Code 13 with early style MAP

[Turbo224]

My brother and I recently finished up a T2 swap into his 86 Shelby Charger and we have one final issue to figure out. We basically swapped the entire T2/555 setup out of an 87 Shelby-Z including the T2 LM into the Charger. We did not have a later style MAP sensor, so we just wired the stock LM mounted MAP sensor into the 87 LM. The car started right up and idled perfectly for about 15 minutes and then died. Now it will start up but will not stay running. The only code it is throwing is a 13 which is MAP sensor related. I am certain that it's wired in correctly as I have checked it numerous times. Is it possible that the MAP sensor is just bad, or does the early style MAP sensor not work with the 87 electronics?

[supercrackerbox]

Sensor should work to the best of my knowledge. That's how I did my '86. Code 13 is an error for the MAP pneumatic circuit, i.e. vacuum lines. 9 times out of 10 there's either a vacuum leak somewhere, or a line is plugged. The other 10% can be the sensor itself, but I'd go over the vacuum system real well first.

Don't feel bad, I'm chasing the same code on my '91. Problem is it's VERY intermittent.

[Turbo224]

So, a little update on this issue. We went out the other day and started the car and it idled perfectly. We let it run for about five minutes and then took it around the block and nothing seemed to be wrong. A few hours later we went back out to try again and suddenly the car wont idle. I checked over the vacuum lines again and I can't find any leaks. Any other suggestions?

[turbovanman²]

Run a dedicated line to the MAP, if your still getting issues, then change the MAP.

[Turbo224]

Good idea, I'll give that a try.

[MiniMopar]

Code 13 is pneumatic failure. That means the wiring is fine but the LM is not seeing the voltage change the way it expects. The 87 mounts the MAP much closer to the manifold, so the extra length into the interior will slow down the response some. If you have some Macgyver action in your vacuum lines, those two can add up and make the LM unhappy. You also might have some sort of blockage or moisture in there.

[supercrackerbox]

Yep, I finally discovered my fuel pressure regulator was seeping into my vacuum system, and it filled the line to my MAP sensor.