Hi all,

First time owner of a Samurai, its a 94, 1.3l, 125k and I was rather disappointed with the fuel economy. Standard size mud tires, 2 inch lift, Soft top, and about 19-20mpg. I was hoping for mid 20s. Anyhow, its was running rich, when I got it, so I sea foamed the engine, which improved the running significantly, but also resulted in a further rich condition (makes sense). So I figured the O2 sensor was out, voltage fluctuated too much for my cheap multi-meter. The old air filter wasn't looking so hot when I replaced it.  When I removed the heat shield with a new O2 sensor in hand, I found my exhaust manifold cracked to hell.
I plan on replacing it (1.6 manifold worth it?), just wondering if this could cause the rich condition. I've heard extra O2 can be introduced through the cracks, but I'd of thought the manifolds would be under positive pressure when the car was running, with exhaust gas being blown out the cracks.
Also, its got a head tick.. checked the valve lash twice, they were fine. I thought the sound was far too mechanical to be an exhaust leak, hopefully I was wrong.
Opinions?
Thanks
Luke

Unless it is a 1.6 8-valve exhaust manifold, it will not fit.

The better choice is an aftermarket manifold.

I have a Thorley that I bought in 2002 when I had a 1.3 block.  When I switched to a 1.6 8-valve, it fit perfectly.

In both situations, the manifold added perfomance and economy (mostly  performance) to my driving experience.

Today, I still can get 22MPG despite some carburetor problems (a weber that needs a bit of TLC) and a heavy right foot.

Replacing with a cast iron manifold is just putting off the same problem for a future date.

Pacesetter and (I believe) Calmini also sell an aftermarket manifold.

I hope that this helps!

I also suggest going with the Thorley header, fantastic piece for the money.

Damn, those are all nice looking headers, but as a modest student college student, my options are rather limited.  Found a used one $35 on ebay. Looking for economy more than performance.. But I do plan on a 1.6 16v when its feasible.. That'll be fun.
So any thoughts on cracked headers causing a rich condition?  I'm guess I'm confused on the theory behind it. Also the MAP checked out, will be replacing the coolant temp sensor too.

Yes, I have heard that a cracked exhaust manifold can cause a rich condition.  It messes with the O2 sensor readings, so the O2 sensor tells the ECM that it is running leaner than what it actually is, so the ECM puts more fuel into the engine, which causes it to run rich.
I don't remember where or who it was, but someone tested a 1.6 8V exhaust manifold vs. an aftermarket header.  The 1.6 8V manifold flowed almost the same and produced nearly the same HP as the header.  So if it were me, I'd just look at getting a 1.6 8V exhaust manifold and save your money.  But if you buy used, make sure they pull the heat shields and check the manifold for cracks....they are as prone to cracking as the samurai ones are.

As far as I remember it was the 16v stock mani that flowed so well, every 8V I have seen responds far better with a tri-Y header than the stock mani.

And yes a crack in the ex mani prior to the o2 sensor introduces fresh air to the exhaust gasses, this additional oxygen makes the o2 sensor think the engine is running VERY lean and litterally dumps raw fuel into the engine. I was sitting at around 7mpg untill I replaced the stock mani with a header. The savings in fuel paid for the new header within days! LOL

I searched several junkyards and couldnt find a stock 16v mani that was not cracked!

Also a cracked mani that is causing the ECU to dump alot of fuel will damage the cat and COULD cause it to actually catch fire.

Thanks you guys,

Looks like the 1.6 8v exhaust manifold is the way to go. Too bad the 16v isn't compatible. I guess I'll patch it with some thermosteel until I get my hands on a new manifold.

Also, just to be sure, the geo tracker has got the same 1.6 8v in it correct? (89-95)
Tracker searches are turning up more manifolds.

Also, just to be sure, the geo tracker has got the same 1.6 8v in it correct? (89-95)
Tracker searches are turning up more manifolds.

Yes.  As long as it is a 2 door tracker, it will have a 1.6 8V in it.  The 4 door trackers had the 16V.