Idle issues after Stock intake cam swap (96 gt stang)

Boomer!

Boomer!

Club Member
Hello,
I have finished quite a few 2 valve P.I conversions over the years so I'm not a noob. Over the weekend I helped a friend install a '99+ intake and cams on his '96 mustang. We degreed the cams to the factory card just to be sure the sohc engine was running in perfect balance. After start up we noticed a small miss so we changed the plugs and wires, afterward it was still there but only at idle in gear(automatic).
Is there anything anyone may have from him to try to resolve this? There is no Check Engine Light. Does it seem logical that it could be a injector needing to be cleaned ? I'm lost after this one, this is the first time I have seen this happen after 6 swaps.

Thanks,
Boomer
 
Thats what I thougtht at first, sprayed the entire engine with starting fluid and carb clean and no changes in idle.
After a little research I found it could be a injector, the ground to the fuel rail may be broke or a weak lash adjuster.

Thanks for your input Sean
 
Could be an air leak behind the MAF from the PCV system tubes. I have seen those hoses split when they get old and you put them back on.

does it sound like its not hitting on all 8 ?



Boomer! said:
Thats what I thougtht at first, sprayed the entire engine with starting fluid and carb clean and no changes in idle.
After a little research I found it could be a injector, the ground to the fuel rail may be broke or a weak lash adjuster.

Thanks for your input Sean
Click to expand...
 
Sean said:
Could be an air leak behind the MAF from the PCV system tubes. I have seen those hoses split when they get old and you put them back on.

does it sound like its not hitting on all 8 ?
Click to expand...

It is hard to describe, it is more of a stumble than a miss and only does it under low/mid rpm load. There is a bit more duration in the P.I cams but not enough to cause what almost feels like a it having a larger/aggressive cam.
What sucks is the dude lives in Canada, I never let a car leave my garage half assed but he had to leave even after I suggest he stay an extra hour to try to diagnos. I did check all the rubber on the engine to ensure the hoses were not split or rotted, for a '97 they looked fairly new. I am going to pick up a good coil pack from a friend and try it out.
You would think if it were a vacuum leak it would do it all the time right? except for WOT. I drove it and at 3/4 throttle it would gradually go away until the next gear change.
The part that really bugs me is there is no CEL, wouldn't a vacuum leak show a lean condition throwing a code. I pulled the #8 coil wire and it ran the same some we changed wires and it was a little better, that is why I'm questioning a coil pack.

Your help is appreciated, any input ? I'm starting to go crazy !!!!! :eek5:
 
It would take a few drive cycles to get it to throw a code for lean driveability codes. Tip in stumble sounds like TPs trouble.

Sean



Boomer! said:
It is hard to describe, it is more of a stumble than a miss and only does it under low/mid rpm load. There is a bit more duration in the P.I cams but not enough to cause what almost feels like a it having a larger/aggressive cam.
What sucks is the dude lives in Canada, I never let a car leave my garage half assed but he had to leave even after I suggest he stay an extra hour to try to diagnos. I did check all the rubber on the engine to ensure the hoses were not split or rotted, for a '97 they looked fairly new. I am going to pick up a good coil pack from a friend and try it out.
You would think if it were a vacuum leak it would do it all the time right? except for WOT. I drove it and at 3/4 throttle it would gradually go away until the next gear change.
The part that really bugs me is there is no CEL, wouldn't a vacuum leak show a lean condition throwing a code. I pulled the #8 coil wire and it ran the same some we changed wires and it was a little better, that is why I'm questioning a coil pack.

Your help is appreciated, any input ? I'm starting to go crazy !!!!! :eek5:
Click to expand...
 
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