yeah but ace like i said, i sprayed soapy water to check for leaks around manifold. wouldnt that be sufficient? i mean id hate to scratch my nice chrome chevy valve covers taking them back off lol!

 

But what if the port is leaking at the bottom and sealed at the top?

I just looked on my LT1 heads and if the LT4 heads follow suit, then the casting number should be around the #3 intake spring or the #6 depending on which valve cover you pull. I think the driver's would be easier.

 

Hmm.. I guess you make a good point.

 

I don't mean to be difficult, but you are in a situation to where the parts are not known. So we need to know what parts you have and then work from there....

These are things your tuner will need to know as well. So this work is going to have to be done if you plan on keeping the car and sorting it out. It's a pain I know but necessary.

 

I've had to deal will a P174 and P171 on my brother's Ford minivan. Of all things, the bottom intake bolt seals go bad over time. That was more than enough of a leak to cause it to throw those codes.

 

Hmm.. Interesting, and you are completely right. thats why i hate the fact that I got it when the work was done and I didn't do it. This was a first and last.

 

From what information I've gathered, there are also different intake manifold gaskets between the LT1 and LT4. It could be something as simple as the LT1 gaskets used instead of the LT4.

The situation I spoke of on the minivan involved a two piece composite intake. The bottom of the intake bolted to the block(from the inside) and was sealed with bolts that have thick seals under the bolt heads. Over time, the engine oil breaks down the seals and causes a leak. It's a common problem on that model minivan from what I understand. The fix was not too bad....just replace the bolts and seals with new ones. We also replaced all the port seals as well.

 

The 3.8 has 4 sensors total, but three of them are pre-cat sensors. The 98 factory manual (page 6-1223) shows the 3.8L has a precat sensor in each bank (Bank 1 HO2S 1; Bank 2 HO2S 1), than a combined pre-cat sensor at the inlet to the single cat (Bank 1 HO2S 2) in order to get a combined exhaust signal to compare the single after-cat sensor (Bank 1 HO2S 3) to.

I have a factory LT4 intake manifold, and it has the cutouts for the EGR valve and the riser tube. Yes, the LT4 intake has its own gaskets.

 

Yes I just read it has its own set of gaskets as well, and Im hoping this is not my issue.

 

Check the part #'s, using the link Eric posted:

http://www.grandsportregistry.com/lt1vslt4.htm

 

I have used madz for my tunes for years. He has always provided myself with great service. I have recommended Ion to any and all.
Good tunes also.

hth

andy schuck