rmarkc

The FSM makes it look soooo easy.
But try it in 90 degree heat in an apartment parking lot on a 20 year old car.

After about 1 1/2 hours I'm about one third of the way done. I got the UIM and DC off.
I don't think this area has been touched since the car was built in 85. Most of the nuts and bolts come off easy enough but the coolant hoses going to the TB and the fuel hoses just wouldn't budge.
The bolts holding the fuel rail refuse to move too. Any tips on getting these off (with hand tools)?

I figure I'll replace all the vacuum lines and fuel hoses (they got a little torn ) and bypass the coolant lines to the TB while I have everything apart. I also have a banjo bolt from a 2nd gen to take care of the pulsation dampner.

Anything else I should look for?

The 3 of the intake runners are caked with carbon. 1,2,and 4 from front to back are black. I was actually able to flake off some with my fingers. Is this normal?

Mark

Rx-7Doctor

iTrader: (13)

Spray some penetrant oil like pb blaster into the bolts that hold the fuel rail on.
It is normal for that build up of gunk, either have the manifold uim and lim dunked in cleaner or scrape out. After you have done this a few times it's easy. I have done so many that it takes me approx 15 minutes to change out the injectors.

LongDuck

It's normal for the outter manifold runners to be a bit carboned up (these are the 'secondaries' which also feed 5/6 ports), but if you have a primary in the center that's carboned up, that's a bit unusual.

If you see this picture, you'll see a normal carbon pattern for a city daily driver with about 80k miles on it without cleaning:


In other words, you may have a constriction in intake pipe, DEI chamber, or even the TB that's causing A/F backflow or reduced flow in the one that's carboned up in the center. Oftentimes, the inconsistent patterns that you see are indicators of other things that are going on in the engine that are worth looking into.

Another case in point is what I found when I removed my header recently


Notice in this picture how the front rotor exhaust port (on the left) is clearly 'gunked up' with flaky carbon reside, whereas the rear port is the burnt brown powder that you'd expect? This is due to a non-functioning front '6'-port actuator that was losing exhaust backpressure due to a faulty gasket from the LIM to the actuator. Once I fixed this gasket, and replaced the actuator, it fixed the problem and also earned back some power from my engine. This could have also been caused by a sticking (open) injector on the front rotor, or a fuel injector wiring short.

The exhaust ports showed me that there was a problem, and by diagnosing and fixing it, the engine is kept in tip-top running condition. But I digress... HTH,

LongDuck

Further evidence in regard to the front '6'-port actuator not working correctly due to an air pressure leak from the actuator gasket:


Here you can see that the front rotor plugs are clearly getting fouled due to an overly rich A/F mixture, whereas the rear rotor plugs have the expected brown powder of a correct A/F mixture.

Just trying to provide some additional information in regard to your LIM carbon pattern. My suggestion would be to look into your injector wiring harness to be sure that everythings solid. If the injector that feeds the primary runner that's carboned up isn't firing correctly, you'll be way down on power. Not to scare you, but this could also be a sign of losing compression on that rotor, which would dramatically decrease the amount of air pulled through that runner, resulting in the unusual carbon pattern.

Have a look and reply back for more ideas,