Rough starting and loves to stall (1 Viewer)

[JesseTygr]

Hey guys,
First time poster, long time browser!
I have a ‘00 Lx470 that I bought about 8 months ago and up until this week, it’s been running amazing! It spent the majority of its life in the Palm Springs area before I brought it up to Canada so besides some very dry seals and a sunburnt roof, it’s a really clean truck!

I recently crossed the 200k mile mark and all of sudden I started experiencing issues and wondering where to start troubleshooting.
Before I start, I just want to say that I have spent hours digging through the forum as there are quite a lot of posts that seem similar to my issues but feel it might be good to lay out what I’m seeing incase there are any clues that I might not see and would be obvious to a seasoned 100series vet! Lost not lazy! LOL

To begin.. here is a series of issues that have somewhat popped up. They might be related or be completely separate problems but I think it best to lay them all out just incase.

About 3 weeks ago, I noticed a bit of a lag when the truck would go from 4th to 5th gear.. this was always around 60mph @ 2000rmp. As I would accelerate thru this range the truck would almost stutter or bog for just a second as if the fuel was cut off. I’d back off the gas and it would correct itself right away. If not, it would result in a bit of hard knock as if the clutch was enganged and quickly slipped off.. I thought it was transmission related but when I brought it to a transmission specialist, they said everything from a transmission perspective was rock solid. They did scan it and came up with the TWO codes:
P0430 B2 & P0470 B1
They cleared the codes and I continued driving for a few more days before taking to a mechanic friend to look at.. He drove it around, rescanned it and found nothing wrong nor any codes popped up.

I took it the following week on a trip about 200miles to the in-laws for Christmas and the truck was running great. I parked it for a few days and when I went to start it (cold), it really really struggled.
The engine would turn but it just catch and fire up. I tried about 10-15 times and finally it started!
Some of the cranks would result in the battery voltage dropping below the 1/2 mark on the gauge and it wouldn’t be able to turn the starter. Some of the cracks would see to catch so the starter would stop but the engine would sputter and die. If I pumped/press the gas, it would eventually fire up!

Once I got it started, I had to drive it back home (about a 200mile trip) and it was super smooth. No lag, loss of power or lack in the throttle at all. It was super smooth and cruised at 70MPH... BUT as I got closer to my house in more urban traffic, it was a nightmare.. As I approached a stop sign or red light, the RPMs would fall as low as 450-500 and then the truck would stall. I would still have power as all the dash icons would light up when it stalled and generally, I would be able to put it in park and fire it back up in one or two tries..

I managed to limp it back to my house (yesterday) and this is where I’m currently at.

From what I’ve read, the “low Idle to stall” and “crank & non-start” seem to be pretty common.

I started digging around under the hood but truth be told, I’m not a very mechanical advanced and this engine is far more electronic than I’m used to so I’m a bit nervous where to begin.
The good news is, the engine bay is super clean and with out testing via a meter, the obvious contacts look clean and free of corrosion. I check the fuse box to inspect everything related to the fuel pump (fuse & EFI relay) and they seem okay. ( I just visually inspected them for contact build up to corrosion but once again pretty clean..) I pulled the air intake to inspect the Throttle body valve to see if it might be jammed open.. (needs a cleaning but seemed to function.)

For what I can manage on my own, I’m going to buy a voltage meter to start actually testing all the relays and the fuseable link attached to the + on the battery. I’m also going to get a cleaner for the ETV & MAF to rule these all out but any other suggestions or thoughts would be awesome..

If my battery wasn’t carrying a significant charge, could this be the cause? ( I’m not sure when the PO last changed it?) I could see how this might effect the starting but would a weak battery effect the idle?

Concerning EFI relay, is there a way to test to see if it is working correctly? The problem feels very much fuel related but that’s based on limited knowledge.

Any advice would be great!

Keep in mind that I have limited skills ( mixed with lots of determination) but anything complex or more advanced i will pass on to my mechanic if I can’t solve it myself!

Thanks
J

 

[Travis Bickle]

Try cleaning the MAF sensor, make sure your air intake plumbing is all secure, CEL on? new codes?

 

[AlpineAccess]

Weak battery or a bad ground could cause an odd idle as a bad battery draws on the circuit simultaneously. A bad battery can also mess with sensors.

More than likely it is a combination of things. I'd start by testing the battery and then testing your charging voltage on the alternator. These cold temps are highlighting a lot of electrical issues related to charging and batteries it seems.

There is another guy on here at this moment with some similar symptoms and it was fuel delivery via an abbraided cable. Might check his thread out for some more ideas.

 

[fooldall1]

When they, "Cleared the Codes"..Did they FIX something, or just cleared them?


Based on the Bank1 and Bank2 codes you referenced above- I would say that you have either bad O2 sensors (not just a bad heater circuit, most likely the "downstream" sensor(s)) and/or some issues with your catalytic converter. Those codes will guide you to the solution.

Be sure to let us know what happens- but your engine codes and issues sound consistent with bad O2 sensors or bad cat.

 

[Noshniv]

Clean your MAF sensor. Sounds like the same issue I had after coming back from Death Valley. After cleaning the MAF, the rough idle and stalling stopped.

 

[JesseTygr]

Try cleaning the MAF sensor, make sure your air intake plumbing is all secure, CEL on? new codes?

Try cleaning the MAF sensor, make sure your air intake plumbing is all secure, CEL on? new codes?

Thanks!!
Cleaning the MAF is 100% on the must do list! I read on a post that these are pretty easy to destroy when cleaning and to never really touch them.. just to use a good “air intake spray cleaner”’. I went to look today at my local auto store but didn’t find anything specifically said to clean MAF.. I’ll try a big store early in the week!

As for the codes, nope, no error codes at all!! (Dumb question but what do you mean when you asked “CEL ON?)
J

 

[JesseTygr]

Weak battery or a bad ground could cause an odd idle as a bad battery draws on the circuit simultaneously. A bad battery can also mess with sensors.

More than likely it is a combination of things. I'd start by testing the battery and then testing your charging voltage on the alternator. These cold temps are highlighting a lot of electrical issues related to charging and batteries it seems.

There is another guy on here at this moment with some similar symptoms and it was fuel delivery via an abbraided cable. Might check his thread out for some more ideas.

Awesome!
Thanks for the insight. I’m not going to rule out this being a battery issue of some kind. It looks like the positive lead on my current battery is pretty chewed up so it could be causing a bad or inconsistent connection!! I’ll start testing the voltage of both the battery and then the output charging voltage of the alternator... any idea what these Volts should be if they are working correctly?
Thanks again

 

[JesseTygr]

Clean your MAF sensor. Sounds like the same issue I had after coming back from Death Valley. After cleaning the MAF, the rough idle and stalling stopped.

Thanks Noshniv!
That’s 3 votes for cleaning the MAF sensor!! I had no idea it’s such a key part. At the end of the day, even if it’s not the cause, it seems like a highly recommended thing to do!!
Thanks again!
J

 

[JesseTygr]

When they, "Cleared the Codes"..Did they FIX something, or just cleared them?


Based on the Bank1 and Bank2 codes you referenced above- I would say that you have either bad O2 sensors (not just a bad heater circuit, most likely the "downstream" sensor(s)) and/or some issues with your catalytic converter. Those codes will guide you to the solution.

Be sure to let us know what happens- but your engine codes and issues sound consistent with bad O2 sensors or bad cat.

Thanks for the feedback Fooldall1!!
When they cleared the codes, nothing was fixed! They gave me the codes and currently, nothing has returned since. I’ve even done a few hundred milles in the truck! I’m going to tackle some basic stuff like cleaning the MAF and see if that helps. If not, I’ll start on the o2 sensors.. any suggestions which one I should change out first??

 

[SAH]

If no CEL (check engine light), could be a fuel pump. Sounds like the engine is starved for fuel and due to the fuel pump being variable, it could be upset when you let off the gas coming to a stop. Also the truck only started when it was cold and you pumped the gas, engaging full fuel pump output, it also made me think fuel pump.

I could be wrong. Hope you get it figured out.

 

[Eicca]

My vote goes to fuel pump. Usually a MAF problem will very gradually crop up as crap accumulates on the sensor, and would manifest itself at all engine temperatures.

Failing fuel pumps will typically work fine when cold and then start to degrade as they heat up.

 

[OEMGUY0720]

As much as I would like to easily vote for Fuel Pump as culprit, this is still a process of elimination. Not in anyway should be in the right sequence, check for the following, if you see it suitable for replacing new ones (assuming all are still original at 200k miles) they are now due to perform these:
• All 8 spark plugs - check for burnt tips and high clearance
• MAF sensor - clean with carb cleaner
• Intake manifold - clean with carb cleaner
• Gas cap - replace only with OEM part
• Use fuel injector cleaner (sea foam or the likes)
• Fuel filter - replace only with OEM part
• Fuel pump - should be the last one to rule out if above parts have already been ruled out by either ensuring all are still in perfect working condition or you have replaced them with new oem or in-spec ones.

 

[Eicca]

As much as I would like to easily vote for Fuel Pump as culprit, this is still a process of elimination. Not in anyway should be in the right sequence, check for the following, if you see it suitable for replacing new ones (assuming all are still original at 200k miles) they are now due to perform these:
• All 8 spark plugs - check for burnt tips and high clearance
• MAF sensor - clean with carb cleaner
• Intake manifold - clean with carb cleaner
• Gas cap - replace only with OEM part
• Use fuel injector cleaner (sea foam or the likes)
• Fuel filter - replace only with OEM part
• Fuel pump - should be the last one to rule out if above parts have already been ruled out by either ensuring all are still in perfect working condition or you have replaced them with new oem or in-spec ones.

I don't disagree with any of this here. I will say though, at over 200k miles, I'd strongly recommend doing the fuel pump anyway as preventative maintenance. Both our Land Cruisers' fuel pumps crapped out around 200k and my 1UZ Lexus is still on its original pump at 215k. I'll be changing it out this weekend. I don't need to be stranded anywhere in the dead of winter.

So, it ought to be done, and you might just solve the problem while you're at it.

 

[OEMGUY0720]

I don't disagree with any of this here. I will say though, at over 200k miles, I'd strongly recommend doing the fuel pump anyway as preventative maintenance. Both our Land Cruisers' fuel pumps crapped out around 200k and my 1UZ Lexus is still on its original pump at 215k. I'll be changing it out this weekend. I don't need to be stranded anywhere in the dead of winter.

So, it ought to be done, and you might just solve the problem while you're at it.

Couldn’t agree more especially if you are pressed with time and the need to have the truck up and running on a reliable mode again so while at it get solved right away.

What I initially presented is a methodological and practical manner to pinpoint the culprit, however takes time and tons of patience (if you have time take that route). But if you have just limited time and have allocated budget for maintenance, getting all these done in one visit to your trusty mechanic or DIY session can really save you the hassle.

 

[kruisinkid]

voltage reading should be ~14.4v while high idling from cold start after sitting overnight. then will drop to 13.6-13.9v depending on RPMs and load (high beams, heat blower, accessories). the owners manual will tell you what the voltmeter and "battery" (charging system) light mean and should look like.

my moms mercury sable in the 90's would do the same thing. started fine, got to the interstate, drove at a near constant for 45-60mins, first light I would come to after getting of the expressway, it would sputter and die and soon as I came to a stop. cool down and started up fine. doesnt help, but we never figured out what it was.

give your battery terminals a good yank. they can seem tight but the funniest things happen when there is the tiniest of air gaps that are not easily seen. check your main fuses for oxidation in the little box. hint: you have to unbolt them, they dont just pull out.

 

[AlpineAccess]

Carb cleaner on MAF sensor? Do not do this. Use MAF cleaner. Carb cleaner leaves residue and is not plastic/electronics safe.

He threw two downstream codes with no idea how many events triggered them. The O2 sensors are reading too much oxygen, aka bad combustion/misfires and/or a lean mixture.

MAF sensor is a good start, spark/ignition and battery and charging system a good second. Don't throw fuel system parts at an unidentified problem like this unless you have money to burn. You can pull a spark plug or two and check them out. Take a picture if you want and add to this thread and check the gap.

He said he's getting a hard start as well which indicates battery and charging - both free to test.

Your cats and your 02 sensors aren't bad.

 

[2001LC]

My first thought was miss-firing under load. This is often a coil or two going bad. Just not bad enough to set of a CEL (Check engine light) or even a pending DTC (code). I test for this using tech steam and watch for miss fire while under load (in gear foot of brake raise rpm).

You may have some spark plugs walking out. They may be near blowing out the head.

Ticking time bomb TICK TICK TICK: Spark plugs Alert Alert Alert!

TICK TICK TICK POP POP POP is a ticking time bomb, often mistaken as exhaust manifold crack or gasket leak leak. ALERT, ALERT, ALERT: Spark plugs are working themselves loose. "Walking Out" Then blowing out of head, taking their female threads of head with them! Very damaging! You think TICK...

forum.ih8mud.com

Battery clamp corroded and damage can inhibit charge by increasing resistance. High resistance causes premature electric motor failure. This may have affected fuel pump and be additional issue or the issue. We seem to be seeing a lot of fuel pump issue lately. They rarely throw a code, other than sometimes a lean bk 1 or bk 2 or both. They tend to work better when cold and more issue when hot, but sometimes just anytime.

I'd give it a good base line tune-up that includes replacing any vacuum hose cracked or loose, spark plugs, coil boot kit, clean radiator fins, coolant flush, thermostat, radiator cap, heater tees, gas cap seal, fuel filter, MAF & Throttle body cleaning. Consider a fuel pump replacement..

Make sure to get battery clamp squared away. Clean and grease the battery post & clamps. Keep battery disconnect while cleaning the MAF. It's best to start with disconnect negative post of battery and end the tune-up reconnect battery negative post.

Make sure you running at around 187F operating temp at idle.

 

[JesseTygr]

Hey guys,
Back in problem solving mode after a few days off over the New Year.

@OEMGUY0720 @Eicca @AlpineAccess THANKS for the suggestions Here’s a bit of an update as of today...

I parked the truck in a heated garage for a few days and when I came in this morning, I turned it over and it fired right up in one crank smooth as silk and idled great without fail for 20 minutes!!Now keep in mind that just a few days ago, it would stall out at every single stop so this was pretty much night and day! I’m not sure if the heat from parking it indoors dried something out (or thawed it) but it felt very strong..
Nonetheless, I know something sketchy so I started attacking some of the suggestions above.

I first really cleaned out the MAF with MAF cleaner and checked to make sure all the intakes were secure. Next I moved over to the throttle control value and gave it a proper cleaning. Since I had the intake hose off, I fired a can of sea foam cleaner into the system just for the hell of it..!

I did a quick pass on the battery to test ground and terminal connections and then tested the cold voltage with a meter. The reading I got with the car off was 12.89v which I assume is pretty sufficient to turn the engine. I did a bit of a hand test on the EFI relay which basically involves touching the relay when the car is turned on.. if the relay is GOOD, you should feel it “click”. I’m not too sure how exact of a test this is LOL but besides swapping it for another 12A relay in the fuse box, I’m not sure how to find out if it’s faulty??

After completing the above, I took it for hour drive. It’s running super well BUT the RPMs are still still around 500 while at a stop and the truck stalled out once. Don’t get me wrong, it’s a big improvement from the 50 stalls during my previous drive but still means something isn’t quite right!

Based on how it feels and the feed back above, I’m thinking more and more this could a fuel pump but wonder why it would only be failing as the truck is slowing down/coming to a stop. The second I press the gas, the truck comes to life. If it was the pump, wouldn’t it still show signs of failure at all speeds?

One thing I did notice (which may be completely normal) is the throttle cable had a lot of slack in it when the gas peddle isn’t pressed. The slack is pulled out the second the peddle is pressed but shouldn’t there always be a bit of tension in the cable?

Would that help the idle? If not the cable, do you think it’s possible the EFI relay is faulty where it would work some times and not others??
I feel I’m at the point of needing to start replacing parts but I feel it’s a bit of a fork in the road.

Smarter to focus on replacing the fuel pump? Or are there any other areas worth testing first.??

Thanks

 

[Eicca]

I still vote for replacing he pump as preventative, just so it doesn’t fail on you when you least expect it, and who knows, it might fix it. You’ve certainly gotten your money’s worth out of the original pump.

Have you checked for vacuum leaks yet? A cold engine that runs rich will hide a decent sized leak until it warms up. If you can get an OBD scanner, read your fuel trim numbers. Those will tell you a lot.

It’s possible you jostled and partially closed whatever was leaking when you took the air hose off, which would account for the change in symptoms.

The throttle cable needs just enough slack to let the computer sense idle position. If it’s too tight, it’ll run funny because the computer thinks your foot is on the gas. Too much slack isn’t necessarily bad, it’s just not the best feel. So that wouldn’t be your problem. The computer handles the idle.

 

[kruisinkid]

shake that money tree, no particular order

-fuel pump
-fuel filter
-air filter
-pcv valve and hose
-all the other evap,fuel vapor, vac hoses running over the engine (6 i think)
-replace spark plugs
- replace fuel filler cap
-replace oil fill cap o-ring
-coil boots
-tighten valve cover bolts
- remove serp belt and check that all the various idlers are spinning freely
-blow propane around engine bay after fully warmed up to see if idle jumps, points to vac leak