AoA

96' 4.0L auto etc. Seems to hit fuel cut at 4200rpm to 5krpm, possibly ignition cut. Fuel pressure is spot on. 270k but top end has been rebuilt and completely new ignition system besides the actual distributor stem (has no play in shaft) did it before and after rebuild and ignition system replacement. Hardly milled the head, mild cam 232 nothing crazy. Stock intake, 2.5" exhaust with flowmaster 60 series.

From my google searches seems that it [I]MIGHT[I] be the CPS but, from the thread I read that in they all seemed like idiots so I don't know...

And go!

jake92

It might be the PCM regulating the fuel or ignition to cut out at that high of RPM to prevent engine damage.

RTorrez1

When it dies does it shut off like you turned off the key or does it give you any kind of warning? It could be the CPS or ignition coil. When you went through the ignition system did you replace the coil? When my coil went out I thought it was the CPS because it had the exact same symptoms as a bad CPS.

AoA

Redline cut is 5k only said 5k because it shifts right before it'd cut out from redline. Shouldn't do that before redline.


No doesn't shut off or 'warning' per say. It cuts then a millisecond of power cuts again and repeat, maybe 2-3 times before it upshifts. Yes coil is brand new as well.

RTorrez1

That sound like it may be the CPS is on the way out. When mine was on it's way out it would do the same thing. It would cut out and come right back on until it got worse then it would completely die and I would have to put it in neutral and restart it then it got even worse and I would have to pull over and wait 5-15 to let it cool down then it would restart.

AoA

Ok, yea that's what I've kinda been reading well there goes $70 down the drain!

RTorrez1

What ever you do get an OEM one the after market one are garbage. Most of the time the are bad right out of the box and if they do work they seem to fail prematurely.

AoA

Ah ok ill keep that in mind!

belvedere

Unfortunately, things like this can be a real b!tch to diagnose. The way I see it, you have two options.

First, you could start changing the most likely suspects: CPS, coil, etc. (BTW, when is that last time a good tune-up was done? Plugs, wires, cap, rotor...) I do think it's ignition-related.

Second, being a '96 and OBD2, you could take it to a good shop with a good diagnostic tool, and have them look at the data at the time the problem occurs. They might be able to nail it on the first try.

So, you take your pick: replace (probably) more parts, or pay a shop, and pay the mark-up on the part(s) plus the labor. It just depends on your mechanical ability, time available, etc.

One more thought: I would try refreshing all the ground points in the engine compartment. Even if it doesn't fix your problem, it can never hurt on an XJ!

AoA

Read original post, CPS is only thing left.

I have a code reader with operational data and everything was normal.

My dads been a mechanic for 30+ years, I've been messing with jeeps for years. Shop would be useless.

Grounds have been replaces during the top end rebuild 3 days ago.

Thanks though...

skife

wondering maybe since you have a bigger cam are you pulling in to much air and one of the sensors is maxing out on voltage or something?

AoA

If you read the original post, I said that it did it before the cam/rebuild. And the 232 is barely a bump up from stock.

AoA

Update: replaced CPS and it still does it. Only thing left is the ECU, the local pick n pull have a couple 97+ with the ecu still intact. Would a 97+ ECU work with a 96 as long as they were both aw4 and what not?