davearm

Hi,

Please bear with me on this post, I fear that this may seem like a completely stupid question, but here goes anyway. I have an 89 944 turbo, 101k miles, stock except for Vitesse chips, 3bar fpr, and Boost Sciences boost enhancer. Just blew my head gasket @ VIR this past weekend. Do not have an aftermarket boost gauge (getting one), or AFM meter (getting one). How do I tune the car for the correct AFM so as not to get a lean condition (which is what I am assuming is the culprit behind the head gasket issue) without an aftermarket MAF system or other piggyback system?
Again, sorry if this is a basic question, but I do not want to fry another head gasket.

Thanks,

Dave

billindenver

Hmmm. Well, you have limited yourself a great deal. Your 3bar FPR is not adjustable I take it, so you have zero control over fuel pressure and without a maf etc you have none over the fuel curve either. To adjust Air/Fuel ratio without any control over fuel....you can only change the air. Turn your boost down until the A/F meter likes what it sees.

fast951

Dave, You have been using the chip for 2 years without setting the boost correctly? You are using a manual boost controller, how do you know how much boost you are running?
The chip you have is designed to work with certain parameters (3bar FPR, 15-16psi boost). Change any of the above, and you will be off!

edit: Before you decide the AFR is off, have you checked it? Once you fix the HG, set the boost correctly, then check the AFR. I doubt you will need to make any changes.
Of course, a failing injector, fuel pump or FPR will cause lean conditions. Once you determine the actual cause of the failed HG you can fix it.

davearm

Once I get the head gasket fixed, on goes the boost gauge, and AFM gauge. Will start from there to see where I am at. If the boost is within 15-16 psi, will look for something on the fuel delivery side as a cause for the lean condition (if it shows up lean), sound right?

sin01bst

i have an autometer boost gauge for sale too. you need it. brand new

Jeremy Himsel

Following a popped head gasket, I always have the injectors flowed/cleaned/balanced (unless they're new). Considering they're in the 20 year range, they're bound to be due for a good cleaning and you can usually get it done locally for $15 and injector. I've also seen the gasket material itself degrade around the fire ring to allow enough distortion for water to leak into the combustion chamber so it may that simple. Just be sure that your mechanic starts to look for the issue as soon as he begins the work and doesn't overlook simple things like vacuum lines, W/G lines, etc.

Renn 951

I blew a head gasket in 2004 at VIR, assumed it was just age and had it replaced with the WF gasket. Blew it again at VIR in 2006, so my shop checked the injectors and found one out of spec and one marginal.