This is topic popping noise from exhaust when cold? in forum Tech Talk at Northern California Ford Owners  .


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Posted by 86xchpstang (Member # 11800) on :
 
Hello all. I have a 1986 mustang with a 90 engine. my mods are.... h/c/I, cold air intake, 340lph areomotive fuel pump, 47lb injectors, o/r x pipe, long tube headers. Might be forgetting something but for the most part that's it!

So on to my question.... my car makes a popping noise under acceleration (almost like a misfire) only when the car is cold. It will do it once or twice and then never do it again under normal operating temperature. It hesitates under acceleration while making the popping noise and then acts normal after that! Just wanna make sure I don't blow my car up. I do have a tune btw. No check engine light or anything like that either.
 
Posted by 92_5.0 (Member # 7624) on :
 
Sounds almost like its not getting fuel. How long do you let the car warm up?
 
Posted by sofresh (Member # 12393) on :
 
Had this problem also, was a cracked spark plug
 
Posted by 86xchpstang (Member # 11800) on :
 
I let the car warm up for 10-15 min? How ever long it takes for the needle to move To normal on my temp gauge!
 
Posted by 92_5.0 (Member # 7624) on :
 
Was it like this before the tune? I would probably contact your tuner and let him know whats going on.
 
Posted by i (Member # 12534) on :
 
I think to much fuel is not burning. Your computer is going nuts probably. I think you should go to your tuner to fix that problem. Check spark plugs and gap them again or replace them. If the problem still there then its your tune. Check maf clean it.
 
Posted by 86xchpstang (Member # 11800) on :
 
How do I clean the maf
 
Posted by i (Member # 12534) on :
 
[QUOTE]Originally posted by 86xchpstang:
[QB] How do I clean the maf https://youtu.be/xQGSkWEC_u4 enjoy [patriot]
 
Posted by Fostang (Member # 3752) on :
 
Of everything is mechanically sound and runs great when warm.

You sir are suffering from a lean pop. You sure the pop isn't thru the intake. Could be mistaken at times.

The maf transfer functions need to be richnened up. Could be related to long tubes and the O2s taking an excess amount of time to generate heat.

Sometimes to cure a drivability issue because of an incorrect tune you create other issues. Long tubes can be a pain to set right as you have to go in and change exhaust pulse width so the ecm knows exactly from what cam timing the sample of oxygen is being taken from.

Good luck just needs some tweaking in tune.

[ 2015-04-21, 08:51 PM: Message edited by: Fostang ]
 
Posted by 86xchpstang (Member # 11800) on :
 
I was checking things out and I have an exhaust leak where the collector meets the x pipe. Could this be the problem?
 
Posted by Fostang (Member # 3752) on :
 
It could exhaust leaks and vacuum leaks cause problems. You could try fixing it and resetting the computer.

If it continues. As a bandaid try raising the the fuel pressure at the regulator a few lbs.
 
Posted by Fostang (Member # 3752) on :
 
Also those cold air kits bring problems to the maf on their own to a daily driver with little to no hp gain.
 
Posted by 86xchpstang (Member # 11800) on :
 
How do I check for vacuum leaks?
 
Posted by 86xchpstang (Member # 11800) on :
 
So I just ran codes on my car and it gave me a 32r- egr valve control system signal out of specification and 33r-egr valve not opening properly. Could this be part of my popping?
 
Posted by Fostang (Member # 3752) on :
 
Yep. Car is running lean, unless of course they shut off the EGR in the tune.

Do you still have cats smog pump and the heads have passages for smog pump tubes and EGR?
 




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