Occasional Engine sputtering-misfire (1 Viewer)

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Apr 27, 2016
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Houston, TX
First real post here, but I could use some second, third, fourth, etc. opinions on a nagging problem I'm having.

Earlier this year I was getting some engine sputtering under load and was burning a lot of oil. Also has some visible oil around the distributor (leak around the shaft). I had had a new distributor and new plugs put in along with a new valve cover gasket and cleaned the throttle body. Oil was leaking into the spark plug tubes. I haven't had any oil leaks since this fix and the LC consumes a lot less oil as well. Also fixed the knocking and pinging I was getting from the engine. A few weeks later I T-boned a truck who failed to stop at an intersection. Thought about just walking away from the LC, but went ahead and put in about $6,000 of work getting it repaired and at the same time taking the opportunity to fix some other issues (like that broken door handle!, new Iron Man bumper!). Then I moved...

Anyway, got my 97 back from Texas in Oct after sitting most of the summer waiting to assemble the parts and get the repair work done. Drove it back to SC. First day drove to Atl and no problem. Engine was humming. Second day I got some occasional engine sputtering. It would miss and felt like someone was pulling on a giant rope behind the Cruiser. Problem mysteriously went away. I thought maybe bad gas. Then it started happening occasionally, but not regularly. It's not predictable, nor does it always occur when I drive. When it happens it will sputter and drop revs under load several times, and then not happen again for miles and miles. Fuel grade doesn't seem to matter. I've run regular unleaded and ethanol-free.

Took it to a local mechanic upon recommendation from a longtime LC owner. They replaced the ignition wires, spark plugs (I didn't ask them if they were fouled), put in new distributor rotor and cap assembly and also adjusted the distributor as it was off a tooth. Cost was more than I expected. Mechanic said that the spark plug wires had small nick in them that was causing an arc and that the LC was fussy about plugs (even though I later checked and had replacement Toyota plugs installed in May) Everything seemed fine for the first couple hundred miles then the intermittent sputtering started again. It's still very intermittent, but seems to be getting more frequent.

I thought fuel pump, but mechanic seemed to think that a problem there would have led to outright failure. He thinks its a dirty fuel injector. If that is the case, wouldn't the problem be constant and not so in frequent? The Cruiser will also occasionally stall out when idling at an intersection. Idle seems to be low. I am thinking that with all of this electrical work, there has to be some problem with the fuel delivery. It almost seems like there is some random blockage I am not an expert, but will get my hands dirty to replace parts, etc. with good instructions. I plan on replacing the fuel pump myself just to rule that out.

One of my best friends just bought a Cruiser and is going all in to make it an off road beast. I can't hit the trails with him until this is fixed.
 
Sounds more like an electrical problem.

Check or replace fusible links first to rule it out. That's about $18 and yes, you can do it.

Otherwise, I would look at the wiring harness near the EGR valve near the firewall on the engine. Will probably need to unwrap it to make sure no it's good.

Check to make sure all 6 of the ground wires are attached to the engine, frame, and body.

If you don't have an FSM, get one for free in here. Search for "hell of a price" and you'll get it. Get the EWD to locate the ground wires.
 
The intermittent nature of this issue is working against you so keep an eye out for how to trigger/duplicate this issue if at all possible. Is it related to moisture/humidity, operating temp?, certain driving patterns, etc.?

Since your truck is a '97 and is ODB2 another relatively inexpensive item that could help is a bluetooth odb2 adapter and the "Torque" app on your phone. With these setup you can watch various sensor output signals from your system. I've not needed to use this for troubleshooting but I've noticed that you can see the 02 sensor output voltages. You may be able to figure out if the engine is going rich (possibly due to lack of spark or bad fuel system info) or going lean due to lack of fuel by watching the o2 sensor numbers in the torque app.

Amazon product ASIN B011NSX27A
 
Thanks to both of you! I did check all of the fuses a couple of weeks ago and they were all good. I ordered the iPhone version of the OBD device.
 
Thanks to both of you! I did check all of the fuses a couple of weeks ago and they were all good. I ordered the iPhone version of the OBD device.
You mention fuses, but not "fusible links".... Do you understand what those are? They are a three-wire set that comes from the positive post of the battery to a small block and to two other harnesses. These control the overload protection of varying circuits. If you have recently been futzing with the battery (and if you had a collision, it's likely) then they may have been yanked on and may be making intermittent connection. They are worth replacing if unknown. I keep a spare set in the glove box.
 
My truck was bucking/hesitating intermittently under load for 18 months, and I was terribly frustrated by it. I replaced the fuel/air (upstream) oxygen sensor with a Denso unit. Problem solved. I had tested the sensor per the FSM, and it tested fine. That is a part which simply wears out, and can apparently work intermittently after failure.
If you do replace your oxygen sensor(s), I suggest going Denso or Toyota. None other.
 
The repair shop did have to mess with the lighting harnesses to get the lights on the Iron Man bumper integrated. I'll be checking them all out this weekend. Keep the hits coming...
 
Previous owner had the fuel filter and both O2 sensors replace about 4 years and 20k miles ago. I went ahead and ordered two new sensors just to be safe though.
 
So I bought the Veepak blue tooth model. I had been having no issues for over 500 miles, then boom. It started happening again. Had the Veepak running several times while the sputtering/ chugging happened, but there were no codes thrown or other data that would indicate that there was any problem. SO whatever problem I'm having its nothing that the ECM is picking up. Frustrating. I'm going to replace the Oxygen sensors and some of the fusible links. Anyone have any handy part numbers on those, and/ or a recommendation on the best place to order them?
 
Have you checked for vacuum leaks? Make sure your intake hose has no cracks and is seated correctly and clamped tight.

I had low-ish idle and random sputtering that got worse over time, to the point where the truck would often die when pulling up to a stop and would hesitate when taking off. Turned out my intake hose was not quite seated correctly. Not even so bad that you could see a air gap or anything, just not quite pushed all the way to the AFM. Fixed it right up and gained a little MPG too.
 
Checked the vacuum hoses and they are fine. They were replaced recently.

One thing I did find is that the fuel pump resistor is not attached to anything it's just laying on the truck body. There are a couple of nearby harnesses with nothing plug into them that look corroded. Where should fuel pump resistor attach? Are these harness plugs for diagnostics or is something missing. The power antenna has been removed. I had assumed they were attached to what was once there.

Loose Fuel Pump resistor
IMG_1215.jpg


What are these for?
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