thissilentstar

I know there are quite a few threads about stalling at stopsigns and such. However, after having some work done, exploring some of those threads - still haven't figured it out:


98 -- 2.7L -- 5-Speed -- 4x4


*RPM's tank while decelerating. (press the brake, clutch in OR gear in neutral - either way) (RPM's drop quickly to 300-600)
*Stalls or comes close to stalling at stoplights or as I am rolling up to stop. (RPM's sitting around 400 at this point)
*I can keep it going by giving some gas, but I felt the actual fuel cut out one time (I think) as I was trying to feather it while braking
*When it stalls, it will not restart for 30+ seconds (like there is no fuel in the line)
*No codes
*If I go out and start it in the cold - idles perfectly fine, no issues. It is only when decelerating and then at a stop that the RPM's are super low and it will die. (and not every time)

I thought it was only happening on the first few minutes of driving (cold), but the RPM's still tank when decelerating when warm - just might stall less when it is warm. I am not 100% sure on that.


Besides this stalling issue, it seems to drive fine.
I have been through 4-5 tanks of gas in the last 6 weeks

I had a few ideas, but didn't have time to figure it out myself --- so, took it to a shop and they:

Oil change
Cleaned MAF
Replaced some vacuum lines
Replaced fuel filter
Replaced IAC Valve (really thought this would be it!)
Tested TPS, Brake Booster/Lines
Checked EGR
Checked for codes

The stuff they did, fit in with the ideas of what I would have checked out and done, but ultimately it is still having the same issue. They spent a lot of time trying to diagnose it, but told me they could not figure it out. I trust this current shop (unlike my last one). They suggested taking it to a town 50 miles away to a shop that specializes in imports since it was an issue they could not figure out.


Additional info:
Last spring I had the valve cover gasket replaced as there was a little oil leak.
I felt like the engine had less power after that (but who knows with this little 4 cylinder in the WY wind)
I replaced the spark plugs and wires

Since then, I have killed it a few times on flat-takeoffs (not a situation where someone driving manual for 15+ years would kill it). AND then it would crank for 30+ seconds before firing and starting. Again - like there is no fuel in the line. Those times the engine was cold.

Timeline:
*The killing it randomly on takeoff started around when I had the valve cover gasket replaced last spring and just was a weird and a slight annoyance. It happened so infrequently, I didn't think about it a whole lot. Also I quit going to that shop as I was unhappy with other things and I would not be surprised if they broke or did not connect something properly.
*Actually seeing the RPM's tank has been something in the last 4 months
*Stalling has been intermittent over the last 4 months - and now happens EVERY time I drive it


Let me know of similar issues you may have had and ideas to help me diagnose this thing.

2ToyGuy

The ECU has a little program in it. IF the RPM is above a specified limit, I believe 1100, but may be wrong, it cuts the injectors off when the throttle is in idle, and the brake is pressed. Toyota figured if you're slowing down, throttle in idle, brakes applied, they could save you a little fuel that way. Sometimes, it doesn't fire up the injectors in time to keep the engine running. If the TPS Idle Switch isn't making properly, the ECU could hold the injectors shut off too long. If the dashpot isn't reacting in the correct time, it could hold the throttle open a little too loong.

Is the dashpot functioning correctly? Allowing the throttle to close all the way, and in the correct time period?
Is your idle RPM above about 1000? Is the o-ring on the idle adjust screw in good shape? Not old, brittle, cracked, or broken? Are the air passages below the idle adjust screw clear and clean?
Are you sure the throttle's idle switch is making when the throttle is released? The one on the TPS. It should have that gap between totally released, and starting to open, adjustable with the little screw to the side.

Hope something in all this is some small help...
Pat☺

thissilentstar

Thanks for a few suggestions to troubleshoot a bit. I edited my post a little as I had meant to be more specific with the RPM's. (basically drop quickly to 300 and almost dies or does die). If I can pull this into the garage tomorrow out of the snow, I will see if I can check a few things out. - thanks

fierohink

It could be the brake booster hemorrhaging vacuum when you apply the brakes. Block the vacuum line going to the booster and take a quick test stop on an empty parking lot. Remember you won’t have power brakes so it’ll be a bear to stop.

thissilentstar

Thanks, I was planning to check the brake booster again (even though the shop said they did). I think it's worth a try.

Right now the town is covered in ice, so hopefully I can get out somewhere safe and try a few things out.

thissilentstar

Well. It has been almost a year since my initial post. I have had it at multiple shops now, and no one can seem to figure it out. Currently, it has become difficult to start EVERY TIME, and stalls out quite often while driving in town. Lacks power. It really seems to me that something is telling the fuel pump to shut off/not give fuel.

Here is what has been done:


*Cleaned MAF
NEW:
*IAC Valve
*Air filter
*Spark Wires
*Ignition Coils
*O2 sensor (I think I did both, but can't find a receipt for the front one)
*TPS
*Crankshaft Position Sensor
*Camshaft Position Sensor
*Some air lines

The import specialist was convinced it was the wax wore out in the Throttle Body. He was not able to source one, but I did find one. (It was a bit of a bummer, as, the new throttle body came with a complete IAC Valve and TPS -- and cost half of what I had paid for the IAC Valve install..I had been too busy at the time)

SO:

*New Throttle Body
*Cleaned Battery Terminals

Normal shop told me to take it to the Import specialists. Import specialists told me to take it to Toyota.

So, the dealership currently has it. They did NOT actually get it to stall out on them (which is VERY strange as it stalls at every third stop sign). However, they seem to have figured out the issue...even though they did not actually observe the issue.

Dealership says the rings are bad in Cylinder #2. (compression tested). They suggested changing the oil more and using an additive and it could clean it up over time... I am not satisfied with that. *Side note - when I called to talk about what they found out, the service department could not find the tech. So when she called me back, she then told me that she actually was not the tech and they do not let people talk to the mechanics. So, all my information was being give 2nd hand both ways.

I do not know much about compressions/cylinders. However, it is odd to me that when I replace any of these sensors, the truck will have FULL power again and not stall for a period of time (20-30 miles of town driving maybe). And then will go back to having issues. I'm not denying that the compression issue could be the cause of lack of power and maybe stalling, but how does it have great power (for a 4 cylinder) and not give me any symptoms in response to a new sensor then?

Anyways. Frustrated at this all. Any ideas or advice would be helpful.

Old83@pincher

Just a dumb thought here...plugged cat?

Has your mileage went down?

I once had a similar problem with my 04 (2.7L) in that the truck would buck every time the clutch was engaged unless I revved the snot out of it, 2000-2500RPM. Quite embarrassing for someone who's drove standard for 40-45 years. I thought the clutch was oil soaked. Turns out it was the dash-pot, specifically I believe its called the idle up dash-pot and can be seen at the lower front of the throttle body. There was a gap between the dash-pot plunger and the idle adjustment set screw on the throttle cam/lever. I adjusted the set screw just touched the plunger, speeding up the idle a bit then turned it back about a 1/4 turn and no more problems. Maybe this was just a hack fix but its worked for the last 10 years.

I think the dealership is shooting you a line. IF that engine has been reasonably maintained those 2.7L's are bullet proof. Did it burn oil? Were the plugs fouled? If you have a vacuum gauge/tester see what you get...a "good" engine should give about 21" vacuum at sea level. Knock off 1" for every 1000' of elevation.

I am guessing when you replace a sensor the ECU will be operating in "open loop" (there is no feedback) and when it warms up and switches to "closed loop", which may explain your last question/statement. Could be a clue to the issue. I think there is a fuel pressure regulator...maybe?

thissilentstar

Cool thanks. That gives me a few things to look at/try. Mileage has went down, yeah. I had heard that about the closed loop, and that could be what is happening at that point then while it learns any new sensor.

I'll get my truck back later this week (dealership is 50 miles away) and will see what is next. I had noticed that dash pot before and there is a gap between it - doesn't hit at all when gas pedal is released. Maybe that will take care of the stalling out issue when coasting to a stop sign. we'll see -

thanks -