3.2 owners in Mississippi / NW. Alabama area, I need help

[Hans H]

I bought a 1986 targa a couple of years ago and it had a miss and backfire when I picked it up. I didn't know much about the car, or Porsches really, at the time and figured it was cheap enough that at the price I could afford to have whatever issue(s) taken care of.

Over the years I have been working to eliminate the backfire which sounds like it is coming from both the exhaust and intake. To try and get rid of it I have tried the following in this order:

0. Had valves adjusted
1. Cleaned out fuel tank and lines
2. New plugs
3. fuel filter
4. Cleaned and checker injectors
5. New injectors
6. New cold start sensor
7. New rotor, cap, wires, plugs again
8. Checked and adjusted MFI arm

Much of this I've done with help from a mechanic friend. Every time he says, I think we got it this time, start it up and no luck...

He is now thinking the valves are not closing all the way and that the top end may need rebuilding. That is not small change for me so I am looking for an experienced mechanic to give a second opinion before I dive into a top end rebuild.

I checked each cylinder and they are all at 172 to 177 psi. Which from what I read on the forum seems decent? I could not do a leak-down test but figure the compression test was a good starting point?

The car has about 95k miles on it and does leak a good bit of oil. I'm not sure if there are vacume leaks or perhaps an intake leak that could cause this issue? I really need someone who knows these engines well.

Any references are appreciated, I'm willing to meet up with any member who might have time to help.

Cheers,
Hans

[shadowjack1]

Try Howard Freeman. He is on this board and lives in East Mississippi.

[Hans H]

Thanks Shadowjack1 I'll look for him.

[DRACO A5OG]

How is your AFR and Base Idle after she gets to operating temps?

[LakeCleElum]

You have done a good job of checking the common causes.....One observation, you don't have a "MFI Arm" on your model.......Dueller lives in East Mississippi, he may know someone?

[COLB]

Originally Posted by LakeCleElum

You have done a good job of checking the common causes.....One observation, you don't have a "MFI Arm" on your model.......Dueller lives in East Mississippi, he may know someone?

I think he means AFM arm.

[Hans H]

Draco + et al,

Thanks for the comments first off. It sounds like there are a number of well informed people in my general area.

The idle is fairly steady and she starts and smooths out after a minute or so. It seems the backfire happens much more after it is warned up and it gets worse the warmer it gets. That said, it seems that above 2000rpm when driving down the road it is not backfiring or missing. It could be that I just cannot hear the backfire because of my custom exhaust and because its a targa so it's hard to hear much of anything beyond wind noise!

And yes, I did mean AFM sorry for any confusion. That adjustment did rid me of balky excelleration below 2000rmp and it is smooth and consistent thru the range.

Any other advice on where to look is happily accepted.

Hans

[Hans H]

Good news, kinda? $$$

I got a hold of Howard Freeman in Meridian, MS (super friendly/helpful on the phone) and he told me it is almost certainly the insulators and gaskets on the intake manifolds. I hope to have it at his shop in the next couple of weeks as I'm not sure this repair is something I am ready to take on.

Cheers,
Hans

[DRACO A5OG]

He is saying you have a vacuum leak at the base of the intake manifolds. You can confirm this by spraying some starter fluid at the 6 suspected areas.

[Hans H]

Just to follow up, Howard was great and I have been driving the car for about 4 months with no issues at all. If anyone is looking for a great mechanic in the MS, AL, TN area I highly recommend Howard Freeman in Meridian, MS. This guy knows his stuff.

[DRACO A5OG]

Outstanding!

Now go and enjoy her :-D

Did he show you the blown gaskets?

[Reiver]

Yes, Howard is a great Air cooled guy....he rebuilt the 930-10 euro I have and it is just sweet.
Runs cool in Az heat and I never have to add oil between changes. Maybe uses 8 to 10 oz in 3 plus K miles.