Rising Sun Member Forums  

Go Back   Rising Sun Member Forums > Toyota 4x4 > General Tech Forum

Reply
 
Thread Tools
  #1  
Old 07-19-2017, 01:59 PM
DouglasVB DouglasVB is offline
Rising Sun Member
 
Join Date: May 2015
Location: Free Republic of Cascadia, Oregon Division
Posts: 1,195
Default Stubborn issue on my 4runner - stumble/jerk/surge when decelerating

Apologies in advance for how long this is going to be... hang in there with me until the end.

In December when I drove my 4runner out to Oregon, I developed an issue as I was coasting down the Blue Mountains into Pendelton. With the truck in 4th or 5th gear and in high range, it felt like the engine was momentarily stuttering like when you have a very brief fuel cut. This was a cyclic thing that would happen once every ten seconds or so for maybe a half second. Just enough to jolt you a little bit.

Shortly after arriving in Oregon, a bunch of my electronics started having issues due to the humidity and wetness out here. I ended up replacing a bunch of stuff to get the truck running well again and to get it to pass emissions.

The problem however persisted.

In the last month or so, the stuttering has become more frequent and showed up across more gears. It happens in 4th and 5th most reliably, 3rd some of the time, and 2nd and 1st very occasionally. Doesn't seem to be affected by temperature. Only happens when decelerating. Doesn't happen in any of my low range options. Happens downhill, flat ground, and uphill. Haven't felt it at all in reverse but then again I don't usually coast in reverse!

This is my 1986 SASed 4runner with 5.29 & ARB-ified diffs, dual t-cases with 4.7 rear crawler gear, 22RE maaaaaybe with a different cam than stock (not confirmed), full floater rear axle. The front and rear diffs were rebuilt last fall with new gears and bearings by Jackson and the rear diff has a brand new ARB locker in it. Break-in on both gearsets has been good with no indication of issues.

I have done the following things in an attempt to solve the problem. Many from Rising Sun and the various Oregon 4x4 groups have provided input. Even Roger Brown offered some suggestions.

Replaced:
  • Spark plugs
  • Spark plug wires
  • Distributor cap
  • Rotor
  • Igniter coil
  • Igniter control module
  • Fuel pump relay
  • O2 sensor
  • Ground wires to engine and truck body
  • Engine oil & filter
  • Trans, T-cases, and diff oil
  • Brake master cylinder
  • Brake fluid
  • Clutch fluid
  • Rear drive line (note that front drive line was rebuilt in Colorado last fall)
  • All vacuum lines (even the hard to reach ones)
  • All coolant lines (last summer)
  • Water pump (last summer)
  • Radiator and radiator cap (last summer)

Repaired/adjusted/checked:
  • Reconnected coolant temp sensor wire for ECU
  • Alternator belt tension adjusted
  • Verified Chevy-style alternator voltage output (14 volts nice and stable)
  • Rebuilt the wiring for my aux lights and redid wiring for alternator-battery connection
  • Adjusted valves (twice!)
  • Verified 22re chain tensioners are intact and in good shape
  • Passenger rear axle seals (verified bearings are good, repacked them, etc.)
  • Lubed all lube points on drive shafts and rear bushings (front bushings claim to not need any lubrication from when I installed them last fall)
  • Compression and leakdown check (everything in spec)
  • Vacuum leaks (didn't find any)
  • Removed fuel pressure VSV per Roger Brown's suggestion (no change) - note that I still have the AC VSV installed but hitting the AC button doesn't seem to impact anything (the AC is inoperative anyway due to a cracked hard line)

I have some additional test data that is relevant to the issue:

This problem only happens (except maybe once! -- more below) when the vacuum gauge I previously installed reads 23inHg or more (up to 27inHg). It has been very consistent in this regard.

Yesterday while the truck was in 1st gear, clutch pushed in (so engine and trans weren't connected), engine idling, and rolling down the driveway, I thought I felt a couple of stuttering incidents. That got me thinking that this could be a mechanical binding issue. However when I've tried coasting on the highway with the clutch pushed in, it doesn't happen. Driving home, I turned on the rear locker and the problem went away. Turning off the rear locker brought the problem back. Jackson (thanks!!!!) suggested that I should jack up the rear end and check a few things. I checked:
  • Play in wheels indicative of bearing issues by trying to wiggle the wheel at 90 degree intervals - no problems, nice and tight
  • Checked for locker disengagement - no problem, wheels would rotate independently
  • Checked for play in diff yolk - no problem. nice and tight, and with correct amount of rotational play
  • Checked for loose drive shaft joints - all nice and tight (this was rebuilt recently)
  • Checked for any binding - none present. Nice and smooth with truck out of gear (didn't have a helper to press clutch in)
  • Checked for any strange noises anywhere - no noises anywhere that were odd. everything sounded smooth from the wheels up to the transmission
  • Checked air locker functionality - locks and unlocks correctly but there is an air leak in the locker somehwere that causes the air compressor to cycle every 5ish seconds for a half second. A bit odd since this locker only has maybe 5000 miles on it since new but still okay.
  • Checked tires - good wear pattern, no obvious out of round issues -- i'm planning to get them checked for balance and rotated soon.

So I think that indicates that I am not having any issues with my drive train that at least is detectable from static testing.

Per Roger Brown's suggestion, I tried jumpering the fuel pump test switch to run the fuel pump continuously. That had no effect.

Roger Brown suggested I install a fuel pressure sensor so I went ahead and did that recently. The measurements appear to indicate that I may have low fuel pressure:
  • At startup when engine is cold - 30PSI
  • 0 vacuum pressure with a cool engine - 36 PSI
  • 27 inHg vacuum on a warm engine - 25 PSI
  • After 5 minutes sitting with the engine off - 32 PSI (I also notice that fuel pressure goes up a few PSI when the engine is off and the truck is sitting in the first minute or so
  • After sitting for 2 hours with the engine off - 0 PSI
  • Hot engine after truck sitting for 10 minutes before restarting engine at 27 inHg - 22PSI
  • Same as above but at 0 inHg vacuum - 34PSI



I also checked the AFM and TPS per the FSM. All readings were normal except the following:

On the AFM, I found:
  • E2-Vs = 1Kohm at plate full closed
  • E1-Fc stays at high resistance until the plate is about a quarter of an inch open before going to 0 ohms

On the TPS, I found:
  • VTA-E2 = 3Kohms in the closed position
  • IDL-E2 = 7.5Kohms in the more closed shimmed position (although I had trouble getting a consistent reading).

Tonight I'm planning on replacing the fuel filter to see if that might be why I have low fuel pressure. After that, I'm undecided on what direction to look toward next. The things I am thinking that I could do are:
  • Replace fuel pump and fuel pump sock
  • Replace fuel pressure regulator
  • Replace injectors with balanced and clean injectors
  • Replace cold start injector
  • Replace TPS
  • Replace AFM
  • Pull and swap rear and front diffs

Does anyone have any thoughts on other things I should test before I start dumping more money on replacement parts or open up all of my drive train for internal inspection?

(I miss you guys! Come visit us in Oregon! We have good beer, wine, and spirits! And some halfway decent kinda okay trails...)
__________________
Douglas in the Free Republic of Cascadia
1986 Toyota 4runner with all of the desirable features - The Albino Rhino
1988 Toyota 4runner DLX - Goldilocks has gone to a new home!
1989 Honda Pacific Coast PC800
2001 Ford Focus ZX3 hot hatch
KD7YBQ
TLCA #23604
Reply With Quote
  #2  
Old 07-19-2017, 02:03 PM
DouglasVB DouglasVB is offline
Rising Sun Member
 
Join Date: May 2015
Location: Free Republic of Cascadia, Oregon Division
Posts: 1,195
Default

I also should note that I can't get a video that shows it happening. I've tried but you can't see it or really hear it in the video. My partner Heather thinks it's feeling a little more like a surge now than it did before. If any of you are in the PDX area, I'll take you for a spin so you can feel it. Pushing the clutch in while decelerating makes it go away.
__________________
Douglas in the Free Republic of Cascadia
1986 Toyota 4runner with all of the desirable features - The Albino Rhino
1988 Toyota 4runner DLX - Goldilocks has gone to a new home!
1989 Honda Pacific Coast PC800
2001 Ford Focus ZX3 hot hatch
KD7YBQ
TLCA #23604
Reply With Quote
  #3  
Old 07-19-2017, 02:33 PM
Romer's Avatar
Romer Romer is offline
Rising Sun Member
 
Join Date: Aug 2005
Location: Englewood, Colorado
Posts: 7,960
Default

Likely not it, but I found this 11 year old thread on a problem with Rachel's 4 runner. Essentially a common problem that the rear axle seal leaks right on to the brake pads. It was giving us a problem in 4WD, maybe it is creating a deceleration problem. Probably not, but this is all I have to offer

http://www.risingsun4x4club.org/foru...hlight=4runner
__________________
Ken Romer - K0ROM
14 URJ200
77 FJ40
16 RX450
16 Kimberley Karavan

Reply With Quote
  #4  
Old 07-20-2017, 09:37 AM
On the RX's Avatar
On the RX On the RX is offline
Lifted
 
Join Date: Nov 2016
Location: Superior
Posts: 156
Default

I had a similar issue on my 93 runner and I believe that I ended up replacing the sending unit and fuel filter. When I replaced the unit in the fuel tank their was a lot of rust flakes in the tank. I vacuumed them out and had to no more issues.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Reply With Quote
  #5  
Old 07-20-2017, 10:40 AM
DouglasVB DouglasVB is offline
Rising Sun Member
 
Join Date: May 2015
Location: Free Republic of Cascadia, Oregon Division
Posts: 1,195
Default

Quote:
Originally Posted by Romer View Post
Likely not it, but I found this 11 year old thread on a problem with Rachel's 4 runner. Essentially a common problem that the rear axle seal leaks right on to the brake pads. It was giving us a problem in 4WD, maybe it is creating a deceleration problem. Probably not, but this is all I have to offer

http://www.risingsun4x4club.org/foru...hlight=4runner

Thanks for the suggestion! I inspected my rear brake pads and they look good (forgot to mention I replaced my front pads and calipers about a month ago). I did fix a leak on the right rear axle seal a few weeks ago but it only showed up recently and it was coming out of the locking hub (I have a full floater conversion).

Quote:
Originally Posted by On the RX View Post
I had a similar issue on my 93 runner and I believe that I ended up replacing the sending unit and fuel filter. When I replaced the unit in the fuel tank their was a lot of rust flakes in the tank. I vacuumed them out and had to no more issues.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Hmm well maybe it's time to open up the hatch under the rear seat and fish out that fuel pump...

Question for anyone with a 1986 truck:

What fuel pressure should I be seeing? I see that the 1988 trucks have a different fuel pressure regulator than the 1986 trucks (according to NAPA) with different max PSI ratings. What are the fuel pressure specs that I should expect on my truck?
__________________
Douglas in the Free Republic of Cascadia
1986 Toyota 4runner with all of the desirable features - The Albino Rhino
1988 Toyota 4runner DLX - Goldilocks has gone to a new home!
1989 Honda Pacific Coast PC800
2001 Ford Focus ZX3 hot hatch
KD7YBQ
TLCA #23604
Reply With Quote
  #6  
Old 07-20-2017, 10:54 AM
Blindranger's Avatar
Blindranger Blindranger is offline
Land Use Co-Coordinator
 
Join Date: Dec 2013
Location: PNW
Posts: 407
Default

Hurry up and get it fixed! Saturday's trail run will be roughly 120miles offroad
Attached Images
 
__________________
Matt Ewalt
KI7IDZ
1996 FZJ80
TLCA #22702
Reply With Quote
  #7  
Old 07-20-2017, 11:06 AM
DouglasVB DouglasVB is offline
Rising Sun Member
 
Join Date: May 2015
Location: Free Republic of Cascadia, Oregon Division
Posts: 1,195
Default

Quote:
Originally Posted by Blindranger View Post
Hurry up and get it fixed! Saturday's trail run will be roughly 120miles offroad


I can still drive it (and have been!) but it's annoying

I'm thinking I might try to round up a MAF/AFM next...
__________________
Douglas in the Free Republic of Cascadia
1986 Toyota 4runner with all of the desirable features - The Albino Rhino
1988 Toyota 4runner DLX - Goldilocks has gone to a new home!
1989 Honda Pacific Coast PC800
2001 Ford Focus ZX3 hot hatch
KD7YBQ
TLCA #23604
Reply With Quote
  #8  
Old 07-20-2017, 03:29 PM
On the RX's Avatar
On the RX On the RX is offline
Lifted
 
Join Date: Nov 2016
Location: Superior
Posts: 156
Default

Quote:
Originally Posted by DouglasVB View Post


I can still drive it (and have been!) but it's annoying

I'm thinking I might try to round up a MAF/AFM next...
The maf just rang a bell. I believe i cleaned mine with mineral spirits on my 97 and it fixed a simamiar problem for a little while. I think I grabbed one from a bone yard and replaced it. This was 10+ years ago and doesn't help much but it might be something to look at. I feel like the sensors were highly corroded.

Sent from my SAMSUNG-SM-G930A using Tapatalk
Reply With Quote
  #9  
Old 07-20-2017, 03:40 PM
DouglasVB DouglasVB is offline
Rising Sun Member
 
Join Date: May 2015
Location: Free Republic of Cascadia, Oregon Division
Posts: 1,195
Default

Quote:
Originally Posted by On the RX View Post
The maf just rang a bell. I believe i cleaned mine with mineral spirits on my 97 and it fixed a simamiar problem for a little while. I think I grabbed one from a bone yard and replaced it. This was 10+ years ago and doesn't help much but it might be something to look at. I feel like the sensors were highly corroded.

Sent from my SAMSUNG-SM-G930A using Tapatalk
I just ordered one from EBay. Here's hoping it fixes the problem!

Also ordered up a used TPS as a spare.
__________________
Douglas in the Free Republic of Cascadia
1986 Toyota 4runner with all of the desirable features - The Albino Rhino
1988 Toyota 4runner DLX - Goldilocks has gone to a new home!
1989 Honda Pacific Coast PC800
2001 Ford Focus ZX3 hot hatch
KD7YBQ
TLCA #23604
Reply With Quote
  #10  
Old 07-21-2017, 11:09 AM
AxleIke's Avatar
AxleIke AxleIke is offline
Rising Sun Member
 
Join Date: Apr 2006
Location: Broomfield, CO
Posts: 4,378
Default

Quote:
Originally Posted by DouglasVB View Post
I just ordered one from EBay. Here's hoping it fixes the problem!

Also ordered up a used TPS as a spare.
You have an AFM (flapper style) on the 22re. Not a MAF like the 97. On the 97, it has a little unit that measures the mass of air coming in (compensates for temp, etc.). This can misread if it gets dusty/oily.

On your 22re, you have a little gate that opens further the more air you pull in. It can get jammed but it doesn't care about a little dust like the 97. If its not jammed, I'd check voltages coming off of it when you move it with your hand. If that is okay, you don't need to replace it.

Just FYI.
__________________
Isaac

Baby Beast 2- 1999 4Runner SR5

Baby Beast -1987 4Runner SR5-Gone, but not forgotten

Generation Dead
Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -6. The time now is 06:23 PM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.