Thanks Mobile....

 

That's sort of correct, but not 100% correct regarding the knock sensor.

Although there isn't an actual knock sensor, the PCM uses the vacuum reading from the MAP sensor to control timing advance and ultimately spark knock. Replacing the MAP sensor often will correct a spark knock condition...carbonized cylinders aside.

 

If I had a bad MAP sensor, would it have thrown a code Alloro?

Where is the MAP sensor located and is there a way to tell if it's bad with no code thrown?

 

The MAP sensor might not be 'bad' as much as it's calibration could be off. Because yes, if it were bad, broken, no good, then you would get a code. It's on the front of the throttle body/air horn.

 

Is it possible for me to recalibrate it with basic tools or can it even be done by the dealer?

 

Nope and nope, if it's bad it gets replaced. Give me an email address and I'll send you the MAP testing procedure in a PDF file.

 

sent you my email addy Alloro. Thanks for your time.

Today, I changed out #5 thru #8 plugs to Champion RC10YC gapped to .040
Two heat ranges cooler. After a test drive with the engine heated to norm...it has reduced the knock to some degree. Not nearly as bad as it was, but still there.

I have to take it to a shop for the other plugs as I can't get to them.

 

Is it possible to adjust the timing on these 5.2L engines ( 99) or is it only controlled by the PCM?

If timing is not adjustable, what happens when one turns the distributor?

 

No the ignition timing is not adjustable. Yes the ignition timing is under the complete control of the PCM. It does this by using the crank sensor, not distributor position.

Turning the distributor adjusts the fuel injector timing. The pick-up coil (cam sensor) inside the distributor is what the PCM uses to time the firing of the injectors. The fuel injector to ignition timing synchronization can only be calibrated (by turning distributor) when using a DRB-III scan tool, most commonly found only at the dealer.

 

Hi Alloro,
As always thanks for your input.

Found a buddy of mine who actually had a vac pump. He helped me test the MAP sensor and the readings were consistent with the info you sent.

Looks like I'm going to need to replace the plenum.

I found a few posts on other boards suggesting several options.

1 - Mopar Performance M1 Intake Manifold
This seems to be the entire IM without a separate plenum...it seems to be all one unit.
About $275 inc. shipping and tax

2 - Hughes Engines sells a full plenum repair kit:
quote from Hughes

"This kit will replace the plenum plate with a one piece, high strength, 1/4" thick aluminum plate. It is supplied with all new, Grade 8 fasteners, new intake gasket set and detailed instructions"

about $130 inc tax ++ shipping

What do you think of these options?

The hughs kit is cheaper but is it any good?

Will I need any special tools to do this job?
Is there an easy way/tool to help remove all the old gasket material?