99 2.7 4runner No CEL Help

[1aimpire]

263,000+

STARTING - will start when pumping the gas pedal, usually within 3-5 seconds. it's starts best when I let the vehicle sit for 2 hours. otherwise it'll take many tries to start (longest 30 min)

WARM UP - when started I have to keep my foot on the gas pedal to keep the engine from dying out. once engine is warm(5 min) I can let off the gas pedal & engine will idle fine.

CUTTING OUT - without a proper 5 min warm up, my engine will cut out when rolling to a stop light or stop sign, usually have to keep my "RPMs up" in order to keep my ride from dying out.
**will cut out every time I place into Drive or Reverse which makes parallel parking tough** still need to keep my RPMs up to keep my engine from stalling

SLUGGISH - randomly upon acceleration from rounding a turn & on freeway acceleration even when flooring it

Vehicle runs great after warm up, gets me to where I need to go. however I try to lessen my stop & go's running errands or doing deliveries


NEW- TPS, IAC, MAF, spark plugs, wires, battery, fuel filter changed a year ago & original fuel pump

 

[gamefreakgc]

Sounds to me like a massive vacuum leak. It may be a hose/gasket that expands while warm and leaks less, if that makes sense.

Although that should throw a P0171 code... any pending codes when it starts doing that?

 

[IBallEngineer]

263,000+

STARTING - will start when pumping the gas pedal, usually within 3-5 seconds. it's starts best when I let the vehicle sit for 2 hours. otherwise it'll take many tries to start (longest 30 min)

WARM UP - when started I have to keep my foot on the gas pedal to keep the engine from dying out. once engine is warm(5 min) I can let off the gas pedal & engine will idle fine.

CUTTING OUT - without a proper 5 min warm up, my engine will cut out when rolling to a stop light or stop sign, usually have to keep my "RPMs up" in order to keep my ride from dying out.
**will cut out every time I place into Drive or Reverse which makes parallel parking tough** still need to keep my RPMs up to keep my engine from stalling

SLUGGISH - randomly upon acceleration from rounding a turn & on freeway acceleration even when flooring it

Vehicle runs great after warm up, gets me to where I need to go. however I try to lessen my stop & go's running errands or doing deliveries


NEW- TPS, IAC, MAF, spark plugs, wires, battery, fuel filter changed a year ago & original fuel pump

Have you checked fuel pressure?

 

[etc.]

EFI relay or CO relay. Quick and free to check.

I just experienced a similar issue. Swap your TAIL relay with the EFI relay...these two are under the hood and labeled in the fuse block. If that doesn't work swap the original TAIL relay with the CO relay that is next to the interior fuse block-under the panel. x4 10mm bolts.

hope this helps.

 

[1aimpire]

Next on the list to R&R is my fuel pump & filter, when I had the time. time marched on & now, my vehicle wouldn't start up. got it towed to a shop. asked for them to diagnose my ride. fuel pressure was good at 40 psi, ignition system working correctly & spark plugs also in good condition. they did a compression test & got 30psi on cylinder #1
I am not losing/burning oil & no white smoke out the tail pipe. I have heard that 3rd Gens have issues with valves getting tighter. I'm maybe leaning into the direction of pulling off the heads & see if that's an option ..... more than taking the shops advice of upgrading to another engine. The cost maybe lower for rebuilt heads, but I'm looking into total cost for both options.....

 

[1aimpire]

EFI relay or CO relay. Quick and free to check.

I just experienced a similar issue. Swap your TAIL relay with the EFI relay...these two are under the hood and labeled in the fuse block. If that doesn't work swap the original TAIL relay with the CO relay that is next to the interior fuse block-under the panel. x4 10mm bolts.

hope this helps.

I did switch the Tail & EFI relays, that made no difference. I was gonna do the CO relay switch out when I was going to R&R the fuel pump ...... but then *hit happened

 

[Biotex]

So sorry for the hi-jack but I can't post new threads due to my lack of posts.

I have the same problem in my 99 2.7L. I am glad to find this thread and will do as suggested. I have a compression gauge as well as a fuel pressure gauge. Will use them and swap relays. Hopefully I can get to the cause soon.

 

[cleanrunner]

Check the intake coupler going to the intake manifold.I had one that was split and was having similar symptom a while back. Sounds like something after the maf

 

[Red October]

Next on the list to R&R is my fuel pump & filter, when I had the time. time marched on & now, my vehicle wouldn't start up. got it towed to a shop. asked for them to diagnose my ride. fuel pressure was good at 40 psi, ignition system working correctly & spark plugs also in good condition. they did a compression test & got 30psi on cylinder #1
I am not losing/burning oil & no white smoke out the tail pipe. I have heard that 3rd Gens have issues with valves getting tighter. I'm maybe leaning into the direction of pulling off the heads & see if that's an option ..... more than taking the shops advice of upgrading to another engine. The cost maybe lower for rebuilt heads, but I'm looking into total cost for both options.....

Before you tear down I would do a leak-down test to find the source of your compression loss. If it is valves, they can be adjusted, or have a valve job done, or your cylinder head replaced, for less than a complete motor. If the leak is in the bottom end, then well, you know...

 

[Red October]

So sorry for the hi-jack but I can't post new threads due to my lack of posts.

I have the same problem in my 99 2.7L. I am glad to find this thread and will do as suggested. I have a compression gauge as well as a fuel pressure gauge. Will use them and swap relays. Hopefully I can get to the cause soon.

You can also check for vacuum leaks.

With the car idling, in a well ventilated area, turn on a propane torch to a steady, low flow of gas, but do not light it, aim the propane near suspected leak points, listen for changes in engine speed.

Edit; Disclaimer, don't use too much propane, for too long, near open flame, etc. If you dont feel confident in your mechanical abilities, ask your mechanic to search for vacuum leaks, or google other ways to do it... Just sayin...

 

[Biotex]

You can also check for vacuum leaks.

With the car idling, in a well ventilated area, turn on a propane torch to a steady, low flow of gas, but do not light it, aim the propane near suspected leak points, listen for changes in engine speed.

Edit; Disclaimer, don't use too much propane, for too long, near open flame, etc. If you dont feel confident in your mechanical abilities, ask your mechanic to search for vacuum leaks, or google other ways to do it... Just sayin...

Thanks Red, I tried to post a new thread and still not able to.:sobbing:

I have excellent mechanical abilities and I did not find any leaks yet. Will keep searching. One thing that bothers me, and again I apologize to the original poster for the thread hijack, but when I look at the rpms according to my Dash Command app, it says the engine is idling at between 700 and 750 rpms. The tach on the dash says 500, and my ear and feel confirms that it is too low an idle. My experience would say the tach in the dash is correct, so why does the computer think it's idling higher?

Bad sensor?

Sure would be nice to have my own thread... :shrug:

 

[Red October]

Hmmm, I'm not sure why you would be seeing different idle speeds, maybe just your tach is calibrated differently? I would look at doing a leak down test instead of just a compression test. These motors are infamous for burning exhaust valves when they get out of adjustment.

 

[1aimpire]

update.....
new fuel pump, fuel filter, fuel pressure regulator, a clean tank, new coolant temp sensor, & fully charged battery

didn't get to do a leak down test but did get the engine to fire up by spraying starter fluid straight into the throttle body.* good news is that the engine sounds great when it is running, however it's a must to keep your foot on the throttle to keep the engine from cutting out. also, the engine seems to crank better with a battery charger on the terminals, without it attached, seems like starting system doesnt draw enough current to fire up on its own.. baffled why it's not starting up & running on its own after upgrading these key parts..*** dunno what to do next, any other testing practices or just keep buying new Vacuum Switching Valves?* Vapor Pressure Sensor?* an ECU? ignition coils?

 

[St Runner]

Two things to check. As someone posted earlier pull the intake off after the maf and check for any tears or leaks. Any extra air that gets into the engine after the maf will make the engine run lean (which is what it sounds like) and will not throw a cel unless it is bad enough to misfire. Check all your ground leads esp the one on the back of the engine and your fender. If it runs better with a battery charger it could be that your grounding is bad not just your charging system. I upgraded the grounds on my 99 2.7 tacoma and it starts much better

 

[zoombyu86]

Part of the symptoms sound like the alternator is going out. I've had them go out on an old foxbody and if I didnt keep the RPMs up, It couldnt provide enough juice. He said that its cranks better when a charger is hooked up. probably because the battery is very weak on start (from bad alternator). as for the sitting for 2 hours and starting better, sounds like something else.

just my $.02.