Hill, NC
Feb 10, 2009
#19
  • Feb 10, 2009
  • #19
badstang02 said:
Hey,dude..i just wanted to ask if you put the pi heads on your car,i didnt see it on you rmod list,and if you didnt i would suggest you get those cause,the car wont run right without them.and I know its head swap and can be a pain in the ass,but you'll probably pick up a few extra horsepower to,because it will bump up the comression on your older short block,i did the same thing on a customer of mine's car and that was the problem...its worth a shot,man..latter
Click to expand...

his car will run fine without them, I dont understand your logic here.
 

cobra2798

New Member
Mar 30, 2005
303
2
0
Clermont, Florida
Feb 10, 2009
#20
  • Feb 10, 2009
  • #20
mustangman9812 said:
his car will run fine without them, I dont understand your logic here.
Click to expand...

I dont understand either, car runs strong. All that work for an extra 10-15whp is really not worth it to me, maybe someday but im happy with it now. Its a DD so im not looking to make it much quicker.
 
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