partsguyct

Ok so I just replaced my head gasket along with putting on a 99+ intake manifold, apn header, and ford blue stick injectors. The issue now is that if I connect the vacuum line for my map sensor my idle sits between 3k to 4k rpm but if I disconnect that line it drops down to normal level but obviously runs rich. This would normally point me toward the map sensor being the culprit but if I disconnect the electrical connector for it it almost stalls completely out, one other thing is that after I got it to idle lower my cel came on with codes 12 and 13 which were for oxygen sensor and I forgot what 12 is lol. Any help is appreciated.

belvedere

Take a close look at your vacuum lines to be sure that they are all connected correctly and that none are damaged.

partsguyct

I checked that first thing, they seem to be connected and in tact, if I had info on the routing with the newer manifold I'd be set but I think I just gotta wing it

Programbo

I was wondering if maybe with the new larger intake manifold you might need to change to a MAP sensor off a '99+ XJ so tthe sensor is reading the correct pressure/volume it was designed for? Try connecting to one of the smaller ports like we mentioned. I might try changing the MAP sensor to a '99+ one on my '94 XJ this weekend just to see what happens since I have the newer intake also.

partsguyct

Ok code 12 and 13 are still coming up so, 12 is battery disconnected so that's no big deal but 13 is a map sensor code which is only there because I have that vacuum line unplugged so it looks like I'm back to square 1. Would a loose intake/exhaust manifold bolt on the bottom side be a possible cause? I'm running out of ideas

tjwalker

Why do you not suspect your map sensor as being the root cause? Sure could be. Test it or replace it.

partsguyct

Only reason I don't suspect it is because it worked fine prior to the gasket change, and if I unplug the electrical side of the connector it drops to about 300rpm until it stalls. And I'm more hoping that its not that rather than not suspecting it. And like I pointed out the code is only due to me not having it plugged in.

OverlandZJ

Did you clearance the intake to manifold at cylinder six? This is common to have to do a bit of grinding so both seat against the cylinder head correctly.

Make sure your seated on the dowels well, an intake leak could cause your symptoms.

partsguyct

I plan on double checking and tightening down intake and exhaust, that might be why my brake pedal is almost solid as well

Programbo

Yes make sure you tighten the exhaust/intake manifold bolts in the order called for and to the torque specified. I have seen a number of people have various problems after doing exhaust or intake work because they just tightened the bolts randomly or to the wrong torque.

partsguyct

It was the bottom bolts for the manifold, runs good now but I had to teach it how to idle for a second.