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Exhaust popping and speed drop on cold start

4K views 30 replies 5 participants last post by  Bullitt95 
#1 · (Edited)
Greetings,

I have a problem with my mustang. I am from Bahrain and my mustang is imported from the US.


My car has enhanced performance parts which are JLT series 3, BBK throttle, C&L mainfold, and cat delete. It has been tuned. The problem is that when I do a cold start, the exhaust starts popping (just like a back fire) and there is some input lag in the throttle.

i replaced spark plugs and ignition coils and fuel pump and all filters

the problem only in the 10 min of the start after that every thing work good

video of the problem



the check engine has gone now and the fuel level is work ok now
 
#2 ·
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#3 ·
my first suspicion is the tune; something is off when the engine is cold, maybe running too rich . . . have you talked with the tuner about the issue?
 
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#5 ·
maybe you can work with the tuner to datalog it when the problem is happening, so they can see what is happening -- I assume the dyno tuning was done when the engine was already warmed up, so they did not see the issue
 
#7 ·
Eyad, as salaam alaikum. :)
To me it looks like your problem is the throttle body. I suggest you remove it and clean it thoroughly inside out. During reassembly make sure that the JLT intake pipe makes a proper air tight seal on the throttle body, make sure that the conical air filter is properly seated onto the JLT intake pipe, and make sure you have the MAF sensor correctly oriented.
Good luck and let us know how it goes. If you're still having problems, try swapping the stock throttle body back into the car (cleaned of course).
 
#11 ·
thx brother we found the problem it was from the exhaust to much air because of the air intake and the throttle bbk and mainfold and i have the stock headers i have to change the headers to performance one like bbk the stock one cant work good with my parts on it thanks for the help
 
#12 ·
hmmmm . . . not sure that is correct diagnosis, car should be able to run fine with the stock exhaust manifolds and the intake modifications; even though it might not get full performance from the intake mods without the exhaust mods . . . this feels kinda like the shop is looking for more work

the EFI system should automatically adjust itself for any additional incoming air, if the tune is correct

upsized aftermarket throttle bodies generally are not needed and produce very little if any gain, but do produce problems often, I'm still guessing that is the issue (or the tune when it is cold)

but if the headers fix it and you're happy, then we're happy too!
 
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#13 ·
well the shop is not working in exhaust i have to go to exhaust shop but he told me the mass flow sensor most take time to realize to see the deferent between the stock exhaust and the after market parts after checking all the car parts and the electronics i think maybe he is right
 
#14 ·
hmmmm . . . well I guess that shop is not just trying to sell more parts and labor, that's somewhat reassuring . . . but that bit about the MAF does not make sense to me; as far as I know, the Mass Air Flow sensor simply measures how much air is coming in the intake and it has nothing to do with the exhaust

during all this work, has the battery been disconnected? if not, it might be worth a try: disconnect the battery for about 20 minutes; this will reset the computer and then it will have to re-learn some of its parameters and that might help it correct for anything that has changed . . . but I doubt it (when you load a new tune it does the same thing, and I guess you have loaded a new tune recently for the modifications)
 
#15 ·
i disconnect the battery that was the first think i did the new tune was for the JLT only the other parts was there and worked the same and the same problem but the MAF i dnot know if he right or wrong but its only for the first 10 min i can live with that until buying some new headers for it
 
#16 ·
What will you do after you spend the money on new headers, and find out it’s still doing the same thing?
 
#17 ·
in the end now or in the future i will change the stock one and i will do it first and we will see if works or not because i dont know what's the problem after all changes and the checking of the car i will give it one more try and i will take it to electronic shop for full checking of the electronic wires inside the car and the engine bay i hop he can find something
 
#18 ·
I can’t diagnose your problem over the internet, but it’s likely (imho) to be related to your new throttle body, and/or the tune. Tuners aren’t necessarily good diagnosticians, but you need a good datalog and an independent calibration expert to examine the log files. Someone who isn’t worried about defending their own work proficiency. I’ve been through this before myself. You needn’t feel any obligation of loyalty to the current tuner. I would would bite-the-bullet and seek a second opinion from someone else. Just my 2¢ worth of opinion.
 
#19 ·
I can’t diagnose your problem over the internet, but it’s likely (imho) to be related to your new throttle body, and/or the tune. Tuners aren’t necessarily good diagnosticians, but you need a good datalog and an independent calibration expert to examine the log files. Someone who isn’t worried about defending their own work proficiency. I’ve been through this before myself. You needn’t feel any obligation of loyalty to the current tuner. I would would bite-the-bullitt and seek a second opinion from someone else. Just my 2¢ worth of opinion.
thank you for helping me i will take your advice and i will got to other tuner for checking the data log and im not loyal to him :D just before this car i have the same one but stock i take it to him and he tuned it was good but now i will see other tuner for it and thanks al lot for helping me
 
#20 ·
if I was in your situation, I'd probably shoot "Lito" an e-mail, describe the problem to him, and ask him if he thinks he might be able to identify the problem with a datalog and provide a tune to address it (if it is a tune issue) . . . I am not sure if it is OK to post contact info directly here, I can PM it to you if you want

or see if there is another tuner in your area who works with datalogs in a similar manner
 
#22 ·
i found the problem its was the front passenger side O2 sensor not working and the fuel pump was not good the workshop who replaced the fuel pump was crazy the fuel pump was not for ford and not working good in my car so i changed that and retuned and the tuner turned off the O2 sensor and make a fake read to the car computer to work good and after that the car was fine no problems and all the power is back thanks all for helping me
 
#24 ·
Are the O2 sensors turned off? The O2 sensor was not causing the problems when the motor was cold because O2 sensors aren’t used until the motor is at operating temperature (warm). The fuel pump was the issue. Turn the O2’s back on if they are still “turned off.”
 
#23 ·
thanks for the update and glad to hear you got it figured out!
 
#28 ·
Eyad, since you've deleted the cats your tune will need to be adjusted as follows:

1. Front O2 sensors should be enabled as normal.

2. Rear O2 sensors should either be disabled altogether, or left enabled but installed in MIL eliminators that are welded in the midpipe where the cats used to be.

These measures will solve your cold start problem.
 
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