Author Topic: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load  (Read 7392 times)

PA_JERO

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #30 on: October 03, 2017, 05:13:07 PM »
It is probably the CAT. No code, no egr, most likely the CAT.

JohnnyBfromPeoria

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #31 on: October 03, 2017, 07:04:16 PM »
Not the cat. The NOX was below the limit before my repair. I've been through this before, two years ago when my plenum was leaking at the front, the NOX failed me, then I drizzled silicone caulk over the front, sealed it up and went back...passed. It's a vacuum leak, brah.

John B.
AZ Crew/East Sider/Former 14th St Crew
95 SR, 35x12.5-15 on 8" steelies, 2" BL, stuff cut off, stuff welded on, lights, sound, front ARB pending
87 Raider, There's a turbo 2.6 under its hood, really
83 "Dodge" Power Ram 50, a bit lifted, way slow and gets more comments from random people than the other two put together
'95 Montero SR. Pretty much stock, Trail Gear Sliders, ADD skid plates, Stereo by Shovel, Timing maintenance by Pa_Jero

Shovel

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #32 on: October 03, 2017, 07:16:32 PM »
It's a vacuum leak, brah.

John B.

I remember one time reading a trick involving a halloween smoke machine and some duct tape,  for finding vacuum leaks..    and it's the right season to buy one.     

Never done it myself, I'm just tossing it out there.

JohnnyBfromPeoria

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #33 on: October 03, 2017, 09:17:46 PM »
A unlit propane torch does the trick (which I haven't done yet this time). The engine speeds up or idles more smoothly when you hit the leak.

John B.
AZ Crew/East Sider/Former 14th St Crew
95 SR, 35x12.5-15 on 8" steelies, 2" BL, stuff cut off, stuff welded on, lights, sound, front ARB pending
87 Raider, There's a turbo 2.6 under its hood, really
83 "Dodge" Power Ram 50, a bit lifted, way slow and gets more comments from random people than the other two put together
'95 Montero SR. Pretty much stock, Trail Gear Sliders, ADD skid plates, Stereo by Shovel, Timing maintenance by Pa_Jero

JohnnyBfromPeoria

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #34 on: October 16, 2017, 10:05:13 PM »
Well, I have found a couple of things out by driving over 1000 miles recently on the Utah trip with the 'Crew. First, my problem isn't fixed. Sometimes the truck runs perfectly and sometimes it runs like crap, and it seems very much throttle position-related when it runs like crap. Thankfully, Pa_Jero has a complete throttle body from a 95 SR I can borrow so I don't have to mess with installing and trying to adjust a TPS (throttle position sensor). There could also be a problem with the wiring harness leading to that sensor, I suppose. He also has an ignition module and a MAF sensor I can swap in/out/back to compare.

Secondly, I have had a set of new O2 sensors laying around that I haven't installed. Since the car has almost 200K on it, I "could" spend the amount equal to two tanks of premium gas and get a bolt-in replacement cat from Rock Auto and go with that and the new O2's and probably pass emissions, provided I get the other issue resolved. I know - don't throw parts at it, but my plugs were pretty good looking, so there doesn't seem to be excessive oil burning taking out my cat and my exhaust has smelled really bad for a long time, another symptom of a bad cat (I should listen to Pa_Jero more). I mean it really smells weird, too, probably has for a couple of years. Even if a new cat fails fairly quickly, it buys me two more years of tags for not a lot of money. My tags expired yesterday...BOO. Just need to make sure the bolt-in will actually bolt in!

John B.
AZ Crew/East Sider/Former 14th St Crew
95 SR, 35x12.5-15 on 8" steelies, 2" BL, stuff cut off, stuff welded on, lights, sound, front ARB pending
87 Raider, There's a turbo 2.6 under its hood, really
83 "Dodge" Power Ram 50, a bit lifted, way slow and gets more comments from random people than the other two put together
'95 Montero SR. Pretty much stock, Trail Gear Sliders, ADD skid plates, Stereo by Shovel, Timing maintenance by Pa_Jero

JohnnyBfromPeoria

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #35 on: October 18, 2017, 06:45:32 PM »
The overall measurements on the replacement cat were correct, so I pulled the trigger over at Rock Auto. It arrives Friday sometime. Meanwhile, the order of a new air filter (I think I should put one in after that Utah stuff) - Wix, of course, and two new oil filters - Wix, of course, arrive tomorrow. I already have oil - Mobil 1 full synth 5W-30 high mileage, of course. And - of course, you may choose to disagree with every single one of my choices, which is fine, I don't care. This is my thread.

Any takers on volunteers to help with all this? Didn't think so, just thought I'd see if there was anybody who had absolutely nothing to do, which is absolutely nobody. Unless Jorge is reading this. In that case, I nominate Jorge.

John B.
AZ Crew/East Sider/Former 14th St Crew
95 SR, 35x12.5-15 on 8" steelies, 2" BL, stuff cut off, stuff welded on, lights, sound, front ARB pending
87 Raider, There's a turbo 2.6 under its hood, really
83 "Dodge" Power Ram 50, a bit lifted, way slow and gets more comments from random people than the other two put together
'95 Montero SR. Pretty much stock, Trail Gear Sliders, ADD skid plates, Stereo by Shovel, Timing maintenance by Pa_Jero

PA_JERO

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #36 on: October 19, 2017, 10:47:36 PM »
I won't have a lot of time this weekend, but maybe I can scoot over and give you a hand with a few things this saturday. First thing in the morning might be easiest for me. I can also bring all of the parts you wanted to try, so you can eliminate a few possibilities. MAF, throttle body from the 95, ignition Transistor, ???. And anything else you can think of.

JohnnyBfromPeoria

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #37 on: October 20, 2017, 05:06:41 AM »
That would be most excellent, Pa_J. If I could just get those parts, I think I can take it from there. Cat should be here when I get home tonight. I'd like to shoot for another try at emissions tomorrow since I have things to attend to in Phoenix later in the day.

John B.
AZ Crew/East Sider/Former 14th St Crew
95 SR, 35x12.5-15 on 8" steelies, 2" BL, stuff cut off, stuff welded on, lights, sound, front ARB pending
87 Raider, There's a turbo 2.6 under its hood, really
83 "Dodge" Power Ram 50, a bit lifted, way slow and gets more comments from random people than the other two put together
'95 Montero SR. Pretty much stock, Trail Gear Sliders, ADD skid plates, Stereo by Shovel, Timing maintenance by Pa_Jero

JohnnyBfromPeoria

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Re: Rough Running 95 SR (3.5 DOHC) When Hot/Under Load
« Reply #38 on: November 12, 2017, 07:41:05 PM »
Update: The new cat bolted right in. Getting the old cat out involved physically breaking one of the bolts that holds the rear flange together. Guess the WD-40 Specialist Rust Penetrant Spray didn't quite get it.

I finally was able to separate the electrical connectors on the O2 sensors (the hard part), and unscrew the old sensors (there are only two on a 95, whether it's Federal or CA emissions). Unfortunately, the front one managed to bugger up some of the threads in the Y-pipe and I decided to jam the new sensor back in there since it was a cheap-o and I wanted to try to pass emissions. Cross-threaded, it held and I drove over to the dreaded emissions station for my third try.

It did not pass. Oh, lucky me, the two measurements that I DID pass before are even lower now; the CO and the hydrocarbons are really low, the NOx is just about the same. I never did try to find any vacuum leak, since work just knocks me out lately (14 hours away from home on Friday, as an example).

This was a couple of weeks ago, and I didn't even try to do anything until yesterday. The battery was dead, so I put my nifty 21st century tech-heavy charger on it on the "refresh" setting. It worked on the battery for 24 hours solid, then timed out, but it seemed to do the trick and I have about 13 volts with everything off. Fair enough. If the thing fails completely before March, I get a new one for free from WalMart, if I want one. What I really want is a group size 27 Odyssey deep cycle, but that's for another time.

I had ordered a tap to rethread the exhaust bung (!) and a new Denso front O2 sensor. I think the size is pretty standard, like a 18mmx1.5 thread pitch, but don't take my word for it, everything on Amazon comes up with the same size. It seemed to work and the new sensor is in.

I previously tried swapping the ignition module that Pa_Jero lent me for the one already on my truck and that made no difference, so I swapped it back. Today I cleaned up the throttle body he lent me, being careful not to get any cleaning spray into the bottom openings in front of the throttle blade, like the FSM says. The TB actually had a coolant passage clog in the two cooling lines that attach to the bottom, which tells you how much fun Pa_Jero is going to have rebuilding that engine. I bolted the TB up and double-checked the routing of the vacuum lines against the underhood sticker and went for a drive after the engine was fully warm. My hesitation issue was still very much present, but strangely, it seemed to be at and just off-idle. Any further press of the accelerator and the truck ran fine.

I went to WalMart, to pick up survival supplies, like ice cream. When I came back out, started the truck and drove home, it ran just fine. This has been the modus operandi (M.O.) of this issue for a while now. Sometimes it works, sometimes it does not. The troubleshooting will continue.

Here's why I may well be flunking emissions: After warming up the engine thoroughly, revving the engine and snapping the throttle shut should result in movement of the EGR valve. It does not move. I'll haul out my Mighty Vac to verify the valve itself holds vacuum, then move on to the solenoid that activates the vacuum circuit (extra came with the T.B. from Pa_J  but I didn't install it), the integrity of the vacuum can attached to the circuit and the temperature sensor that tells the whole thing to turn on after the engine warms up. EGR plays a part in reducing NOx, and if mine isn't working at all, I'll probably never pass emissions. I want to figure this part out first, then hunt for any vacuum leaks afterward, since I think I've addressed the one at the front of the plenum and Shovel found the one at the brake booster and corrected it.

Still no check engine light, either. Sigh...

John B.
AZ Crew/East Sider/Former 14th St Crew
95 SR, 35x12.5-15 on 8" steelies, 2" BL, stuff cut off, stuff welded on, lights, sound, front ARB pending
87 Raider, There's a turbo 2.6 under its hood, really
83 "Dodge" Power Ram 50, a bit lifted, way slow and gets more comments from random people than the other two put together
'95 Montero SR. Pretty much stock, Trail Gear Sliders, ADD skid plates, Stereo by Shovel, Timing maintenance by Pa_Jero