P1635 code after header install 2002 Corvette

[oreobadr]

Hey Guys,

Just as the title says, I installed headers and an x pipe and it seems that I am throwing a p1635 code which is a reference voltage code for the MAF and Oil pressure sending unit. From the log I took, the MAP does not go above 67 KPA and the oil pressure doesnt go above like 30 PSI when cruising.(except for sometimes it randomly goes higher to normal range). I have been driving the car daily in what is mostly open loop I think because of this code setting. I know I had to remove two grounds from the engine during the header install(which I reattached) so maybe is causing the problem? Let me know what you guys think.

Here is the log from today that I took

[joecar]

Can you visually insoect the wire harness and the wiring/connectors for the MAP and OP sensors... we're they disturbed during header install...?

Log MAP and OPS voltage and see if you make then range by unplugging them.

~ posted by phone ~

[oreobadr]

It seems pretty hard to inspect the wire harness and the connectors because they are in the back of the intake. I do not think they were disturbed during the header install as I thought the only way they could have been disturbed is when I took off and reattached the grounds connected to the engine block.

Is there a way to check the voltage for these sensors without taking the intake manifold off?

Do you know what parameters I need to check for MAP and OPS?

Also, if I have a p1635 code, is my car running from the MAF only? The car runs really good still so it seems strange that my MAP could be this far off if it is referencing the VE table.

[oreobadr]

I just remembered, when I first installed headers, I was driving around, the car died for a second, I restarted it, got it back home and I found out I cross threaded a battery terminal a bit. The cable is tight now but could this have fried a circuit?

I was reading a bit, and they were talking about using a test lamp. Would a test lamp just tell me when I have continuity when im looking at pins in the ECM? and how can I distinguish which pins belong to everything?

Thanks for help, Im newer to electrical stuff.

[joecar]

Log these: SAE.MAP, GM.EOPS, CALC.EOPS

[joecar]

I don't know if P1635 causes failover to VE.

More info: 2002 Y-car P1635 (http://www.gearchatter.com/viewtopic10421.php)

[oreobadr]

I don't know if P1635 causes failover to VE.

More info: 2002 Y-car P1635 (http://www.gearchatter.com/viewtopic10421.php)

I did log MAP.SAE in the one I posted. I will do an additional log today with the parameters you listed. I would think if the system thinks there is a fault with the MAP sensor it would not use the VE table because it is based off of MAP. It also seems that my corvette was looking through the VE table even though there was a fault so that is why I am confused.

[joecar]

Do you have a digital multimeter (DMM has high impedance imputs)...?

If you have a test light, it must have be the LED type (TL with LED has high impedance).


DMM is easier than TL because you can see how much voltage drops across any connection.

[joecar]

If you did not disturb the PCM pinouts then these should be ok.

[oreobadr]

Do you have a digital multimeter (DMM has high impedance imputs)...?

If you have a test light, it must have be the LED type (TL with LED has high impedance).


DMM is easier than TL because you can see how much voltage drops across any connection.

How should I use the DMM to see if it is working correctly?

[oreobadr]

Log these: SAE.MAP, GM.EOPS, CALC.EOPS

So it seems that my MAP is updating as it should but the Vref voltage is wrong and hence the MAP reading is wrong. It also seems that my oil pressure voltage is the same regardless of RPM or if I am running or not. I probably have a short in my oil pressure sending unit that is affecting my MAP sensor.

[joecar]

Corvettes have EOP wired to PCM (I'll check s 2002 Y-car wiring diagram later tonite), so it should be working...

[oreobadr]

So I took of the intake manifold and both my EOP sensor and my MAP sensor have a full 5V reference voltage. This means that either one or both of the sensor is bad(at least I think). Does that make sense?

[joecar]

Follow the disgnostic chart I posted above.

~ posted by phone ~