Thread: Popping and backfiring after IACV/AAC VALVE replacement

Another thing that i dont get is when i am cranking i am not getting negative vacuum? i dont see how i could have a boost leak i havent messed with anything at all.

i havent messed with the tune, i havent changed anything at all. i havent removed any hoses pipes or anything

I believe the stat sync should show ON once it reads the position of the CAS....
So check your dizzy/cas

i think my dizzy might be bad, they have one at the junk yard i can pick up for 34.00, if this fixes the issue i dont have a problem investing in a new dizzy internals of course

here are some screen shots





again i have not touched this tune, it cost me $1,200.00 to have this professionally tuned hours and hours on the dyno fabricating parts, driving it is ALL i have done to it, didnt change anything didnt add on anything, take off anything....and surely did not mess with a hair on the tunes head.

its just so weird that out of the blue the car wouldnt start, i picked up my medications from walgreens, came home and it sat til the new aac and iacv came in,but thats nothing new at one point it went for over 4-6 months without a start and started right up with no problem.

so this is off for me

page 68 of aempro pdf
===============
===============
5.1 Pickup Confirmation
Pickup Confirmation
Before the engine will fire the coil(s) and injection fuel, the cam and crank sensor
must be synchronized. If this is a plug n' play application, everything may be fine but
confirmation is always recommended.
· Open AEMPro and Connect
· Go to Options | Injector and uncheck Active for all injectors being used.
· Because the injectors are disabled the engine will not start
· Open the Home template
· View the parameter Stat Sync'd, it should currently be OFF
· Crank the engine and verify that Stat Sync'd turns ON within a few seconds.

replaced the distributor today that i got from a yard it made no difference, i checked the spark at the coil and it was bright white. i checked the spark at the distributor and it was bright white but the coil seemed to be arching taking the spark.

when i spin the distributor it activates the injectors.

im really lost on this.

this makes no sense whatever....im extremely mad

Is the correct tune uploaded?

Looking at your screenshot - O2 is showing really rich

Does the map load drop down when you begin cranking? If its not then you might have a vac leak somewhere.

The uploaded tune is correct.

I don't know what boost leak I could have I haven't touched anything

There is no O2 sensor on this car it's fuel based map tuned. No O2 sensor is used.

I've checked all the sensors and they all look with in spec.

I am getting a lot of backfire but I am also getting a lot of cranking and no firing.

As far as the map sensor it seems like it's working well as far as voltage.

When I crank the engine I am not seeing a negative manifold vacuum. And I think I should be seeing a negative vacuum.

I haven't messed with any vacuum lines or or boost lines or pipes.

The only thing I did do was use black permatex gasket maker for the aac on the side of the intake manifold. But even then it should still try to fire the gas as its not when it cranks and cranks it doesn't even r y to fire. But the coil spark is bright white.

I checked the timing and there are 22 dots from dimple to dimple which is where it should be.

When I crank the engine over it cranks fast and there isn't any abnormal sounds or anything like that. Imo rules out bent valves ect plus I get good compression across the

It just doesn't make any sense.

You keep saying you didn't touch anything but the title of this thread says iacv/AAC replacement. In my book replacing the iacv/AAC is touching something. So to clear things up, did you or did you not remove and replace the iacv?

If so that is the factor of change and should be the first route of correction. Like I stated above this sounds like a vacuum/boost leak. You also stated you see no vacuum while cranking the engine over, you won't see full vac(19-20) but you should see some change. Double check your map sensor and it's source of vacuum.