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Hi guys
I have a 2007 is250 and she has low power at low rpm and intermittent hesitation on lauch...
I've replaced the spark plugs, the injectors, the maf sensor ,the fuel pump, the fuel pressure sensor, and i even walnut blasted my intake valves and it stills does it.
i have an exhaust leak between the upstream and the downstream 02 sensor that i have temporarily patched and still no results.
the things that are weird are the fuel pressure(60 psi at idle and 120psi at 2500 rpm) and my long term fuel ratio(-22% at idle -12% at 2500 rpm and -5% at high rpm) maybe clogged catalytic converters?
Can someone help me?
thanks
Long term fuel ratio Fuel pressure on highway Fuel pressure on small roads
My first guess is a vacuum leak somewhere. Did you do all the work yourself? If so check all vacuum hoses on the car. If you can rotate the hose on the nipple where it's attached there could be a leak. I suggest repositioning the clamp on the hose to get a fresh seal. You will need to take off the intake manifold off to get to the PCV hose. Also make sure your intake manifold is torqued to spec. The bolts only require 10 ft-lbs anything over, and the o-ring will fold on itself.
If that doesn't stabalize your fuel trims. Then the issue is somewhere else. Do you have leaking valve covers?
My first guess is a vacuum leak somewhere. Did you do all the work yourself? If so check all vacuum hoses on the car. If you can rotate the hose on the nipple where it's attached there could be a leak. I suggest repositioning the clamp on the hose to get a fresh seal. You will need to take off the intake manifold off to get to the PCV hose. Also make sure your intake manifold is torqued to spec. The bolts only require 10 ft-lbs anything over, and the o-ring will fold on itself.
If that doesn't stabalize your fuel trims. Then the issue is somewhere else. Do you have leaking valve covers?
Here's all the specs you would need:
Thanks for your reply
yes i have done all the work myself and i'll check for vaccum leaks and torque...i used the old o rings too so maybe new ones could help...
i am no expert but i tought that a vaccum leak would always result in a positive long term fuel trim that is why i didnt check for that. Can it also result in a negative ltfr?
how can i tell if my valve cover is leaking?
thanks
Thanks for your reply
yes i have done all the work myself and i'll check for vaccum leaks and torque...i used the old o rings too so maybe new ones could help...
i am no expert but i tought that a vaccum leak would always result in a positive long term fuel trim that is why i didnt check for that. Can it also result in a negative ltfr?
how can i tell if my valve cover is leaking?
thanks
Well short answer. I copied this from another forum, and you'd probably be confused if I tried to explain it.
[size=16px]Yes, it will make your car run rich, not lean.[/size]
[size=16px]The MAF doesn't read that air coming in since it was leaked in after the MAF. The ECU has a reading for how much air went into that combustion cycle.[/size]
[size=16px]Once the combustion takes place, the ECU takes a reading on the CAT O2 sensors and sees that there is more oxygen than needed. The ECU then compensates by adjusting the gas/air ratio by making the mixture richer to try to bring the CAT's O2 sensor readings back to spec and in line with what should have been the CAT's O2 sensor readings given a particular MAF reading.[/size]
[size=16px]You'll burn more fuel than needed, gas economy and performance would be decreased as the car runs rich...[/size]
Yes a lean condition like you thought would happen if it's a massive leak. Same goes for lean if putting a high flow air filter in front of the MAF sensor. Your short trims would be on the lean side, and a plugged up air filter your trims would be negative rich.
Once you read more about fuel trims. You'll. Understand the basics on what to look for.
As for the valve cover you will notice oil all around the valve covers on both banks on the gasket. Any air being introduced after MAF sensor the O2's will pick it up.
Well short answer. I copied this from another forum, and you'd probably be confused if I tried to explain it.
[size=16px]Yes, it will make your car run rich, not lean.[/size]
[size=16px]The MAF doesn't read that air coming in since it was leaked in after the MAF. The ECU has a reading for how much air went into that combustion cycle.[/size]
[size=16px]Once the combustion takes place, the ECU takes a reading on the CAT O2 sensors and sees that there is more oxygen than needed. The ECU then compensates by adjusting the gas/air ratio by making the mixture richer to try to bring the CAT's O2 sensor readings back to spec and in line with what should have been the CAT's O2 sensor readings given a particular MAF reading.[/size]
[size=16px]You'll burn more fuel than needed, gas economy and performance would be decreased as the car runs rich...[/size]
Yes a lean condition like you thought would happen if it's a massive leak. Same goes for lean if putting a high flow air filter in front of the MAF sensor. Your short trims would be on the lean side, and a plugged up air filter your trims would be negative rich.
Once you read more about fuel trims. You'll. Understand the basics on what to look for.
As for the valve cover you will notice oil all around the valve covers on both banks on the gasket. Any air being introduced after MAF sensor the O2's will pick it up.
okay so a bit more complicated than i tought hahah , i'll give it a read
ok so i'll replace the gasket and check all hoses from the intake and the valve cover
Just by curiosity how can a leaky valve cover affect ltfr?
thanks for your help
okay so a bit more complicated than i tought hahah , i'll give it a read
ok so i'll replace the gasket and check all hoses from the intake and the valve cover
Just by curiosity how can a leaky valve cover affect ltfr?
thanks for your help
It works on the same principle. Unmetered air will wreck havoc on fuel trims. The PCV system draws in air from the intake pipe then it gets sucked out back into the intake to be burned.
The car at idle will have high vacuum. Possible to suck enough air around a bad sealing valve cover gasket. Mostly when looking at the scan tool pay attention to the shorts. Anything higher than 10% lean, or rich is ok, but 0 would be very good.
Always pay attention at how well the car idles if it has lumpy idle, rough idle etc.... Those are tell signs something is off. If anything post a thread, and someone will help you to understand things better.
It works on the same principle. Unmetered air will wreck havoc on fuel trims. The PCV system draws in air from the intake pipe then it gets sucked out back into the intake to be burned.
The car at idle will have high vacuum. Possible to suck enough air around a bad sealing valve cover gasket. Mostly when looking at the scan tool pay attention to the shorts. Anything higher than 10% lean, or rich is ok, but 0 would be very good.
Always pay attention at how well the car idles if it has lumpy idle, rough idle etc.... Those are tell signs something is off. If anything post a thread, and someone will help you to understand things better.
okay so I changed the intake manifold gasket and checked for any obvious vacuum leak but the problem still remains
Tough, a new info has come up thess past few days...i dont know why but the hesitation and lack of power seems to be when the engine is cold but when it reaches operating temp it runs really well...do you have any suggestions regarding that?
Thanks again
okay so I changed the intake manifold gasket and checked for any obvious vacuum leak but the problem still remains
Tough, a new info has come up thess past few days...i dont know why but the hesitation and lack of power seems to be when the engine is cold but when it reaches operating temp it runs really well...do you have any suggestions regarding that?
Thanks again
Ok so you changed all gaskets, and checked for vac leaks? You are still getting the same rich fuel trim -22%? Did you reset the ECU, or disconnected the battery while work was being done?
As for the cold part. You are trying to mash on gas from a complete cold start? Meaning the car was sitting overnight, or a few hours?
Ok so you changed all gaskets, and checked for vac leaks? You are still getting the same rich fuel trim -22%? Did you reset the ECU, or disconnected the battery while work was being done?
As for the cold part. You are trying to mash on gas from a complete cold start? Meaning the car was sitting overnight, or a few hours?
yes i reset the ecu but my STFR goes to -22 immediately and shortly after my ltfr goes to -22 and stfr goes back to normal
i checked for any obvious leaks on hoses and sprayed break cleaner on them to see if the rpm changes and nothing...
yeah im talking cold cold overnight and no when i mash on the gas my car downshifts and from high rpms i dont really feel the hesitation or the lack of power...it does it when i drive normally
yes i reset the ecu but my STFR goes to -22 immediately and shortly after my ltfr goes to -22 and stfr goes back to normal
i checked for any obvious leaks on hoses and sprayed break cleaner on them to see if the rpm changes and nothing...
yeah im talking cold cold overnight and no when i mash on the gas my car downshifts and from high rpms i dont really feel the hesitation or the lack of power...it does it when i drive normally
Ok so let's back track here. Are short fuel trims negative % at idle? Which bank is it affecting Bank 1, or 2 or both the same?
Post up pictures from your scan tool of the fuel trims. Don't graph just post the numbers you're seeing.
I was under the impression it was just one long term being affected.
As for cold the car will hold gear 3 until it reaches temperature. You won't notice on hot days, but in low temps it will be obvious. So it's not a good idea ragging the car cold.
Ok so let's back track here. Are short fuel trims negative % at idle? Which bank is it affecting Bank 1, or 2 or both the same?
Post up pictures from your scan tool of the fuel trims. Don't graph just post the numbers you're seeing.
I was under the impression it was just one long term being affected.
As for cold the car will hold gear 3 until it reaches temperature. You won't notice on hot days, but in low temps it will be obvious. So it's not a good idea ragging the car cold.
at idle right after the ECU reset:
stfr bank 1: -20.3%
stfr bank 2: -20.3%
ltfr bank 1 : 0%
ltfr bank 2: 0%
At idle after a 20 min ride:
stfr bank 1: -1.6%
stfr bank 2: -1.6%
ltfr bank 1: -21.9%
ltfr bank 2: -18.8%
At 2500 rpm after the 20 min ride:
ltfr bank 1: -11.7%
ltfr bank 2: -14.1%
i also noticed that i smell rotten eggs when my windows are open and i accelerate pretty heavy
at idle right after the ECU reset:
stfr bank 1: -20.3%
stfr bank 2: -20.3%
ltfr bank 1 : 0%
ltfr bank 2: 0%
At idle after a 20 min ride:
stfr bank 1: -1.6%
stfr bank 2: -1.6%
ltfr bank 1: -21.9%
ltfr bank 2: -18.8%
At 2500 rpm after the 20 min ride:
ltfr bank 1: -11.7%
ltfr bank 2: -14.1%
i also noticed that i smell rotten eggs when my windows are open and i accelerate pretty heavy
It's going to be tough to diagnose as to what actually causing it. When you pulled the injector rails. Did you notice wet injector nozzles? You also mentioned leaking exhaust. How bad is the exhaust manifolds? Do you think coud be pin hole leaks before the O2 sensors? Loose manifold at the head? Do you notice any ticking noise besides the injectors themselves. Rattling noise perhaps? What ever it is it's affecting both banks equally pretty much. Last is the IS250 has a cold start injector next to the brake booster. You can remove both bolts, and set inside a glass jar of some sort. Just to check if it's not leaking.
How do your brakes work as far as power assist goes? And after sitting, is the pedal stiff when you go to start it? If so, your brake vacuum booster may be leaking or at least its check valve. It's worse during warm up at high idle as there's more vacuum.
It's going to be tough to diagnose as to what actually causing it. When you pulled the injector rails. Did you notice wet injector nozzles? You also mentioned leaking exhaust. How bad is the exhaust manifolds? Do you think coud be pin hole leaks before the O2 sensors? Loose manifold at the head? Do you notice any ticking noise besides the injectors themselves. Rattling noise perhaps? What ever it is it's affecting both banks equally pretty much. Last is the IS250 has a cold start injector next to the brake booster. You can remove both bolts, and set inside a glass jar of some sort. Just to check if it's not leaking.
Other than that I got nothing.
No when i removed the injectors they seemed to be pretty dry
my exhaust leak is at the junction between the exhaust manifold and the rest of the exhaust system( after the upstream but before the doenstream 02 sensor)
Now that you said it i do hear a small rattle on heavy acceleration so maybe loose exhaust manifold like u said...from what i can see, wich is not much, the exhaust manifold seems in good shape and no pin holes from the part that i see...
How do your brakes work as far as power assist goes? And after sitting, is the pedal stiff when you go to start it? If so, your brake vacuum booster may be leaking or at least its check valve. It's worse during warm up at high idle as there's more vacuum.
My brakes and the brake assist are good im pretty sure but ill keep that in mind. The leak could affect long term fuel ratio?
08-09-22, 02:51 PM
Is250 hesitation and low power help
