Offroad rig perf questions. bear with me now.

[JT_Law]

Putting this in here because the performance section looks to be all about the go-fast on pavement crowd.

The 90XJ I am building for trail use was once my dads, then my GFs, now mine. Wjhile she had it the GF overheated it once till it locked up, after it cooled down it starts and runs fine, no smoke or anything other than some oil seeps I am working on chasing down.

When it was dads about 6 years ago he had a tune up done, I just put all new injectors in it.

After her overheat last year it seemed to have lost about I'd say 20% power, and still idles a bit rough even with the new injectors.

Any ideas on what I shoud look to to try and regain the lost HP? Power is becoming an issue even with 31's and I am looking to regear from 3:53 to possibly 4:88's and go to 33's or 35's. Yeah, I know, 35's on a D35 not the greatest combo, but I have a 12k winch and know how to stay off the skinny pedal when need to lol.

Thanks ya'll

 

[Matthew Currie]

I think your first order of business is a compression test, or at least for preliminaries, a vacuum test. You need to find out if the engine is fundamentally healthy. Overheating an engine until it seizes is a quick way to break in an engine, but not necessarily the best.:jester:

If you don't have access to a compression gauge, get a vacuum gauge. Cheap and very useful.

Seriously, I'd look at the fundamental innnards of the engine first, then work my way outward. Even if the overheat didn't cook the rings or do other internal damage, it might have affected something like the manifold gasket enough to cause bad vacuum. And don't forget the plugs. As I found out after sort of forgetting to check my plugs for about 100 thousand miles once, the stock XJ ignition system will fire plugs that have no right to work at all.