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Re: Surging on acceleration. [Re: Trailmonkey] #1106312 06/06/21 11:45 PM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
Spray cleaned the MAF and it ran great, check engine light wanted to stay off even, but it's back at it again and can't get a can of that stuff anywhere.
Gonna get a remanufactured unit tomorrow and see if that is actually the problem, but as good as it ran after a shot of spray I'd say it is.

Thanks guys.


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
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Re: Surging on acceleration. [Re: Trailmonkey] #1106332 06/11/21 05:42 AM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
Damn, she runs soooooo much better. Lol
Remanufactured Mitsubishi MAF sensor unit from O'Reilly's did the trick.
Gonna plug the Idle control back in and see if It was even a problem, seemed to do better when I first unplugged it, but not so sure it had anything to do with it.


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
Re: Surging on acceleration. [Re: Trailmonkey] #1106382 07/21/21 09:53 PM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
Well thought all was good but NOT.. still doing it, but at times never totally clears up, I'm really thinking FPR.. got a new one, will install it when I replace the hydraulic valve lash adjuster on the front pass side, hoping to fix that damn tapping lol.
I may even pull the injectors and check/clean..

Fuel pump seems good, new filter. Pulled and checked catalytic converter and it looked good, pulled muffler and it was all rusted inside, swapped it out with a 2008 Crown Vic cop car muffler, sounds very nice now. So no exhaust blockage.
Anything as in timing that could cause this ? The distributor's inner disc looks clean under the dust cover so I left it alone.
Seems to me it has to be something with the fuel pressure regulator or throttle body ?


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
Re: Surging on acceleration. [Re: Trailmonkey] #1106383 07/22/21 03:32 AM
Joined: Feb 2005
Posts: 7,436
rxinhed Offline
Trail Leader
*****
Have you examined the electromagnets and timing advance weights (if any)?

Re: Surging on acceleration. [Re: rxinhed] #1106384 07/22/21 03:49 AM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
Doesn't have any, has an optical reader that counts slots in a rotating disc, ecu advances/retards timing.


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
Re: Surging on acceleration. [Re: Trailmonkey] #1106385 07/22/21 04:21 PM
Joined: Oct 2020
Posts: 12
L
Lev_from_CA Offline
Need a Spot
Have you confirmed mechanical timing? Is the harmonic balancer/crank pulley wobbling? If so, then the crank pulley bolt may have gotten loose (or was not tightened to spec during last timing belt job) and wollered out the woodruff key slot that aligns the timing gear with the crankshaft. This can cause weird runnability concerns some times (I'm dealing with this on a 2002 Montero Sport with a 6g72 right now). The hydraulic timing belt tensioner is also known to fail if run far past its service interval.

The work to fix it, depending on how much damage was done, is:
  • get down to the crankshaft; similar amount of disassembly as a timing belt job, so this is a good time to think about a full timing kit refresh (also, crankshaft and camshaft seals)
  • clean up the key slot; iirc Loctite 660 or other similar retaining compounds can take up to about 0.5mm of lost tolerance here (the Miata guys have a long, storied history with this repair; "Pine Hollow Auto Diagnostics" on Youtube repaired a Montero Sport with a wollered out key slot by mig-welding it, but he is a more courageous/skilled man than most)
  • replace the woodruff key with a new one; original Mitsu is great, but the keys are a standard metric size that you should be able to find non-model specific options for (use caliper to figure out necessary dimensions)
  • replace crankshaft pulley bolt and washer with new updated part (these were recalled, iirc your year also).
  • reassemble everything:
    • chase all threads (threaded holes and bolts, both), blow out all blind holes with compressed air
    • use plenty of loctite (some people use high-strength red for the cranky bolt, but medium-strength blue is safer, since it doesn't need heat to be removed)
    • follow all torque specs (quadruple check these), for the crankshaft pulley I'd suggest just getting the pulley holder tool (or weld up your own), the torque spec really matters here (i.e. don't use the strap wrench method).


Edit: My bad, your version of the 6g72 seems to use a manually-adjustable pulley-style tensioner (# MD104578). However, this poses the same woodruff key/cranky bolt concern.
PS: a wire thread about balancer wobble, cranky bolts, woodruff keys (and a cameo of a 91 3.0), good read: /1076052/crank-pulley-wobble-with-new-pulley-and-tight-bolt-98-montero.html

Attached Files
91-6g72.png (104.94 KB, 1 downloads)
Last edited by Lev_from_CA; 07/22/21 04:48 PM.
Re: Surging on acceleration. [Re: Trailmonkey] #1106386 07/23/21 12:36 AM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
This engine has about 1000 miles on it, reman unit, no I have not check mechanical timing as it has and does run perfect, then glitches.. did not do this when I first got it.
I'm getting ready to replace the front 2 HVLA on passenger side and the TPS, while its that far ill replace the pressure regulator, clean the throttle body and valves and what ever else is hooked to it, pull and clean and check injectors.
If it still does it ill replace the distributor and start checking wiring.


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
Re: Surging on acceleration. [Re: Trailmonkey] #1106387 07/23/21 11:01 PM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
Seems the first hour of driving it does it and clears up, but after everything gets totally heat soaked it never really clears up, as if what ever this is gets worse after totally warmed up. I'm gonna check for a code tomorrow but this is driving me crazy... well more so than normal.


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
Re: Surging on acceleration. [Re: Trailmonkey] #1106390 07/25/21 02:44 PM
Joined: Dec 2007
Posts: 2,330
Mudraider Offline
Body Damage is Cool
Does it have a code showing? When mine did that, I did the JBfP electric tune-up. Basically, disassembly of the connectors and hitting each wire/connector with a soldering iron, make sure the wire itself wasn't loose in the terminal. Tedious, but it solved all kinds of weird maladies that mine had when I first got it.


89 SWB, V-6 5SPD, OME Shocks, 16.5X37's, 2"BL, SR axle, Gen2 brakes, Lincoln w/Superwinch
Re: Surging on acceleration. [Re: Trailmonkey] #1106392 07/25/21 11:46 PM
Joined: Aug 2020
Posts: 179
T
Trailmonkey Offline OP
Wheeler
Not checked for code yet. Been hot as Satan's nut sak, I've unhooked the fuel line and cut it on and just checked that it shot a stream, but if the fuel pump is somehow acting up would it cause something like this ?

I did notice when it's running right its alot quieter of an exhaust tone, when acting up sounds alot deeper tone like if the packing blowed out of a glass pack. Lol

Before I put on the new pressure regulator I'll also get a new pump, ill find out what it is one day, just wish I had some help around here that knew about these.

As for wiring connections, I've called myself looking, wiggling wires and have only noticed some connection covers are dry and cracked, but the plug and wire under it looks OK. But I will start check these more, as with all those relays under the dash, like did they try and use as many as they could or what ?


91 (Gen1) Monty, 3.0L V6, Auto 4 Door.
Disabled Driver.
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