mjshira

"Intake AirTemp Sensor Open Circuit/short to +"

I have figured this one out. Because I now have the MAF kit on my car I don't have the old barn door AFM this code is intermittant. Here's the info:

"An intake air temporature sensor is integrated into the airflow sensor. If this sensor fails, the control unit adopts the emergency running program (limp home mode) and uses a fixed air temperature signal equivalent to 20 degree C or 68 degrees F."

My car is not in limp mode but I'll ask John to assure me that he has this variable covered with his kit.

I am now working on the other code to determine its cause.

Red rooster

The DME must have an Air temp signal so that it can alter the ignition timing to prevent detonation in hot weather . This function could be mapped out but that is not wise !

Good luck

Geoff
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KS400200,the oldest 964 on Rennlist,unless you know differently !

fast951

The MAF does have a builtin IAT. We use as it should be used!

Red rooster

John,

Why the fault code for a defective Air temperature sensor ? Sorry to be picky but a fault is a fault !

Geoff
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KS400200,the oldest 964 on Rennlist,unless you know differently !

fast951

Geoff, I cannot answer your question as I have not seen the car. The car had issues before the MAF was installed and the same issues remain.

There are others using the "same" MAF kit & software without any errors.
The TEMP sensor in the MAF uses a different curve than the IAT inside the AFM. We rewrote the code to support the new IAT and it works as expected.

Indycam

The fault could be in the wires to the temp sensor or in the connector to the thing .
Can he put a vr in as a test ? Will the hammer read a temp change when the vr is turned ?
If a vr can be used for a test , what ohm range would you think ?

and what ohm equals , freezing your *** off -3 cold ?

fast951

Or the fault could be that the Hammer is not able to interpret the new IAT curve??? The software reads it and uses it properly!

Red rooster

John,
OK , so you are not using a Bosch MAF and its Bosch IAT sensor ?

I am not trying to score points . I was remapping 964s 20 years ago and went through all this stuff so who cares ! I was just trying to be helpful which looks like a mistake .

All the very best

Geoff
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KS400200,the oldest 964 on Rennlist,unless you know differently !

fast951

No, not a Bosch MAF. You are correct, not using the IAT will be a mistake, which is not the case here.

Indycam

Lets all try and focus on the repair ?

mjshira

Ok let's step back here, I've put a lot of time into this thread and I don't want it to turn into a 'bash John' or I am going to ask that the thread be deleted, period.

The fault is intermittant and I agree with John that the different code is probably why the hammer records a fault.

What I am starting to think is that all these checks I am doing are going to check out and that the real cause is a higher compression ratio as a result of the rebuild, head work and cams all working together to contribute to the ping event.

So please those that have questions or doubts about John's kit, save those for a different thread. The purpose of this thread is to determine the root cause of the ping. Again, and p-l-e-a-s-e remember, the car pinged ever since I've run this engine...

So when I check fuel pressure we should then be able to remove that variable from the list. My question to the forum:

Would it be possible that this engine (re-surfaced heads, 5 angle valve job, sport cams) would have higher compression and therefore require a stronger fuel pump? Remember the engine had an adjustable FPR on it. Maybe it came with that from EBS but the previous owner didn't marry the engine to a larger pump and/or set the FPR properly?

Any experienced folks who could comment on this would be great.

Here is a shot of the car when I was out today.

mjshira

I failed to mention why I included the picture, sorry. It shows that she is rich at least in certain parts of the RPM range...

Indycam

A small cut to the head will not raise the cr much , valve job = zero increase in cr , cams = zero cr wise .
Real working compression , cams have a real effect .

"would have higher compression and therefore require a stronger fuel pump?"
I don't think so , the stock fuel pump can "do" 168 mph .

I built a corvair motor way back when I was in high school .
I had a problem with preignition .
Had to take the heads off and replace the heads gaskets .
They were to large for the bored cylinders .

mjshira

All I can tell you is that I've tested everything but fuel pressure (and I have a new fuel pump and filter and regulator) I've changed old parts as needed. I think I need to data log the engine on a dyno and set up a custom map for it. The only thing that has changed from all the testing is 'where' the ping happens. Running stock chips, it pings lower in the RPM range (around 3k) with pushed timing, it pings higher in the range.

So I am going to wait for my fuel pressure gauge and run that test when I get back in town. That should remove that variable.

In my view all of these cars have an element of unique traits. When you add headers, cams, etc. You really need to log the car and then determine what the engine is doing. there is obviously a cost to this and from a cost to HP perspective as has been clearly established the factory set up is by far the best.

Since my engine was already modified, that ship had sailed for me. Having run factory set up and experiencing this issue I've determined that data logging and some adjustments with a custom chip are needed for my car.

I've been over many threads, read through everything in book form I can get my hands on, and have pretty much concluded this is what my engine needs.

Indycam

"So I am going to wait for my fuel pressure gauge "
Electric or mechanical ?