88 Fj62 Surging and rough Idle (1 Viewer)

[Randolph87]

Hey everyone

So I’ve been working on my Fj62 as I just bought it a few weeks ago. Just did the steering knuckle rebuild ..it was a real treat. Luckily 8 hours later wasn’t as big a deal thanks to quarantine and not having anything to do. Anyway, I’ve been noticing some surging when I begin to accelerate right before 1000 RPMs as well as a rough idle when I’m waiting at a stop light. Not sure what to jump after first. I cleaned the IAC valve, replaced the TPS, cleaned out the EGR( filled with carbon gunk) and replaced the gasket. Any thoughts? I read about the fuel filter possible being the culprit. Was going to give that a shot. Trying to go from least expensive and work my way up.

 

[cwwfj60]

You should have started with the fuel filter, that’s a smart move regardless. Take the filter when you have it off and shake the remaining fuel out the inlet side to see if any debris comes out. I usually put a clean white towel on the ground to help see the debris.
Let us know if it’s really bad or not. If so your tank is questionable.

Then I’d suggest checking for vacuum leaks, especially the intake boots to the throttle body.

surging is typically fuel related but everyone’s interpretation of “surging” is a little different. Could have fuel pressure control issues as well.

 

[TheElegantFox]

I'd 2nd checking for vacuum leaks, I just went on this rabbit trail with my 3FE and a round of vacuum tube replacements fixed my idle issues.

 

[Seth S]

Vac leaks, battery terminal clean and tight, and ground wires / connections are the first place to start.

 

[Prairie Swamp]

Trying to go from least expensive and work my way up.

The least expensive route is to test not guess. Parts can add up. The fuel/air management system is not that complex on these. I would (and actually did) just baseline everything. The factory manual is really good at walking you thru it. A cheap multimeter is hugely helpful. Vacuum gage set. I would check fuel pressure (should be able to borrow the test set from the auto parts store) and actual fuel flow into a bucket. The TPS sensor calibration is touchy and important. Air Flow Meter as well but be very careful with this one. Lots of guys have removed the wrong screws and ruined it. Grounds, wire continuity, corrosion on connnectors.

Most components are over 30 years old and just tired. My guess is fuel pressure/flow or TPS.

 

[DirtRoads]

Vacuum leaks first. Then:

I'd stethoscope the injectors to see if they all sound the same. I'd also check out the injector wiring at the connectors to see if the wires are damaged. I had a similar problem on my FJ62, but yours seems more mild.

 

[red66toy]

Check the sensors (and their wires and terminals) that the EFI system uses to run the engine. Those can have a big impact.