Erratic idle

[HITEKBALANCER]

My Grand marquis has an erratic idle. It is supercharged.
we changed egr as it coded and the o2 sensors. we are thinking Idle air control. Anyone have any thoughts?

[Local Boy]

IAC or vac. leak...

ALOHA

[larryo340]

Something in the tune ????

[HITEKBALANCER]

Possible tune and we can't find vac leak. It ran great after the dyno tune. We made 400+ hp and ran perf. for about 500 miles. It recently started the idle issue.

[Local Boy]

In that case, it won't be the tune...

Does it run OK, while into the throttle ?...Just idle has the problem?

When you say "erratic"...Do you mean that the motor "surges" and drops in RPM's, while idling?

Need more info...

ALOHA

[MENINBLK]

At this point in the life of your Marauder, start thinking Coils.
I have replaced two and I think a third is going already.

[red]

Possible tune and we can't find vac leak. It ran great after the dyno tune... It recently started the idle issue.

Have you tried re-flashing the PCM with the dyno tune? If adaptive learning was kept, then your fuel trims could be messed up by now.

[Marauderjack]

Disconnect the negative battery post and reset the AL.....only takes about a minute and you should see a big improvement??

If this works you may want to have your tuner turn the AL...OFF!!

Mine doest this periodically since my AL must still be on!!!

Marauderjack

[Zack]

Be 100% sure all the connections are tight before replacing hard parts.
And yes, definitely turn adaptive learning off.

[HITEKBALANCER]

All excellent replies. The idle just cycles from about 900 rpm to almost a stall every 1-2 seconds. I have a call into my tuner. I will try the battery disconnect. I think it is in the tune because it has no balls through the midrange.

Thanks guys I will let you know what we find.

[Zack]

All excellent replies. The idle just cycles from about 900 rpm to almost a stall every 1-2 seconds. I have a call into my tuner. I will try the battery disconnect. I think it is in the tune because it has no balls through the midrange.

Thanks guys I will let you know what we find.

I dont think its the tune.
The fact that its down on power in the midrange tells me something came loose and you are loosing boost.
If thats not the case, pull the plugs and look at them for a closed gap.

[magindat]

It does sound like a physical issue. I'm gonna point you toward the PCV system. It should have a check preventing boost from entering the crankcase but circulate air from one valve cover to the other in a vac state. That would explain the vac leak AND the lack of 'balls'.

Just my , FWIW...

Red's and Jack's adaptive learning suggestions are a start. If still same trouble after battery off 'reset', then go through the PCV system.

[HITEKBALANCER]

We found water contamination in the intake. The cause may be a wet maf sensor. The fiter placement makes it vulnerable to water contamination. The filter was soaked.We checked pcv system nothing obvious there. We dried everything out and we are putting it back together now.

[Zack]

Not good.
There are 2 members here that have nuked engines because the filter was behind the bumper and took on water, causing hydrolock.
Put a pre-filter on that thing ASAP.

[HITEKBALANCER]

Wet parts not the problem. Anyone had a intake manifold crack? It has been said that this can happen. Thats where we are looking now. We did get a lean code on the o2s