Thread: Popping and backfiring after IACV/AAC VALVE replacement

ok so i havent done anything different to then engine, i just changed out the IACV and AAV primary Valve. i checked spark at the coil and im getting spark at the coil, im getting s[parkl at the plugs.

im getting a backfiring/popping i dont get why?

i have been driving this car all over with no issues, and i havent changed anything at all other than the iacv and aac valve?

someone help this isnt making sense.

when i checked the spark plugs they smelled of gas and i am getting positive pressure from the fuel lines/pump


i checked all the AEM sensors
map sensor is fine
coolant temp sensor is fine
AIT is fine

nothing has been messed with, with the map/tune

Fuel pressure?

well i can check that, my fuel pressure gauge shows positive fuel pressure.

and when i pull my spark plugs i can smell gas and they are covered in gas.

this all started after i replaced the iacv and aac valves. the primary is used but in excellent condition and multimetered within range and the air regulator is brand new which doesnt make any sense i never heard of a iacv or aac valve causing a no start condition.

its like its cranking over and not even trying to fire, and its backfiring.

i pulled the valve cover and everything looks ok, the timing chain is very taunt, theres about 20k or less on the timing chain and assembly and 5k miles on the upgraded timing chain tensioner, i also still have the timing chain guard. so i dont believe that the timing could be off, i will check compression and rule that out

before this i was driving around, getting groceries,meds ect ect ect didnt mess with anything didnt adjust anything, just changed out the valves thats it.

Ground strap?

Sounds like a boost leak, what's the location of the map sensor and how do you have the AAC/iacv plumbed. Sounds like your running aem, on a lot of the car running aem I find it simpler to not use the iacv or AAC. Aem does a very good job that you can just bypass them. So to sort out this issue disconnect the iacv and AAC wires and see if the issue continues. Then block off the iacv and AAC hoses to see if that helps.

when the car was tuned, they setup a general idle control, they couldnt get the iacv to command so they said they would set the settings and then that way when i get a new IACV/aac it would already be set up.

i have been driving on the old iacv/aac no problem, however they start to get real bad not properly working so it replaced the primary and aux valve.

the car wont even try to start it just cranks and cranks it doesnt try to fire or miss just cranks, and sometimes backfire i presume from cranking and gaining fuel then somewhat sparking and creating combustion? just my take on it.

i dont really know where to start, i checked for spark and i get it but it might not be enough? i checked at both coil and plug wire,

i am getting fuel in all cylinders.

when cranking and i try to give it gas it doesnt seem to want to do anything, normally the engine fires right up no problem.


i went into aem and checked all of the following sensors
map
tps
ait

all were within parameter spec

Try disconnecting the the iac and AAC. Sounds like when they tuned it they set start up enrichment with out iac control so now that you have a working iacv your getting an incorrect mixture. Let us know how that works.

No they tuned the enrichment for iacv and a a c it worked a d idled decently but it was tuned more for working iacv and a a c valves.

I did a compression test I got around 10 psi across the board with no divination more that 10%. I have 8:8:1 compression pistons with a thicker cometic head gasket so those numbers around right about where I thought they would be.

I had to wait until my mom got home to do a spark test I tested. I'm getting no spark out of the distributor I am starting to think the cas might have went. I had 9 me go before and the symptoms are simular.

I'm getting fuel and good fuel pressure of compression. ??

are you getting stat sync when you start cranking?


Check for spark?

my stat's sync while the car is off the stat'd sync says off

but i read that the stat's sync comes on when the car is running?

i checked for spark, and im not getting any spark from the distributor, but i manually cranked the engine and the fuel injectors prime?

so can i still be getting fuel injectors priming but no spark?