HudsonN

99 XJ/4.0/AW4/D30/8.25/201,000 miles.

That's the best way I can describe it.

It goes from having power, to when you press the pedal nothing happens - except you kind of feel the jeep surge and then it just regains power again. Normally does it in bursts. Power, no power for 100 feet, power again, no power, etc. (I can watch the RPM gauge spike and drop).

I bought the jeep a few months back with no compression in the third and fourth cylinder. (Ran, but had a real bad misfire and the engine shook like crazy.) Put a new headgasket on along with a head a machine shop just went through. Runs and idles flawlessly.

One thing I've been thinking about and I think I'm crazy is when I put the exhaust and intake manifold on I put RTV on both sides of the gasket (which I read to do online, but totally regret). I'm thinking maybe it's possible some RTV oozed into the intake or exhaust manifold and is preventing air from going into the engine or exhaust from escaping out? But I feel like if it was this it would be constant and wouldn't surge.

It's throwing a P0132 code. (02 sensor high voltage.)

Also, the vacuum line going to the vacuum canister is broken. There's an 8" or so piece missing from the line. Just heard the vacuum leak earlier tonight as it's the first night I've driven the jeep. I'll buy a piece of tygon tubing tomorrow when the stores are open to fix this. Could this lead to surging?

Any ideas?

Just parted out a 97 XJ so I have parts/sensor galore at my house. I'd just like someone to start looking. Thanks!

LilWarWagon

I would swap out the vacuum first, next I would throw the fuel pressure test gauge on there. Make sure it's not a bad pump/clogged filter/bad fuel pressure regulator/leaky injector. Fixing faults I find on a visual inspection usually comes first, then I would check the fuel, as you can rule out a lot with a quick test. If fuel pressure is good, and holds, probably rule out a bad Throttle Position Sensor with the handy multi meter next.
I doubt it's your intake/exhaust gasket, esp on an exhaust port, you would most likely be able to hear that.
I am sure Cruiser and a few others will have more input, hope this helps a little in the mean time, I'm all about doing the simple checks first and working into the more complex problems.

Kalali

The vacuum hose needs to be replaced for sure but I'd also consider replacing the O2 sensor if it has never been replaced.

Kalali

The vacuum hose is definitely the first thing but O2 sensor might be the next step.

HudsonN

Alright. Vacuum line fixed. (Did not fix problem.)

Drove to shop to work on jeep.

Bought a new upstream 02 sensor. Haven't driven it yet to see if that fixed the problem. Could old gas be a possibility here? I drove around the parking lot (maybe did 3 miles total) and I went through one bar of fuel.

Brakes were dragging, but still that seems excessive.

Will test fuel pressure tomorrow.

When driving it to the shop when it surges I can hear this noise under the jeep like something's slamming and it feels like the transmission isn't shifting right. TPS is directly related to that so I might throw one of those at it.

HudsonN

Bump.

Put the throttle body off a 97 I just parted out on this jeep. IACs had different connectors so I swapped the 99 iac onto the 97 throttle body.

Bolted it on the jeep, plugged everything back in. Same problem. No codes. Where to look?